Spectroscopic Methods in Organic Chemistry

Deviations from first-order coupling 3.10 The magnitude of 1H-1H coupling constants 3.10.1 Vicinal coupling 3JHH 3.10.2 Geminal coupling (2JHH) 3.10.3 Long-range coupling (4JHH and 5JHH) 3.11 Line broadening and environmental exchange 3.11.1 Efficient relaxation 3.11.2 Environmental exchange 3.12 Improving the NMR spectrum 3.12.1 The effect of changing the magnetic field 3.12.2 Shift reagents 3.12.3 Solvent effects 3.13 Spin decoupling 3.13.1 Simple spin decoupling 3.13.2 Difference decoupling 3.14 The nuclear Overhauser effect 3.14.1 Origins 3.14.2 NOE Difference spectra 3.15 Assignment of CH3, CH2, CH and quaternary carbons in 13C NMR 3.16 Identifying spin systems--1D-TOCSY 3.17 The separation of chemical shift and coupling onto different axes 3.18 Two-dimensional NMR 3.19 COSY spectra 3.20 NOESY spectra 3.21 2D-TOCSY spectra 3.22 1H-13C COSY spectra 3.22.1 Heteronuclear Multiple Quantum Coherence (HMQC) spectra 3.22.2 Heteronuclear Multiple Bond Connectivity (HMBC) spectra 3.23 Measuring 13C-1H coupling constants (HSQC-HECADE spectra) 3.24 Identifying 13C-13C connections (INADEQUATE spectra) 3.25 Three- and four-dimensional NMR 3.26 Hints for spectroscopic interpretation and structure determination 3.26.1 Carbon spectra 3.26.2 Proton spectra 3.26.3 Hetero-correlations 3.27 Internet 3.28 Bibliography 3.29 Tables of data Chapter 4: Mass spectra 4.1 Introduction 4.2 Ion production from readily volatile molecules 4.2.1 Electron impact (EI) 4.2.2 Chemical Ionisation (CI) 4.3 Ion production from poorly volatile molecules 4.3.1 Fast ion bombardment (FIB or LSIMS) 4.3.2 Laser desorption (LD) and matrix-assisted laser desorption (MALDI) 4.3.3 Electrospray ionisation (ESI) 4.4 Ion analysis 4.4.1 Magnetic analysers 4.4.2 Combined magnetic and electrostatic analysers--high-resolution mass spectra (HRMS) 4.4.3 Ion cyclotron resonance (ICR) analysers 4.4.4 Time-of--flight (TOF) analysers 4.4.5 Quadrupole analysers 4.4.6 Ion-trap analysers 4.5 Structural information from mass spectra 4.5.1 Isotopic abundances 4.5.2 EI spectra 4.5.3 CI spectra 4.5.4 FIB (LSMIS) spectra 4.5.5 MALDI spectra 4.5.6 ESI spectra 4.5.7 ESI-FT-ICR and ESI-FT-Orbitrap spectra 4.6 Separation coupled to mass spectrometry 4.6.1 GC/MS and LC/MS 4.6.2 MS/MS 4.7 MS data systems 4.8 Specific ion monitoring and quantitative MS (SIM and MIM) 4.9 Interpreting the spectrum of an unknown 4.10 Internet 4.11 Bibliography 4.12 Tables of data Chapter 5: Practice in structure determination 5.1 General approach 5.2 Simple worked examples using 13C NMR alone 5.3 Simple worked examples using 1H NMR alone 5.4 Simple worked examples using the combined application of all four spectroscopic methods 5.5 Simple problems using 13C NMR or joint application of IR and 13C NMR 5.6 Simple problems using 1H NMR 5.7 Problems using a combination of spectroscopic methods 5.8 Answers to problems 1-33 Index