Organic Reactions and Their Mechanisms

This textbook is intended for undergraduate and graduate students pursuing courses in chemistry and allied fields. It includes fundamental concepts, equations involved in organic reactions, chemical bonds (ionic and covalent bonds), hybridization, representation of a chemical reaction and mechanism of organic reactions. The book also discusses the displacement of bonding electrons involving inductive effect, electromeric effect, mesomeric effect, hyperconjugative effect and resonance. A number of organic reactions involving formation of intermediates such as carbocations, carbanions, free radicals, carbenes, nitrenes and benzynes have also been included. It also discusses different types of reagents involved in a chemical reactions along with types of additional reactions and its detailed mechanism. The book also includes the use of pedagogical elements such as multiple choice questions and end of chapter exercises to aid self-learning among students Cover Half Title Organic Reactions and Their Mechanisms Copyright Preface to the Second Edition Preface to the First Edition Contents Organic Reactions and Their Mechanisms 1. Introduction 2. Fundamental concepts 2.1 Equations involved in organic reaction 2.2 Chemical Bonds 2.2.1 Ionic Bonds 2.2.2 Covalent Bonds 2.2.3 Hybridisation 2.2.3.1 sp3 Hybridization 2.2.3.2 sp2 Hybridization 2.2.3.3 sp Hybridization 2.3 Representation of a Chemical Reaction 2.4 Mechanism of Organic Reactions 2.4.1 Electron Availability 2.4.1.1 Inductive Effect 2.4.1.2 Electromeric Effect 2.4.1.3 Mesomeric Effect 2.4.1.4 Hyperconjugative Effect 2.4.1.5 Resonance 2.4.2 Breaking and Formation of Bonds 2.4.2.1 Bond Fission 2.4.2.1.1 Homolytic Bond Fission 2.4.2.1.2 Hetrolytic Bond Fission 2.4.2.2 Bond Formation 2.4.3 Reaction Intermediates 2.4.3.1 Carbocations Reactions of Carbocations Generation of Carbocations Reactions Involving Carbocations Friedel-Crafts Reaction Friedel-Crafts Alkylation Friedel-Crafts Acylation Baeyer-Villiger Oxidation Pinacol-Pinacolone Rearrangement Wagner-Meerwein Rearrangement Beckmann Rearrangement 2.4.3.2 Carbanions Structure of Carbanions Generation of Carbanions Reactions of Carbanions Addition Reactions Elimination Reactions Displacement Reactions Rearrangement Reaction Decarboxylation Oxidation of Carbanions Reactions Involving Carbanions Aldol Condensation Acid-Catalysed Aldol Condensation Crossed Aldol Condensation Perkin Reaction Claisen Condensation Dieckmann Condensation Michael Addition 2.4.3.3 Free Radicals Stability of Free Radicals Generation of Free Radicals Photolysis Thermolysis Redox Reactions Reactions of Free Radicals Recombination of Free Radicals Disporportionation Reaction with Olefins Reaction with Iodine and Metals Rearrangements Reactions Involving Free Radicals Sandmeyer reaction Gomberg reaction Wurtz reaction Hunsdiecker reaction Kolbe electrolytic reaction Halogenation Conversion of methane into carbon tetrachloride Conversion of benzene into benzene hexachloride Conversion of toluene into benzyl chloride Conversion of propene into n-propyl bromide Vinyl Polymerisation 2.4.3.4 Carbenes Generation of Carbenes From alkyl halides From Ketenes From Epoxides From diazirines From aliphatic diazo compounds Reactions of Carbenes Addition reactions Insersion into C—H bonds Reaction with hydrazine: Formation of Diazomethane Reaction with primary amines (synthesis of isonitriles) Synthesis of nitriles Reaction with Alcohols Reaction with aldehydes: synthesis of mandelic acids Rearrangements Ring expansion Ring contraction Synthesis of allenes Synthesis of spiro comounds Reactions Involving Carbenes Carbylamine reaction Wolff rearrangement Reimer-Tiemann reaction 2.4.3.5 Nitrenes Generation of Nitrenes From azides From Sulfinylamines From N-benzenesulfonoxy carbamates Reactions of Nitrenes Insersion Dimerisation Abstraction of Hydrogen Reactions Involving Nitrenes Hofmann rearrangement Curtius rearrangement Lossen arrangement 2.4.3.6 Benzyne Generation of Benzynes From aryl halides From o-Aminobenzoic acid From phthaloyl Peroxide From Benzothiazoate 1, 1-dioxide From benzenetrifluoromethane sulfonate Reactions of Benzynes Reaction with nucleophiles Synthesis of t-butyloxyphenol, o-phenyl cyclohexanone and phenyl benzoate Reaction with anthracene, furan and aniline Dimerisation Reaction with olefins 2.5 Types of Reagents Used in a Chemical Reaction 2.5.1 Electrophilic Reagents 2.5.2 Nucleophilic Reagents 2.6 Type of reactions involved in a chemical reaction 2.6.1 Addition Reactions 2.6.1.1 Electrophilic Addition Reactions Electrophilic addition of halogen halides (Hydrohalogenation) Addition of Water (Hydration) Addition of Halogen (Halogenation) Addition of HO–Cl (Formation of Halohydrins) Addition to Conjugated Dienes 2.6.1.2 Free Radical Addition Reactions 2.6.1.3 Concerted Addition Reactions 2.6.1.3.1 Hydroboration 2.6.1.3.2 Diels-Alder Reaction 2.6.1.3.3 Ozonolysis 2.6.1.3.4 Hydroxylation 2.6.1.4 Nucleophilic Additions to Carbonyl Compounds 2.6.1.4.1 Reaction with Hydrogen Cyanide 2.6.1.4.2 Reaction with Sodium Hydrogen Sulphite 2.6.1.4.3 Reaction with Alcohols 2.6.1.4.4 Reaction with Amines 2.6.1.4.5 Reaction with Grignard Reagents 2.6.1.4.6 Wittig Reaction 2.6.1.4.7 Aldol Condensation 2.6.1.4.8 Perkin Condensation 2.6.1.4.9 Claisen Condensation 2.6.1.4.10 Knoevenagel Condensation 2.6.1.4.11 Cannizzaro Reaction 2.6.1.4.12 Michael Addition 2.6.2 Elimination reactions 2.6.2.1 Bimolecular Elimination Reactions (E2) 2.6.2.1.1 Stereochemistry of E2 Reactions 2.6.2.2 Unimolecular Elimination Reaction (E1) 2.6.2.3 E1cB Mechanism 2.6.3 Substitution Reactions 2.6.3.1 Free Radical Substitution Allylic Substitution Vinylic Substitution 2.6.3.2 Ionic Substitution 2.6.3.2.1 Electrophilic Substitution Reactions (SE) 2.6.3.2.1.1 Aromatic Electrophilic Substitution Nitration Halogenation Sulphonation Alkylation and Acylation 2.6.3.2.1.2 Orientation and Reactivity in Aromatic Electrophilic Substitution 2.6.3.2.1.3 Electrophilic Substitution in Heteroaromatic Compounds 2.6.3.2.2 Nucleophilic Substitutions 2.6.3.2.2.1 Bimolecular Nucleophilic Substitutions (SN2) Reactions 2.6.3.2.2.2 Unimolecular Nucleophilic Substitution (SNI) Reactions 2.6.3.2.2.3 Nucleophic Substitutions Involving Neighbouring Group Participation 2.6.3.2.2.4 Nucleophilic Substitution Internal (SNi) 2.6.3.2.2.5 Nucleophilic Substitution on Alcohols–An Indirect Method 2.6.3.2.2.6 Nucleophilic Substitution Reactions in Relatively Non-polar Aprotic Solvents by Phase-Transfer Catalysts 2.6.3.2.2.7 Nucleophilic Aromatic Substitutions 2.6.3.2.2.8 Nucleophilic Heteroaromatic Substitution 2.6.4 Rearrangement reactions 2.6.4.1 Carbon-Carbon Rearrangements Pinacol Rearrangement Benzil Benzilic Acid Rearrangement 2.6.4.2 Carbon-Nitrogen Rearrangements Hofmann Rearrangement 2.6.4.3 Carbon-Oxygen Rearrangements Baeyer-Villiger Oxidation Claisen Rearrangement 2.6.4.4 Isomerisations Conversion of n-propylbromide into isopropyl bromide Conversion of butane to isobutane Conversion of 1,1,1-triphenyl-2-bromoehtane into 1,1,2-triphenylethane Cope Rearrangement Electrolytic Reactions 2.6.5 Photochemical reactions 2.6.5.1 Free Radical Chlorination 2.6.5.2 Photoreductive Dimerisation 2.6.5.3 Photomerisation of cis- and trans-1,2-diphenylethene (Stilbene) 2.6.5.4 Photochemical Cyclo Addition Reactions 2.6.5.5 Photo chemical Erndt-Eistert Synthesis 2.6.5.6 Barton Reaction 2.6.5.7 Photonitrosation 2.6.5.8 Paterno-Bϋchi Reaction 2.6.5.9 Formation of Vitamin D2 from Ergosterol 2.6.6 Oxidations 2.6.6.1 Oxidation of Hydrocarbons 2.6.6.1.1 Oxidation of Alkanes 2.6.6.1.2 Oxidation of Alkenes 2.6.6.1.3 Oxidation of Alkynes 2.6.6.1.4 Oxidation of Aromatic Hydrocarbons 2.6.6.2 Oxidation of Alcohols Oxidation of primary alcohols Oxidation of secondary alcohols 2.6.6.3 Oxidation of Phenols 2.6.6.4 Oxidation of Aldehydes 2.6.6.5 Oxidation of Ketones 2.6.6.6 Oxidation of Amines 2.6.7 Reductions 2.6.7.1 Reduction of Unsaturated Compounds 2.6.7.1.1 Reduction of Alkenes 2.6.7.1.2 Reduction of Alkynes 2.6.7.1.3 Reduction of Aromatic Hydrocarbons 2.6.7.2 Reduction of Alcohols and Phenols 2.6.7.3 Reduction of Aldehydes and Ketones 2.6.7.3.1 Reduction to Alcohols 2.6.7.3.2 Reduction of Aldehydes and Ketones to Hydrocarbons Clemmensens Reduction Wolff-Kishner Reaction 2.6.7.3.3 Reduction of Carboxylic Acids and its Derivatives Reduction of carboxylic acids to aldehydes Reduction of Carboxylic acids to alcohols Reduction of Derivatives of Carboxylic Acids 2.6.7.3.4 Reduction of Cyanides 2.6.7.3.5 Reduction of Aromatic Nitro Compounds Multiple Choice Questions Fill in the Blanks Short Answer Questions Index