Richards S.A. Essential practical NMR for organic chemistry / S.A.Richards, J.C.Hollerton. - Chichester: Wiley, 2011. - x, 206 p.: ill. - Ind.: p.211-216. - ISBN 978-0-470-71092-0  Место хранения:   032 | Институт органической химии им. Н.Н.Ворожцова СО РАН | Новосибирск | Библиотека

Оглавление / Contents

Introduction ................................................... xi 1 Getting Started .............................................. 1 1.1 The Technique ........................................... 1 1.2 Instrumentation ......................................... 2 1.3 CW Systems .............................................. 2 1.4 FT Systems .............................................. 3 1.4.1 Origin of the Chemical Shift ..................... 6 1.4.2 Origin of 'Splitting' ............................ 7 1.4.3 Integration ...................................... 9 2 Preparing the Sample ........................................ 11 2.1 How Much Sample Do I Need? ............................. 12 2.2 Solvent Selection ...................................... 13 2.2.1 Deutero Chloroform (CDCl3) ...................... 14 2.2.2 Deutero Dimethyl Sulfoxide (D6-DMSO) ............ 14 2.2.3 Deutero Methanol (CD3OD) ........................ 15 2.2.4 Deutero Water (D20) ............................. 16 2.2.5 Deutero Benzene (C6D6) .......................... 16 2.2.6 Carbon Tetrachloride (CCl4) ..................... 16 2.2.7 Trifluoroacetic Acid (CF3COOH) .................. 16 2.2.8 Using Mixed Solvents ............................ 17 2.3 Spectrum Referencing (Proton NMR) ...................... 17 2.4 Sample Preparation ..................................... 18 2.4.1 Filtration ...................................... 19 3 Spectrum Acquisition ........................................ 23 3.1 Number of Transients ................................... 23 3.2 Number of Points ....................................... 24 3.3 Spectral Width ......................................... 25 3.4 Acquisition Time ....................................... 25 3.5 Pulse Width/Pulse Angle ................................ 25 3.6 Relaxation Delay ....................................... 27 3.7 Number of Increments ................................... 27 3.8 Shimming ............................................... 28 3.9 Tuning and Matching .................................... 30 3.10 Frequency Lock ......................................... 30 3.10.1 Run Unlocked .................................... 30 3.10.2 Internal Lock ................................... 30 3.10.3 External Lock ................................... 31 3.11 To Spin or Not to Spin? ................................ 31 4 Processing .................................................. 33 4.1 Introduction ........................................... 33 4.2 Zero Filling and Linear Prediction ..................... 33 4.3 Apodization ............................................ 34 4.4 Fourier Transformation ................................. 36 4.5 Phase Correction ....................................... 36 4.6 Baseline Correction .................................... 38 4.7 Integration ............................................ 39 4.8 Referencing ............................................ 39 4.9 Peak Picking ........................................... 39 5 Interpreting Your Spectrum .................................. 41 5.1 Common Solvents and Impurities ......................... 44 5.2 Group 1 - Exchangeables and Aldehydes .................. 46 5.3 Group 2 - Aromatic and Heterocyclic Protons ............ 48 5.3.1 Monosubstituted Benzene Rings ................... 50 5.3.2 Multisubstituted Benzene Rings .................. 54 5.3.3 Heterocyclic Ring Systems (Unsaturated) and Polycyclic Aromatic Systems ..................... 57 5.4 Group 3 - Double and Triple Bonds ...................... 61 5.5 Group 4 - Alkyl Protons ................................ 63 6 Delving Deeper .............................................. 67 6.1 Chiral Centres ......................................... 67 6.2 Enantiotopic and Diastereotopic Protons ................ 72 6.3 Molecular Anisotropy ................................... 74 6.4 Accidental Equivalence ................................. 76 6.5 Restricted Rotation .................................... 78 6.6 Heteronuclear Coupling ................................. 82 6.6.1 Coupling between Protons and 13C ................ 82 6.6.2 Coupling between Protons and 19F ................ 84 6.6.3 Coupling between Protons and 31P ................ 87 6.6.4 Coupling between 1H and other Heteroatoms ....... 89 6.6.5 Cyclic Compounds and the Karplus Curve .......... 91 6.6.6 Salts, Free Bases and Zwitterions ............... 96 7 Further Elucidation Techniques - Part 1 .................... 101 7.1 Chemical Techniques ................................... 101 7.2 Deuteration ........................................... 101 7.3 Basification and Acidification ........................ 103 7.4 Changing Solvents ..................................... 104 7.5 Trifluoroacetylation .................................. 104 7.6 Lanthanide Shift Reagents ............................. 106 7.7 Chiral Resolving Agents ............................... 106 8 Further Elucidation Techniques - Part 2 .................... 111 8.1 Instrumental Techniques ............................... 111 8.2 Spin Decoupling (Homonuclear, 1-D) .................... 111 8.3 Correlated Spectroscopy (2-D) ......................... 112 8.4 Total Correlation Spectroscopy (1-and 2-D) ............ 116 8.5 The Nuclear Overhauser Effect and Associated Techniques ............................................ 116 9 Carbon-13 NMR Spectroscopy ................................. 127 9.1 General Principles and 1-D 13C ........................ 127 9.2 2-D Proton-Carbon (Single Bond) Correlated Spectroscopy .......................................... 130 9.3 2-D Proton-Carbon (Multiple Bond) Correlated Spectroscopy .......................................... 133 9.4 Piecing It All Together ............................... 136 9.5 Choosing the Right Tool ............................... 137 10 Some of the Other Tools .................................... 143 10.1 Linking HPLC with NMR ................................. 143 10.2 Flow NMR .............................................. 144 10.3 Solvent Suppression ................................... 145 10.4 Magic Angle Spinning NMR .............................. 146 10.5 Other 2-D Techniques .................................. 147 10.5.1 INADEQUATE ..................................... 147 10.5.2 J-Resolved ..................................... 147 10.5.3 Diffusion Ordered Spectroscopy ................. 148 10.6 3-D Techniques ........................................ 149 11 Some of the Other Nuclei ................................... 151 11.1 Fluorine .............................................. 151 11.2 Phosphorus ............................................ 152 11.3 Nitrogen .............................................. 152 12 Quantification ............................................. 157 12.1 Introduction .......................................... 157 12.2 Relative Quantification ............................... 157 12.3 Absolute Quantification ............................... 158 12.3.1 Internal Standards ............................. 158 12.3.2 External Standards ............................. 158 12.3.3 Electronic Reference ........................... 159 12.3.4 QUANTAS Technique .............................. 159 12.4 Things to Watch Out For ............................... 160 12.5 Conclusion ............................................ 161 13 Safety ..................................................... 163 13.1 Magnetic Fields ....................................... 163 13.2 Cryogens .............................................. 165 13.3 Sample-Related Injuries ............................... 166 14 Software ................................................... 167 14.1 Acquisition Software .................................. 167 14.2 Processing Software ................................... 167 14.3 Prediction and Simulation Software .................... 169 14.3.1 13C Prediction ................................. 169 14.3.2 1H Prediction .................................. 171 14.3.3 Simulation ..................................... 172 14.3.4 Structural Verification Software ............... 172 14.3.5 Structural Elucidation Software ................ 172 15 Problems ................................................... 173 15.1 Ten NMR Problems ...................................... 173 15.2 Hints ................................................. 194 15.3 Answers ............................................... 195 Glossary ...................................................... 205 Index ......................................................... 211