Essential Practical NMR for Organic Chemistry

Description

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. Cover Half Title Essential Practical NMR for Organic Chemistry Copyright Dedication Contents 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 13C 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 15N 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 15N 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 13C Prediction 15.3.2 1H 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