ORGAN IC STRUCTURAL SPECTROSCOPY

Transcription

1 ORGAN IC STRUCTURAL SPECTROSCOPY JOSEPH B. LAMBERT Northwestern University HERBERT F. SHURVELL Queen's University DAVID A. LIGHTNER University of Nevada at Reno R. GRAHAM COOKS Purdue University Prentice Hall Upper Saddle River, New Jersey 07458

2 Contents Preface, vii 1 Introduction, The Spectroscopic Approach to Structure, Contributions of Different Forms of Spectroscopy, 1 l-2a Nuclear Magnetic Resonance Spectroscopy, 1 l-2b Vibrational Spectroscopy, 2 l-2c Electronic Spectroscopy, 2 l-2d Mass Spectrometry, The Electromagnetic Spectrum, Molecular Weight and Molecular Formula, Structural Isomers and Stereoisomers, 5 Problems, 6 PART I NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2 Introduction and Experimental Methods, Magnetic Properties of Nuclei, The Chemical Shift, Excitation and Relaxation, Pulsed Experiments, 16 \ 2-5 The Coupling Constant, Quantitation, Commonly Studied Nuclides, Experimental Methods, a The Spectrometer and the Sample, b Optimizing the Signal, c Spectral Parameters, Dynamic Effects, Spectra of Solids, 32 Problems, 34 Bibliography, 36 3 The Chemical Shift, Factors That Influence Proton Shifts, Proton Chemical Shifts and Structure, a Saturated Aliphatics, b Unsaturated Aliphatics, c Aromatics, d Protons on Oxygen and Nitrogen, Factors That Influence Carbon Shifts, Carbon Chemical Shifts and Structure, a Saturated Aliphatics, b Unsaturated Compounds, c Carbonyl Croups, Summary and Tables of Chemical Shifts, 55 Problems, 57 Bibliography, 63 4 The Coupling Constant, First- and Second-Order Spectra, Chemical and Magnetic Equivalence, Signs and Mechanisms: One Bond Couplings, Geminal Couplings, Vicinal Couplings, Long-Range Couplings, Spectral Analysis, Tables of Coupling Constants, 79 Problems, 82 Bibliography, 88 5 Further Topics in One-Dimensional NMR, Spin-Lattice and Spin-Spin Relaxation, Reactions on the NMR Time Scale, Multiple Resonance, The Nuclear Overhauser Effect, Spectral Editing, Sensitivity Enhancement, Carbon Connectivity, Phase Cycling and Composite Pulses, 112 Problems, 114 Bibliography, Two-Dimensional NMR, Proton-Proton Correlation Through Coupling, Proton-Heteronucleus Correlation, Proton-Proton Correlation Through Space or Chemical Exchange, Carbon-Carbon Correlation, Higher Dimensions, Pulsed Field Gradients, Summary of Two-Dimensional Methods, 144 Problems, 145 Bibliography, 150 iii

3 iv PART II VIBRATIONAL SPECTROSCOPY 7 Introduction and Experimental Methods, Introduction, Vibrations of Molecules, Vibrational Spectra: Infrared and Raman, Units and Notation, Infrared Spectroscopy: Dispersive and Fourier Transform, a Dispersive Infrared Spectrometers, b Fourier Transform Infrared Spectrometers, Sampling Methods for Infrared Transmission Spectra, a Liquids and Solutions, b Solids, Raman Spectroscopy: Dispersive and Fourier Transform, a Dispersive Raman Spectrometers, b FT-Raman Spectrometers, Raman Sampling Methods, a Liquids and Solutions, b Solids, c Depolarization Measurements, Special Techniques in Infrared Spectroscopy, a Gas Phase Infrared Spectroscopy, b Microsampling, c Infrared Reflection Spectroscopy, d Gas Chromatography and Infrared Spectroscopy (GC-IR), 173 Problems, 174 Bibliography, Group Frequencies: Infrared and Raman, Introduction to Group Frequencies, Factors Affecting Group Frequencies, a Symmetry, b Mechanical Coupling of Vibrations, c Permi Resonance, d Hydrogen Bonding, e Ring Strain, f Electronic Effects, g Constitutional Isomerism, h Stereoisomerism, i Conformational Isomerism, j Tautomerism (Dynamic Isomerism), Infrared Group Frequencies, Raman Group Frequencies, 188 Problems, 199 Bibliography, Structural Analysis, Introduction, Preliminary Analysis, a Introduction, b Hydrocarbons or Hydrocarbon Croups, c Compounds Containing Oxygen, d Compounds Containing Nitrogen, 207 Contents 9-3 The CH Stretching Region ( cm" 1 ), a Introduction, b Alkynes, c Aromatic Compounds, d Unsaturated Nonaromatic Compounds, e Saturated Hydrocarbon Croups, f Aldehydes, The Carbonyl Stretching Region ( cm- 1 ), a Introduction, b Compounds Containing a Single C=0 Group, c Compounds Containing Two C=0 Groups, Aromatic Compounds, a General, b Substituted Aromatic Compounds, c Raman Spectra of Aromatic Compounds, Compounds Containing Methyl Groups, a General, b Isopropyl and tert-butyl Groups, Compounds Containing Methylene Groups, a Introduction, b CH 2 Bending (Scissoring), c CH 2 Wagging and Twisting, d CH 2 Rocking, e CH 2 Wagging in Vinyl and Vinylidene Compounds, f Relative Numbers of CH 2 and CH^ Groups, Unsaturated Compounds, a The C= C Stretching Mode, b Cyclic Compounds, c TheC=C Stretching Mode, d CH= and CH 2 = Bending Modes, Compounds Containing Oxygen, a General, b Ethers, c Alcohols and Phenols, d Carboxylic Acids and Anhydrides, e Esters, Compounds Containing Nitrogen, a General, b Amino Acids, Amines, and Amine Hydrohalides, c Anilines, d Nitriles, e Nitro Compounds, f Amides, g Oximes, Compounds Containing Phosphorus and Sulfur, lla General, llb Phosphorus Acids and Esters, llc Aromatic Phosphorus Compounds, 231

4 Contents 9-lld Compounds Containing C S, S S, and S H Groups, le Compounds Containing S=0 Groups, Heterocyclic Compounds, a General, b Aromatic Heterocycles, c Pyrimidines and Purines, d Five-Membered Ring Compounds, e NH Stretching Bands, Compounds Containing Halogens, a General, b CH 2 X Groups, c Haloalkyl Groups, d Aromatic Halogen Compounds, Boron, Silicon, and Organometallic Compounds, Isotopically Labeled Compounds, a The Effect of 2 H and 13 C Isotopic Substitution on Stretching Modes, b The Effect of Deuterium Substitution on Bending Modes, Using the Literature on Vibrational Spectra, a Collections of Spectra, b Infrared Spectra, c Raman Spectra, d Sources of References to Published Spectra, 242 Problems, 242 Bibliography, 250 PART IM ELECTRONIC ABSORPTION AND CHIROPTICAL SPECTROSCOPY 10 Introduction and Experimental Methods, Introduction, Measurement of Ultraviolet-Visible Light Absorption, a Wavelength and ~K max, b Beer-Bouger-Lambert Law and e max, c Shape of Absorption Curves: The Franck-Condon Principle, d Solvent Effects and X max Shifts, Measurements Using Polarized Light, a Ordinary Absorption and Chiroptical Spectroscopy, b Circular Birefringence and Circular Dichroism, c Optical Rotatory Dispersion (ORD) and Circular Dichroism (CD) Quantities, d ORD and CD Spectra and Cotton Effects, e Relative Advantages of ORD and CD, Quantitative Measurements, a Difference Spectroscopy, b Deviations From Beer's Law, c Isosbestic Points, Experimental Aspects, a Solvents, b Cells (Cuvettes) and Sample Preparation, c Calibration of ORD and CD Instruments, d Possible Sources of Error, 271 Problems, 272 Bibliography, UV-Vis, CD, and ORD, Electronic Transitions and Chromophores, la Classification of Electronic Transitions, lb Singlet and Triplet States, lc Allowed and Forbidden Transitions, ld Absorption Intensity: Oscillator and Rotatory Strengths, Isolated Chromophores, 279 ll-2a Carbonyl: Ketone and Aldehyde Absorption, b Carbonyl: Ketone ORD and CD, c Carbonyl: Acid, Ester, and Amide Absorption, 281 ll-2d Alkenes, Conjugated Chromophores, 285 ll-3a Dienes and Polyenes, 285 ll-3b a,$-unsaturated Carbonyls, Aromatic Compounds, Important Naturally Occurring Chromophores, a Amino Acids, Peptides, and Proteins, b Nucleic Acids and Polynucleotides, c Porphyrins and Metalloporphyrins, Worked Problems, 299 Problems, 301 Bibliography, Structural Analysis, Applications of the Woodward-Fieser Rules, la Conjugated Dienes and Polyenes, lb Conjugated Ketones, Aldehydes, Acids, and Esters, Determination of Absolute Configuration, a The Octant Rule, b Exciton Coupling and the Exciton Chirality Rule, Steric Effects, Solvent Effects and Tautomerism, Conformational Analysis, Hydrogen Bonding Studies, Homoconjugation, Charge Transfer Bands, Worked Problems, 327 Problems, 337 Bibliography, 344 v

5 VI PART IV MASS SPECTROMETRY 13 lonization and Mass Analysis, Scope and Applications of Mass Spectrometry, Sample Introduction, a Direct Introduction, b Introduction via Gas or Liquid Chromatographs, c Other Sample Introduction Methods, lonization, a Electron lonization (EI), b Chemical lonization (CI), c Desorption lonization (DI) Including Matrix-Assisted Laser Desorption lonization (MALDI), d Spray lonization (SI) Including Electrospray lonization (ESI), e lonization Summary, Mass Analysis, a Magnetic Sectors, b Tlme-of-Flight (TOF) Analyzers, c Quadrupole Mass Filters, d Quadrupole Ion Traps, e Ion Cyclotron Resonance (ICR), f High Resolutton Mass Spectrometers, g Tandem Mass Spectrometers, 382 I3-4h Ion Detection and Data Handllng, Worked Problems, 386 Problems, 389 Blbllography, Fragmentation and Ion Chemistry, General Principles of Fragmentation, Ia Energetlcs of Dtssoclatlon, b Odd- and Even-Electron Ions, lc Stevenson's Rule, ld Rearrangement vs. Simple Cleavage, le Ions ofhlgh Internal Energy, f Proximale vs. Remote Fragmentation, lg Dlstonlc Ions, lh Charge Localizaüon, Characterlstlc Fragment Ions and Neutral Fragments, Amine and Ether Type Fragmentation, a Amines, b Ethers, c Alcohols and Phenols, d Halldes, Ketone and Aldehyde Type Fragmentation, Fragmentation of Other Functional Croups, a Carboxyllc Aclds, b Esters, c Amldes, d Allphatic Hydrocarbons, e Aromatic Hydrocarbons, Negative Ion Fragmentation, Fragmentation in CI, DI, and SI, Ion Chemistry, a Unimolecular Fragmentation, b lon-molecule Reactlons, 426 l4-7c Advanced Ion Chemistry, Worked Problems, 432 Problems, 436 Bibliography, Chemical Analysis, Molecular Weight Determination, Molecular Structure Determination, Molecular Formula Determination (Exact Mass Measurement), Isotopic Analysis, a Recognition of Elements: Isotopic Slgnatures, b Number of Carbon Atoms In a Molecule, c Calculation oflon Abundance Ratlos From the Molecular Formula, d Typtcal Molecular Ion Isotopic Profites for Organlc and Blologlcal Compounds, e Determination of Molecular Formula From Isotopic Abundances, f Isotopic Purity Determination, Quantitative Analysis, Mixture Analysis, a Chromatography-Mass Spectrometry, b Tandem Mass Spectrometry (MS-MS), Thermochemical Determinations: Heats of Formation and Ion Affinities, Other Applications of Mass Spectrometry, a Industrial Applications and Process Control, b Isotope Ratio Mass Spectrometry, c Elemental Analysis, d Surface Elemental Analysis, Worked Problems, 458 Problems, 467 Blbllography, 472 Appendix to Part IV, 473 PART V INTEGRATED PROBLEMS, Integrated Problems, 480 Index, 557