Introduction to Spectroscopy, 5th Edition
By Donald L. Pavia, Gary M. Lampman, George S. Kriz and James R. Vyvyan
Contents:
C H A P T E R 1
MOLECULAR FORMULAS AND WHAT CAN BE LEARNED
FROM THEM 1
1.1 Elemental Analysis and Calculations 1
1.2 Determination of Molecular Mass 5
1.3 Molecular Formulas 5
1.4 Index of Hydrogen Deficiency 6
1.5 The Rule of Thirteen 9
1.6 The Nitrogen Rule 12
Problems 12
References 13
C H A P T E R 2
INFRARED SPECTROSCOPY 14
2.1 The Infrared Absorption Process 15
2.2 Uses of the Infrared Spectrum 16
2.3 The Modes of Stretching and Bending 17
2.4 Bond Properties and Absorption Trends 19
2.5 The Infrared Spectrometer 22
A. Dispersive Infrared Spectrometers 22
B. Fourier Transform Spectrometers 24
2.6 Preparation of Samples for Infrared Spectroscopy 25
2.7 What to Look for When Examining Infrared Spectra 26
2.8 Correlation Charts and Tables 28
2.9 How to Approach the Analysis of a Spectrum (Or What You Can Tell at a Glance) 30
2.10 Hydrocarbons: Alkanes, Alkenes, and Alkynes 31
A. Alkanes 31
B. Alkenes 33
C. Alkynes 35
2.11 Aromatic Rings 43
2.12 Alcohols and Phenols 47
2.13 Ethers 50
2.14 Carbonyl Compounds 52
A. Factors That Influence the CJO Stretching Vibration 54
B. Aldehydes 56
C. Ketones 58
D. Carboxylic Acids 62
E. Esters 64
F. Amides 70
G. Acid Chlorides 72
H. Anhydrides 73
2.15 Amines 74
2.16 Nitriles, Isocyanates, Isothiocyanates, and Imines 77
2.17 Nitro Compounds 79
2.18 Carboxylate Salts, Amine Salts, and Amino Acids 80
2.19 Sulfur Compounds 81
2.20 Phosphorus Compounds 84
2.21 Alkyl and Aryl Halides 84
2.22 The Background Spectrum 86
2.23 How to Solve Infrared Spectral Problems 87
Problems 92
References 106
C H A P T E R 3
MASS SPECTROMETRY
PART ONE: BASIC THEORY, INSTRUMENTATION, AND
SAMPLING TECHNIQUES 107
3.1 The Mass Spectrometer: Overview 107
3.2 Sample Introduction 108
3.3 Ionization Methods 109
A. Electron Ionization (EI) 109
B. Chemical Ionization (CI) 110
C. Desorption Ionization Techniques (SIMS, FAB, and MALDI) 115
D. Electrospray Ionization (ESI) 117
3.4 Mass Analysis 119
A. The Magnetic Sector Mass Analyzer 119
B. Double-Focusing Mass Analyzers 120
C. Quadrupole Mass Analyzers 120
D. Time-of-Flight Mass Analyzers 124
3.5 Detection and Quantitation: The Mass Spectrum 125
3.6 Determination of Molecular Weight 129
3.7 Determination of Molecular Formulas 131
A. Precise Mass Determination 131
B. Isotope Ratio Data 132
Problems 137
References 137
C H A P T E R 4
MASS SPECTROMETRY
PART TWO: FRAGMENTATION AND STRUCTURAL ANALYSIS 139
4.1 The Initial Ionization Event 139
4.2 Fundamental Fragmentation Processes 140
A. Stevenson’s Rule 141
B. Radical-Site Initiated Cleavage: á-Cleavage 141
C. Charge-Site Initiated Cleavage: Inductive Cleavage 141
D. Two-Bond Cleavage 142
E. Retro Diels-Alder Cleavage 143
F. McLafferty Rearrangements 143
G. Other Cleavage Types 144
4.3 Fragmentation Patterns of Hydrocarbons 144
A. Alkanes 144
B. Cycloalkanes 147
C. Alkenes 148
D. Alkynes 150
E. Aromatic Hydrocarbons 151
4.4 Fragmentation Patterns of Alcohols, Phenols, and Thiols 156
4.5 Fragmentation Patterns of Ethers and Sulfides 163
4.6 Fragmentation Patterns of Carbonyl-Containing Compounds 166
A. Aldehydes 166
B. Ketones 169
C. Esters 172
D. Carboxylic Acids 175
4.7 Fragmentation Patterns of Amines 178
4.8 Fragmentation Patterns of Other Nitrogen Compounds 182
4.9 Fragmentation Patterns of Alkyl Chlorides and Alkyl Bromides 184
4.10 Computerized Matching of Spectra with Spectral Libraries 189
4.11 Strategic Approach to Analyzing Mass Spectra and Solving Problems 191
4.12 How to Solve Mass Spectral Problems 192
References 214
C H A P T E R 5
NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
PART ONE: BASIC CONCEPTS 215
5.1 Nuclear Spin States 215
5.2 Nuclear Magnetic Moments 216
5.3 Absorption of Energy 217
5.4 The Mechanism of Absorption (Resonance) 219
5.5 Population Densities of Nuclear Spin States 221
5.6 The Chemical Shift and Shielding 222
5.7 The Nuclear Magnetic Resonance Spectrometer 224
A. The Continuous-Wave (CW) Instrument 224
B. The Pulsed Fourier Transform (FT) Instrument 226
5.8 Chemical Equivalence—A Brief Overview 230
5.9 Integrals and Integration 231
5.10 Chemical Environment and Chemical Shift 233
5.11 Local Diamagnetic Shielding 234
A. Electronegativity Effects 234
B. Hybridization Effects 236
C. Acidic and Exchangeable Protons; Hydrogen Bonding 237
5.12 Magnetic Anisotropy 238
5.13 Spin–Spin Splitting (n +1) Rule 241
5.14 The Origin of Spin–Spin Splitting 244
5.15 The Ethyl Group (CH3CH2–) 246
5.16 Pascal’s Triangle 247
5.17 The Coupling Constant 248
5.18 A Comparison of NMR Spectra at Low- and High-Field Strengths 251
5.19 Survey of Typical 1H NMR Absorptions by Type of Compound 252
A. Alkanes 252
B. Alkenes 254
C. Aromatic Compounds 255
D. Alkynes 256
E. Alkyl Halides 258
F. Alcohols 259
G. Ethers 261
H. Amines 262
I. Nitriles 263
J. Aldehydes 264
K. Ketones 265
L. Esters 267
M. Carboxylic Acids 268
N. Amides 269
O. Nitroalkanes 270
5.20 How to Solve NMR Spectra Problems 271
Problems 276
References 288
C H A P T E R 6
NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
PART TWO: CARBON-13 SPECTRA, INCLUDING HETERONUCLEAR COUPLING
WITH OTHER NUCLEI 290
6.1 The Carbon-13 Nucleus 290
6.2 Carbon-13 Chemical Shifts 291
A. Correlation Charts 291
B. Calculation of 13C Chemical Shifts 293
6.3 Proton-Coupled 13C Spectra—Spin–Spin Splitting of Carbon-13 Signals 294
6.4 Proton-Decoupled 13C Spectra 296
6.5 Nuclear Overhauser Enhancement (NOE) 297
6.6 Cross-Polarization: Origin of the Nuclear Overhauser Effect 299
6.7 Problems with Integration in 13C Spectra 302
6.8 Molecular Relaxation Processes 303
6.9 Off-Resonance Decoupling 305
6.10 A Quick Dip into DEPT 305
6.11 Some Sample Spectra—Equivalent Carbons 308
6.12 Non-Equivalent Carbon Atoms 310
6.13 Compounds with Aromatic Rings 311
6.14 Carbon-13 NMR Solvents—Heteronuclear Coupling of Carbon to Deuterium 313
6.15 Heteronuclear Coupling of Carbon-13 to Fluorine-19 316
6.16 Heteronuclear Coupling of Carbon-13 to Phosphorus-31 318
6.17 Carbon and Proton NMR: How to Solve a Structure Problem 319
Problems 323
References 347
C H A P T E R 7
NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
PART THREE: SPIN–SPIN COUPLING 349
7.1 Coupling Constants: Symbols 349
7.2 Coupling Constants: The Mechanism of Coupling 350
A. One-Bond Couplings (1J) 351
B. Two-Bond Couplings (2J) 352
C. Three-Bond Couplings (3J) 355
D. Long-Range Couplings (4J–nJ) 360
7.3 Magnetic Equivalence 363
7.4 Spectra of Diastereotopic Systems 368
A. Diastereotopic Hydrogens: Ethyl 3-Hydroxybutanoate 368
B. Diastereotopic Hydrogens: The Diels-Alder Adduct of
Anthracene-9-methanol and N-Methylmaleimide 372
C. Diastereotopic Hydrogens: 4-Methyl-2-pentanol 374
D. Diastereotopic Methyl Groups: 4-Methyl-2-pentanol 376
7.5 Nonequivalence within a Group—The Use of Tree Diagrams
when the n + 1 Rule Fails 377
7.6 Measuring Coupling Constants from First-Order Spectra 380
A. Simple Multiplets—One Value of J (One Coupling) 380
B. Is the n + 1 Rule Ever Really Obeyed? 382
C. More Complex Multiplets—More Than One Value of J 384
7.7 Second-Order Spectra—Strong Coupling 388
A. First-Order and Second-Order Spectra 388
B. Spin System Notation 389
C. The A2, AB, and AX Spin Systems 390
D. The AB2 . . . AX2 and A2B2 . . . A2X2 Spin Systems 390
E. Simulation of Spectra 392
F. The Absence of Second-Order Effects at Higher Field 392
G. Deceptively Simple Spectra 393
7.8 Alkenes 397
7.9 Measuring Coupling Constants—Analysis of an Allylic System 401
7.10 Aromatic Compounds—Substituted Benzene Rings 405
A. Monosubstituted Rings 405
B. para-Disubstituted Rings 408
C. Other Substitution 410
7.11 Coupling in Heteroaromatic Systems 414
7.12 Heteronuclear Coupling of 1H to 19F and 31P 416
A. 1H to 19F Couplings 416
B. 1H to 31P Couplings 418
7.13 How to Solve Problems Involving Coupling Constant Analysis 420
Problems 424
References 455
C H A P T E R 8
NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
PART FOUR: OTHER TOPICS IN ONE-DIMENSIONAL NMR 457
8.1 Protons on Oxygen: Alcohols 457
8.2 Exchange in Water and D2O 460
A. Acid/Water and Alcohol/Water Mixtures 460
B. Deuterium Exchange 461
C. Peak Broadening Due to Exchange 463
8.3 Other Types of Exchange: Tautomerism 464
8.4 Protons on Nitrogen: Amines 466
8.5 Protons on Nitrogen: Quadrupole Broadening and Decoupling 470
8.6 Amides 471
8.7 Solvent Effects 475
8.8 Chemical Shift Reagents 479
8.9 Chiral Resolving Agents 481
8.10 Determining Absolute and Relative Configuration via NMR 484
A. Determining Absolute Configuration 484
B. Determining Relative Configuration 486
8.11 Nuclear Overhauser Effect Difference Spectra 487
8.12 How to Solve Problems Involving Advanced 1-D Methods 489
Problems 490
References 509
C H A P T E R 9
NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
PART FIVE: ADVANCED NMR TECHNIQUES 511
9.1 Pulse Sequences 511
9.2 Pulse Widths, Spins, and Magnetization Vectors 513
9.3 Pulsed Field Gradients 517
9.4 The DEPT Experiment: Number of Protons Attached to 13C Atoms 519
9.5 Determining the Number of Attached Hydrogens 522
A. Methine Carbons (CH) 522
B. Methylene Carbons (CH2) 523
C. Methyl Carbons (CH3) 525
D. Quaternary Carbons (C) 525
E. The Final Result 526
9.6 Introduction to Two-Dimensional Spectroscopic Methods 526
9.7 The COSY Technique: 1H-1H Correlations 526
A. An Overview of the COSY Experiment 527
B. How to Read COSY Spectra 528
9.8 The HETCOR Technique: 1H-13C Correlations 534
A. An Overview of the HETCOR Experiment 535
B. How to Read HETCOR Spectra 535
9.9 Inverse Detection Methods 539
9.10 The NOESY Experiment 539
9.11 Magnetic Resonance Imaging 541
9.12 Solving a Structural Problem Using Combined 1-D and 2-D Techniques 542
A. Index of Hydrogen Deficiency and Infrared Spectrum 543
B. Carbon-13 NMR Spectrum 543
C. DEPT Spectrum 544
D. Proton NMR Spectrum 545
E. COSY NMR Spectrum 547
F. HETCOR (HSQC) NMR Spectrum 548
Problems 549
References 576
C H A P T E R 1 0
ULTRAVIOLET SPECTROSCOPY 577
10.1 The Nature of Electronic Excitations 577
10.2 The Origin of UV Band Structure 579
10.3 Principles of Absorption Spectroscopy 579
10.4 Instrumentation 580
10.5 Presentation of Spectra 581
10.6 Solvents 582
10.7 What Is a Chromophore? 583
10.8 The Effect of Conjugation 586
10.9 The Effect of Conjugation on Alkenes 587
10.10 The Woodward–Fieser Rules for Dienes 590
10.11 Carbonyl Compounds; Enones 593
10.12 Woodward’s Rules for Enones 596
10.13 _, _-Unsaturated Aldehydes, Acids, and Esters 598
10.14 Aromatic Compounds 598
A. Substituents with Unshared Electrons 600
B. Substituents Capable of _-Conjugation 602
C. Electron-Releasing and Electron-Withdrawing Effects 602
D. Disubstituted Benzene Derivatives 602
E. Polynuclear Aromatic Hydrocarbons and Heterocyclic Compounds 605
10.15 Model Compound Studies 607
10.16 Visible Spectra: Color in Compounds 608
10.17 What to Look for in an Ultraviolet Spectrum: A Practical Guide 609
Problems 611
References 613
C H A P T E R 1 1
COMBINED STRUCTURE PROBLEMS 614
Example 1 616
Example 2 618
Example 3 620
Example 4 623
Problems 624
Sources of Additional Problems 689
ANSWERS TO SELECTED PROBLEMS ANS-1
APPENDICES A-1
Appendix 1 Infrared Absorption Frequencies of Functional Groups A-1
Appendix 2 Approximate 1H Chemical Shift Ranges (ppm) for Selected
Types of Protons A-8
Appendix 3 Some Representative 1H Chemical Shift Values for Various
Types of Protons A-9
Appendix 4 1H Chemical Shifts of Selected Heterocyclic and Polycyclic
Aromatic Compounds A-12
Appendix 5 Typical Proton Coupling Constants A-13
Appendix 6 Calculation of Proton (1H) Chemical Shifts A-18
Appendix 7 Approximate 13C Chemical-Shift Values (ppm) for Selected
Types of Carbon A-22
Appendix 8 Calculation of 13C Chemical Shifts A-23
Appendix 9 13C Coupling Constants to Proton, Deuterium,
Fluorine, and Phosphorus A-33
Appendix 10 1H and 13C Chemical Shifts for Common NMR Solvents A-36
Appendix 11 Common Fragment Ions under Mass 105 A-37
Appendix 12 A Handy-Dandy Guide to Mass Spectral Fragmentation Patterns A-40
Appendix 13 Index of Spectra A-43
INDEX I-1
FROM THEM 1
1.1 Elemental Analysis and Calculations 1
1.2 Determination of Molecular Mass 5
1.3 Molecular Formulas 5
1.4 Index of Hydrogen Deficiency 6
1.5 The Rule of Thirteen 9
1.6 The Nitrogen Rule 12
Problems 12
References 13
C H A P T E R 2
INFRARED SPECTROSCOPY 14
2.1 The Infrared Absorption Process 15
2.2 Uses of the Infrared Spectrum 16
2.3 The Modes of Stretching and Bending 17
2.4 Bond Properties and Absorption Trends 19
2.5 The Infrared Spectrometer 22
A. Dispersive Infrared Spectrometers 22
B. Fourier Transform Spectrometers 24
2.6 Preparation of Samples for Infrared Spectroscopy 25
2.7 What to Look for When Examining Infrared Spectra 26
2.8 Correlation Charts and Tables 28
2.9 How to Approach the Analysis of a Spectrum (Or What You Can Tell at a Glance) 30
2.10 Hydrocarbons: Alkanes, Alkenes, and Alkynes 31
A. Alkanes 31
B. Alkenes 33
C. Alkynes 35
2.11 Aromatic Rings 43
2.12 Alcohols and Phenols 47
2.13 Ethers 50
2.14 Carbonyl Compounds 52
A. Factors That Influence the CJO Stretching Vibration 54
B. Aldehydes 56
C. Ketones 58
D. Carboxylic Acids 62
E. Esters 64
F. Amides 70
G. Acid Chlorides 72
H. Anhydrides 73
2.15 Amines 74
2.16 Nitriles, Isocyanates, Isothiocyanates, and Imines 77
2.17 Nitro Compounds 79
2.18 Carboxylate Salts, Amine Salts, and Amino Acids 80
2.19 Sulfur Compounds 81
2.20 Phosphorus Compounds 84
2.21 Alkyl and Aryl Halides 84
2.22 The Background Spectrum 86
2.23 How to Solve Infrared Spectral Problems 87
Problems 92
References 106
C H A P T E R 3
MASS SPECTROMETRY
PART ONE: BASIC THEORY, INSTRUMENTATION, AND
SAMPLING TECHNIQUES 107
3.1 The Mass Spectrometer: Overview 107
3.2 Sample Introduction 108
3.3 Ionization Methods 109
A. Electron Ionization (EI) 109
B. Chemical Ionization (CI) 110
C. Desorption Ionization Techniques (SIMS, FAB, and MALDI) 115
D. Electrospray Ionization (ESI) 117
3.4 Mass Analysis 119
A. The Magnetic Sector Mass Analyzer 119
B. Double-Focusing Mass Analyzers 120
C. Quadrupole Mass Analyzers 120
D. Time-of-Flight Mass Analyzers 124
3.5 Detection and Quantitation: The Mass Spectrum 125
3.6 Determination of Molecular Weight 129
3.7 Determination of Molecular Formulas 131
A. Precise Mass Determination 131
B. Isotope Ratio Data 132
Problems 137
References 137
C H A P T E R 4
MASS SPECTROMETRY
PART TWO: FRAGMENTATION AND STRUCTURAL ANALYSIS 139
4.1 The Initial Ionization Event 139
4.2 Fundamental Fragmentation Processes 140
A. Stevenson’s Rule 141
B. Radical-Site Initiated Cleavage: á-Cleavage 141
C. Charge-Site Initiated Cleavage: Inductive Cleavage 141
D. Two-Bond Cleavage 142
E. Retro Diels-Alder Cleavage 143
F. McLafferty Rearrangements 143
G. Other Cleavage Types 144
4.3 Fragmentation Patterns of Hydrocarbons 144
A. Alkanes 144
B. Cycloalkanes 147
C. Alkenes 148
D. Alkynes 150
E. Aromatic Hydrocarbons 151
4.4 Fragmentation Patterns of Alcohols, Phenols, and Thiols 156
4.5 Fragmentation Patterns of Ethers and Sulfides 163
4.6 Fragmentation Patterns of Carbonyl-Containing Compounds 166
A. Aldehydes 166
B. Ketones 169
C. Esters 172
D. Carboxylic Acids 175
4.7 Fragmentation Patterns of Amines 178
4.8 Fragmentation Patterns of Other Nitrogen Compounds 182
4.9 Fragmentation Patterns of Alkyl Chlorides and Alkyl Bromides 184
4.10 Computerized Matching of Spectra with Spectral Libraries 189
4.11 Strategic Approach to Analyzing Mass Spectra and Solving Problems 191
4.12 How to Solve Mass Spectral Problems 192
References 214
C H A P T E R 5
NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
PART ONE: BASIC CONCEPTS 215
5.1 Nuclear Spin States 215
5.2 Nuclear Magnetic Moments 216
5.3 Absorption of Energy 217
5.4 The Mechanism of Absorption (Resonance) 219
5.5 Population Densities of Nuclear Spin States 221
5.6 The Chemical Shift and Shielding 222
5.7 The Nuclear Magnetic Resonance Spectrometer 224
A. The Continuous-Wave (CW) Instrument 224
B. The Pulsed Fourier Transform (FT) Instrument 226
5.8 Chemical Equivalence—A Brief Overview 230
5.9 Integrals and Integration 231
5.10 Chemical Environment and Chemical Shift 233
5.11 Local Diamagnetic Shielding 234
A. Electronegativity Effects 234
B. Hybridization Effects 236
C. Acidic and Exchangeable Protons; Hydrogen Bonding 237
5.12 Magnetic Anisotropy 238
5.13 Spin–Spin Splitting (n +1) Rule 241
5.14 The Origin of Spin–Spin Splitting 244
5.15 The Ethyl Group (CH3CH2–) 246
5.16 Pascal’s Triangle 247
5.17 The Coupling Constant 248
5.18 A Comparison of NMR Spectra at Low- and High-Field Strengths 251
5.19 Survey of Typical 1H NMR Absorptions by Type of Compound 252
A. Alkanes 252
B. Alkenes 254
C. Aromatic Compounds 255
D. Alkynes 256
E. Alkyl Halides 258
F. Alcohols 259
G. Ethers 261
H. Amines 262
I. Nitriles 263
J. Aldehydes 264
K. Ketones 265
L. Esters 267
M. Carboxylic Acids 268
N. Amides 269
O. Nitroalkanes 270
5.20 How to Solve NMR Spectra Problems 271
Problems 276
References 288
C H A P T E R 6
NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
PART TWO: CARBON-13 SPECTRA, INCLUDING HETERONUCLEAR COUPLING
WITH OTHER NUCLEI 290
6.1 The Carbon-13 Nucleus 290
6.2 Carbon-13 Chemical Shifts 291
A. Correlation Charts 291
B. Calculation of 13C Chemical Shifts 293
6.3 Proton-Coupled 13C Spectra—Spin–Spin Splitting of Carbon-13 Signals 294
6.4 Proton-Decoupled 13C Spectra 296
6.5 Nuclear Overhauser Enhancement (NOE) 297
6.6 Cross-Polarization: Origin of the Nuclear Overhauser Effect 299
6.7 Problems with Integration in 13C Spectra 302
6.8 Molecular Relaxation Processes 303
6.9 Off-Resonance Decoupling 305
6.10 A Quick Dip into DEPT 305
6.11 Some Sample Spectra—Equivalent Carbons 308
6.12 Non-Equivalent Carbon Atoms 310
6.13 Compounds with Aromatic Rings 311
6.14 Carbon-13 NMR Solvents—Heteronuclear Coupling of Carbon to Deuterium 313
6.15 Heteronuclear Coupling of Carbon-13 to Fluorine-19 316
6.16 Heteronuclear Coupling of Carbon-13 to Phosphorus-31 318
6.17 Carbon and Proton NMR: How to Solve a Structure Problem 319
Problems 323
References 347
C H A P T E R 7
NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
PART THREE: SPIN–SPIN COUPLING 349
7.1 Coupling Constants: Symbols 349
7.2 Coupling Constants: The Mechanism of Coupling 350
A. One-Bond Couplings (1J) 351
B. Two-Bond Couplings (2J) 352
C. Three-Bond Couplings (3J) 355
D. Long-Range Couplings (4J–nJ) 360
7.3 Magnetic Equivalence 363
7.4 Spectra of Diastereotopic Systems 368
A. Diastereotopic Hydrogens: Ethyl 3-Hydroxybutanoate 368
B. Diastereotopic Hydrogens: The Diels-Alder Adduct of
Anthracene-9-methanol and N-Methylmaleimide 372
C. Diastereotopic Hydrogens: 4-Methyl-2-pentanol 374
D. Diastereotopic Methyl Groups: 4-Methyl-2-pentanol 376
7.5 Nonequivalence within a Group—The Use of Tree Diagrams
when the n + 1 Rule Fails 377
7.6 Measuring Coupling Constants from First-Order Spectra 380
A. Simple Multiplets—One Value of J (One Coupling) 380
B. Is the n + 1 Rule Ever Really Obeyed? 382
C. More Complex Multiplets—More Than One Value of J 384
7.7 Second-Order Spectra—Strong Coupling 388
A. First-Order and Second-Order Spectra 388
B. Spin System Notation 389
C. The A2, AB, and AX Spin Systems 390
D. The AB2 . . . AX2 and A2B2 . . . A2X2 Spin Systems 390
E. Simulation of Spectra 392
F. The Absence of Second-Order Effects at Higher Field 392
G. Deceptively Simple Spectra 393
7.8 Alkenes 397
7.9 Measuring Coupling Constants—Analysis of an Allylic System 401
7.10 Aromatic Compounds—Substituted Benzene Rings 405
A. Monosubstituted Rings 405
B. para-Disubstituted Rings 408
C. Other Substitution 410
7.11 Coupling in Heteroaromatic Systems 414
7.12 Heteronuclear Coupling of 1H to 19F and 31P 416
A. 1H to 19F Couplings 416
B. 1H to 31P Couplings 418
7.13 How to Solve Problems Involving Coupling Constant Analysis 420
Problems 424
References 455
C H A P T E R 8
NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
PART FOUR: OTHER TOPICS IN ONE-DIMENSIONAL NMR 457
8.1 Protons on Oxygen: Alcohols 457
8.2 Exchange in Water and D2O 460
A. Acid/Water and Alcohol/Water Mixtures 460
B. Deuterium Exchange 461
C. Peak Broadening Due to Exchange 463
8.3 Other Types of Exchange: Tautomerism 464
8.4 Protons on Nitrogen: Amines 466
8.5 Protons on Nitrogen: Quadrupole Broadening and Decoupling 470
8.6 Amides 471
8.7 Solvent Effects 475
8.8 Chemical Shift Reagents 479
8.9 Chiral Resolving Agents 481
8.10 Determining Absolute and Relative Configuration via NMR 484
A. Determining Absolute Configuration 484
B. Determining Relative Configuration 486
8.11 Nuclear Overhauser Effect Difference Spectra 487
8.12 How to Solve Problems Involving Advanced 1-D Methods 489
Problems 490
References 509
C H A P T E R 9
NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
PART FIVE: ADVANCED NMR TECHNIQUES 511
9.1 Pulse Sequences 511
9.2 Pulse Widths, Spins, and Magnetization Vectors 513
9.3 Pulsed Field Gradients 517
9.4 The DEPT Experiment: Number of Protons Attached to 13C Atoms 519
9.5 Determining the Number of Attached Hydrogens 522
A. Methine Carbons (CH) 522
B. Methylene Carbons (CH2) 523
C. Methyl Carbons (CH3) 525
D. Quaternary Carbons (C) 525
E. The Final Result 526
9.6 Introduction to Two-Dimensional Spectroscopic Methods 526
9.7 The COSY Technique: 1H-1H Correlations 526
A. An Overview of the COSY Experiment 527
B. How to Read COSY Spectra 528
9.8 The HETCOR Technique: 1H-13C Correlations 534
A. An Overview of the HETCOR Experiment 535
B. How to Read HETCOR Spectra 535
9.9 Inverse Detection Methods 539
9.10 The NOESY Experiment 539
9.11 Magnetic Resonance Imaging 541
9.12 Solving a Structural Problem Using Combined 1-D and 2-D Techniques 542
A. Index of Hydrogen Deficiency and Infrared Spectrum 543
B. Carbon-13 NMR Spectrum 543
C. DEPT Spectrum 544
D. Proton NMR Spectrum 545
E. COSY NMR Spectrum 547
F. HETCOR (HSQC) NMR Spectrum 548
Problems 549
References 576
C H A P T E R 1 0
ULTRAVIOLET SPECTROSCOPY 577
10.1 The Nature of Electronic Excitations 577
10.2 The Origin of UV Band Structure 579
10.3 Principles of Absorption Spectroscopy 579
10.4 Instrumentation 580
10.5 Presentation of Spectra 581
10.6 Solvents 582
10.7 What Is a Chromophore? 583
10.8 The Effect of Conjugation 586
10.9 The Effect of Conjugation on Alkenes 587
10.10 The Woodward–Fieser Rules for Dienes 590
10.11 Carbonyl Compounds; Enones 593
10.12 Woodward’s Rules for Enones 596
10.13 _, _-Unsaturated Aldehydes, Acids, and Esters 598
10.14 Aromatic Compounds 598
A. Substituents with Unshared Electrons 600
B. Substituents Capable of _-Conjugation 602
C. Electron-Releasing and Electron-Withdrawing Effects 602
D. Disubstituted Benzene Derivatives 602
E. Polynuclear Aromatic Hydrocarbons and Heterocyclic Compounds 605
10.15 Model Compound Studies 607
10.16 Visible Spectra: Color in Compounds 608
10.17 What to Look for in an Ultraviolet Spectrum: A Practical Guide 609
Problems 611
References 613
C H A P T E R 1 1
COMBINED STRUCTURE PROBLEMS 614
Example 1 616
Example 2 618
Example 3 620
Example 4 623
Problems 624
Sources of Additional Problems 689
ANSWERS TO SELECTED PROBLEMS ANS-1
APPENDICES A-1
Appendix 1 Infrared Absorption Frequencies of Functional Groups A-1
Appendix 2 Approximate 1H Chemical Shift Ranges (ppm) for Selected
Types of Protons A-8
Appendix 3 Some Representative 1H Chemical Shift Values for Various
Types of Protons A-9
Appendix 4 1H Chemical Shifts of Selected Heterocyclic and Polycyclic
Aromatic Compounds A-12
Appendix 5 Typical Proton Coupling Constants A-13
Appendix 6 Calculation of Proton (1H) Chemical Shifts A-18
Appendix 7 Approximate 13C Chemical-Shift Values (ppm) for Selected
Types of Carbon A-22
Appendix 8 Calculation of 13C Chemical Shifts A-23
Appendix 9 13C Coupling Constants to Proton, Deuterium,
Fluorine, and Phosphorus A-33
Appendix 10 1H and 13C Chemical Shifts for Common NMR Solvents A-36
Appendix 11 Common Fragment Ions under Mass 105 A-37
Appendix 12 A Handy-Dandy Guide to Mass Spectral Fragmentation Patterns A-40
Appendix 13 Index of Spectra A-43
INDEX I-1