The Art of Problem Solving in Organic ChemistryThe new edition of the classic textbook that has helped thousands of students understand and solve the complex mechanistic problems posed by organic reactions
The Art of Problem Solving in Organic Chemistry is a must-have workbook for students and professionals alike, offering step-by-step guidance on applying proven strategies and logical techniques to solve complex reaction mechanism problems. The book is organized in two sections: The Toolbox and the Problem Chest. The first part is presented in four chapters covering advanced contemporary issues of molecular structure and orbital configuration, stereoelectronic constraints, electron shifts, redeployment and arrow-pushing allowances and pitfalls, as well as functional groups roles and key intermediate species, all of which dominate the reaction mechanism scenario. These concepts are rounded up by a series of time-tested problem analysis strategies and thinking routes shown in flowcharts and illustrated by application to specific cases. The Problem Chest puts together a set of 50 newly selected fully discussed mechanism problems of increasing difficulty, in which all the power of the Toolbox paraphernalia is put to work.
Now in its third edition,The Art of Problem Solving in Organic Chemistry retains the structure of previous editions, previously rated among the 30 best organic chemistry books of all time by BookAuthority. More than 50 revised organic reaction mechanism problems are complemented by an entirely new set of problems, additional concepts and techniques, expanded coverage of applications in contemporary organic chemistry, embedded cases of the existing reaction pool taken from recent literature, and much more.
Describes the principles, methods, tools, and problem analysis techniques required to solve organic reaction problemsExtends the logic and strategy of the mechanistic approach beyond specific reactions and factsDiscusses practical methods for improved problem solving for organic reaction mechanismsExplains tested strategies for analyzing the possibilities of reaction mechanisms between reactants and productsContains detailed appendices with definitions and examples of principles, reactions, mechanisms, and reagents
The Art of Problem Solving in Organic Chemistry, Third Edition is an essential volume for advanced undergraduates, graduate students, lecturers, and professionals looking to improve their performance in finding solutions to organic reaction problems. It is an ideal textbook for courses on organic reactions and problem analysis, as well as an excellent supplement for courses covering reactive intermediates and mechanisms of molecular transformations.
Preface ix
Acknowledgements xiii
Where Does This Book Level Start How Far Does It Take You? xv
Part I The Toolbox 1
1 Introduction to Problem Analysis in Advanced Organic Reaction Mechanism 3
1.1 Overview 3
1.2 The First Three Steps in Problem Analysis 4
1.2.1 A Birds Eye Overview 4
1.2.2 Change the Molecular Rendering to a Familiar Framework 4
1.2.3 Go for the Relevant, Skip the Superficial Information 5
1.3 Moving Beyond the Primary Answers 7
1.4 Drawing a Preliminary Outline for Guidance 7
1.5 Intuition and Problem Solving 8
1.6 Summing Up 9
1.7 Solution to the 14 16 Conversion in Scheme I.5 10
References and Notes 10
2 Electron Flow in Organic Reactions 11
2.1 Overview 11
2.2 Introduction 12
2.2.1 A Word or Two on Notation 13
2.2.1.1 Lewis Notation and Line Renderings 13
2.2.1.2 Curved or Curly Arrows 14
2.3 Electrons in Covalent Bonding and Redeployment 14
2.3.1 A Preliminary Review of the Essentials 14
2.3.1.1 Electrons and Covalent Bonds: The Still Unsolved Fundamental Questions 14
2.4 Practical Rules Governing Electron Redeployment 15
2.4.1 Issue 1: Electrons Reside Within Orbitals 15
2.4.1.1 The Question of Orbital Restrictions and Electron Deployment 15
2.4.2 Issue 2: The Electron Shield Concept Contributes to Covalent Bonds 18
2.4.2.1 Carbocations 18
2.4.2.2 Carbon Dications 20
2.4.3 Issue 3: AO/MO Overlap is a Requirement for and Bond Formation 21
2.4.3.1 AO/MO Limits and the Quantum Tunneling Effect 26
2.4.4 Issue 4: Electron Traffic and Stereochemistry 27
2.4.5 Issue 5: Electron Energy Level and Accessibility 28
2.4.6 Issue 6: Electron Flow and Molecular Active Sectors 30
2.4.7 Issue 7: Electron Flow and Compatible AO Types 32
2.4.7.1 Interactions 33
2.4.7.2 Interactions 35
2.4.7.3 Interactions 41
2.4.8 Issue 8: Electron Flow, Delocalization of Bonding and Non-bonding Electrons, Resonance Stabilization 44
2.4.8.1 Non-bonding Electron Pairs (NBPs) 44
2.4.9 Issue 9: Electron Traffic and Electronic Density Differences 49
2.4.9.1 Detecting Potential Donors and Acceptors 49
2.4.9.2 What Makes a Given Functional Group a Natural HEDZ or LEDZ? 50
2.4.9.3 A Reminder Takeaway 51
2.4.9.4 Quantum-mechanical Computations and Mechanism 53
2.4.10 Issue 10: Electron Traffic on Account of LEDZ Alone 54
2.4.10.1 Hidden LEDZs Triggering Deep-rooted Skeletal Rearrangements 56
2.4.10.2 Remote CH Activation by LEDZ and Radicals 56
2.4.11 Issue 11: Inverting the Natural Electron Flow, Umpolung 59
2.4.11.1 Umpolung Successful Accomplishments 60
2.4.11.2 The Nitrogen Heterocycle Carbenes (NHC) in Carbonyl Umpolung 62
2.4.11.3 Umpolung of C=O through Imine Derivatives 63
2.4.11.4 The Hydrazone Way to C=O Umpolung 69
2.4.12 Issue 12: One-electron Flow 71
2.4.12.1 Radicals, Reminder Takeaways 71
2.4.12.2 Carbenes, Overview, and Electron Redeployment 76
2.5 Summing Up 84
2.6 Organized Problem Analysis with the Tools Described so Far 85
2.7 Supplementary Schemes: Solutions to Problems Embedded in this Chapter 86
Notes 89
3 Stereochemistry and Mechanism of Molecular Transformations 93
3.1 Overview 93
3.2 Introduction 94
3.2.1 The Question of Planar Molecules and Deviations, an Approach to Steric Effects 94
3.2.1.1 Planar 2D versus 3D 94
3.2.1.2 Perturbation of Planarity by Substituents; Approaching Steric Effects 97
3.2.1.3 Interaction of Distant C=C Bonds by Stereochemical Proximity 100
3.3 Measuring Steric Hindrance 102
3.3.1 The Roadblocks Ahead 102
3.3.2 Steric Requisites for Building Bonds 102
3.3.3 Reaction Rate Retardation Due to Steric Hindrance 103
3.3.4 The Saga of Purely Steric Effects 103
3.3.4.1 Study Case 1: Substitution (S N 2) of Alkyl Bromides by Sodium Methoxide 105
3.3.4.2 Study Case 2: Hydrolysis of Esters and Esterification of Carboxylic Acids 107
3.3.4.3 Study Case 3: Connollys Molecular Volume 109
3.3.4.4 Study Case 4: The Anilines Arylsulfonyl Chloride Model 113
3.3.4.5 Study Case 5: Other Sources of Evidence 115
3.3.5 Steric Acceleration of Reaction Rates 121
3.3.5.1 Steric Acceleration in SN1/E1 Competition during Solvolysis 121
3.3.5.2 Steric Acceleration in the Gas Phase 124
3.3.6 Summary of Steric Hindrance and Reactivity Takeaways 125
3.4 Applications to Stereochemically Competent Reaction Mechanisms 127
3.4.1 A Case of Regio and Stereoselective Reaction in a Sterically Simple Compound 127
3.4.2 The Role of Steric Umbrellas 129
3.5 Stereochemistry in Bimolecular Reactions: Cycloadditions 131
3.5.1 The DielsAlder Cycloaddition: the CA Prototype 132
3.5.1.1 DACA Steric Domain: Essential Takeaways 133
3.5.1.2 DACA Stereoelectronic Domain: Essential Takeaways 134
3.5.1.3 Assessing Steric Effects (SEs) through Products Configuration: the Endo Alders Rule 134
3.5.1.4 The Exo : Endo Ratio and Lewis-acid Catalysis 137
3.5.1.5 Current and Future Prospects for DACA and Other Cycloadditions 138
3.6 The Ultimate Stereo- and Enantio-Control: Oriented External Electric Fields (OEEFS) 139
3.6.1 How OEEF Works 140
3.6.2 OEEF and DACA Stereocontrol 140
3.6.3 The Experimental Array 140
3.7 Summing Up 144
3.8 Supplementary Schemes 145
Notes 146
References 146
4 Additional Techniques to Postulate Organic Reaction Mechanisms 149
4.1 Overview 149
4.2 Take Your Time 150
4.3 Use Clear and Informative Molecular Renderings 150
4.4 Element and Bond Budgets 150
4.5 Looking at Molecules From Different Perspectives 152
4.6 Redraw Reactants Such That They Resemble Products 155
4.7 Fragmentation Analysis (Fa): Dissecting Products in Terms of Reactants 157
4.7.1 The Fundamental Proposition 157
4.7.2 Study Case 1 157
4.7.3 Study Case 2 158
4.7.4 Learning Lessons and Takeaways from FA 161
4.8 Oxidation Levels and Mechanism 163
4.9 The Functionality Number (FN) 164
4.9.1 What Exactly is FN? 164
4.9.2 Organizing Carbon Functionalities in FN Groups 164
4.9.3 Main FN Groups Properties 164
4.9.4 Study Case 1 166
4.9.5 Study Case 2 166
4.9.6 Study Case 3: Heterolytic CC Cleavage and the Electron Sink 166
4.10 Combining Fragmentation Analysis and Functionality Numbers 169
4.11 A Flowchart to Orderly Exploit the Strategies of this Chapter 170
4.12 Summing Up 171
4.13 Supplementary Reaction Schemes 171
4.14 Solution to Problems Embedded in this Chapter 172
References 172
Part II The Problem Chest 173
Subject Index 389
Graphical Index 391
