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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Essential Practical NMR for Organic Chemistry A hands-on resource advocating an ordered approach to gathering and interpreting NMR data The second edition of Essential Practical NMR for Organic Chemistry delivers a pragmatic and accessible text demonstrating an ordered approach to gathering and interpreting NMR data. In this informal guide, you'll learn to make sense of the high density of NMR information through the authors' problem-solving strategies and interpretations. The book also discusses critical aspects of NMR theory, as well as data acquisition and processing strategy. It explains the use of NMR spectroscopy for dealing with problems of small organic molecule structural elucidation and includes a brand-new chapter on Nitrogen-15 NMR. Readers will also find: * Strategies for preparing a sample, spectrum acquisition, processing, and interpreting your spectrum * Fulsome discussions of Carbon-13 NMR spectroscopy * Practical treatments of quantification, safety procedures, and relevant software An ideal handbook for anyone involved in using NMR to solve structural problems, this latest edition of Essential Practical NMR for Organic Chemistry will be particularly useful for chemists running and looking at their own NMR spectra, as well as those who work in small molecule NMR. It will also earn a place in the libraries of undergraduate and post-graduate organic chemistry students.
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Essential Practical NMR for Organic Chemistry
S.A. RICHARDSANDJ.C. HOLLERTON
Second Edition
This second edition first published 2023
© 2023 John Wiley & Sons Ltd
Edition History
John Wiley & Sons Ltd (1e, 2011)
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Library of Congress Cataloging-in-Publication Data
Names: Richards, S.A., author. | Hollerton, J.C. - author.
Title: Essential practical NMR for organic chemistry / S.A. Richards and J.C. Hollerton.
Other titles: Essential practical nuclear magnetic resonance for organic chemistry
Description: Second edition. | Hoboken, NJ : John Wiley & Sons Ltd., 2023. | Includes index.
Identifiers: LCCN 2022035662 (print) | LCCN 2022035663 (ebook) | ISBN 9781119844808 (hardback) | ISBN 9781119844815 (epdf) | ISBN 9781119844822 (epub)
Subjects: LCSH: Proton magnetic resonance spectroscopy. | Nuclear magnetic resonance spectroscopy.
Classification: LCC QD96.P7 E87 2023 (print) | LCC QD96.P7 (ebook) | DDC 543/.66--dc23/eng/20221212
LC record available at https://lccn.loc.gov/2022035662
LC ebook record available at https://lccn.loc.gov/2022035663
Cover image: © Yuichiro Chino/Getty Images
Cover design by Wiley
Set in 10.5/12.5pt TimesNewRoman by Integra Software Services Pvt. Ltd, Pondicherry, India
We would like to dedicate this book to our families and our NMR colleagues past and present.
Contents
Cover
Title page
Copyright
Dedication
Preface
1 Getting Started
1.1 The Technique
1.2 Instrumentation
1.2.1 CW Systems
1.2.2 FT Systems
1.2.3 Probes
1.2.4 Shims
1.3 Origin of the Chemical Shift
1.4 Origin of ‘Splitting’
1.5 Integration
2 Preparing the Sample
2.1 How Much Sample Do I Need?
2.2 Solvent Selection
2.2.1 Deutero Chloroform (CDCl3)
2.2.2 Deutero Dimethyl Sulfoxide (DMSO)
2.2.3 Deutero Methanol (CD3OD)
2.2.4 Deutero Water (D2O)
2.2.5 Deutero Benzene (C6D6)
2.2.6 Carbon Tetrachloride (CCl4)
2.2.7 Trifluoroacetic Acid (CF3COOH)
2.2.8 Using Mixed Solvents
2.3 Spectrum Referencing (Proton NMR)
2.4 Sample Preparation
2.4.1 Filtration
3 Spectrum Acquisition
3.1 Number of Transients
3.2 Number of Points
3.3 Spectral Width
3.4 Acquisition Time
3.5 Pulse Width/Pulse Angle
3.6 Relaxation Delay
3.7 Number of Increments
3.8 Non-Uniform Sampling (NUS)
3.9 Shimming
3.10 Tuning and Matching
3.11 Frequency Lock
3.11.1 Run Unlocked
3.11.2 Internal Lock
3.11.3 External Lock
3.12 To Spin or Not to Spin?
4 Processing
4.1 Introduction
4.2 Zero-Filling and Linear Prediction
4.3 Apodization
4.4 Fourier Transformation
4.5 Phase Correction
4.6 Baseline Correction
4.7 Integration
4.8 Referencing
4.9 Peak Picking
5 Interpreting Your Spectrum
5.1 Common Solvents and Impurities
5.2 Group 1 – Exchangeables and Aldehydes
5.3 Group 2 – Aromatic and Heterocyclic Protons
5.3.1 Monosubstituted Benzene Rings
5.3.2 Multi-substituted Benzene Rings
5.3.3 Heterocyclic Ring Systems (Unsaturated) and Polycyclic Aromatic Systems
5.4 Group 3 – Double and Triple Bonds
5.5 Group 4 – Alkyl Protons
6 Delving Deeper
6.1 Chiral Centres
6.2 Enantiotopic and Diastereotopic Protons
6.3 Molecular Anisotropy
6.4 Accidental Equivalence
6.5 Restricted Rotation
6.6 Heteronuclear Coupling
6.6.1 Coupling between Protons and 13C
6.6.2 Coupling between Protons and 19F
6.6.3 Coupling between Protons and 31P
6.6.4 Coupling between 1H and Other Heteroatoms
6.7 Cyclic Compounds and the Karplus Curve
6.8 Salts, Free Bases and Zwitterions
6.9 Zwitterionic Compounds Are Worthy of Special Mention
7 Further Elucidation Techniques – Part 1
7.1 Chemical Techniques
7.1.1 Deuteration
7.1.2 Basification and Acidification
7.1.3 Changing Solvents
7.1.4 Trifluoroacetylation
7.1.5 Lanthanide Shift Reagents
7.1.6 Chiral Resolving Agents
8 Further Elucidation Techniques – Part 2
8.1 Introduction
8.2 Spin-Decoupling (Homonuclear, 1-D)
8.3 Correlated Spectroscopy (COSY)
8.4 Total Correlation Spectroscopy (TOCSY) 1- and 2-D
8.5 The Nuclear Overhauser Effect (NOE) and Associated Techniques
9 Carbon-13 NMR Spectroscopy
9.1 General Principles and 1-D
13
C
9.2 2-D Proton–Carbon (Single Bond) Correlated Spectroscopy
9.3 2-D Proton–Carbon (Multiple Bond) Correlated Spectroscopy
9.4 Piecing It All Together
9.5 Choosing the Right Tool
10 Nitrogen-15 NMR Spectroscopy
10.1 Introduction
10.2 Referencing
10.3 Using
15
N Data
10.4 Amines
10.4.1 Alkyl
10.4.2 Aryl
10.5 Conjugated Amines
10.6 Amides
10.7 Amidines
10.8 Azides
10.9 Carbamates
10.10 Cyanates and Thiocyanates
10.11 Diazo Compounds
10.12 Formamides
10.13 Hydrazines
10.14 Hydroxamic Acids
10.15 Hydroxylamines
10.16 Imides (Alkyl and Aryl)
10.17 Imines
10.18 Isocyanates and Isothiocyanates
10.19 Nitrogen-Bearing Heterocycles
10.20 Nitriles
10.21 Nitro Compounds
10.22 Nitroso and N-Nitroso Compounds
10.23 N-Oxides
10.24 Oximes
10.25 Sulfonamides
10.26 Ureas and Thioureas
10.27 Other Unusual Compounds
10.28
15
N Topics
10.28.1 1-, 2-, 3- and 4-bond Correlations
10.28.2 ‘Through-Space’ Correlations
10.28.3 Tautomerism in 15N NMR
10.28.4 Restricted Rotation
10.28.5 Protonation and Zwitterions
11 Some Other Techniques and Nuclei
11.1 HPLC-NMR
11.2 Flow NMR
11.3 Solvent Suppression
11.4 MAS (Magic Angle Spinning) NMR
11.5 Pure Shift NMR
11.6 Other 2-D Techniques
11.6.1 INADEQUATE
11.6.2 J-Resolved
11.6.3 DOSY
11.7 3-D Techniques
11.8 Fluorine (19F) NMR
11.9 Phosphorus (31P) NMR
12 Dynamics
12.1 Linewidths
12.2 Chemical Shifts
12.3 Splittings
12.4 Relaxation Pathways
12.5 Experimental Techniques
12.6 In Practice
12.7 In Conclusion
13 Quantification
13.1 Introduction
13.2 Different Approaches to Quantification
13.2.1 Relative Quantification
13.2.2 Absolute Quantification
13.2.3 Internal Standards
13.2.4 External Standards
13.2.5 Electronic Reference (ERETIC)
13.2.6 QUANTAS
13.2.7 ERETIC2
13.3 Things to Watch Out For
13.4 Quantification of Other Nuclei
13.5 Conclusion
14 Safety
14.1 Magnetic Fields
14.2 Cryogens
14.3 Sample-Related Injuries
15 Software
15.1 Acquisition Software
15.2 Processing Software
15.3 Prediction and Simulation Software
15.3.1
13
C Prediction
15.3.2
1
H Prediction
15.3.3 Incremental Approaches
15.3.4 HOSE Code Databases
15.3.5 Semi-Empirical Approaches
15.3.6 Ab Initio Approaches
15.3.7 Neural Networks
15.5.8 Hybrid Approaches
15.5.9 Simulation
15.6 Structural Verification Software
15.7 Structural Elucidation Software
15.8 Summary
16 Problems
16.1 Questions
16.2 Hints
16.3 Answers
16.4 A Closing Footnote
17 Raising Your Game
17.1 Spotting the Pitfalls
17.2 The Wrong Solvent
17.3 Choosing the Right Experiment
Appendix A
Glossary
Index
End User License Agreement
List of Tables
CHAPTER 02
Table 2.1 Amount of material...
CHAPTER 05
Table 5.1 The proton chemical...
Table 5.2 Typical...
Table 5.4 Aromatic protons...
Table 5.3 Aromatic proton...
Table 5.5 Chemical shifts...
Table 5.6 Estimation of chemical...
Table 5.7 Estimation of chemical...
CHAPTER 06
Table 6.1 Some typical...
Table 6.2 F–Ha 2 Hz...
CHAPTER 09
Table 9.1 13C chemical shifts...
Table 9.7 Data for the...
Table 9.2 13C chemical...
Table 9.3 Data for the...
Table 9.4 13C chemical...
Table 9.5 Data for the...
Table 9.6 13C chemical...
CHAPTER 11
Table 11.1 19F Chemical shifts...
List of Illustrations
CHAPTER 01
Figure 1.1 Energy levels...
Figure 1.2 Schematic of...
Figure 1.3 A free induction...
Figure 1.4 Schematic diagram...
Figure 1.5 Pascal’s...
Figure 1.6 Multiplets...
Spectrum 1.1 Proton NMR...
Spectrum 1.2 90 MHz proton...
Spectrum 1.3 90 MHz proton...
CHAPTER 02
Figure 2.1 Sample depth...
Figure 2.2 Undissolved...
Figure 2.3 A convenient...
Spectrum 2.1 Residual...
CHAPTER 03
Figure 3.1 Relative...
Figure 3.2 ‘Flip angle’.
Figure 3.3 The ‘sinc’...
Figure 3.4 Falloff of power...
Figure 3.5 Correct line shape...
CHAPTER 04
Figure 4.1 Exponential multiplication.
Figure 4.2 Gaussian multiplication.
Spectrum 4.1 Gaussian multiplication...
Spectrum 4.2 An absorption signal...
Spectrum 4.3 A well-phased spectrum...
Spectrum 4.4 Too much first-order phase!
CHAPTER 05
Figure 5.1 ‘The confidence...
Spectrum 5.1 An amide NH (5.52 ppm)...
Spectrum 5.2 A very broad...
Spectrum 5.3 A benzene ring bearing...
Spectrum 5.4 A benzene ring bearing...
Spectrum 5.5 A benzene ring bearing...
Spectrum 5.6 A typical aromatic...
Spectrum 5.7 Methyl 3-nitrobenzoate.
Spectrum 5.8 Salbutamol...
Spectrum 5.9 Pyridine in DMSO...
Spectrum 5.10 The alkene protons...
CHAPTER 06
Figure 6.1 NMR and the relationship...
Figure 6.2 Anisotropy...
Figure 6.3 The Karplus curve.
Figure 6.4 The morpholine compound...
Spectrum 6.1 An AB system.
Spectrum 6.2 A typical...
Spectrum 6.3 A complex...
Spectrum 6.4 A mixture...
Spectrum 6.5 Diastereotopic...
Spectrum 6.6 ‘Virtual...
Spectrum 6.7 ‘Deceptive...
Spectrum 6.8 4-bromobenzamide...
Spectrum 6.9 CHCl
3
...
Spectrum 6.10 3-Fluoro propanol.
Spectrum 6.11 4-Fluoro benzoic acid.
Spectrum 6.12 3-Fluoro nicotinic acid.
Spectrum 6.13
31
P–
1
H...
Spectrum 6.14 Typical appearance...
Spectrum 6.15 Boron–proton...
Spectrum 6.16 Mixture of two...
Spectrum 6.17 TMS showing...
Spectrum 6.18 The morpholine...
Spectrum 6.19 Slow inversion...
Spectrum 6.20 Protonated nitrogen...
CHAPTER 07
Spectrum 7.1
n
-Butanol...
Spectrum 7.2
n
-Butanol...
Spectrum 7.3 The use of trifluoroacetic...
Spectrum 7.4 The use of TFAE as...
CHAPTER 08
Figure 8.1 A typical 1-D...
Figure 8.2 A simple COSY...
Figure 8.3 Modulation in...
Figure 8.4 A COSY data set.
Spectrum 8.1 1-D Spin decoupling...
Spectrum 8.2 A COSY contour plot...
Spectrum 8.3 Naphthalene substituted...
Spectrum 8.4 NOE experiment...
Spectrum 8.5 NOE experiment...
Spectrum 8.6 2-D ROESY spectrum...
Spectrum 8.7 An NOE experimentv...
CHAPTER 09
Spectrum 9.1 1-D
13
C...
Spectrum 9.2 1-D
13
C...
Spectrum 9.3 DEPT-edited HSQC...
Spectrum 9.4 HMBC of...
CHAPTER 10
Spectrum 10.1
15
N HMBC.
CHAPTER 11
Spectrum 11.1 Simulated...
Spectrum 11.2 Simulated...
CHAPTER 12
Figure 12.1 Space-fill...
Figure 12.2 Different...
Spectrum 12.1 Proton spectrum...
Spectrum 12.2 Expansion of low...
Spectrum 12.3 Example of partial...
Spectrum 12.4 Example of partial...
CHAPTER 13
Figure 13.1 External standard.
Figure 13.2 Performing peak-fitting.
Spectrum 13.1 Salbutamol with TMS.
Spectrum 13.2 Spectrum...
CHAPTER 14
Figure 14.1 5 Gauss line...
CHAPTER 15
Figure 15.1 Example of...
Figure 15.2 HOSE code in...
Figure 15.3 Example of carbon...
Figure 15.4 Observed distribution...
Figure 15.5 A neural network.
Figure 15.6 ASV outcomes.
CHAPTER 16
Spectrum 16.1 Problem 10 (
1
H).
Spectrum 16.2 (
1
H) Expansion.
Spectrum 16.3 (
13
C).
Spectrum 16.4 (HSQC).
Spectrum 16.5 (HMBC).
Spectrum 16.6 (
1
H).
Spectrum 16.7 (
1
H) Expansion 1.
Spectrum 16.8 (
1
H) Expansion 2.
Spectrum 16.9 (
13
C) Expansion 1.
Spectrum 16.10 (
13
C) Expansion 2.
Spectrum 16.11 (COSY) Expansion 1.
Spectrum 16.12 (COSY) Expansion 2.
Spectrum 16.13 (HSQC) Expansion 1.
Spectrum 16.14 (HSQC) Expansion 2.
Spectrum 16.15 (HMBC) Expansion 1.
Spectrum 16.16 (HMBC) Expansion 2.
Spectrum 16.17 (
1
H).
Spectrum 16.18 (
13
C).
Spectrum 16.19 (COSY).
Spectrum 16.20 (HSQC).
Spectrum 16.21 (HMBC).
Spectrum 16.22 (HMBC) Expansion.
Spectrum 16.23 (
15
N HMBC).
CHAPTER 17
Spectrum 17.1 Proton spectrum...
Spectrum 17.2 (Expansion).
Spectrum 17.3 (HSQC).
Spectrum 17.4 (HMBC).
Spectrum 17.5 Proton spectrum...
Spectrum 17.6 (Expansion).
Spectrum 17.7 (HMBC).
Spectrum 17.8 (HMBC expansion).
Spectrum 17.9 Proton spectrum...
Spectrum 17.10 (Expansion 1).
Spectrum 17.11 (Expansion 2).
Spectrum 17.12 COSY.
Spectrum 17.13 (Expansion 3).
Spectrum 17.14 (13C).
Spectrum 17.15 HSQC expansion.
Spectrum 17.16 (ROESY).
Guide
Cover
Title page
Copyright
Dedication
Table of Contents
Preface
Begin Reading
Appendix A
Glossary
Index
End User License Agreement
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Preface
This second edition of Essential Practical NMR for Organic Chemistry is an updated and improved version of the first edition which was a follow-up to the original Laboratory Guide to Proton NMR Spectroscopy (Blackwell Scientific Publications, 1988). It follows the same informal approach and is hopefully fun to read as well as a useful guide. While still concentrating on proton NMR, it includes 2-D approaches and some heteronuclear examples (specifically 13C, 15N and 19F). This new edition now contains a comprehensive chapter on 15N which we have found increasingly important in the last decade. The greater coverage is devoted to the techniques that you will be likely to make most use of.
The book is here to help you select the right experiment to solve your problem and to then interpret the results correctly. NMR is a funny beast – it throws up surprises no matter how long you have been doing it (at this point, it should be noted that the authors have more than 80 years of NMR experience between them and we still get surprises now and then!).
The strength of NMR, particularly in the small organic molecule area, is that it is very information rich but ironically, this very high density of information can itself create problems for the less experienced practitioner. Information overload can be a problem and we hope to redress this by advocating an ordered approach to handling NMR data. There are huge subtleties in looking at this data; chemical shifts, splitting patterns, integrals, linewidths all have an existence due to physical molecular processes and they each tell a story about the atoms in the molecule. There is a reason for everything that you observe in a spectrum and the better your understanding of spectroscopic principles, the greater can be your confidence in your interpretation of the data in front of you.
So, who is this book aimed at? Well, it contains useful information for anyone involved in using NMR as a tool for solving structural problems. It is particularly useful for chemists who have to run and look at their own NMR spectra and also for people who have been working in small molecule NMR for a relatively short time (less than 20 years, say;-)… It is focused on small organic molecule work (molecular weight less than 1500, commonly about 300). Ultimately, the book is pragmatic – we discuss cost-effective experiments to solve chemical structure problems as quickly as possible. It deals with some of the unglamorous bits, like making up your sample. These are necessary if dull. It also looks at the more challenging aspects of NMR.
While the book touches on some aspects of NMR theory, the main focus of the text is firmly rooted in data acquisition, problem-solving strategy and interpretation. If you find yourself wanting to know more about aspects of theory, we suggest the excellent, High-Resolution NMR Techniques in Organic Chemistry by Timothy D. W. Claridge (Elsevier, ISBN-13: 978–0-08–054818-0) as an approachable next step before delving into the even more theoretical works. Another really good source is Joseph P. Hornak’s ‘The Basics of NMR’ website (you can find it by putting ‘hornak nmr’ into your favourite search engine). While writing these chapters, we have often fought with the problem of statements that are partially true and debated whether to insert a qualifier. To get across the fundamental ideas we have tried to minimise the disclaimers and qualifiers. This aids clarity, but be aware, almost everything is more complicated than it first appears!
Forty years in NMR has been fun. The amazing thing is that it is still fun…and challenging…and stimulating even now!
Please note that all spectra included in this book were acquired at 400 MHz unless otherwise stated.
