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Dr. Laurie Starkey

Dr. Laurie Starkey

Elimination Reactions

Slide Duration:

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
00:45
Common Acids/Bases
00:46
Example: Determine the Direction of Equilibrium
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
03:11
Van Der Waals/ London Forces
03:12
Example: Van Der Waals/ London Forces
04:59
Water Solubility
08:32
Water Solubility
08:34
Example: Water Solubility
09:05
Example: Acetone
11:29
Isomerism
13:51
Definition of Isomers
13:53
Constitutional Isomers and Example
14:17
Stereoisomers and Example
15:34
Introduction to Functional Groups
17:06
Functional Groups: Example, Abbreviation, and Name
17:07
Introduction to Functional Groups
20:48
Functional Groups: Example, Abbreviation, and Name
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
02:14
Cyclohexane Chair Flips
04:06
Axial and Equatorial Groups
04:10
Example: Chair Flip on Methylcyclohexane
06:44
Cyclohexane Conformations Example
09:01
Chair Conformations of cis-1-t-butyl-4-methylcyclohexane
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
01:48
Drawing Stereoisomers
06:37
Draw All Stereoisomers of 2,3-dichlorobutane
06:38
Molecules with Two Chiral Centers
10:22
Draw All Stereoisomers of 2,3-dichlorobutane, cont.
10:23
Optical Activity
14:10
Chiral Molecules
14:11
Angle of Rotation
14:51
Achiral Species
16:46
Physical Properties of Stereoisomers
17:11
Enantiomers
17:12
Diastereomers
18:01
Example
18:26
Physical Properties of Stereoisomers
23:05
When Do Enantiomers Behave Differently?
23:06
Racemic Mixtures
28:18
Racemic Mixtures
28:21
Resolution
29:52
Unequal Mixtures of Enantiomers
32:54
Enantiomeric Excess (ee)
32:55
Unequal Mixture of Enantiomers
34:43
Unequal Mixture of Enantiomers
34:44
Example: Finding ee
36:38
Example: Percent of Composition
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
05:02
Aromatic Nomenclature and Examples
05:03
Aromatic Nomenclature, cont.
09:09
Ortho, Meta, and Para
09:10
Aromatic Nomenclature, cont.
13:27
Common Names for Simple Substituted Aromatic Compounds
13:28
Carboxylic Acid Nomenclature
16:35
Carboxylic Acid Nomenclature and Examples
16:36
Carboxylic Acid Derivatives
22:28
Carboxylic Acid Derivatives
22:42
General Structure
23:10
Acid Halide Nomenclature
24:48
Acid Halide Nomenclature and Examples
24:49
Anhydride Nomenclature
28:10
Anhydride Nomenclature and Examples
28:11
Ester Nomenclature
32:50
Ester Nomenclature
32:51
Carboxylate Salts
38:51
Amide Nomenclature
40:02
Amide Nomenclature and Examples
40:03
Nitrile Nomenclature
45:22
Nitrile Nomenclature and Examples
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?
00:40
Example 1: SN1 or SN2 Mechanisms
00:42
Example 2: SN1 or SN2 Mechanisms
03:00
Example 3: SN1 or SN2 Mechanisms
04:06
Example 4: SN1 or SN2 Mechanisms
06:17
SN1 Mechanism
09:12
Three Steps of SN1 Mechanism
09:13
SN1 Carbocation Rearrangements
14:50
Carbocation Rearrangements Example
14:51
SN1 Carbocation Rearrangements
20:46
Alkyl Groups Can Also Shift
20:48
Leaving Groups
24:26
Leaving Groups
24:27
Forward or Reverse Reaction Favored?
26:00
Leaving Groups
29:59
Making poor LG Better: Method 1
30:00
Leaving Groups
34:18
Making poor LG Better: Tosylate (Method 2)
34:19
Synthesis Problem
38:15
Example: Provide the Necessary Reagents
38:16
Nucleophilicity
41:10
What Makes a Good Nucleophile?
41:11
Nucleophilicity
44:45
Periodic Trends: Across Row
44:47
Periodic Trends: Down a Family
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
00:00
Example 2: Predict the Product
02:10
Example 3: Predict the Product
04:07
Predict the Product: SN2 vs. E2
06:06
Example 4: Predict the Product
06:07
Example 5: Predict the Product
07:29
Example 6: Predict the Product
07:51
Example 7: Predict the Product
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
00:08
Halohydrin: Regiochemistry
03:55
Halohydrin: Regiochemistry
03:56
Bromonium Ion Intermediate
04:26
Example
09:28
Example: Predict Major Product
09:29
Example Cont.
10:59
Example: Predict Major Product Cont.
11:00
Catalytic Hydrogenation of Alkenes
13:19
Features of Catalytic Hydrogenation
13:20
Catalytic Hydrogenation of Alkenes
14:48
Metal Surface
14:49
Heterogeneous Catalysts
15:29
Homogeneous Catalysts
16:08
Catalytic Hydrogenation of Alkenes
17:44
Hydrogenation & Pi Bond Stability
17:45
Energy Diagram
19:22
Catalytic Hydrogenation of Dienes
20:40
Hydrogenation & Pi Bond Stability
20:41
Energy Diagram
23:31
Example
24:14
Example: Predict Product
24:15
Oxidation of Alkenes
27:21
Redox Review
27:22
Epoxide
30:26
Diol (Glycol)
30:54
Ketone/ Aldehyde
31:13
Epoxidation
32:08
Epoxidation
32:09
General Mechanism
36:32
Alternate Epoxide Synthesis
37:38
Alternate Epoxide Synthesis
37:39
Dihydroxylation
41:10
Dihydroxylation
41:12
General Mechanism (Concerted Via Cycle Intermediate)
42:38
Ozonolysis
44:22
Ozonolysis: Introduction
44:23
Ozonolysis: Is It Good or Bad?
45:05
Ozonolysis Reaction
48:54
Examples
51:10
Example 1: Ozonolysis
51:11
Example
53:25
Radical Addition to Alkenes
55:05
Recall: Free-Radical Halogenation
55:15
Radical Mechanism
55:45
Propagation Steps
58:01
Atom Abstraction
58:30
Addition to Alkene
59:11
Radical Addition to Alkenes
59:54
Markovnivok (Electrophilic Addition) & anti-Mark. (Radical Addition)
59:55
Mechanism
01:03
Alkene Polymerization
05:35
Example: Alkene Polymerization
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
01:07
Example 3: Transform
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
01:03
Transformation
01:04
Regiochemistry of Epoxide Ring Openings
05:29
Regiochemistry of Epoxide Ring Openings in Base
05:30
Regiochemistry of Epoxide Ring Openings in Acid
07:34
Example
10:26
Example 1: Epoxide Ring Openings in Base
10:27
Example 2: Epoxide Ring Openings in Acid
12:50
Reactions of Epoxides with Grignard and Hydride
15:35
Reactions of Epoxides with Grignard and Hydride
15:36
Example
21:47
Example: Ethers
21:50
Example
27:01
Example: Synthesize
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
01:43
Predict
01:44
Mechanism
03:08
Mechanism for Acetal Formation
04:10
Mechanism for Acetal Formation
04:11
What is a CTI?
15:04
Tetrahedral Intermediate
15:05
Charged Tetrahedral Intermediate
15:45
CTI: Acid-cat
16:10
CTI: Base-cat
17:01
Acetals & Cyclic Acetals
17:49
Overall
17:50
Cyclic Acetals
18:46
Hydrolysis of Acetals: Regenerates Carbonyl
20:01
Hydrolysis of Acetals: Regenerates Carbonyl
20:02
Mechanism
22:08
Reaction with Nitrogen Nu:
30:11
Reaction with Nitrogen Nu:
30:12
Example
32:18
Mechanism of Imine Formation
33:24
Mechanism of Imine Formation
33:25
Oxidation of Aldehydes
38:12
Oxidation of Aldehydes 1
38:13
Oxidation of Aldehydes 2
39:52
Oxidation of Aldehydes 3
40:10
Reductions of Ketones and Aldehydes
40:54
Reductions of Ketones and Aldehydes
40:55
Hydride/ Workup
41:22
Raney Nickel
42:07
Reductions of Ketones and Aldehydes
43:24
Clemmensen Reduction & Wolff-Kishner Reduction
43:40
Acetals as Protective Groups
46:50
Acetals as Protective Groups
46:51
Example
50:39
Example: Consider the Following Synthesis
50:40
Protective Groups
54:47
Protective Groups
54:48
Example
59:02
Example: Transform
59:03
Example: Another Route
04:54
Example: Transform
08:49
Example
08:50
Transform
08:51
Example
11:05
Transform
11:06
Example
13:45
Transform
13:46
Example
15:43
Provide the Missing Starting Material
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
03:06
Ester Hydrolysis Requires Acide or Base
03:07
Nitrile Hydrolysis
05:22
Nitrile Hydrolysis
05:23
Nitrile Hydrolysis Mechanism
06:53
Nitrile Hydrolysis Mechanism
06:54
Use of Nitriles in Synthesis
12:39
Example: Nitirles in Synthesis
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
01:41
A) Hydride Nu: Review
01:42
A) Hydride Nu: Sodium Borohydride + Ester
02:43
Reactions of Carboxylic Acid Derivatives with Nucleophiles
03:57
Lithium Aluminum Hydride (LAH)
03:58
Mechanism
04:29
Summary of Hydride Reductions
07:09
Summary of Hydride Reductions 1
07:10
Summary of Hydride Reductions 2
07:36
Hydride Reduction of Amides
08:12
Hydride Reduction of Amides Mechanism
08:13
Reaction of Carboxylic Acid Derivatives with Organometallics
12:04
Review 1
12:05
Review 2
12:50
Reaction of Carboxylic Acid Derivatives with Organometallics
14:22
Example: Lactone
14:23
Special Hydride Nu: Reagents
16:34
Diisobutylaluminum Hydride
16:35
Example
17:25
Other Special Hydride
18:41
Addition of Organocuprates to Acid Chlorides
19:07
Addition of Organocuprates to Acid Chlorides
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
00:55
Crossed/Mixed Aldol & Compound with α H's
00:56
Ketone vs. Aldehyde
02:30
Crossed/Mixed Aldol & Compound with α H's Continue
03:10
Crossed/Mixed Aldol
05:21
Mixed Aldol: control Using LDA
05:22
Crossed/Mixed Aldol Retrosynthesis
08:53
Example: Predic Aldol Starting Material (Aldol Retrosyntheiss)
08:54
Claisen Condensation
12:54
Claisen Condensation (Aldol on Esters)
12:55
Claisen Condensation
19:52
Example 1: Claisen Condensation
19:53
Claisen Condensation
22:48
Example 2: Claisen Condensation
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
02:24
Electrophilic Aromatic Substitution: Friedel-Crafts Alkylation
02:25
Example & Mechanism
03:37
Friedel-Crafts Alkylation Drawbacks
05:48
A) Can Over-React (Dialkylation)
05:49
Friedel-Crafts Alkylation Drawbacks
08:21
B) Carbocation Can Rearrange
08:22
Mechanism
09:33
Friedel-Crafts Alkylation Drawbacks
13:35
Want n-Propyl? Use Friedel-Crafts Acylation
13:36
Reducing Agents
16:45
Synthesis with Electrophilic Aromatic Substitution
18:45
Example: Transform
18:46
Synthesis with Electrophilic Aromatic Substitution
20:59
Example: Transform
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
01:27
Explain Why No Diels-Alder Reaction Takes Place in This Case
01:28
Diels-Alder Reaction
03:09
Example: Predict
03:10
Diels-Alder Reaction: Synthesis Problem
05:39
Diels-Alder Reaction: Synthesis Problem
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
07:40
Pericyclic Reaction Example II
07:41
Pericyclic Reaction Example III: Vitamin D - The Sunshine Vitamin
14:22
Pericyclic Reaction Example III: Vitamin D - The Sunshine Vitamin
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
00:28
Isoelectric Point (pI), cont.
02:54
Example: What is the Net Charge of This Tetrapeptide at pH 6.0?
02:55
Nucleic Acids: Ribonucleosides
10:32
Nucleic Acids: Ribonucleosides
10:33
Nucleic Acids: Ribonucleotides
11:48
Ribonucleotides: 5' Phosphorylated Ribonucleosides
11:49
Ribonucleic Acid (RNA) Structure
12:35
Ribonucleic Acid (RNA) Structure
12:36
Nucleic Acids: Deoxyribonucleosides
14:08
Nucleic Acids: Deoxyribonucleosides
14:09
Deoxythymidine (T)
14:36
Nucleic Acids: Base-Pairing
15:17
Nucleic Acids: Base-Pairing
15:18
Double-Stranded Structure of DNA
18:16
Double-Stranded Structure of DNA
18:17
Model of DNA
19:40
Model of DNA
19:41
Space-Filling Model of DNA
20:46
Space-Filling Model of DNA
20:47
Function of RNA and DNA
23:06
DNA & Transcription
23:07
RNA & Translation
24:22
Genetic Code
25:09
Genetic Code
25:10
Lipids/Fats/Triglycerides
27:10
Structure of Glycerol
27:43
Saturated & Unsaturated Fatty Acids
27:51
Triglyceride
28:43
Unsaturated Fats: Lower Melting Points (Liquids/Oils)
29:15
Saturated Fat
29:16
Unsaturated Fat
30:10
Partial Hydrogenation
32:05
Saponification of Fats
35:11
Saponification of Fats
35:12
History of Soap
36:50
Carboxylate Salts form Micelles in Water
41:02
Carboxylate Salts form Micelles in Water
41:03
Cleaning Power of Micelles
42:21
Cleaning Power of Micelles
42:22
3-D Image of a Micelle
42:58
3-D Image of a Micelle
42:59
Synthesis of Biodiesel
44:04
Synthesis of Biodiesel
44:05
Phosphoglycerides
47:54
Phosphoglycerides
47:55
Cell Membranes Contain Lipid Bilayers
48:41
Cell Membranes Contain Lipid Bilayers
48:42
Bilayer Acts as Barrier to Movement In/Out of Cell
50:24
Bilayer Acts as Barrier to Movement In/Out of Cell
50:25
Organic Chemistry Meets Biology… Biochemistry!
51:12
Organic Chemistry Meets Biology… Biochemistry!
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
02:05
Alkyne to Cis Alkene
02:06
Alkyne to Trans Alkene
02:56
Synthesis of Alkenes by Wittig Reaction
03:46
Synthesis of Alkenes by Wittig Reaction
03:47
Retrosynthesis of an Alkene
05:35
Example: Synthesis of an Alkene
06:57
Example: Synthesis of an Alkene
06:58
Making a Wittig Reagent
10:31
Synthesis of Alkynes
13:09
Synthesis of Alkynes
13:10
Synthesis of Alkynes by Elimination (FGI)
13:42
First Step: Bromination of Alkene
13:43
Second Step: KOH Heat
14:22
Synthesis of Alkynes by Alkylation
15:02
Synthesis of Alkynes by Alkylation
15:03
Retrosynthesis of an Alkyne
16:18
Example: Synthesis of an Alkyne
17:40
Example: Synthesis of an Alkyne
17:41
Synthesis of Alkanes
20:52
Synthesis of Alkanes
20:53
Synthesis of Aldehydes & Ketones
21:38
Oxidation of Alcohol Using PCC or Swern
21:39
Oxidation of Alkene Using 1) O₃, 2)Zn
22:42
Reduction of Acid Chloride & Nitrile Using DiBAL-H
23:25
Hydration of Alkynes
24:55
Synthesis of Ketones by Acyl Substitution
26:12
Reaction with R'₂CuLi
26:13
Reaction with R'MgBr
27:13
Synthesis of Aldehydes & Ketones by α-Alkylation
28:00
Synthesis of Aldehydes & Ketones by α-Alkylation
28:01
Retrosynthesis of a Ketone
30:10
Acetoacetate Ester Synthesis of Ketones
31:05
Acetoacetate Ester Synthesis of Ketones: Step 1
31:06
Acetoacetate Ester Synthesis of Ketones: Step 2
32:13
Acetoacetate Ester Synthesis of Ketones: Step 3
32:50
Example: Synthesis of a Ketone
34:11
Example: Synthesis of a Ketone
34:12
Synthesis of Carboxylic Acids
37:15
Synthesis of Carboxylic Acids
37:16
Example: Synthesis of a Carboxylic Acid
37:59
Example: Synthesis of a Carboxylic Acid (Option 1)
38:00
Example: Synthesis of a Carboxylic Acid (Option 2)
40:51
Malonic Ester Synthesis of Carboxylic Acid
42:34
Malonic Ester Synthesis of Carboxylic Acid: Step 1
42:35
Malonic Ester Synthesis of Carboxylic Acid: Step 2
43:36
Malonic Ester Synthesis of Carboxylic Acid: Step 3
44:01
Example: Synthesis of a Carboxylic Acid
44:53
Example: Synthesis of a Carboxylic Acid
44:54
Synthesis of Carboxylic Acid Derivatives
48:05
Synthesis of Carboxylic Acid Derivatives
48:06
Alternate Ester Synthesis
48:58
Using Fischer Esterification
48:59
Using SN2 Reaction
50:18
Using Diazomethane
50:56
Using 1) LDA, 2) R'-X
52:15
Practice: Synthesis of an Alkyl Chloride
53:11
Practice: Synthesis of an Alkyl Chloride
53:12
Patterns of Functional Groups in Target Molecules
59:53
Recall: Aldol Reaction
59:54
β-hydroxy Ketone Target Molecule
01:12
α,β-unsaturated Ketone Target Molecule
02:20
Patterns of Functional Groups in Target Molecules
03:15
Recall: Michael Reaction
03:16
Retrosynthesis: 1,5-dicarbonyl Target Molecule
04:07
Patterns of Functional Groups in Target Molecules
06:38
Recall: Claisen Condensation
06:39
Retrosynthesis: β-ketoester Target Molecule
07:30
2-Group Target Molecule Summary
09:03
2-Group Target Molecule Summary
09:04
Example: Synthesis of Epoxy Ketone
11:19
Synthesize the Following Target Molecule from Cyclohexanone: Part 1 - Retrosynthesis
11:20
Synthesize the Following Target Molecule from Cyclohexanone: Part 2 - Synthesis
14:10
Example: Synthesis of a Diketone
16:57
Synthesis of a Diketone: Step 1 - Retrosynthesis
16:58
Synthesis of a Diketone: Step 2 - Synthesis
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
00:52
Example 8
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'
01:24
Understanding Splitting Patterns: The 'n+1 Rule'
01:25
Explanation of n+1 Rule
02:42
Explanation of n+1 Rule: One Neighbor
02:43
Explanation of n+1 Rule: Two Neighbors
06:23
Summary of Splitting Patterns
06:24
Summary of Splitting Patterns
10:45
Predicting ¹H NMR Spectra
10:46
Example 1: Predicting ¹H NMR Spectra
13:30
Example 2: Predicting ¹H NMR Spectra
19:07
Example 3: Predicting ¹H NMR Spectra
23:50
Example 4: Predicting ¹H NMR Spectra
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)
02:40
Allylic (4-bond) and W-coupling (4-bond) (Rigid Structures Only)
04:05
¹H NMR Advanced Splitting Patterns
05:39
Example 1: ¹H NMR Advanced Splitting Patterns
05:40
Example 2: ¹H NMR Advanced Splitting Patterns
10:01
Example 3: ¹H NMR Advanced Splitting Patterns
13:45
¹H NMR Practice
22:53
¹H NMR Practice 5: C₁₁H₁₇N
22:54
¹H NMR Practice 6: C₉H₁₀O
34:04
¹³C NMR Spectroscopy
44:49
¹³C NMR Spectroscopy
44:50
¹³C NMR Chemical Shifts
47:24
¹³C NMR Chemical Shifts Part 1
47:25
¹³C NMR Chemical Shifts Part 2
48:59
¹³C NMR Practice
50:16
¹³C NMR Practice 1
50:17
¹³C NMR Practice 2
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
01:29
McLafferty Rearrangement
01:30
Mass Spectra of Esters
04:15
Mass Spectra of Esters
01:16
Mass Spectrometry Discussion I
05:01
For the Given Molecule (M=58), Do You Expect the More Abundant Peak to Be m/z 15 or m/z 43?
05:02
Mass Spectrometry Discussion II
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?
08:14
Mass Spectrometry Discussion III
11:42
Explain Why the Mass Spectra of Methyl Ketones Typically have a Peak at m/z 43
11:43
Mass Spectrometry Discussion IV
14:46
In the Mass Spectrum of the Given Molecule (M=88), Account for the Peaks at m/z 45 and m/z 57
14:47
Mass Spectrometry Discussion V
18:25
How Could You Use Mass Spectrometry to Distinguish Between the Following Two Compounds (M=73)?
18:26
Mass Spectrometry Discussion VI
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)?
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 (62)

1 answer

Last reply by: Professor Starkey
Thu Jan 21, 2016 12:07 AM

Post by Jinhai Zhang on January 20, 2016

Dear Prof. Starkey:
when we assign beta or alpha in alkyl halide and ketone it is little bit different right?

1 answer

Last reply by: Professor Starkey
Tue Jan 19, 2016 1:13 PM

Post by Jason Smith on January 18, 2016

Hi professor, do you have any recommendations for where to buy an organic chemistry model set (or what specific brand)? I don't particularly trust Amazon reviews, so I wanted to get your opinion. Thank you.

5 answers

Last reply by: Professor Starkey
Wed Dec 10, 2014 10:34 PM

Post by Parth Shorey on November 19, 2014

At 54:40, I still didn't understand the minor and the major E1, I understand the steric hindrance but what about stability? The major is CIS, isn't the stability lower compared to the minor?

1 answer

Last reply by: Professor Starkey
Wed Nov 19, 2014 9:58 AM

Post by Parth Shorey on November 18, 2014

I still don't understand at 12:05 why the Ph is on the same side?

1 answer

Last reply by: Professor Starkey
Sun Oct 19, 2014 9:53 AM

Post by Brijae Chavarria on October 18, 2014

Hi Prof. Starkey,
Around 48:50 you explain how Sn1 and E1 have the same rates and a benzylic or allylic would be fastest for both, but for the elimination reaction, there would be no beta hydrogens and for the allylic you would form a structure with two double bonds next to it, right? So, wouldn't the benzyl end up leading to an sn1 only and the allyl just get messy?

1 answer

Last reply by: Professor Starkey
Thu Oct 9, 2014 12:23 AM

Post by Foaad Zaid on October 8, 2014

Hi Prof. Starkey,

I have a question with regards to the E1 Stereochemistry slide, the second problem on the slide has a week base and weak nucleophile. and also has heat involved.  Now you mentioned that the major would most likely be SN1 and E1 being a minor.  I was under the impression that anytime you have Heat involved in a reaction the reaction favors an elimination as a major product?  Can you be kind enough to clarify that for me?

1 answer

Last reply by: Professor Starkey
Mon Jun 30, 2014 11:59 AM

Post by John Zou on June 28, 2014

according to my text book. Geminal is more stable than > trans and > cis

1 answer

Last reply by: Professor Starkey
Sat Mar 8, 2014 8:53 PM

Post by Amirali Aghili on March 8, 2014

Dear Dr.Starkey

I am studying for a national exam, and things are very confusing to me regarding tertiary butoxide. Organic Chemistry by Smith does not recognize hofmann product at all and gives zaitsev product with tertiary butoxide even with tertiary alkyl halide. Organic Chemistry by Klein and Solomon give hofmann product with both tertiary and secondary alkyl halides (but no example of what happens with primary), and Organic chemistry by Bruice explicitly says tertiary butoxide with only tertiary gives hofmann but says secondary gives still zatisev. what am I supposed to do on a national exam when I don’t know which reference is used? what is the product with primary and secondary alkyl halide with tertiary butoxide?

Thanks

1 answer

Last reply by: Professor Starkey
Mon Feb 24, 2014 8:54 AM

Post by Toya Monger on February 23, 2014

Hello Dr. Starkey!!! I was wondering if it mattered (for the cyclohexane demonstration) if the LG was in the down position and the beta hydrogen & methyl was up after the flip.  

1 answer

Last reply by: Professor Starkey
Sun Jan 5, 2014 9:29 PM

Post by Calin Cochran on January 5, 2014

Hi Dr. Starkey,

I just wanted to let you know that I survived my first semester of organic chemistry thanks to you & your lectures! I wasn't doing too hot after our second exam & knew I needed to change something. I downloaded educator & watched countless hours of lectures. With your help, I was able to earn an A in a course that I thought would be impossible! Thank you so much for helping me attain that! I will be definitely be visiting again when next semester begins!

1 answer

Last reply by: Professor Starkey
Wed Dec 4, 2013 10:02 PM

Post by Sam Albert on December 4, 2013

Professor Starkey, when I view this lecture, as I get to the "Regiochemistry of E2" slide, my video restarts to the start of the lecture and it will NOT proceed past this point.  This is very frustrating.  Is there anything that would cause this?  Thanks for reading my comment.

Sam

1 answer

Last reply by: Professor Starkey
Thu Nov 21, 2013 11:56 PM

Post by Edwin Trent on November 20, 2013

Dr. Starkey,

Around 28 minutes, you are describing the ring flip involved to allow anti-coplanar interaction for the E2 elimination. In your diagram you show that the methyl is dashed initially then flip the ring. Would that not make the product a wedged methyl since it is now in an axial position, opposite it's original direction which was away from the plane of the page?

1 answer

Last reply by: Professor Starkey
Sat Nov 9, 2013 11:56 AM

Post by Calin Cochran on November 9, 2013

Hi Dr. Starkey,

I am writing out the notes as I watch the lecture and came across a question on the alkene stability slide, example 1. We are drawing both products and picking which is the major product. However, since the leaving group is attached to a carbon bearing 3 other carbons, wouldn't it be tertiary & not want to react in the E2 mechanism?

1 answer

Last reply by: Professor Starkey
Fri Nov 8, 2013 1:22 PM

Post by Ashley Keim on November 7, 2013

Dr. Starkey,
On the last examples of this video, could it be an E1 reaction? We were thinking it could be because it is a tertiary carbon and a weak base.

Thank you!
-Ashley

3 answers

Last reply by: Professor Starkey
Thu Nov 21, 2013 11:42 PM

Post by Nicholas Elias on October 17, 2013

Protic....spellcheck lol

1 answer

Last reply by: Professor Starkey
Fri Oct 18, 2013 2:08 PM

Post by Nicholas Elias on October 17, 2013

In the example at 67:55 since you have a good leaving group, tertiary carbon and a erotic solvent being water would a side reaction involving an alcohol by SN1 mechanism also occur?

1 answer

Last reply by: Professor Starkey
Tue Jul 2, 2013 9:26 AM

Post by Professor Needham on July 1, 2013

When should I use the elimination reactions?

1 answer

Last reply by: Professor Starkey
Wed May 15, 2013 11:30 PM

Post by Some one on May 15, 2013

Hello Professor, why does the base attack the beta hydrogens instead of the alpha hydrogens?

1 answer

Last reply by: Professor Starkey
Sat Apr 13, 2013 11:49 AM

Post by Ki Hargis on April 9, 2013

Hello,

What makes an E2 reaction favored over an SN1 reaction, since both reactions favor tertiary carbons attached to the leaving group?

1 answer

Last reply by: Professor Starkey
Wed Feb 13, 2013 10:24 PM

Post by Artum Silnitsky on February 13, 2013

HI!
at alkene stability the dr. use 2 ex., in the 2nd ex. - why one of the H's from the CH3 is not an option for Elimination?

1 answer

Last reply by: Professor Starkey
Sun Jan 27, 2013 11:11 PM

Post by kathy jarman on January 27, 2013

Hi Dr. Starkey, at 52:52 (the E2 reaction), could another minor product be produced since there is another beta hydrogen (from the methyl group)? If so, I will assume it will be very minor since the alkene is not as substituted as the other alkene.

1 answer

Last reply by: Professor Starkey
Sun Jan 13, 2013 11:55 AM

Post by Aaron Harper on January 11, 2013

I understand know, why Professor Starkey used H2O as the base, because your solvent is H2O, thus more H2O than Cl-, as in this case and before when I commented some videos back.

Thanks for the education!

3 answers

Last reply by: natasha plantak
Sun Dec 16, 2012 11:22 AM

Post by natasha plantak on December 12, 2012

How come the final example, 70:22, can't undergo an E1 Rx?

1 answer

Last reply by: Professor Starkey
Fri Feb 3, 2012 11:27 PM

Post by thuy dinh on February 2, 2012

Thanks for answering my question, I just had my first exam this semester for Organic chem. II. My teacher put a reaction with two leaving groups, it was called 2,5 dichloro-2-methylpentane reacting with a stronger nucleophile that wasn't a base. I know that it is a substitution reaction but would it be SN2 or SN1 since one chlorine is on a teritary carbon and the other chloride is a primary?

1 answer

Last reply by: Professor Starkey
Fri Jan 27, 2012 11:00 PM

Post by thuy dinh on January 26, 2012

Hi Profosser,
Can you explain why SN1 is the more major product than the E1 in the second example please?

1 answer

Last reply by: Professor Starkey
Sat Nov 5, 2011 3:14 PM

Post by Jindou Tian on October 27, 2011

Hi Dr. Starkey, thank you for your quick response! Are we able to judge the basicity based on the electronegativity of the compound? Also, could you please tell me what reaction will take place, Sn1 or E1, when CH2=CH-CH2Br reacts with water? I know that since the carbon cation is allylic, there won't be any rearrangement occurs. But what will happen after the LG leaves?

1 answer

Last reply by: Professor Starkey
Thu Oct 27, 2011 10:56 AM

Post by Jindou Tian on October 26, 2011

Hi Dr. Starkey, could you explain why CN- and NH3 are weak bases? I thought all strong nu: are basically strong bases.

Elimination Reactions

Draw the product for this reaction:
Draw the product for this reaction:
Draw the product for this reaction:
Draw the product for this reaction:
Draw the product for this reaction:
Draw the product for this reaction:

*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

Elimination Reactions

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
  • Elimination Reactions: E2 Mechanism 0:06
    • E2 Mechanism
    • Example of E2 Mechanism
  • Stereochemistry of E2 4:48
    • Anti-Coplanar & Anti-Elimination
    • Example 1: Stereochemistry of E2
    • Example 2: Stereochemistry of E2
  • Regiochemistry of E2 13:04
    • Refiochemistry of E2 and Zaitsev's Rule
    • Alkene Stability
  • Alkene Stability 19:20
    • Alkene Stability Examples
    • Example 1: Draw Both E2 Products and Select Major
    • Example 2: Draw Both E2 Products and Select Major
  • SN2 Vs. E2 Mechanisms 29:06
    • SN2 Vs. E2 Mechanisms
    • When Do They Compete?
  • SN2 Vs. E2 Mechanisms 31:23
    • Compare Rates
  • SN2 Vs. E2 Mechanisms 36:34
    • t-BuBr: What If Vary Base?
    • Preference for E2 Over SN2 (By RX Type)
  • E1 Elimination Mechanism 41:51
    • E1 - Elimination Unimolecular
    • E1 Mechanism: Step 1
    • E1 Mechanism: Step 2
  • E1 Kinetics 46:58
    • Rate = k[RCI]
    • E1 Rate (By Type of Carbon Bearing LG)
  • E1 Stereochemistry 49:49
    • Example 1: E1 Stereochemistry
    • Example 2: E1 Stereochemistry
  • Carbocation Rearrangements 55:57
    • Carbocation Rearrangements
    • Product Mixtures
  • Predict the Product: SN2 vs. E2 59:58
    • Example 1: Predict the Product
    • Example 2: Predict the Product
    • Example 3: Predict the Product
  • Predict the Product: SN2 vs. E2 1:06:06
    • Example 4: Predict the Product
    • Example 5: Predict the Product
    • Example 6: Predict the Product
    • Example 7: Predict the Product

Transcription: Elimination Reactions

Welcome back to Educator.0000

Next we are going to talk about a class of reactions called elimination reactions.0002

The first reaction we will study is called an E2 reaction for an E2 mechanism; and the name of that reaction comes from the fact that it is an elimination reaction; and it is bimolecular.0008

It is a one-step mechanism very similar to the Sn2; the other mechanism we saw that was a single step was also bimolecular.0020

That has the same 2 that the E2, as the Sn2 backside attack substitution reaction.0031

Something that the E2 mechanism needs is a strong base; so what are things that we know of as strong bases?0038

Things like hydroxide or alkoxide; maybe an N- would also be a very strong base; so pretty short list of species that we would describe as strong bases.0044

Those are the kinds of reagents we will need to do an E2 elimination; and here is an example of one.0059

Let's react... we will start with an alkyl halide; and we will react it with sodium hydroxide; that is a nice strong base.0065

What do bases do?--bases go after protons; the proton we are going to attack is located right here.0072

It is not on the same carbon as the leaving group; remember the halide is going to behave as a leaving group just like it did in the substitution reaction.0080

The hydrogen that gets attacked is not on the same carbon as the leaving group; it is the next carbon over.0089

We call this not the α position but the β; this is called a β hydrogen.0095

The hydroxide or whatever strong base we are using is going to come in; and in a single step, it is going to grab that proton, form a π bond, and kick off the leaving group.0101

The product we are going to get will be an alkene; we are going to get an alkene product; we are going to be forming a carbon-carbon double bond as a result of an elimination.0115

The other products that are being formed... if I used hydroxide, I am also forming water, the conjugate acid of hydroxide; and of course I always lose my leaving group, so I also form bromide as well.0131

This is described as an elimination reaction because you have eliminated both the β hydrogen and the leaving group.0144

We lost HBr so sometimes this reaction is described as a dehydrohalogenation; because you have lost the hydrogen and the halogen.0152

What do you think an energy versus POR diagram would look like?--well, it would be a lot like our Sn2 mechanism because that was also a single step reaction.0162

Our energy versus progress of reaction, we would start at some combined energies for our starting materials; the hydroxide, the alkyl halide.0174

We are going to end at some final product energy; assuming it is a favorable reaction, that it is going to be an exothermic reaction.0184

In order to get from the starting material to the product, as usual for our one-step reaction, we are going to go through just a single transition state to go here.0192

So really, the energy diagram looks very similar to that for the Sn2.0202

What does the transition state look like?--the transition state has a lot of bonding changes taking place all in a single step.0206

First of all, we are forming a new bond between the hydroxide and the hydrogen; so forming bonds, we show as partial bonds in the transition state.0215

We are also breaking this carbon-hydrogen bond; so breaking bonds, we are going to draw as a partial bond in the transition state; let me draw the rest of my carbon chain here.0227

We are also forming a π bond between these two carbons so we will show a partial double bond being formed between those two.0239

Finally our leaving group is leaving so we are breaking the carbon-bromine bond; and we will draw that as a partial bond as well; so four bonds involved in this mechanism, being formed or broken.0248

How about any partial charges that we need to account for in our transition state?0260

In our starting materials, our oxygen is negatively charged, but it is neutral in the product so that charge is disappearing; we have a partial minus on the oxygen.0267

Our bromine starts out neutral but ends up as bromide; so we have a negative charge developing on the bromide; so that is what our transition state looks like for the E2 elimination mechanism.0277

What about the stereochemistry for the E2?--if we are dealing with a chiral molecule and we have some asymmetric centers, what is the ramification of that stereochemistry when we do an E2?0292

It turns out that there is a special relationship we have to have between the β hydrogen and the leaving group that got eliminated; they need to be anti-coplanar.0305

That is the relationship we described when we looked at Newman projections; we said two groups were anti if one was straight up and one was straight down; anytime they have 180 degree dihedral angle.0314

That is the required relationship of the leaving group and the β hydrogen; and for that reason, the E2 is described as anti-elimination.0326

Let's see an example of this; here we have... I had to hand draw some of this... we have an alkyl halide--here is our leaving group that is going to be eliminated.0336

We are not just eliminating a leaving group; we also have to eliminate a hydrogen on the next carbon over.0349

We go this carbon and we see there are no hydrogens; so we go to the next carbon, and here we find there is only one possible β hydrogen.0355

But when we look at this conformation as drawn, the H and the Br are not anti to one another; they are both dashed bonds, dashed lines.0365

If we were to look at this from the side, we see that they would be gauche to one another; they are close to one another.0377

But that is okay; this is a molecule that can be rotated; we could rotate around that carbon-carbon single bond.0382

That is what we will do; we are going to rotate first and rearrange it such that the hydrogen and the bromine are 180 degrees.0391

One way to draw that very easily is to show the hydrogen pointing straight up, the bromine pointing straight down, both in the plane; that must mean they are anti-coplanar.0400

Now the next two drawings we see, the H and Br are anti; and that is the necessary conformation; we have to be able to do this before we can do the E2 elimination.0411

But if we are going to rotate this, that is going to move these other groups; where are they going to go?0429

Let's start with, let's look at this bromine; and I built a model of this; so this bromine right now is pointing away from us; it is a dashed line.0436

What we need to do is we need to rotate it into the plane; then we need to bring it forward.0449

What does that do to this phenyl group?--it was in the plane, but when we rotate it, it is like we grab onto this group and turn all three groups clockwise.0455

That pushes the phenyl group backwards; and so on this carbon now, the phenyl is going be a dashed bond.0463

This hydrogen was a wedge; it is still a wedge; it was pointing down a little bit; and now it is pointing up a little bit; but it still pointing towards you.0472

Let's see if we can do this second carbon; we want the hydrogen to be pointing straight up and in the plane; so what did we have to do?0481

We had to grab onto that hydrogen and bring that forward as well; so we grab onto that molecule and twist that carbon.0490

What is going to happen to this ethyl group?--is it now going to be a wedged bond or a dashed bond?--well let's take a look.0498

Here is our drawing; our ethyl group is in the plane; our methyl group is a wedge; hydrogen is a dash.0507

We want to bring this forward so that it is in the plane; and when doing so, that is going to push our ethyl group back.0515

So the ethyl group will also be pointing backwards, CH3CH2; and our methyl group is still a wedge.0524

So wWe are going to need to manipulate our molecule a little bit to get the leaving group and the β hydrogen anti to one another.0533

Another perspective of this drawing is if we stand here and look at it this way.0541

On this front carbon, we see the hydrogen is pointing straight up; on the back carbon, you see the bromine pointing straight down.0548

This is that relationship of anti that we described back when we first learned about these Newman projections.0554

Once it is in the proper conformation, now my base, whatever base I am using, can come in and do the elimination.0562

One, two, three arrows; grab the hydrogen, form the π bond, kick out the leaving group.0568

What happens is because it is a concerted mechanism, all the other groups that are on the carbon chain end up getting frozen in place the relative positions they were in this anti conformation.0574

Notice that the phenyl and the ethyl are on the same side here; after I do the elimination, the phenyl and the ethyl are required to still be on the same side.0587

I could see it in this drawing too here; the ethyl is a dash, the phenyl is a dash; they are both behind the page.0598

So when we flatten it out... remember when we do the elimination, we are going to a planar product.0605

Everything is going to be pushed up or down a little bit; but the phenyl and the ethyl are still going to end up being on the same side.0611

This going to be the only stereochemistry that is observed; in other words, we are not getting this possibility where the ethyl and the hydrogen are on the same side.0618

This product would arrive from a different conformation, one that does not have the hydrogen and the bromine anti originally.0632

Let's try another example; here we have two phenyl groups; let's identify our leaving group; that is always easy to find; it is going to be a halide, maybe a tosylate, but a halide would do great.0639

Where do we have our β hydrogen?--this is another example where there is only one possible β hydrogen right here.0654

Are they anti right now?--they are not anti right now, they are both dashes again; so let's rotate this.0663

The easiest way to rotate this compound would be to bring that bromine slightly forward, bring that hydrogen slightly forward, so that they are both in the plane with one up and one down.0670

Let's fill in our dash and wedge that we know are here and see where those phenyl groups go.0683

What do you think?--this bromine, when you bring that bromine forward, what does that do to the phenyl group?0690

If you bring the bromine forward, that is going to push the phenyl group back; and when you bring this hydrogen forward, that is also going to push this phenyl group back.0697

This is the proper conformation that we have where they are now anti to one another; so what we did here was we just rotated so that they are anti.0710

Now we could have our base come in and do our elimination; three arrows--base attacks the hydrogen, forms a π bond, kicks out the leaving group0722

Since it is just a one-step mechanism, it is a great idea to go ahead and draw the arrows so you have a better chance of drawing the product accurately.0734

We are going to get an alkene product which is planar; and what is the relationship of those two phenyl groups going to be?0741

Because they are both behind the board, one is a little up and one is a little down, they are both going to get flattened out, but they are both still going to be behind the board.0750

So whether you draw them on the top or the bottom, it doesn't matter; but you need to show them on the same side of the double bond.0757

We have two phenyls on the same side; and what are the other two groups?--we have the methyl and a hydrogen; those were both wedges pointing out towards you; and they still will be.0763

Again it doesn't matter if you draw the phenyls up, or you flip it over and draw the arrows down, that is the same exact product.0773

Anti elimination is the way we describe the stereochemistry of the E2 mechanism.0778

What about the regiochemistry of the E2?--regiochemistry is when we ask about what region or site reacts.0786

If we have a choice of more than one site on a molecule to undergo a reaction, how do we make that decision?--and here is such an example.0799

Here we have an alkyl halide; we see our leaving group; we treat it with a strong base; let's say we want to do an E2 elimination.0807

Actually I think there is more than one possibility here so let's consider both possibilities.0816

If we wanted to do an E2, we have our leaving group is on this carbon, where do we have β hydrogens?0823

Well, we have a hydrogen on this carbon; and on this carbon, we have two hydrogens; we have one that is a wedge and one that is a dash.0829

The hydrogen on the far left, we will call that HA; and the hydrogen that is a dash, we will call that HB.0840

And let's call this D; I will refer to that hydrogen in just a moment.0848

What is another thing that can happen?--let's think about this reagent that we are using, hydroxide; what do you know about hydroxide's reactivity?0857

What can it do?--is it an acid or a base or an electrophile or a nucleophile?0866

It certainly can be a strong base; then that is what we are considering right now, doing the E2 elimination as a strong base and attacking a proton.0871

But isn't it also a strong nucleophile?--it definitely is a strong nucleophile; and what mechanism do we associate with strong nucleophiles?--backside attack, Sn2 mechanism.0879

So another thing that hydroxide can do is it can attack in this position; let's call that path C; and that would be an Sn2 path; that would be a backside attack path.0892

Let's look at what those three products would look like A, B, and C; A, if I took this hydrogen, would end up with a double bond between these first two carbons.0905

B, if I took the hydrogen from this middle carbon, would give me a double bond between these middle two carbons; now I went ahead and took that hydrogen and left the carbon chains where they are.0916

Because notice this HB is a dash and the bromine is a wedge so they are already in the anti-conformation; so I don't have to do any rotations.0931

If I wanted to take hydrogen D and do an elimination there, what I would have to do is I would have to twist the molecule to get those two, the hydrogen and the bromine, anti.0941

That would give product D like this; D isn't even formed, but we will draw that up here so you can see what that looks like.0951

What does product C look like if you do the Sn2 mechanism?--backside attack; that means you replace your leaving group, substitute your leaving group for your nucleophile.0960

Tell me about the stereochemistry of that reaction; since the bromine is a wedge, the hydroxide must have come from behind; and you would get a dash here.0968

These are in fact the three major products; 16% of A is isolated; 75% of B and 9% of C; so Sn2, we get a very small amount here.0980

We are going to talk a little later about how we would make that prediction of the E2 versus the Sn2 mechanism.0995

But of these, these are both E2 eliminations, but there is a huge difference on which is the major product.1001

B is favored by far; why is that?--it is the major product because it is the more stable alkene.1012

This is known as Zaitsev's rule; and Zaitsev's rule states that when you have a choice between different alkenes that you can form, you are always going to want to form the more stable alkene.1019

Can you tell between B and D, why B would be favored over D?--why is that the major product?--let me fill these in; looks a little better.1032

Why is B better than D?--well, this is cis versus trans; and the cis is going to have some steric hindrance so that is definitely going to be less stable than the trans.1042

That explains why no D was formed even though it is a possible product.1055

But other than cis and trans, what are some other things we should know about alkene stability?1060

If we want to predict which is the major product, we have to understand which alkene is more stable; let's take a look at some factors that will affect alkene stability.1066

One thing is that if you are ever given conjugate, if it is ever possible to be conjugated, that is going to be a more stable alkene, a more stable diene.1078

If you have multiple π bonds, then it is better to have those double bonds alternating double bond, single bond, double bond, than isolated.1086

Here they have no relationship to each other; here they have one right after another; we have a p orbital here and a p orbital here, and right away we have more p orbitals.1095

This relationship is more stable because we could have resonance delocalization of these π electrons.1104

If you happen to already have a double bond in the structure, when you go to form a second double bond, if it is possible to put that new double bond in conjugation with the original one, that would be a good thing.1110

Another rule is that as you increase the number of alkyl substituents on the double bond, you increase stability.1123

What do I mean by alkyl substituents?--these are the number of carbon groups on the carbon-carbon double bond.1131

What is the maximum number of carbon groups that you can put on a carbon-carbon double bond?1143

Remember each of these carbons wants four bonds; so there is two bonds over here and two bonds over here; that would be a very stable carbon-carbon double bond.1148

Let's take a look at some examples; here is one such example of that; this alkene has four alkyl groups attached; we describe this as being tetra-substituted.1158

This is called a tetra-substituted alkene; that is the most alkyl groups you could possibly have; and this is the most stable alkene that there is; it really likes having those alkyl groups on there.1175

That is going to be more stable than an alkene with just three alkyl groups; we call those tri-substituted.1186

That is more stable than any di-substituted pattern; and look at all these possibilities; these are all di-substituted.1197

But within the di-substituted patterns, we want to know that the trans arrangement where the two alkyl groups are as far apart from each other as possible, that is going to be the best arrangement.1205

That is more stable than cis; cis is not so good because it has some sterics here; remember there is some steric hindrance in cis that makes it less stable, higher energy.1219

That is not such a great arrangement; and this one isn't so great either; this is called geminal or gem for short; having two groups on just one end of the double bond is not a very stable arrangement.1232

I usually don't care too much on trying to compare these two, but for sure you should know that neither of these is as good as the trans relationship; but typically cis is better than geminal.1246

All of these are better than having just a single alkyl group; we would describe that as a mono-substituted alkene.1257

Or you could also describe it as terminal; it is called a terminal alkene because it is at the terminus; it is at the end of a carbon chain if it has just one alkyl group on it.1269

That is not a very good arrangement for alkyl groups as well; this is the least stable.1279

It turns out that this is the same general trend in stability we saw for carbocations; carbocations like to have alkyl groups attached.1286

That one is a little easier to understand or maybe predict because it is an electron deficient species.1293

Why is it that alkyl groups also like to have... I'm sorry, why is it that alkenes also like to have alkyl groups attached?1300

That discussion of that stabilization is a bit beyond our scope here; so we simply need to know that the more alkyl groups we have, the more stable it is.1306

Let's take a look at a few examples and see if we can apply Zaitsev's rule; here is an example--draw both E2 products and select the major.1318

We have our leaving group here; how is it possible to get two different E2 products?--well, let's look for our β hydrogens.1328

There is no hydrogens on this carbon; it is the next carbon over; we could grab one of these hydrogens or one of these hydrogens.1339

Would those give two different products?--actually those would both give the exact same product; so β hydrogen type A is going to be right here or right here.1345

Where is the second type of β hydrogen?--how about going in this direction right here?--going to this methyl group; β hydrogen type B.1359

Product A would form a double bond within the ring; and like I said, whether you go to the right or left, it is the same product.1370

Tell me about this methyl group; is that still a dash?--is that still pointing behind the board?1378

Remember what an sp2 hybridized carbon looks like, an alkene carbon?--this is planar; and so that methyl group now after the elimination is completely flat; and it should be drawn as a straight line.1385

Now you can see that if you just flip it over, taking the hydrogen from either side would give the exact same product.1396

But what is the other possible product we can form?--instead of going to one of the side ones, we can go up to this top carbon.1403

What does he look like now?--he used to be a CH3; it is now going to be a CH2 because one of those hydrogens was taken away.1411

These are the two possible products we can get; and now which is the major product?1419

We are going to look to see which one is more stable; and for that, we are going to see which one is more highly substituted.1426

How would you describe the number of alkyl groups attached to this first carbon, to this first alkene?1431

Here is our alkene; we have one, two, three carbons attached to it; in other words, there is only one hydrogen.1438

This is a tri-substituted alkene; and how about this second one?--we have two hydrogens up here and two carbons.1448

We are not counting the carbons in the double bond; we are asking how many carbons are attached to those double bonds; this is a di-substituted alkene.1459

Which would be the major product?--the tri-substituted would be the major; why?--it is usually not such a great idea to just say because Professor Zaitsev told me so or just invoke the rule.1471

The reason it is the major product is because it is the more stable alkene; that is how we determine the regiochemistry of E2 elimination.1486

Let's take a look at another example--if our leaving group is attached to a six-membered ring.1502

Now it is the chair conformation of that compound that needs to be taken into consideration when we look at the stereochemistry and the regiochemistry.1510

Here again we have a strong base; we forgot to mention that up here just noting we were using hydroxide; now here we are using methoxide, also a strong base.1522

When we look at it in this conformation, if you think about where you are going to take your β hydrogen, we have hydrogens over here and we have hydrogens over here.1532

Which one is more tempting to take based on Zaitsev's rule?--for regiochemistry, where do you think you want to go?1542

I am guessing we might want to go to this side because that would give us a more highly substituted double bond; but there is a problem with that.1549

What did we learn about the stereochemistry of the E2?--let's draw in that hydrogen and see if you can find a problem with that hydrogen.1557

That hydrogen is a wedge; that bromine is a wedge; is it possible to rotate that to get them anti to one another?--it is not; so because this is not anti, I can't eliminate in that direction.1567

Instead I have to look over to this side; this is a CH2; one is a wedge and one is a dash; this is the only anti β hydrogen; so there is only one possible product we can get.1580

When you look at the chair conformation, the most stable chair here has a bromine up; we could put that in an equatorial position.1595

And it has a methyl down; we can also put that in an equatorial position; so the most stable chair has the leaving group in an equatorial position.1603

Unfortunately the hydrogen we want to take next door is not anti; those are not anti to one another; again those are going to be gauche to one another when you take a look at that Newman projection.1614

What we are going to have to do is we are going to have to flip our chair into the other conformation.1628

Let's see; that means we are taking this carbon and bringing it down; so that is down here; this hydrogen is now pointing straight down.1642

This carbon got flipped up; so my bromine up is now axial up instead of equatorial up; and this carbon has my methyl group down; it was equatorial and now my methyl group down is now axial.1650

In this chair conformation, now my H and Br are now anti; we call that anti-diaxial as the necessary conformation.1668

In a chair conformation, the leaving group must be in an axial position in order to be 180 degrees from the β hydrogen.1683

Our base can come in, grab that proton, kick off the leaving group; and what does our final product look like?--we can go back to our line drawing here.1692

We are going to form a double bond on this side; and our original methyl group is still there; and that is the only possible product we can draw.1703

This product was really just a question of regiochemistry only in order to draw the product; but I wanted to point out that the required stereochemistry requires a specific conformation of our chair.1713

That is going to be relevant because depending on the substitution pattern throughout the chair, this chair flip might not be such an easy thing.1727

You will find that some cyclohexyl halides do very fast E2 elimination; some our very very slow; this is an important thing to take a look at when you are considering such cases.1734

Now that we know what an E2 mechanism looks like, let's consider its competition with the Sn2 mechanism.1747

The Sn2 mechanism was described as backside attack; and what is required for the Sn2 is that it needs a strong nucleophile.1754

In an Sn2 substitution, a strong nucleophile attacked the carbon, kicked off the leaving group; that backside attack; we needed a strong nucleophile.1768

Another thing that was important with that backside attack was something about steric hindrance; remember that backside of the carbon had to be very accessible.1778

Let's just write that steric hindrance... so it needs a strong nucleophile; and steric hindrance is bad; it is not a good thing; that slows down the reaction.1787

What do we know about the E2 mechanism?--what does it require?--E2 is when we have something attack a β hydrogen and form a π bond and kick out a leaving group.1802

We are attacking a hydrogen; the E2 needs a strong base... it needs a strong base.1812

It turns out that this deprotonation reaction is not affected by sterics; so the sterics is going to be a major factor in making the decision between an Sn2 and E2, we will see.1821

When do they compete?--when do we have to make this decision?--well, most definitely we are going to see it for reactions that involve hydroxide, that is HO-, or RO-, that is known as alkoxide.1835

In other words, we can have methoxide, ethoxide, propoxide, so an alkyl group with an O-.1853

What is special about these species is they are both strong nucleophiles, meaning they love to do backside attack; they are great for an Sn2 mechanism.1858

And they are strong bases, meaning they can also go after a proton and do an E2 elimination.1868

We really need to be on the lookout when we are using hydroxide or alkoxide; and we will have to make a decision between the E2 and the Sn2.1875

Let's compare some rates; if we took a variety of alkyl halides and treated them with sodium methoxide and ethanol.1885

We could have either a substitution reaction take place; what would the product look like if methoxide decided to act as a nucleophile and do a substitution?1895

That means instead of RBr, we have our ethoxy; so our nucleophile has replaced the leaving group; that is our Sn2.1908

Why don't we draw out the ethoxy here; so I'll do some more abbreviations on this page; it is real good to start getting familiarized and seeing back and forth between these abbreviations.1922

This would be our Sn2 product; what would it look like if we did elimination instead?--well, that of course is going to depend on which alkyl group we started with.1934

But let's just say plus some kind of alkene or mixture of alkenes; in other words, we could do an elimination and form a double bond instead.1942

Let's take a look at these series of alkyl halides and try this reaction and see what product composition we get.1953

The first one we have here is methyl bromide; we could just abbreviate this MeBr for methyl bromide.1961

What kind of carbon is bearing the leaving group in this case?--it is simply just a methyl group; we just describe it as a methyl group.1970

This next one has one, two, three, four carbons; you could call that a butyl bromide or n-butyl bromide since it is the normal butyl group.1977

What kind of carbon is bearing the leaving group here?--well, because we have just one carbon group attached to it, we describe that as a primary carbon.1987

This next one is another common arrangement of four carbons; when we have something that looks like the isopropyl group here, but you have an extra carbon, this is called the isobutyl group.1997

If we had isobutyl bromide, this is still primary; but right next door to that on the β carbon, the next carbon over, we have some branching; so let's call this primary with β branching.2014

The second one, this three-carbon arrangement with the attachment at the middle carbon, that is the isopropyl group.2031

So this is isopropyl bromide; it is an example of the secondary carbon bearing the leaving group.2037

Then once again we come back to good old t-butyl bromide; tert-butyl bromide is just our classic example of a tertiary carbon bearing the leaving group.2043

What have we done?--why have we chosen this series of compounds?--because as we move down this list, we see that we are increasing in our sterics.2054

We have increasing sterics about the carbon bearing the leaving group.2065

What proportion of products do we see as a result?--well, when we have methyl bromide, it turns out that we see 100% Sn2 reaction; no E2 at all.2072

Let's think about what that E2 product would look like; what does E2 mean?--it means you remove the leaving group and a β hydrogen and you form a carbon-carbon double bond.2083

How does that look for methyl bromide?--it is looking pretty impossible because not only does it not have any β hydrogens, it has no β carbons.2095

This is let's just put NA here because there is no β hydrogens; you can't form a carbon-carbon double bond if you only start with one carbon; so of course we expect 100% for Sn2.2103

But when we move to primary, now the E2 is possible; and we do get a mixture of the two; but it is heavily in favor of the Sn2; we get about a 90:10 mixture.2116

Almost all Sn2, but we start to see a little bit of the E2 side product.2125

Adding just the slightest bit of β branching here, slightest bit of sterics, now pushes it in the other direction where the elimination is favored.2132

That is just how sensitive the Sn2 substitution, that backside attack, is to steric hindrance.2140

In fact if we go to a secondary carbon, then it is favored in the opposite direction even more so; where E2 is the major product by far, 4:1.2147

Now we are really shifting; and how about tertiary?--what do you think about the tertiary Sn2 reaction?--does that look like a good reaction?2159

No, we know that there is way too much steric hindrance here; so let's say there is essentially 0 and 100 now in this switch; remember tertiary alkyl halide is no reaction with the Sn2.2166

It is no reaction with the Sn2; but a reaction in fact does take place; instead it is the E2 elimination reaction.2183

Let's continue looking at this comparison and come back to tert-butyl bromide.2196

What we are asking it to do when we react it with ethoxide, or some other strong base that can also be a nucleophile, is it has two choices.2201

It can either attack the β carbon... I'm sorry, attack the carbon bearing the leaving group, do a backside attack; that is the Sn2 path.2210

Or what can it do?--it can attack the β hydrogen; that is the E2 path; attack the β hydrogen, form the π bond, kick out the leaving group.2220

Which of these is possible for the tertiary center like t-butyl bromide?--the Sn2 is impossible; it is impossible to get in here with all this steric hindrance and do backside attack.2231

But look how accessible that β hydrogen is; you can see that sterics is not going to be a problem; anytime we are going after a tiny little hydrogen, eliminations are no problem.2243

Let's just make a note here that the backside attack is too hindered and that the β hydrogen is more accessible.2254

We get 100% E2 with a tertiary leaving group; that is kind of the ultimate in the examples of Sn2 versus E2.2272

Another possibility is to vary the base that you are using; what if you had a primary alkyl halide?2285

Here we have fifteen methylene units; fifteen of these carbons; so it is just a really long carbon chain with a bromine at one end.2292

What if we reacted this with a species that could be either a base or a nucleophile?--what kind of mixture do we get, distribution between Sn2 and E2?2300

If we use a small base like methoxide, what we see, the same thing we saw on the previous slide, is that Sn2 is favored because it is very little steric hindrance for a primary carbon.2311

We get something like 96% of the Sn2 and maybe just a little 1% of the E2.2326

However if we use this guy, what is this structure?--that is a strange looking structure.2331

Remember potassium is just a K+; so that means we have O-; and this is the t-butyl group... t-butyl group.2336

This could be abbreviated as tBuOK; tBuOK is potassium tert-butoxide.2344

When we have a very very bulky base now, that is going to hinder that backside attack; and we see a push in the other direction; now elimination can be favored.2352

This guy is called t-butoxide; he is a very bulky base because he brings along with him that t-butyl group.2363

I brought some models here again just as a reminder about the sterics like we are seeing here.2371

The methyl is so tiny; but the tert-butyl, when you have three methyl groups attached to a carbon, that really inhibits this backside attack.2377

If we are thinking about this coming in and acting as a nucleophile, this is going to have the same problem.2388

This is going to have a hard time getting in to do a backside attack on a carbon bearing a leaving group because it is bringing steric hindrance with it.2395

T-butoxide is a very bulky base so it is never good for an Sn2 unless maybe you are attacking a methyl group that can't do an E2.2402

Really these are classic E2 reaction conditions; if you really want to favor an E2 elimination, then t-butoxide is a great base to choose.2415

By the way, addition of heat also favors eliminations so we should get used to seeing heat as part of the reaction conditions.2424

That is because we are breaking the molecule up into different pieces so that is going to favor the entropy of the reaction; so elimination reactions are also usually done in the present of heat.2430

Let's summarize; what would we say the preference is for E2 over Sn2?--looking at a reaction type, which type of alkyl halide would really like to do the E2 elimination?2443

The tertiary is going to be the best; this is pretty much all E2 and no Sn2 at all; secondary still prefers E2, but you are going to have a little substitution.2455

Here is where we see that big jump when we are looking at primary; this now is essentially all Sn2; so only if it is a primary alkyl halide can you still expect to do an Sn2 with a strong base.2472

As soon as you get to secondary and of course if you are at tertiary, if you take a look at that data from the previous slide, you will see that E2 is now the major product.2487

So only when there is absolutely no steric hindrance, because you have a primary leaving group.2496

Of course, we are leaving off the methyl here intentionally because methyl has no β hydrogens; that would be impossible to do the E2 in that case.2500

Let's take a look a second elimination mechanism; we saw the E2 elimination which is the one-step mechanism; base attacks a β hydrogen, forms a π bond, kicks off the leaving group.2513

Another mechanism that we can have for doing a dehydrohalogenation, losing a hydrogen and a halogen, is an E1 mechanism; that stands for elimination unimolecular.2525

Let's take a look at an example of that; if we take this alkyl halide and we treat it with water, how would we describe water as a reagent?2538

Water is a weak nucleophile; it is weak everything; it is a very stable molecule so it is a weak nucleophile; it is a weak base.2549

But we can still undergo substitution-elimination reactions here; in fact, we do get the substitution product.2559

Would you expect that substitution to occur by Sn2 mechanism, backside attack?--no, because this is such a weak nucleophile and because this is a tertiary leaving group; so this can happen by Sn1.2570

It is also possible to get some elimination product; could this elimination be the one-step E2 mechanism?--no, because we don't have a strong base.2583

Instead a different mechanism must be in operation and it is the E1; so the Sn1 and E1 we will find are always in competition.2598

Just like we saw the E2 and the Sn2 are often in competition, can be in competition, the same is true for Sn1 and E1, these unimolecular reactions; and the Sn1 is usually the major product.2608

In most of the reactions we are going to see, there will be a nucleophile around; it is going to prefer to add; and so we will get this substitution.2627

E1 is maybe a side reaction; so you might see a little bit of elimination and this is how you get it.2635

We will see one example where the E1 is the primary mechanism in action when we do the dehydration of alcohols; but with that exception, Sn1 will be major.2646

The mechanism for an E1 is going to be two steps; and it is going to be via a carbocation; again very similar to Sn1; that is why they compete.2655

Our first step is going to be loss of a leaving group; our chloride is going to leave which results in a carbocation intermediate; notice this is the same slow rate determining step as Sn1.2667

I lose my leaving group and I form a carbocation; but now instead of having that carbocation get attacked by a nucleophile to do a substitution reaction, instead we can do an elimination.2683

What did it mean to eliminate?--you eliminate a leaving group plus a β hydrogen; so what have we done so far?--we've lost our leaving group.2699

What's next?--we lose our β hydrogen; and we have a word for loss of a proton; we call it deprotonate.2707

We are going to take our carbocation, we are going to take a look at one of these β hydrogens, and we are going to eliminate that β hydrogen.2718

Some base comes in; again you can use chloride if you want; I think water is a better choice because that is going to be present in this reaction as well; and it is your solvent so you have more of that around.2731

We are going to do a deprotonation; we grab the proton; why can carbocations get deprotonated so easily?2744

Because when you fill in those electrons as a π bond, you are going to get rid of the carbocation; you are going to add a new bond and get to a stable alkene product.2751

Let's consider the regiochemistry; why did I select this β hydrogen?--we did see that that is the major product; but is that the only β hydrogen that is available?2766

Here is our carbocation; no, this is a β hydrogen; this is a β hydrogen; I could have also made this product.2775

But why was that not listed as one of the products formed here?--this is actually not formed; how would we make that decision?2782

It turns out that this elimination also follows Zaitsev's rule just like the E2 did; and we are going to get the most stable alkene possible.2793

This would be a tri-substituted alkene; that is going to be more stable than a di-substituted alkene.2802

And so as usual we are going to go for the more substituted β hydrogen to give the more substituted alkene.2810

Let's take a look at the kinetics for the E1 mechanism.2820

Because it had the same slow rate-determining step as the Sn1 mechanism, it has the same rate expression, the rate is proportional to simply the concentration of the alkyl halide.2823

That is all you need to lose your leaving group; so that is why it is described as unimolecular like Sn1.2836

The E1 and Sn1 are both referring to the fact that just a single species is present during the rate determining step.2844

It is directly proportional to the rate of the reaction; its concentration is directly proportional.2851

The rate is not dependent on the concentration of water; it doesn't matter how much of that base we have in there; it won't affect the rate.2857

That also reinforces the fact that water is not involved in the rate determining step or whatever base you have; tt is simply the loss of the leaving group from the alkyl halide.2865

How could we speed up this reaction?--well, once again, the more stable the carbocation you have, the faster it is going to be formed.2874

If you bring down the energy of your carbocation intermediate, that is going to have a lower energy transition state as well; and you have a lower energy of activation, faster reaction.2885

Again the faster the carbocation is formed, once you are at that carbocation, you can now do substitution or elimination.2897

The same thing that speeds up the Sn1 reaction is also going to speed up the E1 reaction; and we come back to that competition.2905

So the E1 rate is exactly the same as the Sn1 rate; looking at the type of carbons bearing the leaving group, these are all great carbocations; so they are going to be fast E1 eliminations.2912

Allylic means you have an allylic carbocation; so in other words, an allylic leaving group... let's put a chlorine here.2928

That would be a great substrate to do an E1 elimination just like an Sn1 elimination.2940

Benzyl means it is next to a benzene ring; a leaving group next to a benzene would be great because that would be a resonance stabilized carbocation.2945

And then of course tertiary is what we just looked at because that is also a good carbocation; those are better than secondary.2954

This is where we have our huge jump for carbocations; primary and methyl are so bad; these are poor carbocations so it is going to be a very very slow E1 elimination.2961

Actually let's cross out that methyl again because you can't have an E1 elimination with just a methyl halide because you don't have a second carbon to form the carbon-carbon double bond.2979

How about the stereochemistry of the E1; is there any kind of relationship that we need to have between the leaving group and the β hydrogen?2992

Remember E2 elimination, what did we need?--our leaving group and our β hydrogen had to be anti to one another; one up and one down; they had to be anti-coplanar, 180 degrees.2999

Remember the E1 mechanism is a stepwise mechanism that goes through a carbocation; that carbocation is achiral; it is planar; so this is another case where we are going to see loss of stereochemistry.3011

This is the same story for the Sn1; remember we described it as racemization because we were dealing with chiral carbons in that case; here we just describe it as loss of stereochemistry.3021

Let's see an example; if we take this substrate and we treat it with a strong base, hydroxide; strong base, what does that do?--that is going to come out and attack; this likes to do E2.3031

Let's just define it; hydroxide is a strong base and it is a strong nucleophile; as a strong base, what mechanism can you do?--E2.3045

As a strong nucleophile what mechanism can you do?--backside attack, Sn2; which one is going to be favored in this case?3059

We take a look at the carbon bearing the leaving group; it is a secondary carbon; secondary--E2 is going to be favored.3069

We add in a little heat; that doesn't hurt; but even without that, with secondary, we are going to go with E2; there is just too much steric hindrance to do the backside attack instead.3077

We've conveniently drawn it already so that the hydrogen and the leaving group are anti-coplanar; so we could come right out and we don't have to rotate at all.3088

We could just take our hydroxide, grab the proton, form the π bond, kick off our leaving group; that is going to give us an alkene product.3097

What groups are going to be on the same side?--you have a phenyl that is a dash; and you have a methyl that is a dash; so those are both on the same side of the alkyl halide.3108

They will be trapped on the same side of the alkene; it doesn't matter whether you put them at the top or bottom; the important thing is they just need to be on the same side.3119

What other two groups do we have?--we have a methyl and a hydrogen; those are still on the structure.3128

Remember, because this is anti-elimination, this is our only product; it requires those two groups to be anti; and so this would be the only possible stereochemistry.3136

Now let's compare this same starting material and let's just react it with water; no hydroxide; so now we have a weak base and a weak nucleophile.3152

What kind of reactions are possible there?--is a weak base going to go and attack a β hydrogen?--no.3167

Is a weak nucleophile going to go and do a backside attack and kick off a leaving group?--no way.; so this water does reactions like Sn1 and E1; and of course the E1 is probably going to be major.3174

The Sn1 is probably going to be major, but let's take a look at the E1 to see what its stereochemistry would be.3190

What is going to happen here is because we have no strong base or strong nucleophile, the only other thing that can happen is the leaving group can just leave on its own; so that is exactly what happens.3197

When that chlorine leaves, the resulting carbocation is now planar; it is flat.3212

When we go to deprotonate our β hydrogen, the β hydrogen can be removed now or we can have some rotation; it can rotate here.3223

There is no longer anything trapping these two methyl groups into the trans position; it can rotate around.3237

Because it is a multistep mechanism, we lose that stereochemical relationship; once that leaving group leaves, it is gone.3245

When water comes in and it deprotonates, we now have a mix of relationships between these methyl groups.3254

We are going to get two products; we are going to the one where the phenyl is on the same side as the methyl; and we can also form the one where the methyls are on the same side.3264

You are going to get a mixture; and of course you are also going to get Sn1; and Sn1 is actually going to be your major product probably; but we just want to look at our E1 product composition here.3282

These are both possible; does that mean they are going to be formed in equal amounts?--remember Zaitsev's rule is still holding true; we still want to form the most stable alkene possible.3294

Is there a difference in this case in their stability?--the phenyl remember is a benzene ring; that is going to be larger than a methyl group.3306

This product has more steric hindrance than the other one; so this is going to be our minor E1 because of sterics; and this is going to be our major E1.3315

For anti-elimination, we only have so much say on which alkene we can get; it has to be from anti-elimination.3332

With na E1 elimination coming from a carbocation, we could rotate around and get to the most favorable carbocation conformation.3342

Which leads to the most favorable transition state, leading to the most stable alkene product.3349

Let's talk just a little bit about carbocation rearrangements; because like the Sn1 mechanism, we are going through a carbocation.3362

Carbocations can rearrange; so let's just briefly review what we saw for this Sn1 mechanism.3376

This was a rearrangement when our leaving group left; it gave a secondary carbocation; and that secondary carbocation could have a hydride shift to give a tertiary carbocation.3386

That would be a favorable rearrangement; so that is how we can get this substitution product where the nucleophile has come in to a different position.3405

What is important to remember is that this new carbocation can undergo E1 elimination products.3425

Sometimes our double bond is going to end up in a different place from where our leaving group used to be.3434

Because both of these mechanisms deal with carbocations, and carbocations can rearrange, a lot of times we can get some interesting product mixtures.3441

So these end up becoming excellent practice problems for mechanisms; in other words, how can this combination of reaction conditions lead to all one, two, three, four, five of these products?3450

This is definitely a reaction that looks like it is coming from the carbocation because the carbon chains have rearranged; the positions of the substituents have rearranged.3467

This is another example where our initial secondary carbocation can rearrange, reorganize itself to become a tertiary carbocation.3482

In this case, it is by rearrangement of one of these methyl groups, a shift of a methyl group.3495

If this carbon group moved over here, that carbon has lost its carbocation; it has got four bonds again; but this carbon is where the carbocation is now.3504

Hopefully you can see how that can lead to this substitution product; and it could lead to these two elimination products.3515

This original carbocation can lead to this substitution product and this elimination product down here.3522

Just considering the various carbocations that are possible, and the various Sn1 and E1 products that can result from those, is how we can get to these various products.3530

Of the elimination products, which would you say would be the major elimination product... be the major elimination product?3541

Again the substitution products are going to be the favorable one; and probably this is going to be the major overall because it comes from the most stable carbocation.3550

Because we do have a nucleophile present, that is why we do get a substitution; that nucleophile will attack the carbocation more often than not.3563

This will be our major overall; and of the elimination products, which do you think would be the major elimination product?3570

I am thinking the one where we can have a one, two, three, four, a tetra-substituted alkene.3578

And that comes from the more stable carbocation; so both kinetics and thermodynamics are favoring this as the major E1 product.3588

Let's try a few examples where we are looking at substitution and elimination competition; the ones shown here... let's just focus on the Sn2 and the E2 and see if we can decide which will be major.3600

First of all let's take a look at our starting material, our starting carbon compound, and see what we have; OTs is called a tosylate; that is a good leaving group.3618

What kind of carbon is it on?--is it on a primary carbon?--it's not even on a primary carbon; this carbon has no carbons attached; so we just call him a methyl; so we have a methyl tosylate.3635

What are we reacting it with?--the sodium means that I have a CH3O-; and what do you know about methoxide?3648

This methanol, what is this methanol doing here?--well, it is very common that when you are using methoxide as a reagent, you use methanol as your solvent.3657

But because he is neutral and stable and less reactive, we are not going to consider him for our reaction.3664

It is going to be the less stable, more reactive species that is going to dictate the path of this reaction.3670

What do we know about methoxide?--acid, base, electrophile, nucleophile?--well, it is a strong base; and it is a strong nucleophile.3676

So what mechanisms does it have?--these are perfect for E2 or Sn2.3689

We said that alkoxides like this; like methoxide is a perfect substrate to have this competition between E2 and Sn2.3695

Who is going to win in this case?--if you have a leaving group on a methyl carbon, then it is going to be impossible to do the E2 because there is no β hydrogen.3704

I am expecting to do the Sn2; that means backside attack; attack the carbon, kick off the leaving group.3713

My methoxy group is going to now be attached to my methyl group; it is going to be a substitution, backside attack.3722

We have another alkyl halide; this time it is on a secondary carbon; so this is a secondary leaving group.3731

What do you know about ammonia?--what kind of reactivity does ammonia have?--is it a strong acid, base, electrophile, nucleophile?3737

He is a very good nucleophile; which means he would love to do the Sn2; but is he a strong base?3744

He definitely is basic, but he is not one of the strong bases we identified for the E2; he doesn't have a negative charge on it.3751

Not a really really strong base... so in the case of a neutral amine, our favored reaction is going to be the Sn2 which means backside attack.3760

Tell me about the stereochemistry of that nitrogen; since our leaving group is pointing out towards us, the nucleophile has to come in from behind.3772

Let's keep our carbon chain fixed; and so now instead of the wedge pointing down, we have a dash pointing down.3780

What happens to that nitrogen when it gets a fourth bond?--one, two, three, four; nitrogen wants five; it is going to be an N+.3790

Which means... a lot of times, we draw that leaving group in there because the bromide is not going to get very far; it is going to have an ionic bond with the ammonium.3799

So a lot of times we draw it as the salt here as this product.3808

Who is DMF?--it is another commonly used solvent in organic chemistry; it is an example of an aprotic solvent.3811

A lot of these abbreviations or names, you should be familiar with and get used to seeing them there.3820

Even if we don't draw a solvent, all of our reaction are run in a solvent; so it is good to get some practice seeing those and recognizing those.3826

In most cases, the solvent is not going to be dictating the mechanism we choose.3836

But of course it is possible, if this solvent is the only variation, that you are going to see a difference in the mechanism that you pick.3840

How about this next one?--we still have our same secondary leaving group; but instead of ammonia, we are using this guy, tBuONa.3848

This is Na+ so this is tBuO-; what do you know about tBuO-?--it is t-butoxide; strong bulky base.3856

He loves to do the E2; not so good at the Sn2 because he is so bulky; so even if he was primary, he wouldn't be able to do the Sn2; this looks like perfect E2 conditions.3869

We look for our β hydrogens; we have some over here and we have some over here.3880

First we should consider regiochemistry; where would we prefer to deprotonate?--well, we want to get the most substituted alkene possible; so we are not going to go to the end carbon.3890

Then how about stereochemistry?--well, we know stereochemistry needs to be anti; but remember this is an acyclic structure; so we can rotate; it is not locked into any one hydrogen.3902

In fact, if it took this hydrogen, it would keep the carbon chain the same; and if it took this hydrogen, meaning it had to flip first and then do the elimination, it would give this product.3915

Which of those two products do you think is the better product?--how about stability of the alkene as a guide?3932

Sure, the trans alkene is more stable; so that is going to be the one that we get; so don't be fooled by the conformation that happens to be presented.3938

Remember that you can rotate the molecules and manipulate them around; these are in solution; they are mixing around; they can be any way they want.3952

So we are going to do whatever we can to get the most stable alkene possible, assuming that it is still anti-elimination.3959

Here are a few more; this one is sodium methoxide in ethanol so you could just abbreviate it as EtONa and EtOH.3968

What do we know about ethoxide?--acid, base, electrophile, nucleophile?--strong base, meaning it can do the E2; strong nucleophile, meaning it can do the Sn2.3977

How do we decide which is going to happen?--we take a look at our carbon bearing our leaving group; what do you see?--where is our leaving group?3993

Well, there is a problem; what do you expect to find as a leaving group?--chloride, bromide, iodide, tosylate?--is hydroxide a leaving group?--no, not a leaving group.4003

If you don't have a leaving group, you can't do a substitution; you can't do elimination.4018

It doesn't matter which; you can't do any of the four mechanisms that we've learned for Sn2, E2, or Sn1, E1; no reaction.4022

We learned a couple strategies where we could make this reaction happen; if we had a made a tosylate first, then we could do a substitution-elimination.4031

If we had a strong acid present, then it is possible to do a substitution; but that is not the case here.4039

We have strongly basic conditions; so nothing is going to happen with that alcohol.4045

Same thing is going to be true in this next step; we have sodium azide and acetone; azide is a very good nucleophile.4050

It is not a strong base; it is a good nucleophile; another nucleophile we should get used to seeing for the Sn2.4057

But because this is not a leaving group, again no reaction; nothing it can do.4063

How about our next one?--we have hydroxide; hydroxide is a strong base; it is a strong nucleophile; so this is a great example where we have our E2, Sn2 competition.4072

Do we have a leaving group this time?--yes, we have an iodide; we are back to our alkyl halide so we have a leaving group that we can get rid of.4089

What kind of carbon is that leaving group on?--it is a one, two, three; it is a tertiary carbon; a tertiary leaving group.4096

What do you think?--is that backside attack?--is tertiary good for a backside attack?--no way, impossible because of sterics; so this is going to be all E2.4105

Now we have to think about regiochemistry; we have to think about stereochemistry; we've already identified our leaving group; where is our β hydrogen?4117

We have this β hydrogen; we have either one of these β hydrogens; this is very similar to a substrate we worked with earlier.4127

We are going to want to eliminate one of the inside, one of the ones within the ring; so then we end up with this tri-substituted product, more substituted.4136

Just a little reminder, we don't want to eliminate in this direction because that is going to be di-substituted; this is less stable; we always want to get the more stable alkene possible.4145

Finally here we have our same tertiary leaving group; and we have sodium cyanide; what do we know about sodium cyanide?--great nucleophile; great nucleophile; it loves to do the Sn2.4160

Is it a strong base?--we have our list of strong bases; this is not one of them; this is a weak base so it cannot do the E2.4175

Let's take a look at our Sn2, our backside attack; does it look like a good Sn2?--tertiary leaving group?--no way.4190

So guess what?--we have a great nucleophile; but our carbon bearing the leaving group is too hindered; and it is not a strong base; so it can't do E2 elimination.4198

This is another example where no reaction is going to happen.4207

You might ask, well can't we have the leaving group just leave and make a tertiary carbocation in this case and maybe do an Sn1?--and do the substitution that way?4210

Well, here is one case where the solvent is going to come into play; the cases where we did see an Sn1 reaction like in the solvolysis reactions, we always had a protic solvent.4222

That is going to be true for a carbocation formation; it actually needs a protic solvent; like water or an alcohol.4238

Protic solvents have an acidic proton; they are extremely polar; and they are needed to stabilize if it is an extremely unstable polar carbocation.4249

If you have an aprotic solvent, it is not going to be possible to form a carbocation.4259

Most textbooks aren't testing that much detail; but this is an example where really having an understanding of the details of the solvent capabilities is going to help us determine something about a mechanism.4266

In this case, I was specifically asking you to compare E2 versus Sn2; so with those restrictions, for sure we could conclude that it is no reaction.4279

Sn1 would be a good guess in this case; but it turns out that would not be possible either.4288

That wraps it up for looking at elimination reactions and considering their competition with substitution reactions.4293

Hope to see you again soon; thank you.4299