Perspectives on Structure and Mechanism in Organic Chemistry

ISBN-13: 9781119808619 / Angielski / Twarda / 2023 / 950 str.

Felix A. Carroll

Spis treści

Preface xiChapter 1 Fundamental Models of Organic Chemistry 11.1 Atoms and Molecules 1Basic Concepts 1Molecular Dimensions 51.2 Heats of Formation and Reaction 8Experimental Determination of Heats of Formation 8Bond Increment Calculation of Heats of Formation 10Group Increment Calculation of Heats of Formation 11Heats of Formation and the Concept of Protobranching 13Homolytic and Heterolytic Bond Dissociation Energies 151.3 Bonding Models 18Electronegativity and Bond Polarity 20Complementary Theoretical Models of Bonding 23Pictorial Representations of Bonding Concepts 27sp³ Hybridization 28Are There sp³ Hybrid Orbitals in Methane? 30Hybridization and Molecular Geometry 34Variable Hybridization 351.4 Complementary Models for the Double Bond 41The sigma,pi Description of Ethene 41The Bent Bond Description of Ethene 42Predictions of Physical Properties with the Two Models 421.5 The Role of Complementary Models in Organic Chemistry 46Problems 47Chapter 2 Introduction to Computational Chemistry 532.1 Hückel Molecular Orbital Theory 53Correlation of Physical Properties with Results of HMO Calculations 63Other Parameters Generated Through HMO Theory 67Properties of Odd Alternant Hydrocarbons 69The Frost Circle 742.2 Aromaticity 75Benzene 77Other Aromatic Systems 81Polycyclic Conjugated Systems 85Larger Annulenes 90Dewar Resonance Energy and Absolute Hardness 932.3 Contemporary Computational Methods 95Extended Hückel Theory 95Semiempirical Methods 96Ab Initio Theory 972.4 Localized Molecular Orbitals 100Perturbational Molecular Orbital Theory 104Atoms in Molecules 1082.5 Density Functional Theory 1122.6 Another Look at Valence Bond Theory 114Resonance Structures and Resonance Energies 114Interpreting Computational Results 117Problems 119Chapter 3 Stereochemistry 1273.1 Representations of Three-Dimensional Structures 1273.2 Stereoisomerism 130Isomerism 130Symmetric, Asymmetric, Dissymmetric, and Nondissymmetric Molecules 133Fischer Projections 146Additional Stereochemical Designations 1493.3 Physical Manifestations of Chirality 159Optical Activity 159Configuration and Optical Activity 161Other Physical Properties of Stereoisomers 1663.4 Stereotopicity 167Stereochemical Relationships of Substituents 167Chirotopicity and Stereogenicity 171Problems 172Chapter 4 Molecular Geometry and Steric Energy 1834.1 Designation of Molecular Conformation 1834.2 Conformational Analysis 187Torsional Strain 187van der Waals Strain 191Angle Strain and Baeyer Strain Theory 193Application of Conformational Analysis to Cycloalkanes 194Conformational Analysis of Substituted Cyclohexanes 1984.3 Molecular Mechanics 2044.4 Anomeric Effect 2214.5 Strain and Molecular Stability 225Problems 237Chapter 5 Reactive Intermediates 2435.1 Reaction Coordinate Diagrams 2435.2 Radicals 244Early Evidence for the Existence of Radicals 244Detection and Characterization of Radicals 246Structure and Bonding of Radicals 251Thermochemical Data for Radicals 253Generation of Radicals 255Radical Chain Reactions 2565.3 Carbenes 263Structure and Geometry of Carbenes 263Generation of Carbenes 267Reactions of Carbenes 2685.4 Carbocations 272Carbonium Ions and Carbenium Ions 272Structure and Geometry of Carbocations 274The 2-Norbornyl Cation 281Carbocation Rearrangements 283Radical Cations 2855.5 Carbanions 290Generation of Carbanions 294Stability of Carbanions 296Reactions of Carbanions 2965.6 Choosing Models of Reactive Intermediates 298Problems 299Chapter 6 Determining Reaction Mechanisms 3056.1 Reaction Mechanisms 3056.2 Methods to Determine Reaction Mechanisms 306Identification of Reaction Products 306Determination of Intermediates 306Crossover Experiments 311Isotopic Labeling 313Stereochemical Studies 314Solvent Effects 315Computational Studies 3176.3 Applications of Kinetics in Studying Reaction Mechanisms 3196.4 Arrhenius Theory and Transition State Theory 3266.5 Reaction Barriers and Potential Energy Surfaces 3376.6 Kinetic Isotope Effects 348Primary Kinetic Isotope Effects 349Secondary Kinetic Isotope Effects 354Tunneling and Isotope Effects 359Solvent Isotope Effects 3626.7 Substituent Effects 3636.8 Linear Free Energy Relationships 368Problems 383Chapter 7 Acid and Base Catalysis of Organic Reactions 3937.1 Acidity and Basicity of Organic Compounds 393Acid-Base Measurements in Solution 393Acid-Base Reactions in the Gas Phase 402Comparison of Gas Phase and Solution Acidities 408Acidity Functions 4107.2 Acid and Base Catalysis of Chemical Reactions 413Specific Acid Catalysis 413General Acid Catalysis 414Brønsted Catalysis Law 4177.3 Acid and Base Catalysis of Reactions of Carbonyl Compounds and CarboxylicAcid Derivatives 418Addition to the Carbonyl Group 418Enolization of Carbonyl Compounds 422Hydrolysis of Acetals 426Acid-Catalyzed Hydrolysis of Esters 428Alkaline Hydrolysis of Esters 431Hydrolysis of Amides 437Problems 441Chapter 8 Substitution Reactions 4498.1 Introduction 4498.2 Nucleophilic Aliphatic Substitution 4508.3 The SN1 Reaction 453Kinetics 453Structural Effects in SN1 Reactions 454Solvent Polarity and Nucleophilicity 455Solvated Ions and Ion Pairs 459Anchimeric Assistance in SN1 Reactions 464Nonclassical Carbocations in SN1 Reactions 4698.4 The SN2 Reaction 471Stereochemistry 471Solvent Effects 473Substrate Effects 4778.5 Quantitative Measures of Nucleophilicity 480Brønsted Correlations 481Hard-Soft Acid-Base Theory and Nucleophilicity 482Edwards Equations 483Swain-Scott Equation 484Mayr Equations 485The alpha-Effect 488Leaving Group Effects in SN2 Reactions 489Aliphatic Substitution and Single Electron Transfer 4908.6 Electrophilic Aromatic Substitution 495The SEAr Reaction 495Quantitative Measurement of SEAr Rate Constants: Partial Rate Factors 498Lewis Structures as Models of Reactivity in SEAr Reactions 5008.7 Nucleophilic Aromatic and Vinylic Substitution 504Nucleophilic Aromatic Substitution 504Nucleophilic Vinylic Substitution 5098.8 Substitution Involving Benzyne Intermediates 5118.9 Radical-Nucleophilic Substitution 5188.10 The Impermanence of Mechanistic Labels 521Problems 521Chapter 9 Elimination Reactions 5299.1 Introduction 5299.2 Dehydrohalogenation and Related 1,2-Elimination Reactions 534Potential Energy Surfaces for 1,2-Elimination 534Competition Between Substitution and Elimination 540Stereochemistry of 1,2-Elimination Reactions 541Elimination Reactions to Produce Alkynes 547Regiochemistry of 1,2-Elimination Reactions 5489.3 Other 1,2-Elimination Reactions 558Dehalogenation of Vicinal Dihalides 558Dehydration of Alcohols 561Deamination of Amines 568Pyrolytic Eliminations 572Problems 578Chapter 10 Addition Reactions 58710.1 Introduction 58710.2 Addition of Halogens to Alkenes 588Electrophilic Addition of Bromine to Alkenes 588Role of Charge-Transfer Complexes in Bromine Addition Reactions 592Kinetics of Bromine Addition Reactions 593Solvent Effects in Bromine Additions 596Reversibility of Bromine Addition 598Intermediates in the Addition of Bromine to Alkyl-Substituted Alkenes 599Intermediates in the Addition of Bromine to Aryl-Substituted Alkenes 604Summary of Bromine Addition 608Addition of Other Halogens to Alkenes 60910.3 Other Addition Reactions 618Addition of Hydrogen Halides to Alkenes 618Hydration of Alkenes 625Oxymercuration 628Hydroboration 632Epoxidation 637Electrophilic Addition to Alkynes and Cumulenes 639Nucleophilic Addition to Alkenes and Alkynes 647Nucleophilic Addition to Carbonyl Compounds 651Problems 656Chapter 11 Pericyclic Reactions 66111.1 Introduction 66111.2 Electrocyclic Transformations 665Definitions and Selection Rules 665MO Correlation Diagrams 670State Correlation Diagrams 67511.3 Sigmatropic Reactions 678Selection Rules for Sigmatropic Reactions 679Other Examples of Sigmatropic Reactions 68711.4 Cycloaddition Reactions 691Introduction 691Ethene Dimerization 692The Diels-Alder Reaction 694Selection Rules for Cycloaddition Reactions 69811.5 Other Pericyclic Reactions 705Cheletropic Reactions 705Double Group Transfer Reactions 707Ene Reactions 70911.6 A General Selection Rule for Pericyclic Reactions 71111.7 Alternative Conceptual Models for Pericyclic Reactions 713Frontier Molecular Orbital Theory 713Hückel and Möbius Aromaticity of Transition Structures 719Synchronous and Nonsynchronous Pericyclic Reactions 725Potential Energy Surfaces and Ambimodal Reactions 72911.8 Reaction Dynamics and Potential Energy Surfaces 729Problems 735Chapter 12 Organic Photochemistry 74512.1 Energy and Electronic States 74512.2 Photophysical Processes 747Designation of Spectroscopic Transitions 748Selection Rules for Radiative Transitions 754Fluorescence and Phosphorescence 756Energy Transfer and Electron Transfer 75912.3 Photochemical Kinetics 763Actinometry and Quantum Yield Determinations 763Rate Constants for Unimolecular Processes 764Transient Detection and Monitoring 765Bimolecular Decay of Excited States: Stern-Volmer Kinetics 76812.4 Physical Properties of Excited States 770Acidity and Basicity in Excited States 770Bond Angles and Dipole Moments of Excited-State Molecules 77412.5 Representative Photochemical Reactions 777Photochemical Reactions of Alkenes and Dienes 778Photochemical Reactions of Carbonyl Compounds 790Photochemical Reactions of alpha,ß-Unsaturated Carbonyl Compounds 798Photochemical Reactions of Aromatic Compounds 800Photosubstitution Reactions 802sigma Bond Photodissociation Reactions 803Singlet Oxygen and Organic Photochemistry 80812.6 Applications of Organic Photochemistry 811Problems 822References for Selected Problems 831Index 837

O autorze

Felix A. Carroll, PhD is the Joseph R. Morton Professor of Chemistry Emeritus at Davidson College. His research focuses on organic photochemistry and photophysics, kinetics, the synthesis and characterization of insect pheromone analogues, the correlation of molecular structure with physical properties, the combustion characteristics of organic compounds, and chemical education. Dr. Carroll has published extensively in the peer-reviewed literature and was awarded a patent in the field of insect pheromones.