Home » Chemistry » Organic Chemistry Lab » Nuclear Magnetic Resonance (NMR) Spectroscopy, Part I

Dr. Laurie Starkey

Dr. Laurie Starkey

Nuclear Magnetic Resonance (NMR) Spectroscopy, Part I

Slide Duration:

Table of Contents

Section 1: Reagent Table
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
Section 2: Melting Points
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
Section 3: Recrystallization
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
Section 4: Distillation
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
Section 5: Chromatography
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
Section 6: Extractions
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
Section 7: Spectroscopy
Infrared Spectroscopy, Part I

1h 4m

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

48m 34s

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

1h 32m 14s

Intro
0:00
Purpose of NMR
0:14
Purpose of NMR
0:15
How NMR Works
2:17
How NMR Works
2:18
Information Obtained From a ¹H NMR Spectrum
5:51
# of Signals, Integration, Chemical Shifts, and Splitting Patterns
5:52
Number of Signals in NMR (Chemical Equivalence)
7:52
Example 1: How Many Signals in ¹H NMR?
7:53
Example 2: How Many Signals in ¹H NMR?
9:36
Example 3: How Many Signals in ¹H NMR?
12:15
Example 4: How Many Signals in ¹H NMR?
13:47
Example 5: How Many Signals in ¹H NMR?
16:12
Size of Signals in NMR (Peak Area or Integration)
21:23
Size of Signals in NMR (Peak Area or Integration)
21:24
Using Integral Trails
25:15
Example 1: C₈H₁₈O
25:16
Example 2: C₃H₈O
27:17
Example 3: C₇H₈
28:21
Location of NMR Signal (Chemical Shift)
29:05
Location of NMR Signal (Chemical Shift)
29:06
¹H NMR Chemical Shifts
33:20
¹H NMR Chemical Shifts
33:21
¹H NMR Chemical Shifts (Protons on Carbon)
37:03
¹H NMR Chemical Shifts (Protons on Carbon)
37:04
Chemical Shifts of H's on N or O
39:01
Chemical Shifts of H's on N or O
39:02
Estimating Chemical Shifts
41:13
Example 1: Estimating Chemical Shifts
41:14
Example 2: Estimating Chemical Shifts
43:22
Functional Group Effects are Additive
45:28
Calculating Chemical Shifts
47:38
Methylene Calculation
47:39
Methine Calculation
48:20
Protons on sp³ Carbons: Chemical Shift Calculation Table
48:50
Example: Estimate the Chemical Shift of the Selected H
50:29
Effects of Resonance on Chemical Shifts
53:11
Example 1: Effects of Resonance on Chemical Shifts
53:12
Example 2: Effects of Resonance on Chemical Shifts
55:09
Example 3: Effects of Resonance on Chemical Shifts
57:08
Shape of NMR Signal (Splitting Patterns)
59:17
Shape of NMR Signal (Splitting Patterns)
59:18
Understanding Splitting Patterns: The 'n+1 Rule'
1:01:24
Understanding Splitting Patterns: The 'n+1 Rule'
1:01:25
Explanation of n+1 Rule
1:02:42
Explanation of n+1 Rule: One Neighbor
1:02:43
Explanation of n+1 Rule: Two Neighbors
1:06:23
Summary of Splitting Patterns
1:06:24
Summary of Splitting Patterns
1:10:45
Predicting ¹H NMR Spectra
1:10:46
Example 1: Predicting ¹H NMR Spectra
1:13:30
Example 2: Predicting ¹H NMR Spectra
1:19:07
Example 3: Predicting ¹H NMR Spectra
1:23:50
Example 4: Predicting ¹H NMR Spectra
1:29:27
Nuclear Magnetic Resonance (NMR) Spectroscopy, Part II

2h 3m 48s

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

1h 28m 35s

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

1 answer

Last reply by: Professor Starkey
Sun Feb 12, 2017 10:08 PM

Post by Ay Ayy on February 7, 2017

I have this question
1. (a) Determine the digital resolution of a 12 ppm proton spectrum collected on a 300 MHz NMR instrument.  Number of data points collected for this spectrum was 1K (1024 bytes). [Hint: On a 300MHz instrument, 1PPM=300Hz]              
(b). What would be the resolution of the above spectrum if 2000 data points were collected?            
C. If we increase the spectral width from 12 to 20 ppm and keep all other acquisition parameters same as in problem 1(a) and collect a proton spectrum, what would be the acquisition time and resolution of the newly acquired proton spectrum?

1 answer

Last reply by: Professor Starkey
Fri Feb 3, 2017 9:52 PM

Post by Kaye Lim on November 30, 2016

I have a question regarding how NMR instrument works. This is what I thought, please check if it is correct.

So there is only 1 MHz value of radio wave applied on the sample (like 42.6 MHz for 1 Tesla magnetic field). That powerful pulse of radiowave excites all nuclei including nuclei of F,N,C as well. Then the radio receiver would tune into a correct MHz value to read the released energy from the nuclei (example, 42.6MHz to read proton nuclei, and other corresponding MHz to read nuclei of other atom type). Is everything above correct?

Thank you!

1 answer

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

Post by Tram T on May 4, 2016

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
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