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Lecture Comments (43)

1 answer

Last reply by: Professor Starkey
Fri May 6, 2016 12:50 AM

Post by Tram T on May 4 at 07:00:04 PM

For protons on Carbon table at 37:04, Why proton of Methyl is more upfield (more shielded)than methylene and methine proton?

I thought that since alkyl R is EDG, the more alkyl R group like in the case of methine proton, the more electron rich the area thus methine proton would give the most upfield signal instead of proton on methyl.

Please explain! Thank you! Great lecture!

1 answer

Last reply by: Professor Starkey
Wed Nov 11, 2015 9:10 PM

Post by Jeremy Cohen on November 11, 2015

Dr. Starkey, I didn't know where to put this but I just wanted to say thank you for all of your help this semester.  Your lectures have been incredibly helpful in getting me through orgo 1.

1 answer

Last reply by: Professor Starkey
Fri Jul 17, 2015 1:27 PM

Post by Akilah Futch on July 16, 2015

what if you are not given the formula of the structure and all you have is the H nmr.

3 answers

Last reply by: Professor Starkey
Mon Jul 7, 2014 12:05 AM

Post by Anhtuan Tran on July 1, 2014

Hi Dr. Starkey,
When it comes to calculate the chemical shifts for CH2 group, we use the formula: 1.2 + ΔR1 + ΔR2 and we look up the table for the values of Δ. My question is where those values are coming from and how did they calculate those values and what is the difference between the Δ values and the regular values that we use for H that has only one neighbor.
Thank you.

1 answer

Last reply by: Professor Starkey
Mon Feb 3, 2014 12:04 AM

Post by Andrea Cola on January 31, 2014

How many 1H NMR signals would 1,3,5-trimethylbenzene give?

5 answers

Last reply by: Professor Starkey
Tue Jul 8, 2014 12:03 PM

Post by brian loui on April 2, 2013

on example 2, (the one w/ the carbonyl) aren't the "e" methyls diastereotopic and therefore not equivalent? i made models... and they're not superimposable and aren't enantiomers.

1 answer

Last reply by: Professor Starkey
Sun Feb 17, 2013 5:29 PM

Post by Betty Vowles on February 17, 2013

Like Marina, I too am having difficulties with the last portion of the video. Have the technical difficulties been resolved?

1 answer

Last reply by: Professor Starkey
Thu Feb 7, 2013 10:58 AM

Post by Synthia Gratia on February 6, 2013

On the last example on example 5, when figuring out the number of signals in an NMR, I'm a little confused on how you designated the different protons. when you did the stereochemistry for the H and t-butyl group that's not a real stereocenter right? I mean that C has a t-butyl group a H and when you try to figure out the other 2 groups it is the same because the molecule is symmetrical. So how did you apply stereochemistry there? Or was that to explain the different H's?

1 answer

Last reply by: Professor Starkey
Fri Dec 14, 2012 11:21 AM

Post by Natalie Bossi on December 13, 2012

How can I move on ahead of what the lecturer is talking about?? It appears that I am stuck with wherever she is talking about, no matter what I click on in the contents. This is wasting a huge amount of time.
Please help.
Natalie

2 answers

Last reply by: Amirali Aghili
Sat Apr 6, 2013 4:38 PM

Post by Marina Bossi on November 22, 2012

In addition to this, if the video reaches a certain point where the data hasn't been loaded yet, it goes back to the very beginning again!

2 answers

Last reply by: Marina Bossi
Tue Nov 27, 2012 6:50 AM

Post by Marina Bossi on November 22, 2012

Hi,

The lectures are very helpful but why can't wait click on the exact position we wish to see? It is quite frustrating because I have to watch the whole lecture before I get to the bit I was up to. Thanks

1 answer

Last reply by: Professor Starkey
Fri Sep 21, 2012 12:11 PM

Post by fiorella alzamora on September 19, 2012

Hello,
Why is Toluene 7ppm? y wouldnt it be 2.3 ? Thanks

2 answers

Last reply by: Gabriella Kaminer-Levin
Tue Jul 3, 2012 4:58 PM

Post by Gabriella Kaminer-Levin on June 29, 2012

Dear Dr. Starkey:

How come hydrogens bonded to an oxygen (say in an alcohol group) don't show up on an NMR (or do they)? At around 45 minutes in this video you are describing the approximate positions of hydrogens in an ester/ alcohol and you do not include the hydrogen bonded to an oxygen in an alcohol group in your analysis.
Thanks!
Gabriella

1 answer

Last reply by: Professor Starkey
Fri Feb 17, 2012 8:33 PM

Post by janine jones on February 15, 2012

trying to work a problem that I am stuck on about signals is there any way I can upload an image to you>

1 answer

Last reply by: Professor Starkey
Sun Feb 5, 2012 10:02 PM

Post by Kimberly McDevitt on February 5, 2012

Can you please inform me how to fast forward the lectures or to select the section that I previously left off on without having to watch the entire lecture over again?

2 answers

Last reply by: Sitora Muhamedova
Wed Jun 19, 2013 4:19 PM

Post by Jason Jarduck on October 17, 2011

Hi
Excellent lecture very detailed explanation.

Thank You

Jason Jarduck

Nuclear Magnetic Resonance (NMR) Spectroscopy, Part I

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.

  1. Intro
    • Purpose of NMR
    • How NMR Works
    • Information Obtained From a ¹H NMR Spectrum
    • Number of Signals in NMR (Chemical Equivalence)
    • Size of Signals in NMR (Peak Area or Integration)
    • Using Integral Trails
    • Location of NMR Signal (Chemical Shift)
    • ¹H NMR Chemical Shifts
    • ¹H NMR Chemical Shifts (Protons on Carbon)
    • Chemical Shifts of H's on N or O
    • Estimating Chemical Shifts
    • Calculating Chemical Shifts
    • Effects of Resonance on Chemical Shifts
    • Shape of NMR Signal (Splitting Patterns)
    • Understanding Splitting Patterns: The 'n+1 Rule'
    • Explanation of n+1 Rule
    • Summary of Splitting Patterns
    • Predicting ¹H NMR Spectra
    • Intro 0:00
    • Purpose of NMR 0:14
      • Purpose of NMR
    • How NMR Works 2:17
      • How NMR Works
    • Information Obtained From a ¹H NMR Spectrum 5:51
      • # of Signals, Integration, Chemical Shifts, and Splitting Patterns
    • Number of Signals in NMR (Chemical Equivalence) 7:52
      • Example 1: How Many Signals in ¹H NMR?
      • Example 2: How Many Signals in ¹H NMR?
      • Example 3: How Many Signals in ¹H NMR?
      • Example 4: How Many Signals in ¹H NMR?
      • Example 5: How Many Signals in ¹H NMR?
    • Size of Signals in NMR (Peak Area or Integration) 21:23
      • Size of Signals in NMR (Peak Area or Integration)
    • Using Integral Trails 25:15
      • Example 1: C₈H₁₈O
      • Example 2: C₃H₈O
      • Example 3: C₇H₈
    • Location of NMR Signal (Chemical Shift) 29:05
      • Location of NMR Signal (Chemical Shift)
    • ¹H NMR Chemical Shifts 33:20
      • ¹H NMR Chemical Shifts
    • ¹H NMR Chemical Shifts (Protons on Carbon) 37:03
      • ¹H NMR Chemical Shifts (Protons on Carbon)
    • Chemical Shifts of H's on N or O 39:01
      • Chemical Shifts of H's on N or O
    • Estimating Chemical Shifts 41:13
      • Example 1: Estimating Chemical Shifts
      • Example 2: Estimating Chemical Shifts
      • Functional Group Effects are Additive
    • Calculating Chemical Shifts 47:38
      • Methylene Calculation
      • Methine Calculation
      • Protons on sp³ Carbons: Chemical Shift Calculation Table
      • Example: Estimate the Chemical Shift of the Selected H
    • Effects of Resonance on Chemical Shifts 53:11
      • Example 1: Effects of Resonance on Chemical Shifts
      • Example 2: Effects of Resonance on Chemical Shifts
      • Example 3: Effects of Resonance on Chemical Shifts
    • Shape of NMR Signal (Splitting Patterns) 59:17
      • Shape of NMR Signal (Splitting Patterns)
    • Understanding Splitting Patterns: The 'n+1 Rule' 1:01:24
      • Understanding Splitting Patterns: The 'n+1 Rule'
    • Explanation of n+1 Rule 1:02:42
      • Explanation of n+1 Rule: One Neighbor
      • Explanation of n+1 Rule: Two Neighbors
    • Summary of Splitting Patterns 1:06:24
      • Summary of Splitting Patterns
    • Predicting ¹H NMR Spectra 1:10:46
      • Example 1: Predicting ¹H NMR Spectra
      • Example 2: Predicting ¹H NMR Spectra
      • Example 3: Predicting ¹H NMR Spectra
      • Example 4: Predicting ¹H NMR Spectra