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Dr. Laurie Starkey

Dr. Laurie Starkey

Ethers

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Table of Contents

I. Introduction to Organic Molecules
Introduction and Drawing Structures

49m 51s

Intro
0:00
Organic Chemistry
0:07
Organic
0:08
Inorganic
0:26
Examples of Organic Compounds
1:16
Review Some Chemistry Basics
5:23
Electrons
5:42
Orbitals (s,p,d,f)
6:12
Review Some Chemistry Basics
7:35
Elements & Noble Gases
7:36
Atom & Valance Shell
8:47
Review Some Chemistry Basics
11:33
Electronegative Elements
11:34
Which Is More Electronegative, C or N?
13:45
Ionic & Covalent Bonds
14:07
Ionic Bonds
14:08
Covalent Bonds
16:17
Polar Covalent Bonds
19:35
Polar Covalent Bonds & Electronegativities
19:37
Polarity of Molecules
22:56
Linear molecule
23:07
Bent Molecule
23:53
No Polar Bonds
24:21
Ionic
24:52
Line Drawings
26:36
Line Drawing Overview
26:37
Line Drawing: Example 1
27:12
Line Drawing: Example 2
29:14
Line Drawing: Example 3
29:51
Line Drawing: Example 4
30:34
Line Drawing: Example 5
31:21
Line Drawing: Example 6
32:41
Diversity of Organic Compounds
33:57
Diversity of Organic Compounds
33:58
Diversity of Organic Compounds, cont.
39:16
Diversity of Organic Compounds, cont.
39:17
Examples of Polymers
45:26
Examples of Polymers
45:27
Lewis Structures & Resonance

44m 25s

Intro
0:00
Lewis Structures
0:08
How to Draw a Lewis Structure
0:09
Examples
2:20
Lewis Structures
6:25
Examples: Lewis Structure
6:27
Determining Formal Charges
8:48
Example: Determining Formal Charges for Carbon
10:11
Example: Determining Formal Charges for Oxygen
11:02
Lewis Structures
12:08
Typical, Stable Bonding Patterns: Hydrogen
12:11
Typical, Stable Bonding Patterns: Carbon
12:58
Typical, Stable Bonding Patterns: Nitrogen
13:25
Typical, Stable Bonding Patterns: Oxygen
13:54
Typical, Stable Bonding Patterns: Halogen
14:16
Lewis Structure Example
15:17
Drawing a Lewis Structure for Nitric Acid
15:18
Resonance
21:58
Definition of Resonance
22:00
Delocalization
22:07
Hybrid Structure
22:38
Rules for Estimating Stability of Resonance Structures
26:04
Rule Number 1: Complete Octets
26:10
Rule Number 2: Separation of Charge
28:13
Rule Number 3: Negative and Positive Charges
30:02
Rule Number 4: Equivalent
31:06
Looking for Resonance
32:09
Lone Pair Next to a p Bond
32:10
Vacancy Next to a p Bond
33:53
p Bond Between Two Different Elements
35:00
Other Type of Resonance: Benzene
36:06
Resonance Example
37:29
Draw and Rank Resonance Forms
37:30
Acid-Base Reactions

1h 7m 46s

Intro
0:00
Acid-Base Reactions
0:07
Overview
0:08
Lewis Acid and Lewis Base
0:30
Example 1: Lewis Acid and Lewis Base
1:53
Example 2: Lewis Acid and Lewis Base
3:04
Acid-base Reactions
4:54
Bonsted-Lowry Acid and Bonsted-Lowry Base
4:56
Proton Transfer Reaction
5:36
Acid-Base Equilibrium
8:14
Two Acids in Competition = Equilibrium
8:15
Example: Which is the Stronger Acid?
8:40
Periodic Trends for Acidity
12:40
Across Row
12:41
Periodic Trends for Acidity
19:48
Energy Diagram
19:50
Periodic Trends for Acidity
21:28
Down a Family
21:29
Inductive Effects on Acidity
25:52
Example: Which is the Stronger Acid?
25:54
Other Electron-Withdrawing Group (EWG)
30:37
Inductive Effects on Acidity
32:55
Inductive Effects Decrease with Distance
32:56
Resonance Effects on Acidity
36:35
Examples of Resonance Effects on Acidity
36:36
Resonance Effects on Acidity
41:15
Small and Large Amount of Resonance
41:17
Acid-Base Example
43:10
Which is Most Acidic? Which is the Least Acidic?
43:12
Acid-Base Example
49:26
Which is the Stronger Base?
49:27
Acid-Base Example
53:58
Which is the Strongest Base?
53:59
Common Acids/Bases
1:00:45
Common Acids/Bases
1:00:46
Example: Determine the Direction of Equilibrium
1:04:51
Structures and Properties of Organic Molecules

1h 23m 35s

Intro
0:00
Orbitals and Bonding
0:20
Atomic Orbitals (AO)
0:21
Molecular Orbitals (MO)
1:46
Definition of Molecular Orbitals
1:47
Example 1: Formation of Sigma Bond and Molecular Orbitals
2:20
Molecular Orbitals (MO)
5:25
Example 2: Formation of Pi Bond
5:26
Overlapping E Levels of MO's
7:28
Energy Diagram
7:29
Electronic Transitions
9:18
Electronic Transitions
9:23
Hybrid Orbitals
12:04
Carbon AO
12:06
Hybridization
13:51
Hybrid Orbitals
15:02
Examples of Hybrid Orbitals
15:05
Example: Assign Hybridization
20:31
3-D Sketches
24:05
sp3
24:24
sp2
25:28
sp
27:41
3-D Sketches of Molecules
29:07
3-D Sketches of Molecules 1
29:08
3-D Sketches of Molecules 2
32:29
3-D Sketches of Molecules 3
35:36
3D Sketch
37:20
How to Draw 3D Sketch
37:22
Example 1: Drawing 3D Sketch
37:50
Example 2: Drawing 3D Sketch
43:04
Hybridization and Resonance
46:06
Example: Hybridization and Resonance
46:08
Physical Properties
49:55
Water Solubility, Boiling Points, and Intermolecular Forces
49:56
Types of 'Nonbonding' Interactions
51:47
Dipole-Dipole
52:37
Definition of Dipole-Dipole
52:39
Example: Dipole-Dipole Bonding
53:27
Hydrogen Bonding
57:14
Definition of Hydrogen Bonding
57:15
Example: Hydrogen Bonding
58:05
Van Der Waals/ London Forces
1:03:11
Van Der Waals/ London Forces
1:03:12
Example: Van Der Waals/ London Forces
1:04:59
Water Solubility
1:08:32
Water Solubility
1:08:34
Example: Water Solubility
1:09:05
Example: Acetone
1:11:29
Isomerism
1:13:51
Definition of Isomers
1:13:53
Constitutional Isomers and Example
1:14:17
Stereoisomers and Example
1:15:34
Introduction to Functional Groups
1:17:06
Functional Groups: Example, Abbreviation, and Name
1:17:07
Introduction to Functional Groups
1:20:48
Functional Groups: Example, Abbreviation, and Name
1:20:49
Alkane Structures

1h 13m 38s

Intro
0:00
Nomenclature of Alkanes
0:12
Nomenclature of Alkanes and IUPAC Rules
0:13
Examples: Nomenclature of Alkanes
4:38
Molecular Formula and Degrees of Unsaturation (DU)
17:24
Alkane Formula
17:25
Example: Heptane
17:58
Why '2n+2' Hydrogens?
18:35
Adding a Ring
19:20
Adding a p Bond
19:42
Example 1: Determine Degrees of Unsaturation (DU)
20:17
Example 2: Determine Degrees of Unsaturation (DU)
21:35
Example 3: Determine DU of Benzene
23:30
Molecular Formula and Degrees of Unsaturation (DU)
24:41
Example 4: Draw Isomers
24:42
Physical properties of Alkanes
29:17
Physical properties of Alkanes
29:18
Conformations of Alkanes
33:40
Conformational Isomers
33:42
Conformations of Ethane: Eclipsed and Staggered
34:40
Newman Projection of Ethane
36:15
Conformations of Ethane
40:38
Energy and Degrees Rotated Diagram
40:41
Conformations of Butane
42:28
Butane
42:29
Newman Projection of Butane
43:35
Conformations of Butane
44:25
Energy and Degrees Rotated Diagram
44:30
Cycloalkanes
51:26
Cyclopropane and Cyclobutane
51:27
Cyclopentane
53:56
Cycloalkanes
54:56
Cyclohexane: Chair, Boat, and Twist Boat Conformations
54:57
Drawing a Cyclohexane Chair
57:58
Drawing a Cyclohexane Chair
57:59
Newman Projection of Cyclohexane
1:02:14
Cyclohexane Chair Flips
1:04:06
Axial and Equatorial Groups
1:04:10
Example: Chair Flip on Methylcyclohexane
1:06:44
Cyclohexane Conformations Example
1:09:01
Chair Conformations of cis-1-t-butyl-4-methylcyclohexane
1:09:02
Stereochemistry

1h 40m 54s

Intro
0:00
Stereochemistry
0:10
Isomers
0:11
Stereoisomer Examples
1:30
Alkenes
1:31
Cycloalkanes
2:35
Stereoisomer Examples
4:00
Tetrahedral Carbon: Superimposable (Identical)
4:01
Tetrahedral Carbon: Non-Superimposable (Stereoisomers)
5:18
Chirality
7:18
Stereoisomers
7:19
Chiral
8:05
Achiral
8:29
Example: Achiral and Chiral
8:45
Chirality
20:11
Superimposable, Non-Superimposable, Chiral, and Achiral
20:12
Nomenclature
23:00
Cahn-Ingold-Prelog Rules
23:01
Nomenclature
29:39
Example 1: Nomenclature
29:40
Example 2: Nomenclature
31:49
Example 3: Nomenclature
33:24
Example 4: Nomenclature
35:39
Drawing Stereoisomers
36:58
Drawing (S)-2-bromopentane
36:59
Drawing the Enantiomer of (S)-2-bromopentane: Method 1
38:47
Drawing the Enantiomer of (S)-2-bromopentane: Method 2
39:35
Fischer Projections
41:47
Definition of Fischer Projections
41:49
Drawing Fischer Projection
43:43
Use of Fisher Projection: Assigning Configuration
49:13
Molecules with Two Chiral Carbons
51:49
Example A
51:42
Drawing Enantiomer of Example A
53:26
Fischer Projection of A
54:25
Drawing Stereoisomers, cont.
59:40
Drawing Stereoisomers Examples
59:41
Diastereomers
1:01:48
Drawing Stereoisomers
1:06:37
Draw All Stereoisomers of 2,3-dichlorobutane
1:06:38
Molecules with Two Chiral Centers
1:10:22
Draw All Stereoisomers of 2,3-dichlorobutane, cont.
1:10:23
Optical Activity
1:14:10
Chiral Molecules
1:14:11
Angle of Rotation
1:14:51
Achiral Species
1:16:46
Physical Properties of Stereoisomers
1:17:11
Enantiomers
1:17:12
Diastereomers
1:18:01
Example
1:18:26
Physical Properties of Stereoisomers
1:23:05
When Do Enantiomers Behave Differently?
1:23:06
Racemic Mixtures
1:28:18
Racemic Mixtures
1:28:21
Resolution
1:29:52
Unequal Mixtures of Enantiomers
1:32:54
Enantiomeric Excess (ee)
1:32:55
Unequal Mixture of Enantiomers
1:34:43
Unequal Mixture of Enantiomers
1:34:44
Example: Finding ee
1:36:38
Example: Percent of Composition
1:39:46
II. Understanding Organic Reactions
Nomenclature

1h 53m 47s

Intro
0:00
Cycloalkane Nomenclature
0:17
Cycloalkane Nomenclature and Examples
0:18
Alkene Nomenclature
6:28
Alkene Nomenclature and Examples
6:29
Alkene Nomenclature: Stereochemistry
15:07
Alkenes With Two Groups: Cis & Trans
15:08
Alkenes With Greater Than Two Groups: E & Z
18:26
Alkyne Nomenclature
24:46
Alkyne Nomenclature and Examples
24:47
Alkane Has a Higher Priority Than Alkyne
28:25
Alcohol Nomenclature
29:24
Alcohol Nomenclature and Examples
29:25
Alcohol FG Has Priority Over Alkene/yne
33:41
Ether Nomenclature
36:32
Ether Nomenclature and Examples
36:33
Amine Nomenclature
42:59
Amine Nomenclature and Examples
43:00
Amine Nomenclature
49:45
Primary, Secondary, Tertiary, Quaternary Salt
49:46
Aldehyde Nomenclature
51:37
Aldehyde Nomenclature and Examples
51:38
Ketone Nomenclature
58:43
Ketone Nomenclature and Examples
58:44
Aromatic Nomenclature
1:05:02
Aromatic Nomenclature and Examples
1:05:03
Aromatic Nomenclature, cont.
1:09:09
Ortho, Meta, and Para
1:09:10
Aromatic Nomenclature, cont.
1:13:27
Common Names for Simple Substituted Aromatic Compounds
1:13:28
Carboxylic Acid Nomenclature
1:16:35
Carboxylic Acid Nomenclature and Examples
1:16:36
Carboxylic Acid Derivatives
1:22:28
Carboxylic Acid Derivatives
1:22:42
General Structure
1:23:10
Acid Halide Nomenclature
1:24:48
Acid Halide Nomenclature and Examples
1:24:49
Anhydride Nomenclature
1:28:10
Anhydride Nomenclature and Examples
1:28:11
Ester Nomenclature
1:32:50
Ester Nomenclature
1:32:51
Carboxylate Salts
1:38:51
Amide Nomenclature
1:40:02
Amide Nomenclature and Examples
1:40:03
Nitrile Nomenclature
1:45:22
Nitrile Nomenclature and Examples
1:45:23
Chemical Reactions

51m 1s

Intro
0:00
Chemical Reactions
0:06
Reactants and Products
0:07
Thermodynamics
0:50
Equilibrium Constant
1:06
Equation
2:35
Organic Reaction
3:05
Energy vs. Progress of Rxn Diagrams
3:48
Exothermic Reaction
4:02
Endothermic Reaction
6:54
Estimating ΔH rxn
9:15
Bond Breaking
10:03
Bond Formation
10:25
Bond Strength
11:35
Homolytic Cleavage
11:59
Bond Dissociation Energy (BDE) Table
12:29
BDE for Multiple Bonds
14:32
Examples
17:35
Kinetics
20:35
Kinetics
20:36
Examples
21:49
Reaction Rate Variables
23:15
Reaction Rate Variables
23:16
Increasing Temperature, Increasing Rate
24:08
Increasing Concentration, Increasing Rate
25:39
Decreasing Energy of Activation, Increasing Rate
27:49
Two-Step Mechanisms
30:06
E vs. POR Diagram (2-step Mechanism)
30:07
Reactive Intermediates
33:03
Reactive Intermediates
33:04
Example: A Carbocation
35:20
Carbocation Stability
37:24
Relative Stability of Carbocation
37:25
Alkyl groups and Hyperconjugation
38:45
Carbocation Stability
41:57
Carbocation Stabilized by Resonance: Allylic
41:58
Carbocation Stabilized by Resonance: Benzylic
42:59
Overall Carbocation Stability
44:05
Free Radicals
45:05
Definition and Examples of Free Radicals
45:06
Radical Mechanisms
49:40
Example: Regular Arrow
49:41
Example: Fish-Hook Arrow
50:17
Free Radical Halogenation

26m 23s

Intro
0:00
Free Radical Halogenation
0:06
Free Radical Halogenation
0:07
Mechanism: Initiation
1:27
Mechanism: Propagation Steps
2:21
Free Radical Halogenation
5:33
Termination Steps
5:36
Example 1: Terminations Steps
6:00
Example 2: Terminations Steps
6:18
Example 3: Terminations Steps
7:43
Example 4: Terminations Steps
8:04
Regiochemistry of Free Radical Halogenation
9:32
Which Site/Region Reacts and Why?
9:34
Bromination and Rate of Reaction
14:03
Regiochemistry of Free Radical Halogenation
14:30
Chlorination
14:31
Why the Difference in Selectivity?
19:58
Allylic Halogenation
20:53
Examples of Allylic Halogenation
20:55
Substitution Reactions

1h 48m 5s

Intro
0:00
Substitution Reactions
0:06
Substitution Reactions Example
0:07
Nucleophile
0:39
Electrophile
1:20
Leaving Group
2:56
General Reaction
4:13
Substitution Reactions
4:43
General Reaction
4:46
Substitution Reaction Mechanisms: Simultaneous
5:08
Substitution Reaction Mechanisms: Stepwise
5:34
SN2 Substitution
6:21
Example of SN2 Mechanism
6:22
SN2 Kinetics
7:58
Rate of SN2
9:10
Sterics Affect Rate of SN2
9:12
Rate of SN2 (By Type of RX)
14:13
SN2: E vs. POR Diagram
17:26
E vs. POR Diagram
17:27
Transition State (TS)
18:24
SN2 Transition State, Kinetics
20:58
SN2 Transition State, Kinetics
20:59
Hybridization of TS Carbon
21:57
Example: Allylic LG
23:34
Stereochemistry of SN2
25:46
Backside Attack and Inversion of Stereochemistry
25:48
SN2 Summary
29:56
Summary of SN2
29:58
Predict Products (SN2)
31:42
Example 1: Predict Products
31:50
Example 2: Predict Products
33:38
Example 3: Predict Products
35:11
Example 4: Predict Products
36:11
Example 5: Predict Products
37:32
SN1 Substitution Mechanism
41:52
Is This Substitution? Could This Be an SN2 Mechanism?
41:54
SN1 Mechanism
43:50
Two Key Steps: 1. Loss of LG
43:53
Two Key Steps: 2. Addition of nu
45:11
SN1 Kinetics
47:17
Kinetics of SN1
47:18
Rate of SN1 (By RX type)
48:44
SN1 E vs. POR Diagram
49:49
E vs. POR Diagram
49:51
First Transition Stage (TS-1)
51:48
Second Transition Stage (TS-2)
52:56
Stereochemistry of SN1
53:44
Racemization of SN1 and Achiral Carbocation Intermediate
53:46
Example
54:29
SN1 Summary
58:25
Summary of SN1
58:26
SN1 or SN2 Mechanisms?
1:00:40
Example 1: SN1 or SN2 Mechanisms
1:00:42
Example 2: SN1 or SN2 Mechanisms
1:03:00
Example 3: SN1 or SN2 Mechanisms
1:04:06
Example 4: SN1 or SN2 Mechanisms
1:06:17
SN1 Mechanism
1:09:12
Three Steps of SN1 Mechanism
1:09:13
SN1 Carbocation Rearrangements
1:14:50
Carbocation Rearrangements Example
1:14:51
SN1 Carbocation Rearrangements
1:20:46
Alkyl Groups Can Also Shift
1:20:48
Leaving Groups
1:24:26
Leaving Groups
1:24:27
Forward or Reverse Reaction Favored?
1:26:00
Leaving Groups
1:29:59
Making poor LG Better: Method 1
1:30:00
Leaving Groups
1:34:18
Making poor LG Better: Tosylate (Method 2)
1:34:19
Synthesis Problem
1:38:15
Example: Provide the Necessary Reagents
1:38:16
Nucleophilicity
1:41:10
What Makes a Good Nucleophile?
1:41:11
Nucleophilicity
1:44:45
Periodic Trends: Across Row
1:44:47
Periodic Trends: Down a Family
1:46:46
Elimination Reactions

1h 11m 43s

Intro
0:00
Elimination Reactions: E2 Mechanism
0:06
E2 Mechanism
0:08
Example of E2 Mechanism
1:01
Stereochemistry of E2
4:48
Anti-Coplanar & Anti-Elimination
4:50
Example 1: Stereochemistry of E2
5:34
Example 2: Stereochemistry of E2
10:39
Regiochemistry of E2
13:04
Refiochemistry of E2 and Zaitsev's Rule
13:05
Alkene Stability
17:39
Alkene Stability
19:20
Alkene Stability Examples
19:22
Example 1: Draw Both E2 Products and Select Major
21:57
Example 2: Draw Both E2 Products and Select Major
25:02
SN2 Vs. E2 Mechanisms
29:06
SN2 Vs. E2 Mechanisms
29:07
When Do They Compete?
30:34
SN2 Vs. E2 Mechanisms
31:23
Compare Rates
31:24
SN2 Vs. E2 Mechanisms
36:34
t-BuBr: What If Vary Base?
36:35
Preference for E2 Over SN2 (By RX Type)
40:42
E1 Elimination Mechanism
41:51
E1 - Elimination Unimolecular
41:52
E1 Mechanism: Step 1
44:14
E1 Mechanism: Step 2
44:48
E1 Kinetics
46:58
Rate = k[RCI]
47:00
E1 Rate (By Type of Carbon Bearing LG)
48:31
E1 Stereochemistry
49:49
Example 1: E1 Stereochemistry
49:51
Example 2: E1 Stereochemistry
52:31
Carbocation Rearrangements
55:57
Carbocation Rearrangements
56:01
Product Mixtures
57:20
Predict the Product: SN2 vs. E2
59:58
Example 1: Predict the Product
1:00:00
Example 2: Predict the Product
1:02:10
Example 3: Predict the Product
1:04:07
Predict the Product: SN2 vs. E2
1:06:06
Example 4: Predict the Product
1:06:07
Example 5: Predict the Product
1:07:29
Example 6: Predict the Product
1:07:51
Example 7: Predict the Product
1:09:18
III. Alkanes, Alkenes, & Alkynes
Alkenes

36m 39s

Intro
0:00
Alkenes
0:12
Definition and Structure of Alkenes
0:13
3D Sketch of Alkenes
1:53
Pi Bonds
3:48
Alkene Stability
4:57
Alkyl Groups Attached
4:58
Trans & Cis
6:20
Alkene Stability
8:42
Pi Bonds & Conjugation
8:43
Bridgehead Carbons & Bredt's Rule
10:22
Measuring Stability: Hydrogenation Reaction
11:40
Alkene Synthesis
12:01
Method 1: E2 on Alkyl Halides
12:02
Review: Stereochemistry
16:17
Review: Regiochemistry
16:50
Review: SN2 vs. E2
17:34
Alkene Synthesis
18:57
Method 2: Dehydration of Alcohols
18:58
Mechanism
20:08
Alkene Synthesis
23:26
Alcohol Dehydration
23:27
Example 1: Comparing Strong Acids
26:59
Example 2: Mechanism for Dehydration Reaction
29:00
Example 3: Transform
32:50
Reactions of Alkenes

2h 8m 44s

Intro
0:00
Reactions of Alkenes
0:05
Electrophilic Addition Reaction
0:06
Addition of HX
2:02
Example: Regioselectivity & 2 Steps Mechanism
2:03
Markovnikov Addition
5:30
Markovnikov Addition is Favored
5:31
Graph: E vs. POR
6:33
Example
8:29
Example: Predict and Consider the Stereochemistry
8:30
Hydration of Alkenes
12:31
Acid-catalyzed Addition of Water
12:32
Strong Acid
14:20
Hydration of Alkenes
15:20
Acid-catalyzed Addition of Water: Mechanism
15:21
Hydration vs. Dehydration
19:51
Hydration Mechanism is Exact Reverse of Dehydration
19:52
Example
21:28
Example: Hydration Reaction
21:29
Alternative 'Hydration' Methods
25:26
Oxymercuration-Demercuration
25:27
Oxymercuration Mechanism
28:55
Mechanism of Oxymercuration
28:56
Alternative 'Hydration' Methods
30:51
Hydroboration-Oxidation
30:52
Hydroboration Mechanism
33:22
1-step (concerted)
33:23
Regioselective
34:45
Stereoselective
35:30
Example
35:58
Example: Hydroboration-Oxidation
35:59
Example
40:42
Example: Predict the Major Product
40:43
Synthetic Utility of 'Alternate' Hydration Methods
44:36
Example: Synthetic Utility of 'Alternate' Hydration Methods
44:37
Flashcards
47:28
Tips On Using Flashcards
47:29
Bromination of Alkenes
49:51
Anti-Addition of Br₂
49:52
Bromination Mechanism
53:16
Mechanism of Bromination
53:17
Bromination Mechanism
55:42
Mechanism of Bromination
55:43
Bromination: Halohydrin Formation
58:54
Addition of other Nu: to Bromonium Ion
58:55
Mechanism
1:00:08
Halohydrin: Regiochemistry
1:03:55
Halohydrin: Regiochemistry
1:03:56
Bromonium Ion Intermediate
1:04:26
Example
1:09:28
Example: Predict Major Product
1:09:29
Example Cont.
1:10:59
Example: Predict Major Product Cont.
1:11:00
Catalytic Hydrogenation of Alkenes
1:13:19
Features of Catalytic Hydrogenation
1:13:20
Catalytic Hydrogenation of Alkenes
1:14:48
Metal Surface
1:14:49
Heterogeneous Catalysts
1:15:29
Homogeneous Catalysts
1:16:08
Catalytic Hydrogenation of Alkenes
1:17:44
Hydrogenation & Pi Bond Stability
1:17:45
Energy Diagram
1:19:22
Catalytic Hydrogenation of Dienes
1:20:40
Hydrogenation & Pi Bond Stability
1:20:41
Energy Diagram
1:23:31
Example
1:24:14
Example: Predict Product
1:24:15
Oxidation of Alkenes
1:27:21
Redox Review
1:27:22
Epoxide
1:30:26
Diol (Glycol)
1:30:54
Ketone/ Aldehyde
1:31:13
Epoxidation
1:32:08
Epoxidation
1:32:09
General Mechanism
1:36:32
Alternate Epoxide Synthesis
1:37:38
Alternate Epoxide Synthesis
1:37:39
Dihydroxylation
1:41:10
Dihydroxylation
1:41:12
General Mechanism (Concerted Via Cycle Intermediate)
1:42:38
Ozonolysis
1:44:22
Ozonolysis: Introduction
1:44:23
Ozonolysis: Is It Good or Bad?
1:45:05
Ozonolysis Reaction
1:48:54
Examples
1:51:10
Example 1: Ozonolysis
1:51:11
Example
1:53:25
Radical Addition to Alkenes
1:55:05
Recall: Free-Radical Halogenation
1:55:15
Radical Mechanism
1:55:45
Propagation Steps
1:58:01
Atom Abstraction
1:58:30
Addition to Alkene
1:59:11
Radical Addition to Alkenes
1:59:54
Markovnivok (Electrophilic Addition) & anti-Mark. (Radical Addition)
1:59:55
Mechanism
2:01:03
Alkene Polymerization
2:05:35
Example: Alkene Polymerization
2:05:36
Alkynes

1h 13m 19s

Intro
0:00
Structure of Alkynes
0:04
Structure of Alkynes
0:05
3D Sketch
2:30
Internal and Terminal
4:03
Reductions of Alkynes
4:36
Catalytic Hydrogenation
4:37
Lindlar Catalyst
5:25
Reductions of Alkynes
7:24
Dissolving Metal Reduction
7:25
Oxidation of Alkynes
9:24
Ozonolysis
9:25
Reactions of Alkynes
10:56
Addition Reactions: Bromination
10:57
Addition of HX
12:24
Addition of HX
12:25
Addition of HX
13:36
Addition of HX: Mechanism
13:37
Example
17:38
Example: Transform
17:39
Hydration of Alkynes
23:35
Hydration of Alkynes
23:36
Hydration of Alkynes
26:47
Hydration of Alkynes: Mechanism
26:49
'Hydration' via Hydroboration-Oxidation
32:57
'Hydration' via Hydroboration-Oxidation
32:58
Disiamylborane
33:28
Hydroboration-Oxidation Cont.
34:25
Alkyne Synthesis
36:17
Method 1: Alkyne Synthesis By Dehydrohalogenation
36:19
Alkyne Synthesis
39:06
Example: Transform
39:07
Alkyne Synthesis
41:21
Method 2 & Acidity of Alkynes
41:22
Conjugate Bases
43:06
Preparation of Acetylide Anions
49:55
Preparation of Acetylide Anions
49:57
Alkyne Synthesis
53:40
Synthesis Using Acetylide Anions
53:41
Example 1: Transform
57:04
Example 2: Transform
1:01:07
Example 3: Transform
1:06:22
IV. Alcohols
Alcohols, Part I

59m 52s

Intro
0:00
Alcohols
0:11
Attributes of Alcohols
0:12
Boiling Points
2:00
Water Solubility
5:00
Water Solubility (Like Dissolves Like)
5:01
Acidity of Alcohols
9:39
Comparison of Alcohols Acidity
9:41
Preparation of Alkoxides
13:03
Using Strong Base Like Sodium Hydride
13:04
Using Redox Reaction
15:36
Preparation of Alkoxides
17:41
Using K°
17:42
Phenols Are More Acidic Than Other Alcohols
19:51
Synthesis of Alcohols, ROH
21:43
Synthesis of Alcohols from Alkyl Halides, RX (SN2 or SN1)
21:44
Synthesis of Alcohols, ROH
25:08
Unlikely on 2° RX (E2 Favored)
25:09
Impossible on 3° RX (E2) and Phenyl/Vinyl RX (N/R)
25:47
Synthesis of Alcohols, ROH
26:26
SN1 with H₂O 'Solvolysis' or 'Hydrolysis'
26:27
Carbocation Can Rearrange
29:00
Synthesis of Alcohols, ROH
30:08
Synthesis of Alcohols From Alkenes: Hydration
30:09
Synthesis of Alcohols From Alkenes: Oxidation/Diol
32:20
Synthesis of Alcohols, ROH
33:14
Synthesis of Alcohols From Ketones and Aldehydes
33:15
Organometallic Reagents: Preparation
37:03
Grignard (RMgX)
37:04
Organolithium (Rli)
40:03
Organometallic Reagents: Reactions
41:45
Reactions of Organometallic Reagents
41:46
Organometallic Reagents: Reactions as Strong Nu:
46:40
Example 1: Reactions as Strong Nu:
46:41
Example 2: Reactions as Strong Nu:
48:57
Hydride Nu:
50:52
Hydride Nu:
50:53
Examples
53:34
Predict 1
53:35
Predict 2
54:45
Examples
56:43
Transform
56:44
Provide Starting Material
58:18
Alcohols, Part II

45m 35s

Intro
0:00
Oxidation Reactions
0:08
Oxidizing Agents: Jones, PCC, Swern
0:09
'Jones' Oxidation
0:43
Example 1: Predict Oxidation Reactions
2:29
Example 2: Predict Oxidation Reactions
3:00
Oxidation Reactions
4:11
Selective Oxidizing Agents (PCC and Swern)
4:12
PCC (Pyridiniym Chlorochromate)
5:10
Swern Oxidation
6:05
General [ox] Mechanism
8:32
General [ox] Mechanism
8:33
Oxidation of Alcohols
10:11
Example 1: Oxidation of Alcohols
10:12
Example 2: Oxidation of Alcohols
11:20
Example 3: Oxidation of Alcohols
11:46
Example
13:09
Predict: PCC Oxidation Reactions
13:10
Tosylation of Alcohols
15:22
Introduction to Tosylation of Alcohols
15:23
Example
21:08
Example: Tosylation of Alcohols
21:09
Reductions of Alcohols
23:39
Reductions of Alcohols via SN2 with Hydride
24:22
Reductions of Alcohols via Dehydration
27:12
Conversion of Alcohols to Alkyl Halides
30:12
Conversion of Alcohols to Alkyl Halides via Tosylate
30:13
Conversion of Alcohols to Alkyl Halides
31:17
Using HX
31:18
Mechanism
32:09
Conversion of Alcohols to Alkyl Halides
35:43
Reagents that Provide LG and Nu: in One 'Pot'
35:44
General Mechanisms
37:44
Example 1: General Mechanisms
37:45
Example 2: General Mechanisms
39:25
Example
41:04
Transformation of Alcohols
41:05
V. Ethers, Thiols, Thioethers, & Ketones
Ethers

1h 34m 45s

Intro
0:00
Ethers
0:11
Overview of Ethers
0:12
Boiling Points
1:37
Ethers
4:34
Water Solubility (Grams per 100mL H₂O)
4:35
Synthesis of Ethers
7:53
Williamson Ether Synthesis
7:54
Example: Synthesis of Ethers
9:23
Synthesis of Ethers
10:27
Example: Synthesis of Ethers
10:28
Intramolecular SN2
13:04
Planning an Ether Synthesis
14:45
Example 1: Planning an Ether Synthesis
14:46
Planning an Ether Synthesis
16:16
Example 2: Planning an Ether Synthesis
16:17
Planning an Ether Synthesis
22:04
Example 3: Synthesize Dipropyl Ether
22:05
Planning an Ether Synthesis
26:01
Example 4: Transform
26:02
Synthesis of Epoxides
30:05
Synthesis of Epoxides Via Williamson Ether Synthesis
30:06
Synthesis of Epoxides Via Oxidation
32:42
Reaction of Ethers
33:35
Reaction of Ethers
33:36
Reactions of Ethers with HBr or HI
34:44
Reactions of Ethers with HBr or HI
34:45
Mechanism
35:25
Epoxide Ring-Opening Reaction
39:25
Epoxide Ring-Opening Reaction
39:26
Example: Epoxide Ring-Opening Reaction
42:42
Acid-Catalyzed Epoxide Ring Opening
44:16
Acid-Catalyzed Epoxide Ring Opening Mechanism
44:17
Acid-Catalyzed Epoxide Ring Opening
50:13
Acid-Catalyzed Epoxide Ring Opening Mechanism
50:14
Catalyst Needed for Ring Opening
53:34
Catalyst Needed for Ring Opening
53:35
Stereochemistry of Epoxide Ring Opening
55:56
Stereochemistry: SN2 Mechanism
55:57
Acid or Base Mechanism?
58:30
Example
1:01:03
Transformation
1:01:04
Regiochemistry of Epoxide Ring Openings
1:05:29
Regiochemistry of Epoxide Ring Openings in Base
1:05:30
Regiochemistry of Epoxide Ring Openings in Acid
1:07:34
Example
1:10:26
Example 1: Epoxide Ring Openings in Base
1:10:27
Example 2: Epoxide Ring Openings in Acid
1:12:50
Reactions of Epoxides with Grignard and Hydride
1:15:35
Reactions of Epoxides with Grignard and Hydride
1:15:36
Example
1:21:47
Example: Ethers
1:21:50
Example
1:27:01
Example: Synthesize
1:27:02
Thiols and Thioethers

16m 50s

Intro
0:00
Thiols and Thioethers
0:10
Physical Properties
0:11
Reactions Can Be Oxidized
2:16
Acidity of Thiols
3:11
Thiols Are More Acidic Than Alcohols
3:12
Synthesis of Thioethers
6:44
Synthesis of Thioethers
6:45
Example
8:43
Example: Synthesize the Following Target Molecule
8:44
Example
14:18
Example: Predict
14:19
Ketones

2h 18m 12s

Intro
0:00
Aldehydes & Ketones
0:11
The Carbonyl: Resonance & Inductive
0:12
Reactivity
0:50
The Carbonyl
2:35
The Carbonyl
2:36
Carbonyl FG's
4:10
Preparation/Synthesis of Aldehydes & Ketones
6:18
Oxidation of Alcohols
6:19
Ozonolysis of Alkenes
7:16
Hydration of Alkynes
8:01
Reaction with Hydride Nu:
9:00
Reaction with Hydride Nu:
9:01
Reaction with Carbon Nu:
11:29
Carbanions: Acetylide
11:30
Carbanions: Cyanide
14:23
Reaction with Carbon Nu:
15:32
Organometallic Reagents (RMgX, Rli)
15:33
Retrosynthesis of Alcohols
17:04
Retrosynthesis of Alcohols
17:05
Example
19:30
Example: Transform
19:31
Example
22:57
Example: Transform
22:58
Example
28:19
Example: Transform
28:20
Example
33:36
Example: Transform
33:37
Wittig Reaction
37:39
Wittig Reaction: A Resonance-Stabilized Carbanion (Nu:)
37:40
Wittig Reaction: Mechanism
39:51
Preparation of Wittig Reagent
41:58
Two Steps From RX
41:59
Example: Predict
45:02
Wittig Retrosynthesis
46:19
Wittig Retrosynthesis
46:20
Synthesis
48:09
Reaction with Oxygen Nu:
51:21
Addition of H₂O
51:22
Exception: Formaldehyde is 99% Hydrate in H₂O Solution
54:10
Exception: Hydrate is Favored if Partial Positive Near Carbonyl
55:26
Reaction with Oxygen Nu:
57:45
Addition of ROH
57:46
TsOH: Tosic Acid
58:28
Addition of ROH Cont.
59:09
Example
1:01:43
Predict
1:01:44
Mechanism
1:03:08
Mechanism for Acetal Formation
1:04:10
Mechanism for Acetal Formation
1:04:11
What is a CTI?
1:15:04
Tetrahedral Intermediate
1:15:05
Charged Tetrahedral Intermediate
1:15:45
CTI: Acid-cat
1:16:10
CTI: Base-cat
1:17:01
Acetals & Cyclic Acetals
1:17:49
Overall
1:17:50
Cyclic Acetals
1:18:46
Hydrolysis of Acetals: Regenerates Carbonyl
1:20:01
Hydrolysis of Acetals: Regenerates Carbonyl
1:20:02
Mechanism
1:22:08
Reaction with Nitrogen Nu:
1:30:11
Reaction with Nitrogen Nu:
1:30:12
Example
1:32:18
Mechanism of Imine Formation
1:33:24
Mechanism of Imine Formation
1:33:25
Oxidation of Aldehydes
1:38:12
Oxidation of Aldehydes 1
1:38:13
Oxidation of Aldehydes 2
1:39:52
Oxidation of Aldehydes 3
1:40:10
Reductions of Ketones and Aldehydes
1:40:54
Reductions of Ketones and Aldehydes
1:40:55
Hydride/ Workup
1:41:22
Raney Nickel
1:42:07
Reductions of Ketones and Aldehydes
1:43:24
Clemmensen Reduction & Wolff-Kishner Reduction
1:43:40
Acetals as Protective Groups
1:46:50
Acetals as Protective Groups
1:46:51
Example
1:50:39
Example: Consider the Following Synthesis
1:50:40
Protective Groups
1:54:47
Protective Groups
1:54:48
Example
1:59:02
Example: Transform
1:59:03
Example: Another Route
2:04:54
Example: Transform
2:08:49
Example
2:08:50
Transform
2:08:51
Example
2:11:05
Transform
2:11:06
Example
2:13:45
Transform
2:13:46
Example
2:15:43
Provide the Missing Starting Material
2:15:44
VI. Organic Transformation Practice
Transformation Practice Problems

38m 58s

Intro
0:00
Practice Problems
0:33
Practice Problem 1: Transform
0:34
Practice Problem 2: Transform
3:57
Practice Problems
7:49
Practice Problem 3: Transform
7:50
Practice Problems
15:32
Practice Problem 4: Transform
15:34
Practice Problem 5: Transform
20:15
Practice Problems
24:08
Practice Problem 6: Transform
24:09
Practice Problem 7: Transform
29:27
Practice Problems
33:08
Practice Problem 8: Transform
33:09
Practice Problem 9: Transform
35:23
VII. Carboxylic Acids
Carboxylic Acids

1h 17m 51s

Intro
0:00
Review Reactions of Ketone/Aldehyde
0:06
Carbonyl Reactivity
0:07
Nu: = Hydride (Reduction)
1:37
Nu: = Grignard
2:08
Review Reactions of Ketone/Aldehyde
2:53
Nu: = Alcohol
2:54
Nu: = Amine
3:46
Carboxylic Acids and Their Derivatives
4:37
Carboxylic Acids and Their Derivatives
4:38
Ketone vs. Ester Reactivity
6:33
Ketone Reactivity
6:34
Ester Reactivity
6:55
Carboxylic Acids and Their Derivatives
7:30
Acid Halide, Anhydride, Ester, Amide, and Nitrile
7:43
General Reactions of Acarboxylic Acid Derivatives
9:22
General Reactions of Acarboxylic Acid Derivatives
9:23
Physical Properties of Carboxylic Acids
12:16
Acetic Acid
12:17
Carboxylic Acids
15:46
Aciditiy of Carboxylic Acids, RCO₂H
17:45
Alcohol
17:46
Carboxylic Acid
19:21
Aciditiy of Carboxylic Acids, RCO₂H
21:31
Aciditiy of Carboxylic Acids, RCO₂H
21:32
Aciditiy of Carboxylic Acids, RCO₂H
24:48
Example: Which is the Stronger Acid?
24:49
Aciditiy of Carboxylic Acids, RCO₂H
30:06
Inductive Effects Decrease with Distance
30:07
Preparation of Carboxylic Acids, RCO₂H
31:55
A) By Oxidation
31:56
Preparation of Carboxylic Acids, RCO₂H
34:37
Oxidation of Alkenes/Alkynes - Ozonolysis
34:38
Preparation of Carboxylic Acids, RCO₂H
36:17
B) Preparation of RCO₂H from Organometallic Reagents
36:18
Preparation of Carboxylic Acids, RCO₂H
38:02
Example: Preparation of Carboxylic Acids
38:03
Preparation of Carboxylic Acids, RCO₂H
40:38
C) Preparation of RCO₂H by Hydrolysis of Carboxylic Acid Derivatives
40:39
Hydrolysis Mechanism
42:19
Hydrolysis Mechanism
42:20
Mechanism: Acyl Substitution (Addition/Elimination)
43:05
Hydrolysis Mechanism
47:27
Substitution Reaction
47:28
RO is Bad LG for SN1/SN2
47:39
RO is okay LG for Collapse of CTI
48:31
Hydrolysis Mechanism
50:07
Base-promoted Ester Hydrolysis (Saponification)
50:08
Applications of Carboxylic Acid Derivatives:
53:10
Saponification Reaction
53:11
Ester Hydrolysis
57:15
Acid-Catalyzed Mechanism
57:16
Ester Hydrolysis Requires Acide or Base
1:03:06
Ester Hydrolysis Requires Acide or Base
1:03:07
Nitrile Hydrolysis
1:05:22
Nitrile Hydrolysis
1:05:23
Nitrile Hydrolysis Mechanism
1:06:53
Nitrile Hydrolysis Mechanism
1:06:54
Use of Nitriles in Synthesis
1:12:39
Example: Nitirles in Synthesis
1:12:40
Carboxylic Acid Derivatives

1h 21m 4s

Intro
0:00
Carboxylic Acid Derivatives
0:05
Carboxylic Acid Derivatives
0:06
General Structure
1:00
Preparation of Carboxylic Acid Derivatives
1:19
Which Carbonyl is the Better E+?
1:20
Inductive Effects
1:54
Resonance
3:23
Preparation of Carboxylic Acid Derivatives
6:52
Which is Better E+, Ester or Acid Chloride?
6:53
Inductive Effects
7:02
Resonance
7:20
Preparation of Carboxylic Acid Derivatives
10:45
Which is Better E+, Carboxylic Acid or Anhydride?
10:46
Inductive Effects & Resonance
11:00
Overall: Order of Electrophilicity and Leaving Group
14:49
Order of Electrophilicity and Leaving Group
14:50
Example: Acid Chloride
16:26
Example: Carboxylate
19:17
Carboxylic Acid Derivative Interconversion
20:53
Carboxylic Acid Derivative Interconversion
20:54
Preparation of Acid Halides
24:31
Preparation of Acid Halides
24:32
Preparation of Anhydrides
25:45
A) Dehydration of Acids (For Symmetrical Anhydride)
25:46
Preparation of Anhydrides
27:29
Example: Dehydration of Acids
27:30
Preparation of Anhydrides
29:16
B) From an Acid Chloride (To Make Mixed Anhydride)
29:17
Mechanism
30:03
Preparation of Esters
31:53
A) From Acid Chloride or Anhydride
31:54
Preparation of Esters
33:48
B) From Carboxylic Acids (Fischer Esterification)
33:49
Mechanism
36:55
Preparations of Esters
41:38
Example: Predict the Product
41:39
Preparation of Esters
43:17
C) Transesterification
43:18
Mechanism
45:17
Preparation of Esters
47:58
D) SN2 with Carboxylate
47:59
Mechanism: Diazomethane
49:28
Preparation of Esters
51:01
Example: Transform
51:02
Preparation of Amides
52:27
A) From an Acid Cl or Anhydride
52:28
Preparations of Amides
54:47
B) Partial Hydrolysis of Nitriles
54:48
Preparation of Amides
56:11
Preparation of Amides: Find Alternate Path
56:12
Preparation of Amides
59:04
C) Can't be Easily Prepared from RCO₂H Directly
59:05
Reactions of Carboxylic Acid Derivatives with Nucleophiles
1:01:41
A) Hydride Nu: Review
1:01:42
A) Hydride Nu: Sodium Borohydride + Ester
1:02:43
Reactions of Carboxylic Acid Derivatives with Nucleophiles
1:03:57
Lithium Aluminum Hydride (LAH)
1:03:58
Mechanism
1:04:29
Summary of Hydride Reductions
1:07:09
Summary of Hydride Reductions 1
1:07:10
Summary of Hydride Reductions 2
1:07:36
Hydride Reduction of Amides
1:08:12
Hydride Reduction of Amides Mechanism
1:08:13
Reaction of Carboxylic Acid Derivatives with Organometallics
1:12:04
Review 1
1:12:05
Review 2
1:12:50
Reaction of Carboxylic Acid Derivatives with Organometallics
1:14:22
Example: Lactone
1:14:23
Special Hydride Nu: Reagents
1:16:34
Diisobutylaluminum Hydride
1:16:35
Example
1:17:25
Other Special Hydride
1:18:41
Addition of Organocuprates to Acid Chlorides
1:19:07
Addition of Organocuprates to Acid Chlorides
1:19:08
VIII. Enols & Enolates
Enols and Enolates, Part 1

1h 26m 22s

Intro
0:00
Enols and Enolates
0:09
The Carbonyl
0:10
Keto-Enol Tautomerization
1:17
Keto-Enol Tautomerization Mechanism
2:28
Tautomerization Mechanism (2 Steps)
2:29
Keto-Enol Tautomerization Mechanism
5:15
Reverse Reaction
5:16
Mechanism
6:07
Formation of Enolates
7:27
Why is a Ketone's α H's Acidic?
7:28
Formation of Other Carbanions
10:05
Alkyne
10:06
Alkane and Alkene
10:53
Formation of an Enolate: Choice of Base
11:27
Example: Choice of Base
11:28
Formation of an Enolate: Choice of Base
13:56
Deprotonate, Stronger Base, and Lithium Diisopropyl Amide (LDA)
13:57
Formation of an Enolate: Choice of Base
15:48
Weaker Base & 'Active' Methylenes
15:49
Why Use NaOEt instead of NaOH?
19:01
Other Acidic 'α' Protons
20:30
Other Acidic 'α' Protons
20:31
Why is an Ester Less Acidic than a Ketone?
24:10
Other Acidic 'α' Protons
25:19
Other Acidic 'α' Protons Continue
25:20
How are Enolates Used
25:54
Enolates
25:55
Possible Electrophiles
26:21
Alkylation of Enolates
27:56
Alkylation of Enolates
27:57
Resonance Form
30:03
α-Halogenation
32:17
α-Halogenation
32:18
Iodoform Test for Methyl Ketones
33:47
α-Halogenation
35:55
Acid-Catalyzed
35:57
Mechanism: 1st Make Enol (2 Steps)
36:14
Whate Other Eloctrophiles ?
39:17
Aldol Condensation
39:38
Aldol Condensation
39:39
Aldol Mechanism
41:26
Aldol Mechanism: In Base, Deprotonate First
41:27
Aldol Mechanism
45:28
Mechanism for Loss of H₂O
45:29
Collapse of CTI and β-elimination Mechanism
47:51
Loss of H₂0 is not E2!
48:39
Aldol Summary
49:53
Aldol Summary
49:54
Base-Catalyzed Mechanism
52:34
Acid-Catalyzed Mechansim
53:01
Acid-Catalyzed Aldol Mechanism
54:01
First Step: Make Enol
54:02
Acid-Catalyzed Aldol Mechanism
56:54
Loss of H₂0 (β elimination)
56:55
Crossed/Mixed Aldol
1:00:55
Crossed/Mixed Aldol & Compound with α H's
1:00:56
Ketone vs. Aldehyde
1:02:30
Crossed/Mixed Aldol & Compound with α H's Continue
1:03:10
Crossed/Mixed Aldol
1:05:21
Mixed Aldol: control Using LDA
1:05:22
Crossed/Mixed Aldol Retrosynthesis
1:08:53
Example: Predic Aldol Starting Material (Aldol Retrosyntheiss)
1:08:54
Claisen Condensation
1:12:54
Claisen Condensation (Aldol on Esters)
1:12:55
Claisen Condensation
1:19:52
Example 1: Claisen Condensation
1:19:53
Claisen Condensation
1:22:48
Example 2: Claisen Condensation
1:22:49
Enols and Enolates, Part 2

50m 57s

Intro
0:00
Conjugate Additions
0:06
α, β-unsaturated Carbonyls
0:07
Conjugate Additions
1:50
'1,2-addition'
1:51
'1,-4-addition' or 'Conjugate Addition'
2:24
Conjugate Additions
4:53
Why can a Nu: Add to this Alkene?
4:54
Typical Alkene
5:09
α, β-unsaturated Alkene
5:39
Electrophilic Alkenes: Michael Acceptors
6:35
Other 'Electrophilic' Alkenes (Called 'Michael Acceptors)
6:36
1,4-Addition of Cuprates (R2CuLi)
8:29
1,4-Addition of Cuprates (R2CuLi)
8:30
1,4-Addition of Cuprates (R2CuLi)
11:23
Use Cuprates in Synthesis
11:24
Preparation of Cuprates
12:25
Prepare Organocuprate From Organolithium
12:26
Cuprates Also Do SN2 with RX E+ (Not True for RMgX, RLi)
13:06
1,4-Addition of Enolates: Michael Reaction
13:50
1,4-Addition of Enolates: Michael Reaction
13:51
Mechanism
15:57
1,4-Addition of Enolates: Michael Reaction
18:47
Example: 1,4-Addition of Enolates
18:48
1,4-Addition of Enolates: Michael Reaction
21:02
Michael Reaction, Followed by Intramolecular Aldol
21:03
Mechanism of the Robinson Annulation
24:26
Mechanism of the Robinson Annulation
24:27
Enols and Enolates: Advanced Synthesis Topics
31:10
Stablized Enolates and the Decarboxylation Reaction
31:11
Mechanism: A Pericyclic Reaction
32:08
Enols and Enolates: Advanced Synthesis Topics
33:32
Example: Advance Synthesis
33:33
Enols and Enolates: Advanced Synthesis Topics
36:10
Common Reagents: Diethyl Malonate
36:11
Common Reagents: Ethyl Acetoacetate
37:27
Enols and Enolates: Advanced Synthesis Topics
38:06
Example: Transform
38:07
Advanced Synthesis Topics: Enamines
41:52
Enamines
41:53
Advanced Synthesis Topics: Enamines
43:06
Reaction with Ketone/Aldehyde
43:07
Example
44:08
Advanced Synthesis Topics: Enamines
45:31
Example: Use Enamines as Nu: (Like Enolate)
45:32
Advanced Synthesis Topics: Enamines
47:56
Example
47:58
IX. Aromatic Compounds
Aromatic Compounds: Structure

1h 59s

Intro
0:00
Aromatic Compounds
0:05
Benzene
0:06
3D Sketch
1:33
Features of Benzene
4:41
Features of Benzene
4:42
Aromatic Stability
6:41
Resonance Stabilization of Benzene
6:42
Cyclohexatriene
7:24
Benzene (Actual, Experimental)
8:11
Aromatic Stability
9:03
Energy Graph
9:04
Aromaticity Requirements
9:55
1) Cyclic and Planar
9:56
2) Contiguous p Orbitals
10:49
3) Satisfy Huckel's Rule
11:20
Example: Benzene
12:32
Common Aromatic Compounds
13:28
Example: Pyridine
13:29
Common Aromatic Compounds
16:25
Example: Furan
16:26
Common Aromatic Compounds
19:42
Example: Thiophene
19:43
Example: Pyrrole
20:18
Common Aromatic Compounds
21:09
Cyclopentadienyl Anion
21:10
Cycloheptatrienyl Cation
23:48
Naphthalene
26:04
Determining Aromaticity
27:28
Example: Which of the Following are Aromatic?
27:29
Molecular Orbital (MO) Theory
32:26
What's So Special About '4n + 2' Electrons?
32:27
π bond & Overlapping p Orbitals
32:53
Molecular Orbital (MO) Diagrams
36:56
MO Diagram: Benzene
36:58
Drawing MO Diagrams
44:26
Example: 3-Membered Ring
44:27
Example: 4-Membered Ring
46:04
Drawing MO Diagrams
47:51
Example: 5-Membered Ring
47:52
Example: 8-Membered Ring
49:32
Aromaticity and Reactivity
51:03
Example: Which is More Acidic?
51:04
Aromaticity and Reactivity
56:03
Example: Which has More Basic Nitrogen, Pyrrole or Pyridine?
56:04
Aromatic Compounds: Reactions, Part 1

1h 24m 4s

Intro
0:00
Reactions of Benzene
0:07
N/R as Alkenes
0:08
Substitution Reactions
0:50
Electrophilic Aromatic Substitution
1:24
Electrophilic Aromatic Substitution
1:25
Mechanism Step 1: Addition of Electrophile
2:08
Mechanism Step 2: Loss of H+
4:14
Electrophilic Aromatic Substitution on Substituted Benzenes
5:21
Electron Donating Group
5:22
Electron Withdrawing Group
8:02
Halogen
9:23
Effects of Electron-Donating Groups (EDG)
10:23
Effects of Electron-Donating Groups (EDG)
10:24
What Effect Does EDG (OH) Have?
11:40
Reactivity
13:03
Regioselectivity
14:07
Regioselectivity: EDG is o/p Director
14:57
Prove It! Add E+ and Look at Possible Intermediates
14:58
Is OH Good or Bad?
17:38
Effects of Electron-Withdrawing Groups (EWG)
20:20
What Effect Does EWG Have?
20:21
Reactivity
21:28
Regioselectivity
22:24
Regioselectivity: EWG is a Meta Director
23:23
Prove It! Add E+ and Look at Competing Intermediates
23:24
Carbocation: Good or Bad?
26:01
Effects of Halogens on EAS
28:33
Inductive Withdrawal of e- Density vs. Resonance Donation
28:34
Summary of Substituent Effects on EAS
32:33
Electron Donating Group
32:34
Electron Withdrawing Group
33:37
Directing Power of Substituents
34:35
Directing Power of Substituents
34:36
Example
36:41
Electrophiles for Electrophilic Aromatic Substitution
38:43
Reaction: Halogenation
38:44
Electrophiles for Electrophilic Aromatic Substitution
40:27
Reaction: Nitration
40:28
Electrophiles for Electrophilic Aromatic Substitution
41:45
Reaction: Sulfonation
41:46
Electrophiles for Electrophilic Aromatic Substitution
43:19
Reaction: Friedel-Crafts Alkylation
43:20
Electrophiles for Electrophilic Aromatic Substitution
45:43
Reaction: Friedel-Crafts Acylation
45:44
Electrophilic Aromatic Substitution: Nitration
46:52
Electrophilic Aromatic Substitution: Nitration
46:53
Mechanism
48:56
Nitration of Aniline
52:40
Nitration of Aniline Part 1
52:41
Nitration of Aniline Part 2: Why?
54:12
Nitration of Aniline
56:10
Workaround: Protect Amino Group as an Amide
56:11
Electrophilic Aromatic Substitution: Sulfonation
58:16
Electrophilic Aromatic Substitution: Sulfonation
58:17
Example: Transform
59:25
Electrophilic Aromatic Substitution: Friedel-Crafts Alkylation
1:02:24
Electrophilic Aromatic Substitution: Friedel-Crafts Alkylation
1:02:25
Example & Mechanism
1:03:37
Friedel-Crafts Alkylation Drawbacks
1:05:48
A) Can Over-React (Dialkylation)
1:05:49
Friedel-Crafts Alkylation Drawbacks
1:08:21
B) Carbocation Can Rearrange
1:08:22
Mechanism
1:09:33
Friedel-Crafts Alkylation Drawbacks
1:13:35
Want n-Propyl? Use Friedel-Crafts Acylation
1:13:36
Reducing Agents
1:16:45
Synthesis with Electrophilic Aromatic Substitution
1:18:45
Example: Transform
1:18:46
Synthesis with Electrophilic Aromatic Substitution
1:20:59
Example: Transform
1:21:00
Aromatic Compounds: Reactions, Part 2

59m 10s

Intro
0:00
Reagents for Electrophilic Aromatic Substitution
0:07
Reagents for Electrophilic Aromatic Substitution
0:08
Preparation of Diazonium Salt
2:12
Preparation of Diazonium Salt
2:13
Reagents for Sandmeyer Reactions
4:14
Reagents for Sandmeyer Reactions
4:15
Apply Diazonium Salt in Synthesis
6:20
Example: Transform
6:21
Apply Diazonium Salt in Synthesis
9:14
Example: Synthesize Following Target Molecule from Benzene or Toluene
9:15
Apply Diazonium Salt in Synthesis
14:56
Example: Transform
14:57
Reactions of Aromatic Substituents
21:56
A) Reduction Reactions
21:57
Reactions of Aromatic Substituents
23:24
B) Oxidations of Arenes
23:25
Benzylic [ox] Even Breaks C-C Bonds!
25:05
Benzylic Carbon Can't Be Quaternary
25:55
Reactions of Aromatic Substituents
26:21
Example
26:22
Review of Benzoic Acid Synthesis
27:34
Via Hydrolysis
27:35
Via Grignard
28:20
Reactions of Aromatic Substituents
29:15
C) Benzylic Halogenation
29:16
Radical Stabilities
31:55
N-bromosuccinimide (NBS)
32:23
Reactions of Aromatic Substituents
33:08
D) Benzylic Substitutions
33:09
Reactions of Aromatic Side Chains
37:08
Example: Transform
37:09
Nucleophilic Aromatic Substitution
43:13
Nucleophilic Aromatic Substitution
43:14
Nucleophilic Aromatic Substitution
47:08
Example
47:09
Mechanism
48:00
Nucleophilic Aromatic Substitution
50:43
Example
50:44
Nucleophilic Substitution: Benzyne Mechanism
52:46
Nucleophilic Substitution: Benzyne Mechanism
52:47
Nucleophilic Substitution: Benzyne Mechanism
57:31
Example: Predict Product
57:32
X. Dienes & Amines
Conjugated Dienes

1h 9m 12s

Intro
0:00
Conjugated Dienes
0:08
Conjugated π Bonds
0:09
Diene Stability
2:00
Diene Stability: Cumulated
2:01
Diene Stability: Isolated
2:37
Diene Stability: Conjugated
2:51
Heat of Hydrogenation
3:00
Allylic Carbocations and Radicals
5:15
Allylic Carbocations and Radicals
5:16
Electrophilic Additions to Dienes
7:00
Alkenes
7:01
Unsaturated Ketone
7:47
Electrophilic Additions to Dienes
8:28
Conjugated Dienes
8:29
Electrophilic Additions to Dienes
9:46
Mechanism (2-Steps): Alkene
9:47
Electrophilic Additions to Dienes
11:40
Mechanism (2-Steps): Diene
11:41
1,2 'Kinetic' Product
13:08
1,4 'Thermodynamic' Product
14:47
E vs. POR Diagram
15:50
E vs. POR Diagram
15:51
Kinetic vs. Thermodynamic Control
21:56
Kinetic vs. Thermodynamic Control
21:57
How? Reaction is Reversible!
23:51
1,2 (Less Stable product)
23:52
1,4 (More Stable Product)
25:16
Diels Alder Reaction
26:34
Diels Alder Reaction
26:35
Dienophiles (E+)
29:23
Dienophiles (E+)
29:24
Alkyne Diels-Alder Example
30:48
Example: Alkyne Diels-Alder
30:49
Diels-Alder Reaction: Dienes (Nu:)
32:22
Diels-Alder ReactionL Dienes (Nu:)
32:23
Diels-Alder Reaction: Dienes
33:51
Dienes Must Have 's-cis' Conformation
33:52
Example
35:25
Diels-Alder Reaction with Cyclic Dienes
36:08
Cyclic Dienes are Great for Diels-Alder Reaction
36:09
Cyclopentadiene
37:10
Diels-Alder Reaction: Bicyclic Products
40:50
Endo vs. Exo Terminology: Norbornane & Bicyclo Heptane
40:51
Example: Bicyclo Heptane
42:29
Diels-Alder Reaction with Cyclic Dienes
44:15
Example
44:16
Stereochemistry of the Diels-Alder Reaction
47:39
Stereochemistry of the Diels-Alder Reaction
47:40
Example
48:08
Stereochemistry of the Diels-Alder Reaction
50:21
Example
50:22
Regiochemistry of the Diels-Alder Reaction
52:42
Rule: 1,2-Product Preferred Over 1,3-Product
52:43
Regiochemistry of the Diels-Alder Reaction
54:18
Rule: 1,4-Product Preferred Over 1,3-Product
54:19
Regiochemistry of the Diels-Alder Reaction
55:02
Why 1,2-Product or 1,4-Product Favored?
55:03
Example
56:11
Diels-Alder Reaction
58:06
Example: Predict
58:07
Diels-Alder Reaction
1:01:27
Explain Why No Diels-Alder Reaction Takes Place in This Case
1:01:28
Diels-Alder Reaction
1:03:09
Example: Predict
1:03:10
Diels-Alder Reaction: Synthesis Problem
1:05:39
Diels-Alder Reaction: Synthesis Problem
1:05:40
Pericyclic Reactions and Molecular Orbital (MO) Theory

1h 21m 31s

Intro
0:00
Pericyclic Reactions
0:05
Pericyclic Reactions
0:06
Electrocyclic Reactions
1:19
Electrocyclic Reactions
1:20
Electrocyclic Reactions
3:13
Stereoselectivity
3:14
Electrocyclic Reactions
8:10
Example: Predict
8:11
Sigmatropic Rearrangements
12:29
Sigmatropic Rearrangements
12:30
Cope Rearrangement
14:44
Sigmatropic Rearrangements
16:44
Claisen Rearrangement 1
16:45
Claisen Rearrangement 2
17:46
Cycloaddition Reactions
19:22
Diels-Alder
19:23
1,3-Dipolar Cycloaddition
20:32
Cycloaddition Reactions: Stereochemistry
21:58
Cycloaddition Reactions: Stereochemistry
21:59
Cycloaddition Reactions: Heat or Light?
26:00
4+2 Cycloadditions
26:01
2+2 Cycloadditions
27:23
Molecular Orbital (MO) Theory of Chemical Reactions
29:26
Example 1: Molecular Orbital Theory of Bonding
29:27
Molecular Orbital (MO) Theory of Chemical Reactions
31:59
Example 2: Molecular Orbital Theory of Bonding
32:00
Molecular Orbital (MO) Theory of Chemical Reactions
33:33
MO Theory of Aromaticity, Huckel's Rule
33:34
Molecular Orbital (MO) Theory of Chemical Reactions
36:43
Review: Molecular Orbital Theory of Conjugated Systems
36:44
Molecular Orbital (MO) Theory of Chemical Reactions
44:56
Review: Molecular Orbital Theory of Conjugated Systems
44:57
Molecular Orbital (MO) Theory of Chemical Reactions
46:54
Review: Molecular Orbital Theory of Conjugated Systems
46:55
Molecular Orbital (MO) Theory of Chemical Reactions
48:36
Frontier Molecular Orbitals are Involved in Reactions
48:37
Examples
50:20
MO Theory of Pericyclic Reactions: The Woodward-Hoffmann Rules
51:51
Heat-promoted Pericyclic Reactions and Light-promoted Pericyclic Reactions
51:52
MO Theory of Pericyclic Reactions: The Woodward-Hoffmann Rules
53:42
Why is a [4+2] Cycloaddition Thermally Allowed While the [2+2] is Not?
53:43
MO Theory of Pericyclic Reactions: The Woodward-Hoffmann Rules
56:51
Why is a [2+2] Cycloaddition Photochemically Allowed?
56:52
Pericyclic Reaction Example I
59:16
Pericyclic Reaction Example I
59:17
Pericyclic Reaction Example II
1:07:40
Pericyclic Reaction Example II
1:07:41
Pericyclic Reaction Example III: Vitamin D - The Sunshine Vitamin
1:14:22
Pericyclic Reaction Example III: Vitamin D - The Sunshine Vitamin
1:14:23
Amines

34m 58s

Intro
0:00
Amines: Properties and Reactivity
0:04
Compare Amines to Alcohols
0:05
Amines: Lower Boiling Point than ROH
0:55
1) RNH₂ Has Lower Boiling Point than ROH
0:56
Amines: Better Nu: Than ROH
2:22
2) RNH₂ is a Better Nucleophile than ROH Example 1
2:23
RNH₂ is a Better Nucleophile than ROH Example 2
3:08
Amines: Better Nu: than ROH
3:47
Example
3:48
Amines are Good Bases
5:41
3) RNH₂ is a Good Base
5:42
Amines are Good Bases
7:06
Example 1
7:07
Example 2: Amino Acid
8:27
Alkyl vs. Aryl Amines
9:56
Example: Which is Strongest Base?
9:57
Alkyl vs. Aryl Amines
14:55
Verify by Comparing Conjugate Acids
14:56
Reaction of Amines
17:42
Reaction with Ketone/Aldehyde: 1° Amine (RNH₂)
17:43
Reaction of Amines
18:48
Reaction with Ketone/Aldehyde: 2° Amine (R2NH)
18:49
Use of Enamine: Synthetic Equivalent of Enolate
20:08
Use of Enamine: Synthetic Equivalent of Enolate
20:09
Reaction of Amines
24:10
Hofmann Elimination
24:11
Hofmann Elimination
26:16
Kinetic Product
26:17
Structure Analysis Using Hofmann Elimination
28:22
Structure Analysis Using Hofmann Elimination
28:23
Biological Activity of Amines
30:30
Adrenaline
31:07
Mescaline (Peyote Alkaloid)
31:22
Amino Acids, Amide, and Protein
32:14
Biological Activity of Amines
32:50
Morphine (Opium Alkaloid)
32:51
Epibatidine (Poison Dart Frog)
33:28
Nicotine
33:48
Choline (Nerve Impulse)
34:03
XI. Biomolecules & Polymers
Biomolecules

1h 53m 20s

Intro
0:00
Carbohydrates
1:11
D-glucose Overview
1:12
D-glucose: Cyclic Form (6-membered ring)
4:31
Cyclic Forms of Glucose: 6-membered Ring
8:24
α-D-glucopyranose & β-D-glucopyranose
8:25
Formation of a 5-Membered Ring
11:05
D-glucose: Formation of a 5-Membered Ring
11:06
Cyclic Forms of Glucose: 5-membered Ring
12:37
α-D-glucofuranose & β-D-glucofuranose
12:38
Carbohydrate Mechanism
14:03
Carbohydrate Mechanism
14:04
Reactions of Glucose: Acetal Formation
21:35
Acetal Formation: Methyl-α-D-glucoside
21:36
Hemiacetal to Acetal: Overview
24:58
Mechanism for Formation of Glycosidic Bond
25:51
Hemiacetal to Acetal: Mechanism
25:52
Formation of Disaccharides
29:34
Formation of Disaccharides
29:35
Some Polysaccharides: Starch
31:33
Amylose & Amylopectin
31:34
Starch: α-1,4-glycosidic Bonds
32:22
Properties of Starch Molecule
33:21
Some Polysaccharides: Cellulose
33:59
Cellulose: β-1,4-glycosidic bonds
34:00
Properties of Cellulose
34:59
Other Sugar-Containing Biomolecules
35:50
Ribonucleoside (RNA)
35:51
Deoxyribonucleoside (DMA)
36:59
Amino Acids & Proteins
37:32
α-amino Acids: Structure & Stereochemistry
37:33
Making a Protein (Condensation)
42:46
Making a Protein (Condensation)
42:47
Peptide Bond is Planar (Amide Resonance)
44:55
Peptide Bond is Planar (Amide Resonance)
44:56
Protein Functions
47:49
Muscle, Skin, Bones, Hair Nails
47:50
Enzymes
49:10
Antibodies
49:44
Hormones, Hemoglobin
49:58
Gene Regulation
50:20
Various Amino Acid Side Chains
50:51
Nonpolar
50:52
Polar
51:15
Acidic
51:24
Basic
51:55
Amino Acid Table
52:22
Amino Acid Table
52:23
Isoelectric Point (pI)
53:43
Isoelectric Point (pI) of Glycine
53:44
Isoelectric Point (pI) of Glycine: pH 11
56:42
Isoelectric Point (pI) of Glycine: pH 1
57:20
Isoelectric Point (pI), cont.
58:05
Asparatic Acid
58:06
Histidine
1:00:28
Isoelectric Point (pI), cont.
1:02:54
Example: What is the Net Charge of This Tetrapeptide at pH 6.0?
1:02:55
Nucleic Acids: Ribonucleosides
1:10:32
Nucleic Acids: Ribonucleosides
1:10:33
Nucleic Acids: Ribonucleotides
1:11:48
Ribonucleotides: 5' Phosphorylated Ribonucleosides
1:11:49
Ribonucleic Acid (RNA) Structure
1:12:35
Ribonucleic Acid (RNA) Structure
1:12:36
Nucleic Acids: Deoxyribonucleosides
1:14:08
Nucleic Acids: Deoxyribonucleosides
1:14:09
Deoxythymidine (T)
1:14:36
Nucleic Acids: Base-Pairing
1:15:17
Nucleic Acids: Base-Pairing
1:15:18
Double-Stranded Structure of DNA
1:18:16
Double-Stranded Structure of DNA
1:18:17
Model of DNA
1:19:40
Model of DNA
1:19:41
Space-Filling Model of DNA
1:20:46
Space-Filling Model of DNA
1:20:47
Function of RNA and DNA
1:23:06
DNA & Transcription
1:23:07
RNA & Translation
1:24:22
Genetic Code
1:25:09
Genetic Code
1:25:10
Lipids/Fats/Triglycerides
1:27:10
Structure of Glycerol
1:27:43
Saturated & Unsaturated Fatty Acids
1:27:51
Triglyceride
1:28:43
Unsaturated Fats: Lower Melting Points (Liquids/Oils)
1:29:15
Saturated Fat
1:29:16
Unsaturated Fat
1:30:10
Partial Hydrogenation
1:32:05
Saponification of Fats
1:35:11
Saponification of Fats
1:35:12
History of Soap
1:36:50
Carboxylate Salts form Micelles in Water
1:41:02
Carboxylate Salts form Micelles in Water
1:41:03
Cleaning Power of Micelles
1:42:21
Cleaning Power of Micelles
1:42:22
3-D Image of a Micelle
1:42:58
3-D Image of a Micelle
1:42:59
Synthesis of Biodiesel
1:44:04
Synthesis of Biodiesel
1:44:05
Phosphoglycerides
1:47:54
Phosphoglycerides
1:47:55
Cell Membranes Contain Lipid Bilayers
1:48:41
Cell Membranes Contain Lipid Bilayers
1:48:42
Bilayer Acts as Barrier to Movement In/Out of Cell
1:50:24
Bilayer Acts as Barrier to Movement In/Out of Cell
1:50:25
Organic Chemistry Meets Biology… Biochemistry!
1:51:12
Organic Chemistry Meets Biology… Biochemistry!
1:51:13
Polymers

45m 47s

Intro
0:00
Polymers
0:05
Monomer to Polymer: Vinyl Chloride to Polyvinyl Chloride
0:06
Polymer Properties
1:32
Polymer Properties
1:33
Natural Polymers: Rubber
2:30
Vulcanization
2:31
Natural Polymers: Polysaccharides
4:55
Example: Starch
4:56
Example: Cellulose
5:45
Natural Polymers: Proteins
6:07
Example: Keratin
6:08
DNA Strands
7:15
DNA Strands
7:16
Synthetic Polymers
8:30
Ethylene & Polyethylene: Lightweight Insulator & Airtight Plastic
8:31
Synthetic Organic Polymers
12:22
Polyethylene
12:28
Polyvinyl Chloride (PVC)
12:54
Polystyrene
13:28
Polyamide
14:34
Polymethyl Methacrylate
14:57
Kevlar
15:25
Synthetic Material Examples
16:30
How are Polymers Made?
21:00
Chain-growth Polymers Additions to Alkenes can be Radical, Cationic or Anionic
21:01
Chain Branching
22:34
Chain Branching
22:35
Special Reaction Conditions Prevent Branching
24:28
Ziegler-Natta Catalyst
24:29
Chain-Growth by Cationic Polymerization
27:35
Chain-Growth by Cationic Polymerization
27:36
Chain-Growth by Anionic Polymerization
29:35
Chain-Growth by Anionic Polymerization
29:36
Step-Growth Polymerization: Polyamides
32:16
Step-Growth Polymerization: Polyamides
32:17
Step-Growth Polymerization: Polyesters
34:23
Step-Growth Polymerization: Polyesters
34:24
Step-Growth Polymerization: Polycarbonates
35:56
Step-Growth Polymerization: Polycarbonates
35:57
Step-Growth Polymerization: Polyurethanes
37:18
Step-Growth Polymerization: Polyurethanes
37:19
Modifying Polymer Properties
39:35
Glass Transition Temperature
40:04
Crosslinking
40:42
Copolymers
40:58
Additives: Stabilizers
42:08
Additives: Flame Retardants
43:03
Additives: Plasticizers
43:41
Additives: Colorants
44:54
XII. Organic Synthesis
Organic Synthesis Strategies

2h 20m 24s

Intro
0:00
Organic Synthesis Strategies
0:15
Goal
0:16
Strategy
0:29
Example of a RetroSynthesis
1:30
Finding Starting Materials for Target Molecule
1:31
Synthesis Using Starting Materials
4:56
Synthesis of Alcohols by Functional Group Interconversion (FGI)
6:00
Synthesis of Alcohols by Functional Group Interconversion Overview
6:01
Alcohols by Reduction
7:43
Ketone to Alcohols
7:45
Aldehyde to Alcohols
8:26
Carboxylic Acid Derivative to Alcohols
8:36
Alcohols by Hydration of Alkenes
9:28
Hydration of Alkenes Using H₃O⁺
9:29
Oxymercuration-Demercuration
10:35
Hydroboration Oxidation
11:02
Alcohols by Substitution
11:42
Primary Alkyl Halide to Alcohols Using NaOH
11:43
Secondary Alkyl Halide to Alcohols Using Sodium Acetate
13:07
Tertiary Alkyl Halide to Alcohols Using H₂O
15:08
Synthesis of Alcohols by Forming a New C-C Bond
15:47
Recall: Alcohol & RMgBr
15:48
Retrosynthesis
17:28
Other Alcohol Disconnections
19:46
19:47
Synthesis Using PhMGgBr: Example 2
23:05
Synthesis of Alkyl Halides
26:06
Synthesis of Alkyl Halides Overview
26:07
Synthesis of Alkyl Halides by Free Radical Halogenation
27:04
Synthesis of Alkyl Halides by Free Radical Halogenation
27:05
Synthesis of Alkyl Halides by Substitution
29:06
Alcohol to Alkyl Halides Using HBr or HCl
29:07
Alcohol to Alkyl Halides Using SOCl₂
30:57
Alcohol to Alkyl Halides Using PBr₃ and Using P, I₂
31:03
Synthesis of Alkyl Halides by Addition
32:02
Alkene to Alkyl Halides Using HBr
32:03
Alkene to Alkyl Halides Using HBr & ROOR (Peroxides)
32:35
Example: Synthesis of Alkyl Halide
34:18
Example: Synthesis of Alkyl Halide
34:19
Synthesis of Ethers
39:25
Synthesis of Ethers
39:26
Example: Synthesis of an Ether
41:12
Synthesize TBME (t-butyl methyl ether) from Alcohol Starting Materials
41:13
Synthesis of Amines
46:05
Synthesis of Amines
46:06
Gabriel Synthesis of Amines
47:57
Gabriel Synthesis of Amines
47:58
Amines by SN2 with Azide Nu:
49:50
Amines by SN2 with Azide Nu:
49:51
Amines by SN2 with Cyanide Nu:
50:31
Amines by SN2 with Cyanide Nu:
50:32
Amines by Reduction of Amides
51:30
Amines by Reduction of Amides
51:31
Reductive Amination of Ketones/Aldehydes
52:42
Reductive Amination of Ketones/Aldehydes
52:43
Example : Synthesis of an Amine
53:47
Example 1: Synthesis of an Amine
53:48
Example 2: Synthesis of an Amine
56:16
Synthesis of Alkenes
58:20
Synthesis of Alkenes Overview
58:21
Synthesis of Alkenes by Elimination
59:04
Synthesis of Alkenes by Elimination Using NaOH & Heat
59:05
Synthesis of Alkenes by Elimination Using H₂SO₄ & Heat
59:57
Synthesis of Alkenes by Reduction
1:02:05
Alkyne to Cis Alkene
1:02:06
Alkyne to Trans Alkene
1:02:56
Synthesis of Alkenes by Wittig Reaction
1:03:46
Synthesis of Alkenes by Wittig Reaction
1:03:47
Retrosynthesis of an Alkene
1:05:35
Example: Synthesis of an Alkene
1:06:57
Example: Synthesis of an Alkene
1:06:58
Making a Wittig Reagent
1:10:31
Synthesis of Alkynes
1:13:09
Synthesis of Alkynes
1:13:10
Synthesis of Alkynes by Elimination (FGI)
1:13:42
First Step: Bromination of Alkene
1:13:43
Second Step: KOH Heat
1:14:22
Synthesis of Alkynes by Alkylation
1:15:02
Synthesis of Alkynes by Alkylation
1:15:03
Retrosynthesis of an Alkyne
1:16:18
Example: Synthesis of an Alkyne
1:17:40
Example: Synthesis of an Alkyne
1:17:41
Synthesis of Alkanes
1:20:52
Synthesis of Alkanes
1:20:53
Synthesis of Aldehydes & Ketones
1:21:38
Oxidation of Alcohol Using PCC or Swern
1:21:39
Oxidation of Alkene Using 1) O₃, 2)Zn
1:22:42
Reduction of Acid Chloride & Nitrile Using DiBAL-H
1:23:25
Hydration of Alkynes
1:24:55
Synthesis of Ketones by Acyl Substitution
1:26:12
Reaction with R'₂CuLi
1:26:13
Reaction with R'MgBr
1:27:13
Synthesis of Aldehydes & Ketones by α-Alkylation
1:28:00
Synthesis of Aldehydes & Ketones by α-Alkylation
1:28:01
Retrosynthesis of a Ketone
1:30:10
Acetoacetate Ester Synthesis of Ketones
1:31:05
Acetoacetate Ester Synthesis of Ketones: Step 1
1:31:06
Acetoacetate Ester Synthesis of Ketones: Step 2
1:32:13
Acetoacetate Ester Synthesis of Ketones: Step 3
1:32:50
Example: Synthesis of a Ketone
1:34:11
Example: Synthesis of a Ketone
1:34:12
Synthesis of Carboxylic Acids
1:37:15
Synthesis of Carboxylic Acids
1:37:16
Example: Synthesis of a Carboxylic Acid
1:37:59
Example: Synthesis of a Carboxylic Acid (Option 1)
1:38:00
Example: Synthesis of a Carboxylic Acid (Option 2)
1:40:51
Malonic Ester Synthesis of Carboxylic Acid
1:42:34
Malonic Ester Synthesis of Carboxylic Acid: Step 1
1:42:35
Malonic Ester Synthesis of Carboxylic Acid: Step 2
1:43:36
Malonic Ester Synthesis of Carboxylic Acid: Step 3
1:44:01
Example: Synthesis of a Carboxylic Acid
1:44:53
Example: Synthesis of a Carboxylic Acid
1:44:54
Synthesis of Carboxylic Acid Derivatives
1:48:05
Synthesis of Carboxylic Acid Derivatives
1:48:06
Alternate Ester Synthesis
1:48:58
Using Fischer Esterification
1:48:59
Using SN2 Reaction
1:50:18
Using Diazomethane
1:50:56
Using 1) LDA, 2) R'-X
1:52:15
Practice: Synthesis of an Alkyl Chloride
1:53:11
Practice: Synthesis of an Alkyl Chloride
1:53:12
Patterns of Functional Groups in Target Molecules
1:59:53
Recall: Aldol Reaction
1:59:54
β-hydroxy Ketone Target Molecule
2:01:12
α,β-unsaturated Ketone Target Molecule
2:02:20
Patterns of Functional Groups in Target Molecules
2:03:15
Recall: Michael Reaction
2:03:16
Retrosynthesis: 1,5-dicarbonyl Target Molecule
2:04:07
Patterns of Functional Groups in Target Molecules
2:06:38
Recall: Claisen Condensation
2:06:39
Retrosynthesis: β-ketoester Target Molecule
2:07:30
2-Group Target Molecule Summary
2:09:03
2-Group Target Molecule Summary
2:09:04
Example: Synthesis of Epoxy Ketone
2:11:19
Synthesize the Following Target Molecule from Cyclohexanone: Part 1 - Retrosynthesis
2:11:20
Synthesize the Following Target Molecule from Cyclohexanone: Part 2 - Synthesis
2:14:10
Example: Synthesis of a Diketone
2:16:57
Synthesis of a Diketone: Step 1 - Retrosynthesis
2:16:58
Synthesis of a Diketone: Step 2 - Synthesis
2:18:51
XII. Organic Synthesis & Organic Analysis
Organic Analysis: Classical & Modern Methods

46m 46s

Intro
0:00
Organic Analysis: Classical Methods
0:17
Classical Methods for Identifying Chemicals
0:18
Organic Analysis: Classical Methods
2:21
When is Structure Identification Needed?
2:22
Organic Analysis: Classical Methods
6:17
Classical Methods of Structure Identification: Physical Appearance
6:18
Classical Methods of Structure Identification: Physical Constants
6:42
Organic Analysis: Classical Methods
7:37
Classical Methods of Structure Identification: Solubility Tests - Water
7:38
Organic Analysis: Classical Methods
10:51
Classical Methods of Structure Identification: Solubility Tests - 5% aq. HCl Basic FG (Amines)
10:52
Organic Analysis: Classical Methods
11:50
Classical Methods of Structure Identification: Solubility Tests - 5% aq. NaOH Acidic FG (Carboxylic Acids, Phenols)
11:51
Organic Analysis: Classical Methods
13:28
Classical Methods of Structure Identification: Solubility Tests - 5% aq. NaHCO3 Strongly Acidic FG (Carboxylic Acids)
13:29
Organic Analysis: Classical Methods
15:35
Classical Methods of Structure Identification: Solubility Tests - Insoluble in All of the Above
15:36
Organic Analysis: Classical Methods
16:49
Classical Methods of Structure Identification: Idoform Test for Methyl Ketones
16:50
Organic Analysis: Classical Methods
22:02
Classical Methods of Structure Identification: Tollens' Test or Fehling's Solution for Aldehydes
22:03
Organic Analysis: Classical Methods
25:01
Useful Application of Classical Methods: Glucose Oxidase on Glucose Test Strips
25:02
Organic Analysis: Classical Methods
26:26
Classical Methods of Structure Identification: Starch-iodide Test
26:27
Organic Analysis: Classical Methods
28:22
Classical Methods of Structure Identification: Lucas Reagent to Determine Primary/Secondary/Tertiary Alcohol
28:23
Organic Analysis: Classical Methods
31:35
Classical Methods of Structure Identification: Silver Nitrate Test for Alkyl Halides
31:36
Organic Analysis: Classical Methods
33:23
Preparation of Derivatives
33:24
Organic Analysis: Modern Methods
36:55
Modern Methods of Chemical Characterization
36:56
Organic Analysis: Modern Methods
40:36
Checklist for Manuscripts Submitted to the ACS Journal Organic Letters
40:37
Organic Analysis: Modern Methods
42:39
Checklist for Manuscripts Submitted to the ACS Journal Organic Letters
42:40
Analysis of Stereochemistry

1h 2m 52s

Intro
0:00
Chirality & Optical Activity
0:32
Levorotatory & Dextrorotatory
0:33
Example: Optically Active?
2:22
Example: Optically Active?
2:23
Measurement of Specific Rotation, [α]
5:09
Measurement of Specific Rotation, [α]
5:10
Example: Calculation of Specific Rotation
8:56
Example: Calculation of Specific Rotation
8:57
Variability of Specific Rotation, [α]
12:52
Variability of Specific Rotation, [α]
12:53
Other Measures of Optical Activity: ORD and CD
15:04
Optical Rotary Dispersion (ORD)
15:05
Circular Dischroism (CD)
18:32
Circular Dischroism (CD)
18:33
Mixtures of Enantiomers
20:16
Racemic Mixtures
20:17
Unequal Mixtures of Enantiomers
21:36
100% ee
22:48
0% ee
23:34
Example: Definition of ee?
24:00
Example: Definition of ee?
24:01
Analysis of Optical Purity: [α]
27:47
[α] Measurement Can Be Used for Known Compounds
27:48
Analysis of Optical Purity: [α]
34:30
NMR Methods Using a Chiral Derivatizing Agent (CDA): Mosher's Reagent
34:31
Analysis of Optical Purity: [α]
40:01
NMR Methods Using a Chiral Derivatizing Agent (CDA): CDA Salt Formation
40:02
Analysis of Optical Purity: Chromatography
42:46
Chiral Chromatography
42:47
Stereochemistry Analysis by NMR: J Values (Coupling Constant)
51:28
NMR Methods for Structure Determination
51:29
Stereochemistry Analysis by NRM: NOE
57:00
NOE - Nuclear Overhauser Effect ( 2D Versions: NOESY or ROESY)
57:01
XIII. Spectroscopy
Infrared Spectroscopy, Part I

1h 4m

Intro
0:00
Infrared (IR) Spectroscopy
0:09
Introduction to Infrared (IR) Spectroscopy
0:10
Intensity of Absorption Is Proportional to Change in Dipole
3:08
IR Spectrum of an Alkane
6:08
Pentane
6:09
IR Spectrum of an Alkene
13:12
1-Pentene
13:13
IR Spectrum of an Alkyne
15:49
1-Pentyne
15:50
IR Spectrum of an Aromatic Compound
18:02
Methylbenzene
18:24
IR of Substituted Aromatic Compounds
24:04
IR of Substituted Aromatic Compounds
24:05
IR Spectrum of 1,2-Disubstituted Aromatic
25:30
1,2-dimethylbenzene
25:31
IR Spectrum of 1,3-Disubstituted Aromatic
27:15
1,3-dimethylbenzene
27:16
IR Spectrum of 1,4-Disubstituted Aromatic
28:41
1,4-dimethylbenzene
28:42
IR Spectrum of an Alcohol
29:34
1-pentanol
29:35
IR Spectrum of an Amine
32:39
1-butanamine
32:40
IR Spectrum of a 2° Amine
34:50
Diethylamine
34:51
IR Spectrum of a 3° Amine
35:47
Triethylamine
35:48
IR Spectrum of a Ketone
36:41
2-butanone
36:42
IR Spectrum of an Aldehyde
40:10
Pentanal
40:11
IR Spectrum of an Ester
42:38
Butyl Propanoate
42:39
IR Spectrum of a Carboxylic Acid
44:26
Butanoic Acid
44:27
Sample IR Correlation Chart
47:36
Sample IR Correlation Chart: Wavenumber and Functional Group
47:37
Predicting IR Spectra: Sample Structures
52:06
Example 1
52:07
Example 2
53:29
Example 3
54:40
Example 4
57:08
Example 5
58:31
Example 6
59:07
Example 7
1:00:52
Example 8
1:02:20
Infrared Spectroscopy, Part II

48m 34s

Intro
0:00
Interpretation of IR Spectra: a Basic Approach
0:05
Interpretation of IR Spectra: a Basic Approach
0:06
Other Peaks to Look for
3:39
Examples
5:17
Example 1
5:18
Example 2
9:09
Example 3
11:52
Example 4
14:03
Example 5
16:31
Example 6
19:31
Example 7
22:32
Example 8
24:39
IR Problems Part 1
28:11
IR Problem 1
28:12
IR Problem 2
31:14
IR Problem 3
32:59
IR Problem 4
34:23
IR Problem 5
35:49
IR Problem 6
38:20
IR Problems Part 2
42:36
IR Problem 7
42:37
IR Problem 8
44:02
IR Problem 9
45:07
IR Problems10
46:10
Nuclear Magnetic Resonance (NMR) Spectroscopy, Part I

1h 32m 14s

Intro
0:00
Purpose of NMR
0:14
Purpose of NMR
0:15
How NMR Works
2:17
How NMR Works
2:18
Information Obtained From a ¹H NMR Spectrum
5:51
No. of Signals, Integration, Chemical Shifts, and Splitting Patterns
5:52
Number of Signals in NMR (Chemical Equivalence)
7:52
Example 1: How Many Signals in ¹H NMR?
7:53
Example 2: How Many Signals in ¹H NMR?
9:36
Example 3: How Many Signals in ¹H NMR?
12:15
Example 4: How Many Signals in ¹H NMR?
13:47
Example 5: How Many Signals in ¹H NMR?
16:12
Size of Signals in NMR (Peak Area or Integration)
21:23
Size of Signals in NMR (Peak Area or Integration)
21:24
Using Integral Trails
25:15
Example 1: C₈H₁₈O
25:16
Example 2: C₃H₈O
27:17
Example 3: C₇H₈
28:21
Location of NMR Signal (Chemical Shift)
29:05
Location of NMR Signal (Chemical Shift)
29:06
¹H NMR Chemical Shifts
33:20
¹H NMR Chemical Shifts
33:21
¹H NMR Chemical Shifts (Protons on Carbon)
37:03
¹H NMR Chemical Shifts (Protons on Carbon)
37:04
Chemical Shifts of H's on N or O
39:01
Chemical Shifts of H's on N or O
39:02
Estimating Chemical Shifts
41:13
Example 1: Estimating Chemical Shifts
41:14
Example 2: Estimating Chemical Shifts
43:22
Functional Group Effects are Additive
45:28
Calculating Chemical Shifts
47:38
Methylene Calculation
47:39
Methine Calculation
48:20
Protons on sp³ Carbons: Chemical Shift Calculation Table
48:50
Example: Estimate the Chemical Shift of the Selected H
50:29
Effects of Resonance on Chemical Shifts
53:11
Example 1: Effects of Resonance on Chemical Shifts
53:12
Example 2: Effects of Resonance on Chemical Shifts
55:09
Example 3: Effects of Resonance on Chemical Shifts
57:08
Shape of NMR Signal (Splitting Patterns)
59:17
Shape of NMR Signal (Splitting Patterns)
59:18
Understanding Splitting Patterns: The 'n+1 Rule'
1:01:24
Understanding Splitting Patterns: The 'n+1 Rule'
1:01:25
Explanation of n+1 Rule
1:02:42
Explanation of n+1 Rule: One Neighbor
1:02:43
Explanation of n+1 Rule: Two Neighbors
1:06:23
Summary of Splitting Patterns
1:06:24
Summary of Splitting Patterns
1:10:45
Predicting ¹H NMR Spectra
1:10:46
Example 1: Predicting ¹H NMR Spectra
1:13:30
Example 2: Predicting ¹H NMR Spectra
1:19:07
Example 3: Predicting ¹H NMR Spectra
1:23:50
Example 4: Predicting ¹H NMR Spectra
1:29:27
Nuclear Magnetic Resonance (NMR) Spectroscopy, Part II

2h 3m 48s

Intro
0:00
¹H NMR Problem-Solving Strategies
0:18
Step 1: Analyze IR Spectrum (If Provided)
0:19
Step 2: Analyze Molecular Formula (If Provided)
2:06
Step 3: Draw Pieces of Molecule
3:49
Step 4: Confirm Pieces
6:30
Step 5: Put the Pieces Together!
7:23
Step 6: Check Your Answer!
8:21
Examples
9:17
Example 1: Determine the Structure of a C₉H₁₀O₂ Compound with the Following ¹H NMR Data
9:18
Example 2: Determine the Structure of a C₉H₁₀O₂ Compound with the Following ¹H NMR Data
17:27
¹H NMR Practice
20:57
¹H NMR Practice 1: C₁₀H₁₄
20:58
¹H NMR Practice 2: C₄H₈O₂
29:50
¹H NMR Practice 3: C₆H₁₂O₃
39:19
¹H NMR Practice 4: C₈H₁₈
50:19
More About Coupling Constants (J Values)
57:11
Vicinal (3-bond) and Geminal (2-bond)
57:12
Cyclohexane (ax-ax) and Cyclohexane (ax-eq) or (eq-eq)
59:50
Geminal (Alkene), Cis (Alkene), and Trans (Alkene)
1:02:40
Allylic (4-bond) and W-coupling (4-bond) (Rigid Structures Only)
1:04:05
¹H NMR Advanced Splitting Patterns
1:05:39
Example 1: ¹H NMR Advanced Splitting Patterns
1:05:40
Example 2: ¹H NMR Advanced Splitting Patterns
1:10:01
Example 3: ¹H NMR Advanced Splitting Patterns
1:13:45
¹H NMR Practice
1:22:53
¹H NMR Practice 5: C₁₁H₁₇N
1:22:54
¹H NMR Practice 6: C₉H₁₀O
1:34:04
¹³C NMR Spectroscopy
1:44:49
¹³C NMR Spectroscopy
1:44:50
¹³C NMR Chemical Shifts
1:47:24
¹³C NMR Chemical Shifts Part 1
1:47:25
¹³C NMR Chemical Shifts Part 2
1:48:59
¹³C NMR Practice
1:50:16
¹³C NMR Practice 1
1:50:17
¹³C NMR Practice 2
1:58:30
C-13 DEPT NMR Experiments

23m 10s

Intro
0:00
C-13 DEPT NMR Spectoscopy
0:13
Overview
0:14
C-13 DEPT NMR Spectoscopy, Cont.
3:31
Match C-13 Peaks to Carbons on Structure
3:32
C-13 DEPT NMR Spectoscopy, Cont.
8:46
Predict the DEPT-90 and DEPT-135 Spectra for the Given Compound
8:47
C-13 DEPT NMR Spectoscopy, Cont.
12:30
Predict the DEPT-90 and DEPT-135 Spectra for the Given Compound
12:31
C-13 DEPT NMR Spectoscopy, Cont.
17:19
Determine the Structure of an Unknown Compound using IR Spectrum and C-13 DEPT NMR
17:20
Two-Dimensional NMR Techniques: COSY

33m 39s

Intro
0:00
Two-Dimensional NMR Techniques: COSY
0:14
How Do We Determine Which Protons are Related in the NMR?
0:15
Two-Dimensional NMR Techniques: COSY
1:48
COSY Spectra
1:49
Two-Dimensional NMR Techniques: COSY
7:00
COSY Correlation
7:01
Two-Dimensional NMR Techniques: COSY
8:55
Complete the COSY NMR Spectrum for the Given Compoun
8:56
NMR Practice Problem
15:40
Provide a Structure for the Unknown Compound with the H NMR and COSY Spectra Shown
15:41
Two-Dimensional NMR Techniques: HETCOR & HMBC

15m 5s

Intro
0:00
HETCOR
0:15
Heteronuclear Correlation Spectroscopy
0:16
HETCOR
2:04
HETCOR Example
2:05
HMBC
11:07
Heteronuclear Multiple Bond Correlation
11:08
HMBC
13:14
HMB Example
13:15
Mass Spectrometry

1h 28m 35s

Intro
0:00
Introduction to Mass Spectrometry
0:37
Uses of Mass Spectrometry: Molecular Mass
0:38
Uses of Mass Spectrometry: Molecular Formula
1:04
Uses of Mass Spectrometry: Structural Information
1:21
Uses of Mass Spectrometry: In Conjunction with Gas Chromatography
2:03
Obtaining a Mass Spectrum
2:59
Obtaining a Mass Spectrum
3:00
The Components of a Mass Spectrum
6:44
The Components of a Mass Spectrum
6:45
What is the Mass of a Single Molecule
12:13
Example: CH₄
12:14
Example: ¹³CH₄
12:51
What Ratio is Expected for the Molecular Ion Peaks of C₂H₆?
14:20
Other Isotopes of High Abundance
16:30
Example: Cl Atoms
16:31
Example: Br Atoms
18:33
Mass Spectrometry of Chloroethane
19:22
Mass Spectrometry of Bromobutane
21:23
Isotopic Abundance can be Calculated
22:48
What Ratios are Expected for the Molecular Ion Peaks of CH₂Br₂?
22:49
Determining Molecular Formula from High-resolution Mass Spectrometry
26:53
Exact Masses of Various Elements
26:54
Fragmentation of various Functional Groups
28:42
What is More Stable, a Carbocation C⁺ or a Radical R?
28:43
Fragmentation is More Likely If It Gives Relatively Stable Carbocations and Radicals
31:37
Mass Spectra of Alkanes
33:15
Example: Hexane
33:16
Fragmentation Method 1
34:19
Fragmentation Method 2
35:46
Fragmentation Method 3
36:15
Mass of Common Fragments
37:07
Mass of Common Fragments
37:08
Mass Spectra of Alkanes
39:28
Mass Spectra of Alkanes
39:29
What are the Peaks at m/z 15 and 71 So Small?
41:01
Branched Alkanes
43:12
Explain Why the Base Peak of 2-methylhexane is at m/z 43 (M-57)
43:13
Mass Spectra of Alkenes
45:42
Mass Spectra of Alkenes: Remove 1 e⁻
45:43
Mass Spectra of Alkenes: Fragment
46:14
High-Energy Pi Electron is Most Likely Removed
47:59
Mass Spectra of Aromatic Compounds
49:01
Mass Spectra of Aromatic Compounds
49:02
Mass Spectra of Alcohols
51:32
Mass Spectra of Alcohols
51:33
Mass Spectra of Ethers
54:53
Mass Spectra of Ethers
54:54
Mass Spectra of Amines
56:49
Mass Spectra of Amines
56:50
Mass Spectra of Aldehydes & Ketones
59:23
Mass Spectra of Aldehydes & Ketones
59:24
McLafferty Rearrangement
1:01:29
McLafferty Rearrangement
1:01:30
Mass Spectra of Esters
1:04:15
Mass Spectra of Esters
1:01:16
Mass Spectrometry Discussion I
1:05:01
For the Given Molecule (M=58), Do You Expect the More Abundant Peak to Be m/z 15 or m/z 43?
1:05:02
Mass Spectrometry Discussion II
1:08:13
For the Given Molecule (M=74), Do You Expect the More Abundant Peak to Be m/z 31, m/z 45, or m/z 59?
1:08:14
Mass Spectrometry Discussion III
1:11:42
Explain Why the Mass Spectra of Methyl Ketones Typically have a Peak at m/z 43
1:11:43
Mass Spectrometry Discussion IV
1:14:46
In the Mass Spectrum of the Given Molecule (M=88), Account for the Peaks at m/z 45 and m/z 57
1:14:47
Mass Spectrometry Discussion V
1:18:25
How Could You Use Mass Spectrometry to Distinguish Between the Following Two Compounds (M=73)?
1:18:26
Mass Spectrometry Discussion VI
1:22:45
What Would be the m/z Ratio for the Fragment for the Fragment Resulting from a McLafferty Rearrangement for the Following Molecule (M=114)?
1:22:46
XIV. Organic Chemistry Lab
Completing the Reagent Table for Prelab

21m 9s

Intro
0:00
Sample Reagent Table
0:11
Reagent Table Overview
0:12
Calculate Moles of 2-bromoaniline
6:44
Calculate Molar Amounts of Each Reagent
9:20
Calculate Mole of NaNO₂
9:21
Calculate Moles of KI
10:33
Identify the Limiting Reagent
11:17
Which Reagent is the Limiting Reagent?
11:18
Calculate Molar Equivalents
13:37
Molar Equivalents
13:38
Calculate Theoretical Yield
16:40
Theoretical Yield
16:41
Calculate Actual Yield (%Yield)
18:30
Actual Yield (%Yield)
18:31
Introduction to Melting Points

16m 10s

Intro
0:00
Definition of a Melting Point (mp)
0:04
Definition of a Melting Point (mp)
0:05
Solid Samples Melt Gradually
1:49
Recording Range of Melting Temperature
2:04
Melting Point Theory
3:14
Melting Point Theory
3:15
Effects of Impurities on a Melting Point
3:57
Effects of Impurities on a Melting Point
3:58
Special Exception: Eutectic Mixtures
5:09
Freezing Point Depression by Solutes
5:39
Melting Point Uses
6:19
Solid Compound
6:20
Determine Purity of a Sample
6:42
Identify an Unknown Solid
7:06
Recording a Melting Point
9:03
Pack 1-3 mm of Dry Powder in MP Tube
9:04
Slowly Heat Sample
9:55
Record Temperature at First Sign of Melting
10:33
Record Temperature When Last Crystal Disappears
11:26
Discard MP Tube in Glass Waste
11:32
Determine Approximate MP
11:42
Tips, Tricks and Warnings
12:28
Use Small, Tightly Packed Sample
12:29
Be Sure MP Apparatus is Cool
12:45
Never Reuse a MP Tube
13:16
Sample May Decompose
13:30
If Pure Melting Point (MP) Doesn't Match Literature
14:20
Melting Point Lab

8m 17s

Intro
0:00
Melting Point Tubes
0:40
Melting Point Apparatus
3:42
Recording a melting Point
5:50
Introduction to Recrystallization

22m

Intro
0:00
Crystallization to Purify a Solid
0:10
Crude Solid
0:11
Hot Solution
0:20
Crystals
1:09
Supernatant Liquid
1:20
Theory of Crystallization
2:34
Theory of Crystallization
2:35
Analysis and Obtaining a Second Crop
3:40
Crystals → Melting Point, TLC
3:41
Supernatant Liquid → Crude Solid → Pure Solid
4:18
Crystallize Again → Pure Solid (2nd Crop)
4:32
Choosing a Solvent
5:19
1. Product is Very Soluble at High Temperatures
5:20
2. Product has Low Solubility at Low Temperatures
6:00
3. Impurities are Soluble at All Temperatures
6:16
Check Handbooks for Suitable Solvents
7:33
Why Isn't This Dissolving?!
8:46
If Solid Remains When Solution is Hot
8:47
Still Not Dissolved in Hot Solvent?
10:18
Where Are My Crystals?!
12:23
If No Crystals Form When Solution is Cooled
12:24
Still No Crystals?
14:59
Tips, Tricks and Warnings
16:26
Always Use a Boiling Chip or Stick!
16:27
Use Charcoal to Remove Colored Impurities
16:52
Solvent Pairs May Be Used
18:23
Product May 'Oil Out'
20:11
Recrystallization Lab

19m 7s

Intro
0:00
Step 1: Dissolving the Solute in the Solvent
0:12
Hot Filtration
6:33
Step 2: Cooling the Solution
8:01
Step 3: Filtering the Crystals
12:08
Step 4: Removing & Drying the Crystals
16:10
Introduction to Distillation

25m 54s

Intro
0:00
Distillation: Purify a Liquid
0:04
Simple Distillation
0:05
Fractional Distillation
0:55
Theory of Distillation
1:04
Theory of Distillation
1:05
Vapor Pressure and Volatility
1:52
Vapor Pressure
1:53
Volatile Liquid
2:28
Less Volatile Liquid
3:09
Vapor Pressure vs. Boiling Point
4:03
Vapor Pressure vs. Boiling Point
4:04
Increasing Vapor Pressure
4:38
The Purpose of Boiling Chips
6:46
The Purpose of Boiling Chips
6:47
Homogeneous Mixtures of Liquids
9:24
Dalton's Law
9:25
Raoult's Law
10:27
Distilling a Mixture of Two Liquids
11:41
Distilling a Mixture of Two Liquids
11:42
Simple Distillation: Changing Vapor Composition
12:06
Vapor & Liquid
12:07
Simple Distillation: Changing Vapor Composition
14:47
Azeotrope
18:41
Fractional Distillation: Constant Vapor Composition
19:42
Fractional Distillation: Constant Vapor Composition
19:43
Distillation Lab

24m 13s

Intro
0:00
Glassware Overview
0:04
Heating a Sample
3:09
Bunsen Burner
3:10
Heating Mantle 1
4:45
Heating Mantle 2
6:18
Hot Plate
7:10
Simple Distillation Lab
8:37
Fractional Distillation Lab
17:13
Removing the Distillation Set-Up
22:41
Introduction to TLC (Thin-Layer Chromatography)

28m 51s

Intro
0:00
Chromatography
0:06
Purification & Analysis
0:07
Types of Chromatography: Thin-layer, Column, Gas, & High Performance Liquid
0:24
Theory of Chromatography
0:44
Theory of Chromatography
0:45
Performing a Thin-layer Chromatography (TLC) Analysis
2:30
Overview: Thin-layer Chromatography (TLC) Analysis
2:31
Step 1: 'Spot' the TLC Plate
4:11
Step 2: Prepare the Developing Chamber
5:54
Step 3: Develop the TLC Plate
7:30
Step 4: Visualize the Spots
9:02
Step 5: Calculate the Rf for Each Spot
12:00
Compound Polarity: Effect on Rf
16:50
Compound Polarity: Effect on Rf
16:51
Solvent Polarity: Effect on Rf
18:47
Solvent Polarity: Effect on Rf
18:48
Example: EtOAc & Hexane
19:35
Other Types of Chromatography
22:27
Thin-layer Chromatography (TLC)
22:28
Column Chromatography
22:56
High Performance Liquid (HPLC)
23:59
Gas Chromatography (GC)
24:38
Preparative 'prep' Scale Possible
28:05
TLC Analysis Lab

20m 50s

Intro
0:00
Step 1: 'Spot' the TLC Plate
0:06
Step 2: Prepare the Developing Chamber
4:06
Step 3: Develop the TLC Plate
6:26
Step 4: Visualize the Spots
7:45
Step 5: Calculate the Rf for Each Spot
11:48
How to Make Spotters
12:58
TLC Plate
16:04
Flash Column Chromatography
17:11
Introduction to Extractions

34m 25s

Intro
0:00
Extraction Purify, Separate Mixtures
0:07
Adding a Second Solvent
0:28
Mixing Two Layers
0:38
Layers Settle
0:54
Separate Layers
1:05
Extraction Uses
1:20
To Separate Based on Difference in Solubility/Polarity
1:21
To Separate Based on Differences in Reactivity
2:11
Separate & Isolate
2:20
Theory of Extraction
3:03
Aqueous & Organic Phases
3:04
Solubility: 'Like Dissolves Like'
3:25
Separation of Layers
4:06
Partitioning
4:14
Distribution Coefficient, K
5:03
Solutes Partition Between Phases
5:04
Distribution Coefficient, K at Equilibrium
6:27
Acid-Base Extractions
8:09
Organic Layer
8:10
Adding Aqueous HCl & Mixing Two Layers
8:46
Neutralize (Adding Aqueous NaOH)
10:05
Adding Organic Solvent Mix Two Layers 'Back Extract'
10:24
Final Results
10:43
Planning an Acid-Base Extraction, Part 1
11:01
Solute Type: Neutral
11:02
Aqueous Solution: Water
13:40
Solute Type: Basic
14:43
Solute Type: Weakly Acidic
15:23
Solute Type: Acidic
16:12
Planning an Acid-Base Extraction, Part 2
17:34
Planning an Acid-Base Extraction
17:35
Performing an Extraction
19:34
Pour Solution into Sep Funnel
19:35
Add Second Liquid
20:07
Add Stopper, Cover with Hand, Remove from Ring
20:48
Tip Upside Down, Open Stopcock to Vent Pressure
21:00
Shake to Mix Two Layers
21:30
Remove Stopper & Drain Bottom Layer
21:40
Reaction Work-up: Purify, Isolate Product
22:03
Typical Reaction is Run in Organic Solvent
22:04
Starting a Reaction Work-up
22:33
Extracting the Product with Organic Solvent
23:17
Combined Extracts are Washed
23:40
Organic Layer is 'Dried'
24:23
Finding the Product
26:38
Which Layer is Which?
26:39
Where is My Product?
28:00
Tips, Tricks and Warnings
29:29
Leaking Sep Funnel
29:30
Caution When Mixing Layers & Using Ether
30:17
If an Emulsion Forms
31:51
Extraction Lab

14m 49s

Intro
0:00
Step 1: Preparing the Separatory Funnel
0:03
Step 2: Adding Sample
1:18
Step 3: Mixing the Two Layers
2:59
Step 4: Draining the Bottom Layers
4:59
Step 5: Performing a Second Extraction
5:50
Step 6: Drying the Organic Layer
7:21
Step 7: Gravity Filtration
9:35
Possible Extraction Challenges
12:55
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Lecture Comments (26)

1 answer

Last reply by: Professor Starkey
Sun Feb 11, 2018 11:01 PM

Post by Robert White on February 8 at 01:58:06 AM

Hello, at 22:00 when you try to synthesize bromopropane could you use TsCl with Pyridine to make the OH into a good LG then add NaBr to cause a SN2 reaction to form the bromopropane?  

1 answer

Last reply by: Professor Starkey
Mon Nov 14, 2016 2:42 PM

Post by Danielle Taylor on November 12, 2016

Dr. Starkey,

At 26 minutes in making the phenol , why could you not have brominated the tertiary carbon and made the phenol group an alcohol and allowed the reaction to take place via sn1?

1 answer

Last reply by: Professor Starkey
Mon Nov 14, 2016 2:35 PM

Post by Danielle Taylor on November 12, 2016

Hi Dr. Starkey, at 22 minutes when your talking about the systhesis of dipropyl ether, why would you need to even use a alkyl halide, could you not just react two moles of propanol with H2SO4 to create the symmetric ether ?

1 answer

Last reply by: s n
Sat Aug 6, 2016 6:40 PM

Post by s n on August 6, 2016

Hi Dr. Starkey, as usual, fantastic lecture. I did, however, have a question on "Example 4: Transform" (minute 28). You say that the reaction of Ph-C-Cl with tBuO- is an example of a great SN2 reaction mechanism, but in the elimination reactions video, you said that tBuO- is so bulky of a base/nucleophile that it us unable to perform a backside attack. So, I am confused because I thought that SN2 would not be possible with tBuO-. I thought that there will be no reaction because E2 cannot work either because the neighboring carbon has no beta hydrogens for de-protonation. Any help would be much appreciated. Thanks for being such an awesome professor.  

1 answer

Last reply by: Professor Starkey
Sun Mar 27, 2016 11:45 AM

Post by Rey Ganado on March 27, 2016

Hi Dr. Starkey,
I just want to know if I'm doing this right. If I react epoxide with H2SO4 and water, will I form a diol?

1 answer

Last reply by: Professor Starkey
Thu Apr 18, 2013 10:56 AM

Post by Dr. Son's Statistics Class on April 16, 2013

Dr. Starkey, In McMurry's 8th Edition, it states that during acid catalyzed ring opening, the nucleophillic attack will occur in primary if primary and secondary occurs due to the primary being less substituted. However if there is a tertiary, the nucleophile will attack there. I am not sure which one is right. Dr. Athar Ata also states that tertiary carbon will have carbocation character therefore it explains the nucleophilic attack. Could you let me know if this is right.

1 answer

Last reply by: Professor Starkey
Tue Dec 11, 2012 4:19 PM

Post by Organic Chemistry on December 10, 2012

What exactly is the difference between a good nucleophile and a good base? Are we just supposed to memorize a list of the common ones of each? You mention both in your lecture but don't they mean the same thing?

3 answers

Last reply by: Professor Starkey
Mon Oct 15, 2012 10:00 PM

Post by Nigel Hessing on October 11, 2012

At 29:11, you say that the secondary partial positive has more electrophilic character but alkyl groups are electron donating so I don't understand why it would be more electrophilic?? Can you please clarify?

1 answer

Last reply by: Professor Starkey
Mon Jul 30, 2012 12:04 AM

Post by Bien Grama on July 27, 2012

in 29:00 can i use PBr3 to convert the SM to alkylhalide? thank you =D

1 answer

Last reply by: Professor Starkey
Mon Feb 13, 2012 12:01 AM

Post by Rua Oshana on February 11, 2012

Hi Dr. Starkey,
what is it exactly about the Epoxide that makes it highly reactive?
Thank you

1 answer

Last reply by: Professor Starkey
Sat Jul 30, 2011 12:07 AM

Post by Daniela Valencia on July 9, 2011

Dr. Starkey
in 32:12 It is possible to deprotonate the OH with NaOH instead of using a stronger base such as NaH to create an alkoxide?

1 answer

Last reply by: Professor Starkey
Sat Jul 30, 2011 12:44 AM

Post by Jamie Spritzer on June 24, 2011

in 64:20 do you also need NaOH or KOH as well?

Ethers

Draw the mechanism and predict the product for this reaction:
  • Step 1: Formation of an alkoxide nucleophile
  • Step 2: SN2 reaction to form ether
Draw the two possible synthesis routes for the following target molecule and state which route is preferred:
  • Route 1:
  • Route 2:
  • The preferred path has the less hindered halide (RX)
  • Route 1 has a 1o halide and while route 2 has a 2o halide
The preferred route is route 1.
Draw the product formed from this reaction:
Draw the product formed from this reaction:
Draw the product formed from this reaction:
  • This is an acid-catalyzed reaction therefore CH3CH2O ends up on the more substituted Carbon.
Draw the product formed from this reaction:
  • This is a base-catalyzed reaction therefore CN ends up on the less substituted Carbon.

*These practice questions are only helpful when you work on them offline on a piece of paper and then use the solution steps function to check your answer.

Answer

Ethers

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Ethers 0:11
    • Overview of Ethers
    • Boiling Points
  • Ethers 4:34
    • Water Solubility (Grams per 100mL H₂O)
  • Synthesis of Ethers 7:53
    • Williamson Ether Synthesis
    • Example: Synthesis of Ethers
  • Synthesis of Ethers 10:27
    • Example: Synthesis of Ethers
    • Intramolecular SN2
  • Planning an Ether Synthesis 14:45
    • Example 1: Planning an Ether Synthesis
  • Planning an Ether Synthesis 16:16
    • Example 2: Planning an Ether Synthesis
  • Planning an Ether Synthesis 22:04
    • Example 3: Synthesize Dipropyl Ether
  • Planning an Ether Synthesis 26:01
    • Example 4: Transform
  • Synthesis of Epoxides 30:05
    • Synthesis of Epoxides Via Williamson Ether Synthesis
    • Synthesis of Epoxides Via Oxidation
  • Reaction of Ethers 33:35
    • Reaction of Ethers
  • Reactions of Ethers with HBr or HI 34:44
    • Reactions of Ethers with HBr or HI
    • Mechanism
  • Epoxide Ring-Opening Reaction 39:25
    • Epoxide Ring-Opening Reaction
    • Example: Epoxide Ring-Opening Reaction
  • Acid-Catalyzed Epoxide Ring Opening 44:16
    • Acid-Catalyzed Epoxide Ring Opening Mechanism
  • Acid-Catalyzed Epoxide Ring Opening 50:13
    • Acid-Catalyzed Epoxide Ring Opening Mechanism
  • Catalyst Needed for Ring Opening 53:34
    • Catalyst Needed for Ring Opening
  • Stereochemistry of Epoxide Ring Opening 55:56
    • Stereochemistry: SN2 Mechanism
    • Acid or Base Mechanism?
  • Example 1:01:03
    • Transformation
  • Regiochemistry of Epoxide Ring Openings 1:05:29
    • Regiochemistry of Epoxide Ring Openings in Base
    • Regiochemistry of Epoxide Ring Openings in Acid
  • Example 1:10:26
    • Example 1: Epoxide Ring Openings in Base
    • Example 2: Epoxide Ring Openings in Acid
  • Reactions of Epoxides with Grignard and Hydride 1:15:35
    • Reactions of Epoxides with Grignard and Hydride
  • Example 1:21:47
    • Example: Ethers
  • Example 1:27:01
    • Example: Synthesize

Transcription: Ethers

Welcome back to Educator.0000

Next we are going to talk about a functional group called ethers.0002

We will discuss their physical properties; we will discuss how to synthesize them; then we will talk about the reactions they undergo.0004

An ether is defined as a functional group that has an oxygen with a carbon group on either side.0013

Because this has no OH group like an alcohol, it cannot undergo hydrogen bonding between ether molecules; that is going to be a very big difference.0020

What it is really going to be doing, because we have no hydrogen bonding, is we are going to see a decrease in boiling points of ethers when compared to alcohols.0029

However it is a polar molecule; when we think about the hybridization of that oxygen, it is tetrahedral; it is sp3 hybridized.0039

These are both polar bonds; there is a net dipole moment; so ethers are polar molecules; we will see that they make very good solvents for that reason.0050

Because of the oxygen that they contain, they can accept hydrogen bonds from water.0062

Although an ether cannot hydrogen bond with another ether molecule, it can be a hydrogen bond acceptor.0067

Meaning if there was another molecule with an O-H bond like water, then we can have a hydrogen bond forming between the partial negative oxygen and the partial positive hydrogen.0078

That means the interaction between water and an ether molecule is very good; we expect to have some water solubility as a result.0091

Let's take a look at some boiling points; again we have seen some of these molecules in the past when we were looking at alcohols.0098

I think it is still very useful to compare alcohols and ethers because they are both oxygen containing functional groups.0103

The simplest ether we could have here is dimethyl ether; you can see that there is very little attraction between dimethyl ether molecules .0110

So that the boiling point is -24 degrees C; that means at room temperature, this is a gas; the simplest ether is not a liquid.0119

It is only when we get to diethyl ether which has about the same molecular weight as pentane that we get to a liquid form.0128

Just like alkanes, you have to have a significant molecular weight before you have strong enough intermolecular attractions because of those van der Waals forces.0136

That you are going to be maintained as a liquid at room temperature; you can see these have about the same molecular weight and they have about the same boiling point.0144

Even though this is a slightly more polar molecule, you can see there is not a huge attraction between ether molecules.0154

Because it has about the same boiling point as if it didn't have an oxygen at all, just a plain old alkane.0161

However when we go from a diethyl ether to this one, this is called MTBE for short; we have a methyl over here; we have a tert-butyl over here.0168

That is a way that we can have a common name for an ether--is we simply list the two alkyl groups on either side of the ether.0180

Just like we call this diethyl ether, this is commonly known as methyl tert-butyl ether; you can see that we have a jump in our boiling point.0188

The reason for that now is we are increasing our molecular weight; as usual as we increase our molecular weight, we increase our boiling point.0199

But you can see that all these are so much lower boiling than something like ethanol even though this is a very small molecule.0207

The fact that it has an OH group means that it can undergo hydrogen bonding; that is really the number one thing you want to look for for things that affect the boiling point.0213

Because that is such a strong intermolecular attraction; it is going to have huge impacts on the boiling point temperature.0229

I mention MTBE because this is something... these letters are something you might see on a gas dispenser at a gas station; this is a fuel additive.0236

We look for oxygenated fuel additives to affect the efficiency of the burning and how cleanly it burns and whether or not it knocks and all those sorts of things.0254

There are a variety of things that go into gasoline mixtures other than just the plain old hydrocarbons--that is really all you need to do the combustion part.0262

But what we can see on the next slide when we look at the water solubility of these ethers, we find that because it can accept hydrogen bonding, we do have some water solubility.0273

Again comparing our pentane to our diethyl ether, we go from something that is completely nonpolar to something that is polar and can accept hydrogen bonds.0285

Suddenly we have a decent interaction with water; we do get some water solubility; about 8 grams of diethyl ether can dissolve in about 100 milliters of water.0298

I discussed this a little before when we looked at this molecule for looking at the alcohol boiling points.0312

Just a little note here that anytime we do an extractive workup in a reaction, our ether layer, when we say we are using ether in a reaction or ether as a solvent.0318

This is the ether we are talking about--is diethyl ether; this is the one we most commonly use; it is referred to as just plain ether.0328

When we do an extractive workup like in a sep funnel where we have both ether and water, we will note that the ether layer is wet, meaning it contains water.0337

It must be dried as part of your workup procedure in order to isolate your product from that organic layer, that ether layer.0348

We expect alcohols to be fairly soluble in water; but again depending on the length of our polar and nonpolar, we see increased solubility when we have a smaller nonpolar group.0359

This is because it has a large nonpolar region, that is going to decrease the water solubility; but a smaller alcohol like ethanol is going to be miscible.0376

We are back to showing MTBE; what is interesting about showing MTBE is that because it is an ether, it has some water solubility.0389

Even though it has this tert-butyl group, it is compact and won't disrupt the water molecules too much.0397

What is interesting about this is if you have a component in your gasoline that is water soluble, then if that gasoline were ever to spill onto the ground.0405

Or if it were to leak from a container, then this component is something that can make its way into the ground water because it is soluble in water.0415

The reason, MTBE, you might find some of that in the news or an issue of discussion is because MTBE is very easily detected by humans at very very low concentrations.0426

If you get some of this in your water supply, the water is going to taste a little funny or smell a little funny; of course that is not acceptable to consumers.0441

It is not that this is necessarily something that is going to be real bad for you.0448

But if it is something that gives your water a bad taste, then this is something that we need to find replacements for.0452

There is a lot research going into just the perfect kind of oxygenated structure that is going to improve our gasoline performance but not be something that has significant water solubility.0460

How would we synthesize an ether structure?--there are a few options that we have for us; one of the most common ways is something known as the Williamson ether synthesis.0475

Here is an example of it; if we take an alkoxide, in other words, we have an RO-, an alkoxide, and we react it with an alkyl halide.0485

It looks like we have a perfect situation for a nucleophile, electron rich negative charge, coming together with an electrophile; this carbon bearing the leaving group is partially positive.0498

Electrophile and nucleophile coming together, they are going to react; what reaction mechanism would you expect to happen for these pair of compounds?0510

I would expect that my lone pair on my oxygen can attack that partially positive carbon, that electrophilic carbon, and kick off the leaving group.0518

It looks like backside attack; it looks like an Sn2 mechanism; that can happen quite nicely.0526

What product do we get?--our methoxy group has replaced our bromine; how would you describe the structure we just made?--we just made an ether.0532

This is one thing that is very useful to note--is that if you take an alkoxide and an alkyl halide, you can make an ether by doing an Sn2 mechanism.0548

That is very good to keep in mind; it is going to be very useful to us when we are trying to make a variety of ethers.0559

An example of this strategy would be to start with this alcohol; step one, we would react the alcohol with NaH, sodium hydride; that looks like we have H-.0565

Where have we seen sodium hydride before?--this is very good base; this is a very good base; we have seen it as a way to convert an alcohol to an alkoxide.0576

In other words, this can be used to deprotonate the oxygen and form an alkoxide.0590

Once we have an alkoxide, now in step two, we could add a phenyl CH2I; that is benzyl iodide; there is our electrophile.0598

If we react our alkoxide with our alkyl halide, we can do an Sn2; we have just created an ether.0609

This would be a way of going from an alcohol to an ether--make the alkoxide and react it with an alkyl halide.0619

Let's look at another example; how about if we had not just an alcohol but we had this structure that has both a chlorine, a leaving group and an alcohol on the same structure.0629

We react this with something that can act as a base; that can act as a base; one thing you might imagine is that hydroxide can also act as a nucleophile.0639

The hydroxide might come right out and want to attack the carbon and kick off the leaving group.0652

While that is a reaction that can happen, there is another reaction that is going to be happening faster; that is the acid-base reaction.0659

Acid-base reactions are the fastest reactions we can have; if there is a possibility of that, that is the first path we want to take.0666

In other words, what is going to happen is it is going to act as a base; it is going to deprotonate; this is not a strong enough base like sodium hydride to 100% deprotonate the alcohol.0674

But we will set up an equilibrium; we will form some of this O- to generate some of this alkoxide.0686

What that does for us is that makes an excellent nucleophile; this oxygen is now negatively charged.0696

Guess what?--if we see in the same structure, we see a partially positive carbon, we see an electrophile.0704

Then we can have an intramolecular reaction take place if those two are properly separated, properly situated.0710

Let's see what size ring we would form; anytime we have an intramolecular reaction between a nucleophile and an electrophile, that means we are going to form a ring.0719

With this oxygen, we would be forming a one, two, three, four, five-membered ring; it turns out that is a great size ring to form; so we do expect this reaction to happen.0727

As usual, an Sn2 like this, a backside attack, kicking off a good leaving group is not going to be a reversible reaction.0739

Kicking off that better leaving group is going to be what drives this reaction in the forward direction.0749

Even though this deprotonation is reversible and maybe we will just form a very small concentration of this alkoxide, the fact that as soon as the alkoxide is formed.0754

It can do an Sn2 to give this product; then that is something that forces the reaction in the forward direction; it does make this a favorable reaction.0766

We can number our atoms one, two, three, four, five, so you can follow along to see how we just made that ring.0776

We can describe this as an intramolecular Sn2; really it is better to describe this as an intramolecular backside attack; but it is similar to our Sn2 mechanism.0785

When it is intramolecular, it is going to give cyclic ethers; when can we have such cyclization reactions?--remember we can have it when we have a very very small ring like a three-membered ring.0792

That is where our nucleophile and our electrophile are just so close to each other that they will react.0803

But then we jump to five or six-membered rings; those are best ones because those have very little ring strain, little to no ring strain.0809

It is going to be a very favorable transition state, very low energy, and will be a fast reaction.0818

When you consider that this intermolecular Sn2 could have taken place, what we will find is that the intramolecular reaction is always going to be favored.0825

If there is a possibility for an intramolecular reaction, that is going to be the favorable reaction; that will be our major product; that is simply a factor of entropy.0835

The fact that the nucleophile and the electrophile are tethered together, they are already connected, means that they no longer have to come together and collide randomly.0843

Because it is so well favored entropically, when we see an intramolecular reaction is an option, that is the one we should go for as the major product.0854

How might I be suspicious here?--look we have a single starting material here; it has two functional groups.0862

It has something that is potentially nucleophilic and something that is potentially electrophilic.0868

That is something that you would really want to tip off to--let's consider an intramolecular reaction.0872

When we have a haloalcohol and we treat it with any kind of base, we can get a cyclic ether being formed.0877

If we wanted to plan a synthesis, how do we go about that?0888

Knowing that we can do a Williamson ether synthesis, the disconnection that we would make to form an ether would be either one of these carbon-oxygen bonds.0893

We would disconnect on either side of the oxygen; we make a disconnection; remember we are asking what starting materials do I need in this retrosynthesis?0905

When we consider these two atoms that we are trying to bring together in the reaction, we are trying to react an oxygen with a carbon.0921

The oxygen of course is electron rich; that makes a good nucleophile; this was my nucleophile; this was my electrophile.0928

What we should go backwards to is to make this oxygen a good nucleophile, we use the alkoxide; to make this carbon a good electrophile, we use an alkyl halide.0937

An alkoxide plus an alkyl halide gives an ether; an alkoxide plus an alkyl halide gives an ether.0955

That means if we have an ether target molecule, one possible retrosynthesis would be go backwards to the corresponding alkoxide and alkyl halide.0961

Let's see a sample ether; because this is not a symmetrical ether, there is two possible disconnections; I could disconnect this carbon-oxygen bond; let's call that disconnection A.0978

We are going back to some kind of alkoxide and alkyl halide; the group on the right is obviously my oxygen containing group.0995

That would be my alkoxide; that would be my nucleophile; what would that nucleophile be reacting with?1006

It would be this one carbon alkyl halide, CH3... let's pick any halogen; I think the iodide is the best choice because there is just the methyl; that is a liquid reagent.1014

This combination of alkoxide and alkyl halide would combine to give this ether target molecule.1026

But there is another disconnection; we can go on this side; as our synthesis formed, this is our new carbon-oxygen bond; let's consider that synthesis as well.1033

If we disconnected here then it would be the methoxy group that would come in as my nucleophile; that would be my alkoxide; what would it react with?1044

We need an alkyl halide; we need this three-carbon alkyl halide; again your choice--bromide, chlorine, iodine, any halogen that you want is fine.1056

There is two possible disconnections; are they both equally good?--in order to answer that question, we need to imagine doing the synthesis then and taking this reaction.1071

Taking isoproproxide and methyl iodide and combining the two, what reaction do you expect to have happen?--we know we want to do an Sn2 mechanism.1083

Is this a good Sn2 mechanism?--backside attack is very sensitive to steric hindrance; we want to make sure there is very little steric hindrance.1094

We look at the carbon bearing the leaving group; that is the carbon that needs to get approached by the nucleophile; this is a methyl leaving group.1103

Is that good for an Sn2?--it is the best fastest Sn2 we can have; this is a great Sn2; I would expect this to work very nicely to give the target molecule.1115

How about the second case?--again we want to do an Sn2; our alkoxide needs to attack the alkyl halide; how would you describe the carbon bearing the leaving group in synthesis B?1129

Here we have a secondary leaving group; clearly it has more steric hindrance; now we have these two methyl groups we need to get around.1141

Remember that an alkoxide is a nucleophile but it is also a very good base; it is a very strong base.1149

What we have with methoxide, just like we would have for hydroxide, we have a competition between the Sn2 and the E2.1159

If it acts as a base, in other words, instead of attacking the carbon bearing the leaving group.1167

If it attacked one of these β hydrogens and formed a π bond and kicked out the leaving group that would be the E2; in fact the E2 for secondary is major.1172

What would my product look like?--I would get a CH2CHCH3; I would get an elimination reaction instead.1185

Which is my better synthesis?--A is the better retrosynthesis because it leads to the better Sn2 mechanism, less sterics.1194

Anytime we come across an ether that is not symmetrical, we need to consider both possible disconnections; then choose the one that gives the alkyl halide that is less sterically hindered.1218

We have done our plan; we said this is the better plan up here as a way to make our target molecule; let's do the synthesis then because our goal was to synthesize this target molecule.1232

What we need is methyl iodide and propoxide, isopropoxide; where does isopropoxide come from do you think?--how could I make isopropoxide if that was not commercially available?1246

I think I would start with isopropanol; I would need to deprotonate that to make the propoxide, to make the alkoxide.1256

How do I deprotonate?--we need some kind of strong base; how about sodium hydroxide?--is that a nice strong base that would completely deprotonate my alcohol?1267

No, that is not strong enough because we can't make this RO- from this HO-; what would be a better base?1276

We saw sodium hydride being used to make alkoxide; remember we also saw sodium metal as an option to do a redox reaction; you can make an alkoxide that way.1283

We need some super strong base that is not going to be reversible; that makes my alkoxide.1294

What did I do with that alkoxide?--I am going to add the methyl iodide to do my Sn2; that is going to give me my target molecule.1300

So ether synthesis is a very nice illustration of how to do different retrosyntheses and evaluate your choices before carrying on.1315

Let's try another one; starting with propanol as the only source of carbon; what is propanol?--three carbons with an OH--as the only source of carbon, synthesize dipropyl ether.1326

Dipropyl ether means I have a propyl group on one side and a propyl group on the other side; one, two, three; this is dipropyl ether; that is my target molecule, TM.1339

It asks us to synthesize it, but it gives us a restriction on where the sources of carbon can come from; we have to consider that when we are doing our synthesis.1351

A synthesis problem really should start the same way every time; that is by doing a retrosynthesis, planning your synthesis first.1364

What starting materials do I need to make this target molecule?--I recognize that this is an ether; what starting materials could I use to make an ether?1373

What are the two ingredients--alkoxide plus an alkyl halide; I can disconnect this one on either side; it would give the same set of alkoxide and alkyl halide.1384

I need this propoxide as my alkoxide, in this case n-propoxide; my alkyl halide would be one, two, three carbons; bromine, chlorine, iodine, your choice.1395

The planning is very useful because it tells me where I have to go; I know that I need this alkoxide; I know that I need this alkyl halide.1413

If I had free range to a stockroom, maybe I could just go and ask for both of those; but since I know I have to start from propanol, I need to synthesize both of them.1421

Here is my synthesis; I will start with propanol; let's first make the alkyl halide; how do I go from propanol to bromopropane?1432

Propanol to bromopropane--it looks like a substitution reaction; this in fact is a conversion we have seen for the reactions of alcohols.1448

We saw a few different strategies for this; the most direct one would be to use one of the reagents that does it just as a one pot transformation, something like PBr3.1457

Of course if you remembered SOCl2 and you wanted to use that, thionyl chloride, then you could use that as well.1469

We just picked a halide here; whichever halide you want to use would be great.1473

This is another case where HBr, although tempting because we are probably more familiar with that reagent, HBr would probably not be a very good choice because we have this primary alcohol.1480

It is very likely that after we protonate the OH, it could leave, lose water along with rearrangement to give a secondary carbocation.1490

We could get a mixture; we could get some rearranged product here; we wouldn't necessarily get this as the only bromide.1500

So PBr3 is a way to get this bromopropane; how do we get the alkoxide?--we need to start with to start alcohol again; we need to start with the propanol.1508

The way we go from the propanol to the propoxide is we need that strong base again, something like sodium hydride.1518

Your choice--sodium hydride, sodium metal, just pick one and go with it; a lot times there is going to be more than one choice for reagents.1527

Then we can combine these two and make our target molecule or we could just follow this one and use the bromopropane that we already showed how to make up here.1535

We do our Sn2 to do our target molecule; great Sn2 because it is a primary alkyl halide; we would expect this synthesis to work pretty well.1547

Here is one more; let's transform the following; we start with this alcohol; we go to this ether.1563

What is very tempting when you see a problem like this is a transform-type problem--is to start with your starting material and just move forward and say I have the OH.1572

How about if I just make the alkoxide with my sodium hydride?--I know how to make an ether; all I need to do is have an alkoxide.1585

Then I add in my alkyl halide; here it is a three carbon chain with another methyl here; chloride, bromide, iodide, my choice; add my alkoxide and my alkyl halide.1594

And I am done; what do you think?--is this synthesis going to work?--we have a good nucleophile; how would you describe the carbon bearing the leaving group?1608

It is a tertiary RX; how good is that Sn2?--impossible Sn2; no Sn2 on a tertiary center; this reaction would not work.1619

What would happen instead is you would form the alkene from the tert-butyl bromide; you would make the alkene because you would do an E2 instead of an Sn2.1630

I think the reason that students are most likely to make a mistake on a problem like this is because they forgot to plan.1646

If you are doing any kind of a synthesis problem or transformation problem, you need to start by making a plan and think about where you are going.1655

If you had made a plan, then you would look at this target molecule which is an ether and you would have asked how could I make this ether?1662

You would realize that there is two possible disconnections; the better disconnection is the one here because that is going to lead to a more sterically available, less sterically crowded alkyl halide.1669

If I put the leaving group on this carbon and I use the oxygen as part of my tert-butyl group, this combination of alkoxide and alkyl halide would work great.1691

This is a great Sn2; we have a benzylic primary alkyl halide, fantastic for the Sn2; even though this is bulky, there is no elimination that can take place.1704

This is going to be something that will work very well to make our target molecule.1720

What do we need to do with this benzyl alcohol then?--what we need to do is we need to convert it to benzyl chloride; we need to convert this to benzyl chloride.1725

How could we do that?--again SOCl2 is our best choice because that is going to work more often than the others.1739

But in this case if we used HCl, that would work pretty well because there is no other rearrangements that can occur; this is the only product that you can form.1752

Remember sometimes we need the zinc chloride in here though as a catalyst; maybe we would just make the bromide instead of the chloride.1764

But yes, we can convert the alcohol to our alkyl halide; now we can add in the alkoxide; we needed tert-butoxide.1771

Potassium tert-butoxide is going to be the reagent that we use most commonly when we need that alkoxide; we would expect to form the target molecule very nicely.1781

Please do consider planning and thinking about a retrosynthesis because you might have a choice of which bonds to form in your reaction and which sets of nucleophiles and electrophiles that you can use.1794

If we take a look at epoxides, these are a special unique class of ethers--that is the cyclic ether when we have a three-membered ring; this is known as an epoxide.1807

We are going to talk specifically about the synthesis of epoxides; later we are going to see some reactions that are unique to expoxides.1819

If we wanted to make a three-membered ring ether, we could do it the same way we have seen our other ether formations--Williamson ether synthesis; but this would have to a intramolecular case.1827

The way we would get the ingredients in place, the nucleophile and the electrophile on the same carbon chain.1841

We could do that very nicely by starting with an alkene and reacting with bromine and water; what does this do to an alkene?1851

Bromine reacts with the alkene to form the bromonium ion; then water as our solvent is going to come in and open up that bromonium ion; this adds a bromine and an OH across the π bond.1859

Where does that water go?--let's just do a quick review here of this mechanism; we have this bromine, this bromonium ion intermediate.1876

We have two choices here on where the water can attack, the nucleophile can attack; where is it going to want to go?1885

We saw that because of this positive charge, it goes to the more partially positive carbon, which means the more substituted carbon.1891

We saw the regiochemistry of this reaction was very similar to Markovnikov's regiochemistry where instead of H+, we are dealing with a Br+.1901

That goes to the carbon with more hydrogens; the nucleophile, in this case water, goes to the more substituted internal carbon; this adds a Br and an OH.1910

What would happen if I took this molecule and react it with some kind of base like sodium hydroxide?1920

I would expect to deprotonate that alcohol; then I would expect to do an intramolecular displacement, backside attack.1925

Remember three-membered rings were okay for doing this intramolecular attack even though there is ring strain in this epoxide.1935

The fact that that oxygen and the carbon bearing the leaving group are so close; they are overlapping; there is no way for that reaction to not happen.1944

This would be a suitable way to make an epoxide; probably we would be starting with an alkene as a way to get the OH and the Br into the structure.1952

But we have also seen another reaction that gives epoxides specifically as products; that is via oxidation of the alkene.1963

We learned about mCPBA as a peroxide reagent; it is a peroxy acid; we learned that when an alkene sees a peroxy acid, it gets converted to an epoxide.1974

Which synthesis would we use?--it depends on the complexity of the rest of our molecule.1989

If the rest of the molecule can tolerate mCPBA or oxidative conditions, then this might be the simpler path.1996

But there are other paths that are more acidic, acid-base type conditions rather than oxidative conditions; either of these would be useful for synthesizing an epoxide ring.2003

Now that we know how to make ethers, let's think about the reactions that ethers can undergo; there is not a long list to talk about here.2017

Ethers are generally very very stable; they are not too reactive; that is because they have no leaving group.2025

If you compare them to something like an alkyl halide which can undergo substitutions and eliminations, there is no leaving group here.2031

There is also no acidic protons like we might have in an alcohol where that can be the source of some of our reactions.2037

They are really quite unreactive which means that they make very good solvents because they don't do a lot of reactions themselves; because they are polar, that helps for properties of a solvent.2044

In other words, if we take an ether, we try and react it with a nucleophile or we try and react it with a base.2059

Or maybe some of the oxidation conditions we have seen for alcohols like PCC or Swern or Jones oxidation; nothing is going to happen here; no reaction.2067

There is very few reactions that ethers can undergo; one of the only reactions that we are going to be studying is this one; that is the reaction with either HBr or HI.2080

What is the difference between all the reagents that I was just suggesting on the previous slide?--the difference here is that HBr and HI are both strong acids.2093

That is the one vulnerability of an ether--is that it is subject to reaction with a strong acid; the reaction that happens is we see that we cleave our ether apart.2106

We break both of these bonds; we replace the oxygen bond on both sides with a bromine on both sides or an iodine if we are using HI.2118

Let's see if we can come up with a mechanism for this; what will happen if we take an ether and we expose it to a strong acid?2127

Same thing that happens with anything exposed to a strong acid--we are going to protonate it.2135

The ether reacts as a base; HBr is going to act as an acid; so step one of our mechanism is protonate.2141

We have seen this happening for alcohols; let's use that as our analogy; what happened when we protonated an alcohol?2155

When we protonated an alcohol, it turned the OH group in a water molecule that is attached which made it a very good leaving group; guess what?--we have the same thing here.2165

This is also a good leaving group because, if it left, it would leave as an ethanol molecule, again a very stable neutral molecule; by protonating, we turned this into a good leaving group.2178

Because HBr is a source of not only the acid but also Br-, that Br- is going to see a carbon with a good leaving group attached to it; it is going to do a substitution.2192

The substitution... I jumped the gun here... it can be either an Sn1 or Sn2 substitution with a good leaving group; that is simply going to depend on the substrate we are given.2207

Because this is a methyl group, it has very low steric hindrance; backside attack is great; carbocation is awful; in this case, it is going to be an Sn2 mechanism.2221

We are going to be forming one of our products; we just brominated this methyl group; we have bromomethane as a product.2232

What else did we form?--we just kicked off a molecule of ethanol, again very stable great leaving group; this is how we can cleave an ether with HBr and HI.2245

But if we have an excess of this, if we have plenty of this to go around, then this alcohol that is formed in this reaction does not stick around.2258

Because we have seen a reaction of alcohols with HBr, what happens?--we replace the OH with that halide; what is going to happen is we are going to repeat process.2266

Our alcohol under these conditions is also going to get protonated; we are going to protonate the alcohol; now the rest of the mechanism, this is simply a reaction we have seen for alcohols.2278

We protonate the OH; we make it a good leaving group; because we have bromide around, we have something that can substitute for that leaving group.2294

Again this second part of the mechanism can be Sn1; it could be Sn2; because in this case we have a primary, it is going to be Sn2.2304

Our bromide can come in and attack and kick off our water molecule; that is how we get our other alkyl halide.2316

Here is one of our products is bromoethane; one of our products is bromomethane; what was our other product here?--look what we also formed; we formed water.2331

If you would like to balance your reaction here, you can see that not only do we get these two organic products, but we also form a molecule of water.2344

This oxygen get kicked out eventually completely for both carbon groups; these two protons from the HBr will combine with that to give an equivalent of water as well.2352

Ethers in general are going to go just that one reaction as the most common reaction we will see--ether cleavage with HBr or HI.2369

But when we look at an example of an epoxide as a class of compounds, we will find that epoxides can undergo a lot of reactions.2377

They are much more reactive than an ordinary ether; that is what we will spend the rest of our time talking about.2387

This is an epoxide; if we think about the reactivity we might have for an epoxide, I know this is a polar bond and I know this is a polar bond.2394

That puts a lot of partial positive character on the carbons of the epoxide ring; what kind of reactivity do you expect for a partially positive carbon?2405

I think it is going to be an electrophile; this is what we are going to find for an epoxide--is it is going to be an electrophile.2420

In other words, it is going to be E+; it is going to be something that wants to react with nucleophiles.2432

The reaction that occurs is called a ring opening reaction; we are going to see lots of examples of those.2438

The general mechanism that we have, the general thing is we have an epoxide; we react it with some nucleophile; that nucleophile is going to attack one of the carbons of the epoxide ring.2444

As usual, if we have a nucleophile attacking a carbon that already has four bonds, we have to break a bond as well; one of these C-O bonds is going to break.2455

If I attack this carbon, this C-O bond is going to break; the product we get is we have an O- in this case, two carbon chain, and a nucleophile is now attached.2465

The nucleophile is attached to one carbon; the next carbon over still has the oxygen from the epoxide attached.2479

If you take a look at this mechanism, how would you describe the mechanism?--nucleophile attacks, kicks off a leaving group; have we seen that before?--yes, it looks like Sn2 mechanism, backside attack.2487

But this is a strange example of an Sn2 because normally who is your leaving group in an Sn2 mechanism?0--if you have to name a leaving group.2497

Maybe we have a halide--bromide, chloride, iodide, or a tosylate as a good leaving group; we need a good leaving group.2505

Our leaving group in this case is an alkoxide; we just kicked off an O- that has no resonance stabilization; we have never seen that before.2513

Why is it happening okay?--we said that wouldn't happen on an ordinary ether; why is it happening here?2521

Because in the course of this substitution reaction, in this Sn2, we are also opening up the epoxide ring; that three-membered ring has a lot of ring strain.2529

By breaking that bond and opening the ring, we relieve the ring strain; that is what makes epoxides very reactive and readily undergoing reactions with nucleophiles.2541

It is because of the ring strain they have in that three-membered ring; any other ether is lacking that; that is why we don't expect Sn2s in those cases.2554

Let's see an example; if we take our simplest epoxide--it is called ethylene oxide; that is the epoxide made from ethylene, the two carbon alkene.2563

If we take ethylene oxide and we react it with methanol, we could react it with methanol and acid or methanol with base, methoxide.2573

This little or means that it can be either acid or base catalyzed, the mechanism; we are going to see two different mechanisms for this; but either way, we have a methoxy group acting as our nucleophile.2581

The product we are going to get will have a methoxy group attached to one carbon and a hydroxyl group, an alcohol, on the other carbon; it follows that pattern of our nucleophilic ring opening.2603

Here the methoxy group is our nucleophile; as usual we are going to get an alcohol; epoxide ring opening reactions are always going to give an alcohol product out.2617

The oxygen that used to be part of the epoxide ring will end up as a hydroxyl group on the carbon chain; it will end up as an OH group.2629

Let's one by one take a look at these two different reaction conditions and see what the mechanisms look like for this epoxide ring opening.2638

You can see in this case we get the exact same product out whether it is acid or base catalyzed; in some other cases, we will see how we might see some differences in those products.2645

What does the mechanism look like for an acid catalyzed ring opening?--again here is the product that we are expecting; we are going to get this methoxy group in.2660

Here our reaction conditions, we have the epoxide, we have methanol, we have an acid; what is going to happen as our first step in the reaction?2668

It is going to be reaction with the acid; remember as soon as you see a strong acid present, your first step of your mechanism is going to be to protonate something.2677

Where do we protonate?--we can protonate this oxygen; but that doesn't really lead us anywhere; if we protonate the epoxide oxygen, that is going to be a better step to take.2686

Which means now we have a hydrogen attached to the oxygen; there is now just one lone pair here because the other one was used; remember proton transfer is always two arrows.2702

What does this oxygen look like now?--it has one, two, three, four, five electrons; we know oxygen wants six; it is missing an electron; so we can protonate and give an O+.2712

That is our first step--is to protonate; how does that help us?--why is that a good move to make?--our epoxide remember is an electrophile.2721

How about after protonating it?--do you think this structure now is something that is going to be more of an electrophile or less of an electrophile?2734

We have a positive charge now on our structure; is that something that is good for electrophiles, that we associate with electrophilicity, being electron poor?2742

Absolutely; what we did now is we just made a great electrophile by protonating the epoxide; we have a great super electrophile; let's look around for a nucleophile.2750

We look back to our reaction conditions; what nucleophile do we have?--we have the alcohol; we have methanol as our nucleophile; what is that going to do?2762

Every time a nucleophile sees an epoxide ring, same thing--it attacks the carbon and breaks the C-O bond; Sn2--attack the carbon, kick off the leaving group.2777

But because this leaving group is still attached to the carbon chain, it doesn't just disappear from our structure; it stays connected to our structure.2789

This oxygen is now an OH; it has its two lone pairs back; now it is neutral again; let's take a look at this oxygen; this was our methanol oxygen; what does this oxygen still have attached to it?2801

It has the CH3 and the OH... I'm sorry, the CH3 and the H; it has just one lone pair still; this looks like another charged oxygen.2813

One, two, three, four, five; oxygen wants six; this is another O+; we describe this second step as attack of the nucleophile.2829

We are almost there; we are getting towards our product; we still have an oxygen with a positive charge so I know this can't be my final step; I know I can't be done with my mechanism.2841

I need to get rid of that positive charge; how can I get rid of it and end up with an oxygen with just two bonds?--it is this proton that is most easily removed.2849

What we could show is A-; we formed A- in this first step when we used our strong acid; we can show that A- coming back and deprotonating the oxygen; our third step of our mechanism is deprotonate.2859

There we are; we have our product, our substitution product, our ring opening product where our nucleophile has been attached and we have an alcohol where the epoxide used to be.2875

It is a three step mechanism; we protonate, we attack, we deprotonate; we are going to see that pattern for an acid catalyzed mechanism; we are going to see that pattern again and again and again.2888

First step is protonate; then that makes it possible to attack; then we need to deprotonate to finish things up; protonate, attack, deprotonate.2902

A couple other things I want to point out about this mechanism--notice there aren't any O- charges in acid.2912

This would be a strong base like hydroxide; there is no hydroxide; there is no alkoxide; those are very strong bases; we can't have those.2917

What kinds of charges to you see in this mechanism?--you see that each structure is either neutral or it is positively charged; only neutral or + charges.2929

That is very much consistent with acid promoted or acid catalyzed mechanisms; I do see a negative charge here; I see this A-; what does A- represent?2944

Remember if HA is a strong acid, A- represents some very stable weak conjugate base; it is around, but it is not something that would be a strong base.2956

It would be unstable; that is a reasonable species to have around; but not hydroxide, not alkoxide.2968

Another thing I want to point out is this is an acid catalyst; you just need a drop of this acid.2977

Because for every step where you use the acid, for every protonation step, there is also a step where you get that acid back; you regenerate it; there is a deprotonation step.2983

It is used and regenerated; it is not consumed; that is our definition of a catalyst, something we don't need a stoichiometric amount.2994

We don't need a full equivalent of this; because all we need is a little bit of it to get the reaction going.3001

Every time we use the acid, we will have another step somewhere in the mechanism that recreates the acid to be used again.3006

Let's compare this with the base catalyzed epoxide ring opening reaction; again we get the same product where we have this methoxy group attached and the alcohol here.3015

But our reaction conditions are different; now we have methanol still but we use sodium methoxide as our reagent.3027

If we want to do our mechanism, we have our epoxide as an electrophile; we have sodium methoxide as a very strong nucleophile; this is a great nucleophile, strong nucleophile.3033

The very first step in this mechanism is going to be attack of that strong nucleophile onto the electrophile; methoxide is something that would great at doing an Sn2; it doesn't need a push at all.3053

We are simply going to attack the carbon and kick off the leaving group; the methoxy group is now attached; this was the carbon that the nucleophile attacked.3066

It is the next carbon over that will have my epoxide oxygen; this oxygen now has three lone pairs on it; let's check the formal charge here.3081

We have one, two, three, four, five, six, seven; oxygen wants only six; we have an extra electron; we will get an O- on that oxygen.3091

It looks like our reaction isn't done; we need to neutralize this; how do we take care of this O-?--we need to protonate to get to the OH.3102

Where do we have a proton source?--we have this methanol here as our solvent; our methanol can come in and protonate the O-; our final step here is protonate; and we are done.3113

It is not uncommon for a base promoted or a base catalyzed mechanism to be shorter than an acid catalyzed mechanism; we are going to see lots of examples of this down the road.3134

But there is our mechanism; we simply attack; then we protonate; and we are done; let's take a look at this overall reaction and ask what kind of charges do you identify in this base catalyzed reaction?3145

There is no positive charges; that is going to be true in all of our base catalyzed reactions; we never want to have an O+ species; that is very strongly acidic.3160

Everything is either neutral or it has a negative charge; neutral or negative charge.3169

Once again, just like the acid situation, this is a catalytic reaction in terms of base; it is not consumed.3179

Even though we used our methoxide here in the first step, this last step, the second step, regenerated it because the methanol acted as the proton source; we remade the methoxide.3187

Again we just need a catalytic amount of this base; it doesn't even have to be methoxide; it could be any base.3201

As long as methanol is our solvent, we are going to get this methoxy group down here because that is what we will have in the largest proportion.3206

We have seen an acid catalyzed mechanism; we have seen a base catalyzed mechanism.3216

It is important to point out that you must have one of those conditions in order for the epoxide ring opening to take place; it must be either strongly acidic or strong basic.3221

If we tried to do this reaction without the H2SO4 or without the sodium methoxide; what we are doing is we are taking a neutral epoxide which is a weak electrophile.3231

There is nothing super about this electrophile; we are mixing with methanol; methanol itself is a weak nucleophile.3243

If we are asking to bring these two reagents together, if we tried this mechanism to just have the neutral epoxide... this is a neutral epoxide.3252

We have it being attacked by a neutral nucleophile; let's see what product we would get, what intermediate we would get.3264

This oxygen is now an O-; this oxygen is now an O+; what is the problem with this mechanism?3272

If we tried that and you ended up with this structure, what alarm should be going off in your head as how this is not consistent with the mechanisms we have seen so far?3285

You have an O- which is a strong base, very strong reactive base, and an O+ which is an extremely unstable strong acid.3296

These cannot coexist in the same reaction medium; we will never see a mechanism with an O+ and O- in the same mechanism.3309

Our mechanisms are either going to have negative charges throughout or positive charges throughout; we can't have an O+ and an O-.3325

This is a key that you have made a mistake; you need to back up; you need to look at your reaction conditions and see do we actually have a strongly nucleophilic, strongly basic conditions?3332

Or do we have strong acid conditions?--but the neutral epoxide is too weak of an electrophile to be attacked by a neutral nucleophile, weak nucleophile like methanol.3342

Let's look closer at this epoxide ring opening and think about the stereochemistry and the regiochemistry of the reaction.3357

The stereochemistry, we know it is an Sn2 mechanism; Sn2 means backside attack; what does that typically result in for the stereochemistry if this is happening on a chiral center?3364

It leads to inversion of stereochemistry; that is going to be true in an epoxide ring opening, just like it is in a straight chain Sn2.3379

Let's take a look at these reaction conditions; I see I have an epoxide; now I have NaSH and methanol.3392

Every time I have an epoxide, I know have an electrophile; that part is not going to change; I have to look now at my reaction conditions to decide where is my nucleophile?3401

Who is my nucleophile?--I have NaSH and I have methanol; which component is going to be my strongest nucleophile; who is my best nucleophile in this case?3412

NaSH means I have an Na+SH-; we have a negatively charged nucleophile; here we have a neutral nucleophile; who is the best one?--the SH-.3423

Not only is it negatively charged, remember sulfur is bigger than oxygen; it is polarizable; so for a couple reasons, this is the better nucleophile.3438

That is the nucleophile we are going to have; how can we predict our product?--that nucleophile is going to attack the carbon.3447

In this case, either one is fine; attack the carbon, open up the ring; tell me about the stereochemistry of that attack.3454

If the epoxide ring is coming out toward you as a wedge, that means the sulfur nucleophile has to come in from behind the plane; it will end up as a dash; so I have SH.3465

What I have on this carbon is I still have this oxygen attached as a wedge; there is no chemistry that happened at this carbon so there is no reason to invert that center.3478

This is still a wedge as an O-; the purpose of this methanol here is our protic solvent; this is going to be our source of H+.3487

We needed a protic solvent here so that we can get a neutral product out; we get inversion of stereochemistry at the carbon undergoing any Sn2 mechanism.3499

I showed here that this is attacking right away without really thinking about it; but which mechanism would you expect?3514

Is this going to follow the acid catalyzed mechanism or the base catalyzed mechanism?--the question is: is there any strong acid?3521

We know how to recognize strong acids; it is a pretty short list; things like HX or H2SO4; what is another strong acid?3532

Maybe nitric acid, phosphoric acid, those sorts of thing, tosic acid is an acid we have seen before; these are the things that tell us we were under acidic conditions3540

Because there is no strong acid, we are going to be following the base mechanism here; the base catalyzed mechanism.3552

Even though there is no strong base in this case either, it is the lack of a strong acid that causes us to follow a base mechanism.3561

In other words, we do step one; we are just going to come out and attack like I have shown here; then step two, we are going to protonate.3569

You could try that mechanism to convince yourself that that would be how you get to this product.3576

The other thing I want to point out is in this case, we can attack either of these carbons; if I attack the bottom carbon, what would my other structure look like?3583

That is where the sulfur is attached down here as a dash; then the OH would be attached to the other carbon, the top carbon, again still as a wedge.3596

We are always going to get this anti relationship of the incoming nucleophile and the epoxide oxygen; we get this trans anti type product depending on how you are looking at your product.3606

In this case we are seeing, because we started with an achiral starting material, we have a meso compound here.3629

We can't form just a single chiral product; we are going to get a mixture of enantiomers here; this is an example of a racemate.3637

Anytime we are dealing with stereochemistry, we have to be very careful about thinking do we need to say +enantiomer?--are we expecting an enantiomer or are we not?3644

But in terms of the carbon undergoing the Sn2, we will observe an inversion of stereochemistry like we have always seen.3654

How about if we wanted to do this transformation?--we are starting with an alkene and we are going to a diol.3665

The relationship of those two OHs are anti to one another, trans to one another; we have trans OHs; it is a trans-1,2-diol.3674

We have seen a reaction that converts an alkene to a trans... I'm sorry, to a diol; that was one of our oxidation reactions.3686

Remember we saw KMnO4 or OsO4; that would give us two OHs; but what would the stereochemistry be for that transformation?3695

Remember KMnO4 or OsO4 did a syn dihydroxylation; both of those oxygens got added at the same time; that gave cis OHs; this is an example of syn dihydroxylation.3706

We need another approach to get the trans out; but we just saw a reaction that does give a trans relationship between an OH and something else.3722

That would be if this had come from an epoxide; if we had an epoxide and we opened up that epoxide, the position of the nucleophile and the OH would be trans to one another.3735

That might be a little harder to recognize here because they are both OHs; but you can open up an epoxide ring with an OH; so that would be a possible synthesis.3754

Let's imagine this; if we converted it first to the epoxide and then we opened up that epoxide ring, that would give us a trans diol.3767

Let's think about those reaction conditions; how do we make an epoxide?--we just talked about the synthesis of epoxides.3776

One of the simplest ways is to do just an oxidation with something like mCPBA; a peroxy acid like mCPBA gives us the epoxide; then how do we open up an epoxide ring?3782

We can either have a strong nucleophile like sodium hydroxide; if we have water as our solvent, then we could attack and then protonate to give the trans diol.3798

Or remember we could have base catalyzed reactions; we could also have acid catalyzed reactions; if we just had H2O and acid, H2SO4.3810

Or you could just write H3O+ sometimes to represent that you have water in acidic conditions.3820

That would also work; you could protonate the epoxide ring and open up with water; this would also give the trans diols.3827

This is a nice synthetic trick to know is that, if we need this trans relationship, we could go through the epoxide; that is very useful.3834

In fact instead of doing this in this two-step procedure where first we make the epoxide and then we open it up.3845

We can actually do this transformation in a single step, in a single pot by using peracetic acid or peroxy acetic acid and water as our solvent.3852

What is cool about this is it makes the epoxide; it also gives acidic reaction conditions; it does so in the presence of the nucleophile.3872

What this does is it forms the epoxide in situ, meaning in the reaction conditions; in situ is the Latin term you see italicized.3886

We are making the epoxide in the reaction and we are reacting that epoxide at the same time.3897

So this is a handy set of reagents to be familiar with as well anytime we want to do an anti dihydroxylation.3903

A syn dihydroxylation can happen with osmium tetraoxide or KMnO4; anti dihydroxylation can happen with peroxy acid in the presence of water.3917

Finally let's talk about the regiochemistry of this epoxide ring opening; let's say we have an epoxide like this which is not symmetrical; we have just been looking at symmetrical epoxides so far.3931

If we have a nucleophile attacking this epoxide, where does it go?--in other words, it can attack this carbon or it can attack this carbon; that would give two different products.3943

Anytime we are deciding what region or what site of a substrate to react, we call that regiochemistry.3953

The regiochemistry of these epoxide ring openings actually depends on the mechanism of the reaction; we saw base catalyzed; we saw acid catalyzed; let's look at them one by one.3962

If we are in base, in other words, there is no strong acid present; it is not necessarily that we are looking for the presence of a base, but we are looking for the absence of an acid.3975

In that case, remember the very first step of our mechanism is right here; we have some strong nucleophile, negative charge; strong nucleophile is attacking the neutral epoxide.3988

That was our very step; a nucleophile attacks a neutral epoxide; in that case, what we are looking at is just a straight out Sn2 mechanism; how is an Sn2 mechanism going to be controlled?3999

It is going to be governed by sterics; in other words... there is a typo there, sorry... it is going to attack the less hindered carbon.4011

We come back here; we see that this is a secondary carbon; it has two carbon groups attached; this is a primary carbon; it has just one carbon group attached.4021

Which is going to be the faster Sn2, the better Sn2?--the one where it goes after the primary carbon; the nucleophile goes to the less substituted carbon.4033

It is governed by sterics; it is the plain old Sn2; we do what we would normally expect for our regiochemistry.4047

When it is an acid, in other words, there is a strong acid present, remember the very first step of our mechanism is going to be protonate the epoxide.4057

The attack then happens on that protonated epoxide; we are going to have this species, a protonated epoxide, getting attacked by a weaker nucleophile, some kind of neutral nucleophile.4068

We are asking the same question: which site is going to be preferred?--we have a nucleophile attacking a protonated epoxide; the presence of that charge means that it is not a simple Sn2 any longer.4081

The way we describe it is we say it is an Sn2, but it has some Sn1 character; an Sn1, we describe as having a carbocation that gets attacked by a nucleophile.4097

There is no carbocation here; both of these carbons are just partial positive; let's keep that in mind; it is partial positive, not a full positive.4109

That is why we are still describing it as an Sn2; it is still backside attack; but the presence of that partial positive gives it some Sn1 character.4121

Which means we are no longer being governed simply by the Sn2 sterics, the backside attack sterics.4131

The presence of that charge means we are concerned a little bit more with electronics, electron density.4138

Now what we look at is we see this partial positive is on a secondary carbon; we have a secondary partial positive; this partial positive is a primary partial positive.4146

Which of those partial positives, those δ+'s has more electrophilic character?--which of those carbons better handles the partial positive?4161

Just like carbocation stability goes, the more carbon groups we have, the better; this secondary partial positive, this is better.4173

It is the better electrophile; it is the more partial positive of the two carbons; in this case, the nucleophile doesn't want to go to the primary center.4184

It wants to go to the secondary center, the more substituted; in this case, because we are being governed by electronics and not sterics, the nucleophile goes to the more substituted carbon.4197

We end up getting exactly opposite regiochemistries; if it is protonated, it goes to the more substituted carbon; if it is neutral, it goes the less substituted carbon.4213

Let's take a look at a few examples; here we have a not symmetrical epoxide; in other words, attack at either carbon would give a different product; let's look at this.4224

What if we reacted this with sodium cyanide and water?--sodium cyanide and water; what we have here is a very strong nucleophile; we have water as our solvent; we have no strong acid.4240

That means our mechanism is going to be simply the cyanide attacking the epoxide right off the bat; which of these two carbons is it going to prefer to attack?4260

We are looking at a plain old Sn2 mechanism; it is going to be governed by sterics; we have a secondary carbon over here; we have a tertiary carbon over here.4271

It is going to prefer to go to the less sterically hindered carbon; what does our product look like?4282

Here is our carbon chain; how do we draw our epoxide ring opening products without going through the complete mechanism?4290

This is the carbon that got attacked by the cyano group; it is attached here; the other carbon didn't get attacked; it still has the oxygen here.4297

Because we have a protic solvent here, we have something to work this up; we are going to get this alcohol.4309

Notice the pattern of epoxide ring opening; we always have the nucleophile added to the carbon next to the carbon that has the OH remaining.4314

This is going to be like our base catalyzed one; it is controlled by sterics; take a look at my stereochemistry; why did I draw by cyano group up here and not down here?4324

Shouldn't I have drawn it down here because it is backside attack?--yes, except no stereochemistry has been shown for this starting material.4340

Even though the cyanide is attacking at the bottom here, whether I draw the CN up here or down here, it doesn't matter.4349

This chiral carbon has not been shown any stereochemistry; so we could just draw it anywhere we want.4355

Stereochemistry is only going to be relevant when we are dealing with a chiral carbon and the stereochemistry of that chiral carbon is indicated at the beginning.4362

How about the next case?--if we react this with HI, the same epoxide with HI; now I see that we have a strong acid.4371

Do I have a nucleophile?--remember an epoxide is always an electrophile; our goal in looking at our reaction conditions is to find our nucleophile.4384

There it is; we have HI so I- will be our nucleophile; where is that nucleophile going to prefer to add?--remember we are going to protonate our epoxide first.4394

Where will that nucleophile prefer to add?--it is going to prefer this tertiary partial positive because this is more electrophilic; what does our product look like?4407

Again here is our carbon chain; our iodide is going to be attached to the carbon on the right, the more substituted carbon; the alcohol, the OH, is going to be attached to the other carbon.4418

Again no worry about stereochemistry here in this case because no stereochemistry has been shown for our starting epoxide; these are acid conditions; it is controlled by the better partial positive.4431

A little note here, a little note, this is not about the more stable carbocation; we have seen that argument before.4453

When we looked at Markovnikov's rule in addition to alkenes when we had a carbocation in the mechanism, absolutely we always want to go for the more stable carbocation.4461

Why is it not correct here to say that the reason I get this regiochemistry is because it is the more stable carbocation?--because the mechanism has no carbocation.4470

It has a protonated epoxide; the I- attacks this; in other words, the ring doesn't open first and then have the iodide attack; the iodide attacks; that is what forces open the ring.4481

We want to be very careful not to mention anything about a carbocation when we are discussing epoxide ring opening reactions.4495

But instead refer to the partial positive in the intermediate in the transition state; that is what is governing it.4502

How do I know it is Sn2 here?--how do I know it is backside attack and not a stepwise where the ring opens and then the nucleophile adds in?4511

The stereochemistry of the mechanism is what gives evidence that it is an Sn2; remember we observe backside attack; we observe inversion of stereochemistry.4520

We know it must be a concerted substitution and not a stepwise substitution.4529

What other nucleophiles can we have?--we have seen Grignards and hydrides attacking carbonyls; these would be great for attacking epoxides as well.4537

Let's see an example of that; we have an epoxide; we know that is our electrophile; we look at our reaction conditions; step one here, we look for a nucleophile.4546

LiAlD4; I have seen LiAlH4 before; that is lithium aluminum hydride; what do you think this reagent would be?4558

We could call this lithium aluminum deuteride; just like hydride is a source of H-, deuteride is a source of D-.4569

D represents a deuterium; it is simply an isotope of hydrogen; it is a hydrogen that has a neutron in there; but we use it so commonly that it has its own name.4582

Anytime you see a D in a structure, you are going to treat it just like you would a hydrogen; it is going to do the same reactions.4597

Just like this was an H-, this is going to be a D-; we will keep those quotes around it because it will always be coordinated with the aluminum.4602

It is the aluminum that is delivering it; it is not ionic; but that is going to be our nucleophile; we have a D-.4614

Now we need to decide... we know what we are adding; we have to decide where are we adding?--we have to decide the stereochemistry.4620

We want to consider both the regiochemistry--where we are adding it?--we want to consider the stereochemistry.4628

What is the stereochemistry of that addition?--because we are clearly dealing with some chiral centers here; we have some dashes and wedges in our starting material.4635

What we need to decide for the regiochemistry, we need to decide is this an acid catalyzed mechanism or a base catalyzed mechanism?4644

We take a look at our reaction; it is tempting to think it might be acid catalyzed because I certainly see some acid here; I see some H3O+.4653

But see these numbers here; this tells us that the first thing we are doing is reaction with lithium aluminum deuteride; after that is done is when we add in the acid.4662

The important thing to note is there is no acid in step one, in the first step; in fact the reason this is separated and we don't have them combined like we did before.4671

You can't have acid in the presence of a really strong nucleophile like a Grignard or anhydride; you can't mix water with that because those would quench those.4683

With those really strong nucleophiles, what we do is we do it in a two-step procedure; first we react it with that nucleophile.4692

Then we do an aqueous workup to protonate anything that needs protonating; this is going to be our base type mechanism.4699

In other words, we have nothing in step one to protonate this epoxide; it is just being attacked right off by the nucleophile; it is the neutral epoxide being attacked.4708

How are we going to decide where it goes?--it is just a plain old Sn2; it is going to be governed by sterics; let's look at the two carbons that are being attacked.4718

How would you describe this first carbon or the carbon on the right?--this is a secondary carbon; it has two carbons attached; how about this carbon?4732

Be careful; it might be tempting to say it is tertiary because we see this tert-butyl group; but if you look carefully, this is also secondary.4743

But is there a difference in their sterics?--absolutely, the one group attached here is just a methyl group; the other group attached here is this tert-butyl group offering a lot of sterics.4751

Most definitely the less sterically hindered one will be the carbon on the right; there is our mechanism; but you want to be careful in your explanation.4762

If you were asked to describe or explain why this regiochemistry was observed, you want to be careful not to say it prefers the secondary over the tertiary site.4772

You want to say it prefers the carbon without the tert-butyl group because it is going to be less sterically crowded.4780

Let's draw our carbon chain; we can keep our carbon chain in the plane here; because our epoxide was drawn as a wedge, we are going to add the deuterium here.4788

Tell me about the stereochemistry of that group; it has to be backside attack; if the epoxide is sticking out, that means the deuterium comes from behind.4797

We could keep our carbon chain the same and show the deuterium coming in from the back here; what is the stereochemistry?--what is on this other carbon?4806

It still is a wedge; we have an O-; if we just show our mechanism, we could show it is stepwise just as a little review here.4816

We would get the O- first as a wedge; but then after step two when we did our work up, that is what we would use to protonate to get to our final product.4827

You wouldn't need to show this whole mechanism for a predict-the-product; but I just want to add a little detail here so we are clear on the purpose of that aqueous workup.4837

Step one, we still are doing our attack and our protonate; but in this case, it required two separate steps for our reagents.4848

Because our nucleophile was too strong of a reagent to tolerate a protic acid; we would have to do it stepwise.4855

Any enantiomer here, +enantiomer?--I know we have that reaction every time to say yes I want to get the enantiomer as well because I have drawn a chiral product here; this is clearly chiral.4865

Where would the enantiomer come from?--what does the enantiomer look like?--that would have a wedged deuterium and a dashed oxygen; how could that come from this starting material?4877

It couldn't; because we were given just a single enantiomer as our starting material, it is okay to have just a single enantiomer product here; that is going to be common for many of these products.4887

This is the only product; this is the only regiochemistry; this is the only stereochemistry; we do get this single enantiomer as our major product.4901

Let's take a look at another example; here we have an alcohol and a bromine; in our first step, we are reacting it with sodium.4908

Sodium all by itself means that it is not Na+; it is actually sodium metal; sodium metal has that electron it is dying to get rid of; that makes it a good reducing agent.4919

Where have we seen that as a reagent?--we have seen it reduce an alkyne to a trans alkene; that is a possibility.4930

We have also seen it reduce any acidic proton, reduce that and give off hydrogen gas; as a result then we are going to get the alkoxide.4940

To make an alkoxide, we could use a base or we could use a metal like sodium lithium potassium; to do a redox reaction, we do that same process.4958

Step one here, we make the alkoxide; is that our final product then after the first step or is there something that alkoxide can do before we get to our second step?4968

I just made an alkoxide in the presence of an alkyl halide; I think we are going to have a reaction take place here.4981

Furthermore the O- is a wedge and the bromine is a dash; which means when we want to do a backside attack, we are perfectly set up stereochemistry to do that anti attack.4988

Sure enough, we are going to get attack of the alkoxide to kick off the leaving group; we are going to make this epoxide.5000

Step one after we deprotonate the OH, we are going to do an intramolecular Sn2, an intramolecular Williamson ether synthesis; we would get an epoxide after step one.5012

An epoxide is an electrophile; I am hoping in step two we have some kind of nucleophile; who is that nucleophile?5023

I see that I have NaOH; that is Na+ which means I have hydroxide, HO-; I also have water.5033

This 18 is simply an isoptopic label; it is useful to be able to track the incoming OH and track him as a different oxygen than the one that is already here.5042

Just like we used deuterium in the last example, that was useful so we could see where the new hydrogen, the deuterium, ended up even though we already had a hydrogen in the structure.5057

This labeled oxygen is going to be doing the same thing; we have hydroxide, labeled hydroxide, as our nucleophile; that is going to open up the epoxide ring.5066

When we do that, we have to think about two things; we have to think about the regiochemistry because in this case, our two carbons are differently substituted.5081

And we have to think about the stereochemistry; how do we decide the regiochemistry?--we need to decide whether it is an acid catalyzed or a base catalyzed mechanism; what do you think in this case?5089

Surely I see hydroxide in here, clearly base catalyzed; there is clearly no strong acid here; this is going to be our base mechanism.5100

Which means our hydroxide is simply going to attack the epoxide as shown, the neutral epoxide.5110

It is going to be our ordinary Sn2; there is no Sn1 character, ordinary Sn2; it is going to be about sterics.5117

When I compare my two carbons, I have a secondary carbon over here; I have a tertiary carbon over here.5126

My hydroxide is going to attack the carbon on my left and open up the ring; tell me about the stereochemistry of that Sn2.5134

Since the epoxide is a wedge, that means the new oxygen has to come in from behind to do backside attack; it must come in as a dash.5147

Here is my 18, my labeled oxygen is on the carbon on the left, is a dash; what do we have on the right?5156

This stereochemistry remains unchanged; there is no reaction here; so my methyl group is a dash and my oxygen is a wedge.5165

Because I have a protic solvent here, then I can expect to protonate this after I open up the ring; I would have an O-; then I can protonate it to get this OH.5174

We have formed an epoxide; then we have opened it up; we considered the regiochemistry; we considered the stereochemistry.5185

It is okay to have this single enantiomer as my product because I started with a single enantiomer as a starting material.5192

It looks interesting; the nucleophile has the same stereochemistry as this leaving group; it looks like we had retention of stereochemistry.5200

How did we do that?--really there were two Sn2s; there was an inversion in this first Sn2; then there was an inversion in the second Sn2.5207

A double inversion ends up giving us retention of stereochemistry; that makes this problem an interesting one.5215

Finally let's look at an example of a synthesis; if I asked you to synthesize this target molecule and I gave you a hint; I said you should start with some kind of epoxide and some kind of nucleophile.5223

That will help you maybe see the pattern in the target molecule that makes it look like a product that might have come from an epoxide ring opening.5236

What do those ring opening products look like?--they always have an OH on one carbon; the next carbon over, we have a nucleophile that has been added.5246

It is possible to add a methyl or an ethyl via a Grignard reagent; but this oxygen group most definitely he couldn't have been there in the epoxide form.5256

So this was my nucleophile; this was the group that was added; so that is the disconnection we are making here.5266

If you want to imagine doing in your retrosynthesis, we are asking what starting materials do I need?5276

You can almost doing that backwards reaction where the epoxide ring closes back up and kicks the leaving group out.5283

Instead of just doing a disconnection, you could think about that reverse mechanism, that imaginary reverse mechanism.5293

The stereochemistry on this carbon stays the same; I still have a methyl back and a hydrogen out.5302

But I want you to think carefully about the stereochemistry of this; what did the stereochemistry used to be over here?--we have a wedge and a dash that we need to fill in.5310

What did these groups used to look like so that after the nucleophile added in, we ended up with this stereochemistry at the carbon?5319

Think about what it means to be an Sn2 and do an inversion of stereochemistry; I want to point this out.5326

Because when our leaving group is in the plane, it is a little different than some of the examples we have seen.5333

Just by having this oxygen come in from in the plane, it causes the dash and wedge bonds to be pointing in the up direction; then the inversion now points them in the down direction.5340

Because my ethyl group was a wedge and my methyl group was a dash, there is still going to be a wedge and a dash when this nucleophile adds in.5355

My nucleophile... because my leaving group in this case... let's think about it in the forward direction.5368

My nucleophile in this case is in the plane... I'm sorry... my leaving group is in the plane; that means my nucleophile must come in from in the plane, approach from in the plane.5373

It is not going to come in as a wedge or a dash because my leaving group is a straight line; that means the nucleophile comes in, ends up as a straight line.5386

So the inversion... you have already seen the 180 degrees; it used to be up here; now it is down here; there is your inversion.5395

The other two groups are simply like your umbrella flip; the one group that was pointing out towards you is still pointing out towards you; but instead of going down, it is going up a little bit.5402

There is no way for these groups to do this; that would again be a double inversion; you can check your stereochemistries here.5410

If you want to assign R and S before and assign R and S afterwards, you will be able to confirm that they have indeed inverted.5416

If you are not convinced by this or you are having some trouble with this; of course working with a model can help as well.5423

This is my epoxide; that is my electrophile; I know I need a nucleophile; who is my nucleophile?--it needs to be this ethoxy group; maybe I can have sodium ethoxide.5431

That would certainly be a nucleophile; this might be a good way to do this synthesis; but what we need to do after we do our planning is we need to check to make sure that would work.5444

If I took these two, this epoxide and ethoxide and I went to predict the product, would this give the target molecule?--how do we decide that?5458

We take a look at our reaction; we think about the regiochemistry; we think about the stereochemistry; we need to confirm it as if it were a predict-the-product.5469

Do we have acid catalyzed conditions or base catalyzed conditions here?--clearly this is a strong base; there is no acid here.5479

Which means the ethoxy group would go where?--it would go to the less sterically hindered carbon; what product would I get?5488

I would get the product where my ethoxy group adds to the carbon on the left; the alcohol would end up on the carbon on the right.5498

Let's think about that stereochemistry here; my ethoxy group would come in from down here; that kicked off the oxygen.5514

What happens with this methyl and this hydrogen?--the hydrogen is still a wedge but it is up here a little bit; the methyl is still a dash but it is up here a little bit.5520

This would be the product formed by this synthesis; is that the product we want?--no, that is the wrong regiochemistry; I don't want the OH on this tertiary carbon.5528

I want the OH over here on the secondary carbon; this is not going to work; this gives the wrong product; it gives the wrong regiochemistry.5539

How do I force my nucleophile into this carbon?--I want the nucleophile to attack this carbon; how do we force it over there?5552

How do we get the nucleophile to the more substituted carbon?--we do it by using a strong acid so that it will be the protonated epoxide that gets attacked.5562

How do I do that?--I don't use methoxide; I use methanol... I'm sorry... I don't use ethoxide; I use ethanol and a strong acid, H2SO4.5576

I can't use ethoxide anymore; what would happen to ethoxide if I tried to mix that with acid?--it would simply get protonated.5591

Remember it is okay to have a weak nucleophile; we need to have a weak nucleophile; we are in acidic conditions.5599

It is impossible to have a strong nucleophile in acidic conditions; so I would use ethanol and H2SO4.5604

Now when I go to predict the product, I protonate the oxygen; my ethanol goes to the more substituted carbon; I get this target molecule out instead.5611

This is an interesting thing to point out; I have a tertiary carbon here; I am doing an Sn2 on a tertiary carbon; this is the first time we have ever seen that.5622

This is the only time we are ever going to see that; what is unique about this mechanism is that it is not an ordinary Sn2; we have always said Sn2s don't happen on tertiary carbons.5630

What is different about this mechanism?--because of the strong acid, because we are protonating the oxygen, it now is an Sn2 with some Sn1 character.5640

It is that Sn1 character, it is that presence of that positive charge that makes it different from an ordinary Sn2.5650

Now we go to the more substituted carbon, even if it is tertiary, and we do our backside attack.5656

We saw lots examples here about ethers, how to synthesize ethers, what reactions do ethers undergo, what are some physical properties.5663

Of course the most interesting ether that we have is the epoxide; we saw lots of examples of epoxide ring opening reactions and stereochemistry and regiochemistry implications of those.5671

Hope to see you next time at Educator.com; thank you.5682