Spectroscopic Methods in Organic Chemistry

ISBN-13: 9783030182519 / Angielski / Miękka / 2020 / 432 str.

Ian Fleming; Dudley Williams

Spis treści

Chapter 1: Mass spectra

1.1       Introduction                                                                                               

1.2       Ion production                                                                                           

            1.2.1  Electron impact (EI)                                                                         

            1.2.2  Chemical Ionisation (CI)                                                                  

            1.2.3  Electrospray ionisation (ESI)                                                            

            1.2.4  Fast ion bombardment (FIB or LSIMS)                                            

            1.2.5  Laser desorption (LD) and matrix-assisted laser

                     desorption (MALDI)                                                                        

1.3       Ion analysis                                                                                               

            1.3.1  Magnetic analysers                                                                          

          1.3.2  Time-of–flight (TOF) analysers                                                       

            1.3.3  Quadrupole analysers                                                                      

            1.3.4  Ion cyclotron resonance (ICR) analysers                                         

            1.3.5  Ion-trap analysers                                                                            

1.4       Structural information from EI mass spectra                                             

            1.4.1  The features of an EI spectrum                                                       

            1.4.2  The molecular ion                                                                            

            1.4.3  Isotopic abundances                                                                        

            1.4.4  Identifying the molecular ion                                                           

            1.4.5  Fragmentation in EI spectra                                                            

1.5       Fragmentation in CI and FIB spectra                                                       

            1.5.1  Fragmentation in CI spectra                                                           

            1.5.2  Fragmentation in FIB (LSMIS) spectra                                           

1.6       Some examples of mass spectrometry in action                                      

            1.6.1 San Joaquin oil                                                                               

            1.6.2 Oleic acid                                                                                       

            1.6.3 The oviposition pheromone                                                            

            1.6.4 Identifying antibodies                                                                     

            1.6.5 The ESI spectra of melittin and the human parathyroid hormone   

            1.6.6 ESI-FT-ICR and ESI-FT-Orbitrap spectra                                       

1.7       Separation coupled to mass spectrometry                                                

            1.7.1  GC/MS and LC/MS                                                                        

            1.7.2  MS/MS                                                                                           

1.8       Interpreting the spectrum of an unknown                                                

1.9       Internet                                                                                                    

1.10     Bibliography                                                                                            

1.11     Problems                                                                                                 

1.12     Tables of data                                                                                          

Chapter 2: Ultraviolet and visible spectra 2.1       Introduction                                                                                             

2.2       Chromophores                                                                                         

2.3       The absorption laws                                                                                

2.4       Measurement of the spectrum                                                                 

2.5       Vibrational fine structure                                                                         

2.6       Selection rules and intensity                                                                    

2.7       Solvent effects                                                                                        

2.8       Searching for a chromophore                                                                  

2.9       Definitions                                                                                              

2.10     Conjugated dienes                                                                                   

2.11     Polyenes and poly-ynes                                                                           

2.12     Ketones and aldehydes; p®p* transitions                                               

2.13     Ketones and aldehydes; n®p* transitions                                               

2.14     a,b-Unsaturated acids, esters, nitriles and amides                                   

2.15     Aromatic compounds                                                                              

2.16     Quinones                                                                                                 

2.17     Corroles, chlorins and porphyrins                                                           

2.18     Non-conjugated interacting chromophores                                              

2.19     The effect of steric hindrance to coplanarity                                           

2.20     Internet                                                                                                    

2.21     Bibliography                                                                                            

2.22     Problems                                                                                                 

Chapter 3: Infrared spectra 3.1       Introduction                                                                                             

3.2       Preparation of samples and examination in an infrared spectrometer      

3.3       Selection rules                                                                                         

3.4       The infrared spectrum                                                                             

3.5       The use of the tables of characteristic group frequencies                        

3.6       Stretching frequencies of single bonds to hydrogen                                

3.7     Stretching frequencies of triple and cumulated double bonds                 

3.8       Stretching frequencies in the double-bond region                                    

3.9       Characteristic vibrations of aromatic rings                                               

3.10     Groups absorbing in the fingerprint region                                              

3.11     Raman spectra                                                                                         

3.12     Internet                                                                                                    

3.13     Bibliography                                                                                            

3.14     Problems                                                                                                 

3.15     Correlation charts                                                                                    

3.16     Tables of data                                                                                          

Chapter 4: 1D-NMR spectra 4.1       Nuclear spin and resonance                                                                     

4.2       Taking a spectrum                                                                                   

4.3       The chemical shift                                                                                   

4.4       Factors affecting the chemical shift                                                       

            4.4.1    The inductive effect                                                                  

            4.4.2    Anisotropy of chemical bonds                                                  

            4.4.3    Polar effects of conjugation                                                      

            4.4.4    Van der Waals forces                                                                

            4.4.5    Isotope effects                                                                           

            4.4.6    Estimating a chemical shift                                                        

            4.4.7    Hydrogen bonds                                                                        

            4.4.8    Solvent effects and temperature                                                

4.5       Spin-spin coupling to ¹³C                                                                       

            4.5.1    ¹³C-²H Coupling                                                                        

            4.5.2    ¹³C-¹H Coupling                                                                        

            4.5.3    ¹³C-¹³C Coupling                                                                       

4.6       ¹H-¹H Coupling—multiplicity and coupling patterns                             

            4.6.1    ¹H-¹H Vicinal coupling (³J_HH)                                                    

            4.6.2    AB systems                                                                               

            4.6.3    ¹H-¹H Geminal coupling (²J_HH)                                                  

            4.6.4    ¹H-¹H Long-range coupling (⁴J_HH and ⁵J_HH)                               

            4.6.5    Deviations from first-order coupling                                         

4.7       ¹H-¹H Coupling—the magnitude of coupling constants                         

            4.7.1    The sign of coupling constants                                                  

            4.7.2    Vicinal coupling (³J_HH)                                                              

            4.7.3    Geminal coupling (²J_HH)                                                            

            4.7.4    Long-range coupling (⁴J_HH and ⁵J_HH)                                         

            4.7.5    C–H coupling (¹J_CH, ²J_CH and ³J_CH)                                            

4.8       Coupling from ¹H and ¹³C to ¹⁹F and ³¹P                                               

            4.8.1    ¹³C NMR spectra of compounds containing ¹⁹F and ³¹P             

            4.8.2    ¹H NMR spectra of compounds containing ¹⁹F and ³¹P              

4.9       Relaxation and its consequences                                                           

            4.9.1    Longitudinal relaxation                                                              

            4.9.2    Transverse relaxation and exchange                                          

4.10     Improving the NMR spectrum                                                               

            4.10.1  The effect of changing the magnetic field                                 

            4.10.2  Solvent effects                                                                          

            4.10.3  Shift reagents                                                                             

4.11     Spin decoupling                                                                                     

            4.11.1  Simple spin decoupling                                                             

            4.11.2  Difference decoupling                                                               

4.12     Identifying spin systems—1D-TOCSY                                                  

4.13     The nuclear Overhauser effect                                                              

            4.13.1  Origins                                                                                       

            4.13.2  NOE-Difference spectra                                                            

4.14     The rotating frame of reference                                                             

4.15     Assignment of CH₃, CH₂, CH and fully substituted carbons in ¹³C NMR 

            4.15.1  The Attached Proton Test (APT)                                                

            4.15.2  DEPT                                                                                         

4.16     Hints for structure determination using 1D-NMR                                  

            4.16.1  Carbon spectra                                                                          

            4.16.2  Proton spectra                                                                            

4.17     Further information                                                                               

            4.17.1  The internet                                                                               

            4.17.2  Bibliography                                                                              

4.18     Tables of data                                                                                        

 

Chapter 5: 2D-NMR spectra

5.1       The basic pulse sequence                                                                      

5.2       COSY                                                                                                    

            5.2.1    Cross peaks from scalar coupling                                              

            5.2.2    Polarisation transfer                                                                   

            5.2.3    The origin of cross peaks                                                          

            5.2.4    Displaying COSY spectra                                                          

            5.2.5    Interpreting COSY spectra                                                         

            5.2.6    Axial peaks                                                                               

            5.2.7    Gradient pulses                                                                          

            5.2.8    DQF-COSY                                                                               

            5.2.9    Phase structure in COSY spectra                                               

5.3       2D-TOCSY                                                                                            

5.4       NOESY                                                                                                 

5.5       Cross-correlated 2D spectra identifying 1-bond connections                 

            5.5.1    Heteronuclear Multiple Quantum Coherence (HMQC) spectra  

            5.5.2    Heteronuclear Single Quantum Coherence (HSQC) spectra       

            5.5.3    Examples of HSQC spectra                                                       

            5.5.4    Non-uniform sampling (NUS)                                                   

            5.5.5    Cross-peak detail—determining the sign of coupling constants 

            5.5.6    CLIP-HSQC                                                                               

            5.5.7    Deconvoluting a ¹H spectrum using the HSQC spectrum           

            5.5.8    HSQC-TOCSY                                                                          

            5.5.9    HETCOR                                                                                   

5.6       Cross-correlated 2D spectra identifying 2- and 3-bond connections      

            5.6.1    The HMBC pulse sequence                                                       

            5.6.2    HMBC spectra                                                                           

5.7       Some specialised NMR techniques                                                        

            5.7.1    ADEQUATE—identifying ¹³C-¹³C connections                         

            5.7.2    INADEQUATE—identifying ¹³C-¹³C connections                     

            5.7.3    HSQC-HECADE—measuring the sign and magnitude of ¹³C-¹H

                        coupling constants                                                                     

5.8       Three- and four-dimensional NMR                                                       

5.9       Hints for structure determination using 2D-NMR                                  

5.10     Bibliography                                                                                          

5.11     Table of information                                                                             

Chapter 6: Worked examples in structure determination 6.1       General approach                                                                                  

6.2       Simple worked examples using ¹³C NMR alone                                    

6.3       Simple worked examples using ¹H NMR alone                                     

6.4     Simple worked examples using the combined application of MS, UV, IR and 1D-NMR spectroscopic methods          

6.5     Simple worked examples using the combined application of MS, UV, IR and 1D-NMR and 2D-NMR spectroscopic methods                                                                          

Chapter 7: Problem sets

7.1       Chemical shift problems                                                              

7.2       1D-NMR chemical shift and coupling problems                                 

7.3       Problems using all the spectroscopic methods                                  

 

Answers to problems 1-34                                                                            

Index                                                                                                                                                  

O autorze

Professor Ian Fleming graduated from the University of Cambridge in 1959, obtained his PhD in 1962, and a Research Fellowship from 1962-64. He spent a post-doctoral year with R. B. Woodward at Harvard (1963-64), and then spent the rest of his career in the University of Cambridge, with sabbatical visits to teach at the University of Wisconsin, Madison (1980) and at Harvard (1990). He is well known in the organic chemistry world having been elected as a Fellow of the Royal Society in 1993 for his contributions to research in synthetic organic chemistry, with a special emphasis on the uses of organosilicon chemistry. After formal retirement from research in 2002, he has been writing, and continuing to carry out tutorial teaching in Pembroke College. From 2012 to 2018 he taught a one-semester course at the University of Illinois Urbana Champaign.

Blurb

This book is a well-established guide to the interpretation of the mass, ultraviolet, infrared and nuclear magnetic resonance spectra of organic compounds. It is designed for students of organic chemistry taking a course in the application of these techniques to structure determination. The text also remains useful as a source of data for organic chemists to keep on their desks throughout their career.

In the seventh edition, substantial portions of the text have been revised reflecting knowledge gained during the author's teaching experience over the last seven years. The chapter on NMR has been divided into two separate chapters covering the 1D and 2D experiments. The discussion is also expanded to include accounts of the physics at a relatively simple level, following the development of the magnetization vectors as each pulse sequence is introduced. The emphasis on the uses of NMR spectroscopy in structure determination is retained. Worked examples and problem sets are included on a chapter level to allow students to practise their skills by determining the chemical structures of unknown compounds.