Organlc Chemlstry FrFTH EDrrloN Marc Loudon Purdue University ROBERTS AND COMPANY PUBLISHERS Greenwood Village Colorado r Contents Preface Reviewers and Consultants About the Author 1 CHEMIGAT BONDING AND CHEMIGAT STRUGTURE 1 1 1 2 1 3 lntroduction xxxl xxxvi xxxix 1 1 A What Is Organic Chemistry B Emergence of Organic Chemistry C Why Study Organic Chemistry 2 Classical Theories of Chemical Bonding 3 A Electrons in Atoms B The Ionic Bond 3 C The Covalent Bond D The Polar Covalent Bond 5 Structures of Covalent Gompounds A Methods for Determining Molecular Geometry B Prediction of Molecular Geometry 1 1 3 9 13 13 I4 1 4 Resonance Structures 20 1 5 Wave Nature of the Electron 22 Electronic structure of the Hydrogen Atom 23 1 6 A Orbitals Quantum Numbers and Energy B Spatial Characteristics of Orbitals C Summary Atomic Orbitals of Hydrogen 23 25 28 1 7 Electronic Structures of More Complex Atoms 29 1 8 Another took at the Covalent Bond Molecular Orbitals 32 A Molecular Orbital Theory B Molecular Orbital Theory and the Lewis Structure of H 32 36 1 9 Hybrid Orbitals 37 A Bonding in Methane B Bonding in Ammonia 40 37 vii viii coNrENrs Key ldeas in Chapter Additional Problems 2 1 ALKANES 43 46 2 1 Hydrocarbons 2 2 Unbranched Alkanes 2 3 conformations of Alkanes 46 A Conformation of Ethane B Conformations of Butane 50 Gonstitutional lsomers and Nomenclature 57 A Isomers B Organic Nomenclature 57 58 59 2 4 C Substitutive Nomenclature of Alkanes D Highly Condensed Structures E Classification of Carbon Substitution 2 5 Cycloalkanes and skeletal structures 2 6 Physical Properties of Alkanes 50 53 64 66 67 70 70 C Other Physical Properties 74 A Functional Groups and Compound Classes B R Notation Key ldeas in Chapter 2 Additional Problems ACIDS AND BASES THE CURVED ARROW NOTATION 3 1 48 A Boiling Points B Melting Points 2 7 Gombustion 2 8 occurrence and use of Alkanes 2 9 Functional Groups Gompound Classes and the R Notation 3 42 Lewis Acid Base Association Reactions A Electron Deficient Compounds B Reactions of Electron Deficient Compounds with Lewis Bases C The Curved Arrow Notation for Lewis Acid Base Association and Dissociation Reactions 73 76 78 81 81 82 83 83 87 87 87 88 89 CONTENTS iX 3 2 Electron pair oisplacement Reactions 90 B The Curved Arrow Notation for Electron Pair Displacement Reactions 91 3 3 Review of the Curued Arrow Notation A Use of the Curved Arrow Notation to Represent Reactions B Use of the Curved Arrow Notation to Derive Resonance Structures 3 4 Bronsted Lowry Acids and Bases A Definition of Brgnsted Acids and Bases B Nucleophiles Electrophiles and Leaving Groups C Strengths of Brpnsted Acids D Strengths of Brgnsted Bases E Equilibria in Acid Base Reactions 3 5 Free Energy and Chemical Equilibrium 3 6 Relationship of Structure to Acidity A The Element Effect B The Charge Effect C The Polar Effect Key ldeas in Chapter 3 Additional Problems 4 90 A Donation of Electrons to Atoms That Are Not Electron Deficient INTRODUGTION TO AIKENES STRUCTURE AND REACTIVITY 4 1 Structure and Bonding in Rfkenes 94 94 94 95 96 98 101 103 104 106 108 108 110 lll 116 117 122 122 A Carbon Hybridization in Alkenes B The n Pi Bond r23 r25 C Double Bond Stereoisomers 128 4 2 Nomenclature of Alkenes A IUPAC Substitutive Nomenclature B Nomenclature of Double Bond Stereoisomers The E Z Svstem 4 3 Unsaturation Humber 4 4 Phy ical Propefties of Alkenes 4 5 Relative tabilities of Allcene lsomers A Heats of Formation B Relative Stabilities of Alkene Isomers 4 5 Additisn Reactions of Alkenes 4 7 Addition of Hydrcgen Halides to nlilrenas A Regioselectivity of Hydrogen Halide Addition B Carbocation Intermediates in Hydrogen Halide Addition 131 131 t34 139 140 141 I4I r44 147 147 148 r49 CONTENTS C Structure and Stability of Carbocations D Carbocation Rearrangement in Hydrogen Halide Addition 4 8 158 160 r62 r64 D Hammond s Postulate 166 catalysis 168 A Catalytic Hydrogenation of Alkenes B Hydration of Alkenes C Enzyme Catalysis r69 172 172 174 Key ldeas in Chapter 4 Additional Problems 5 r54 157 Reaction Rates A The Transition State B The Energy Barrier C Multistep Reactions and the Rate Limiting Step 4 9 151 178 ADDITION REACTIONS OF ALKENES 5 1 An Overuiew of Electrophilic Addition Reactions 5 2 Reactions of Alkenes with Halogens 178 181 A Addition of Chlorine and Bromine B Halohydrins 181 183 5 3 writing organic Reactions 186 5 4 Gonverion of Alkenes into Alcohols 187 A Oxymercuration Reduction of Alkenes B Hydroboration Oxidation of Alkenes C Comparison of Methods for the Synthesis of Alcohols from Alkenes r87 190 194 5 5 Ozonolysis of Alkenes 196 5 6 Free Radical Addition of Hydrogen Bromide to Rlkenes 200 A The Peroxide Effect B Free Radicals and the Fishhook Notation 200 C Free Radical Chain Reactions D Explanation of the Peroxide Effect E Bond Dissociation Energies 202 5 7 Polymeni Free Radical Polymerization 5 8 Alkenes in the Ghemical lndustry Key ldeas in Chapter 5 Additional Problems 20r 207 zrl of Alkenes 214 216 219 220 CONTENTS 6 PRINCIPLES OF STEREOCHEMISTRY 226 6 1 Enantiomelri Chirality and Symmetry 226 A Enantiomers and Chirality B Asymmetric Carbon and Stereocenters C Chirality and Symmetry 226 229 229 6 2 Nomenclature of Enantiomers The R S System 6 3 Physical Properties of Enantiomers Optical Activity A Polarized Light B Optical Activity C Optical Activities of Enantiomers 6 4 Racemates 5 5 Stereochemical Correlation 6 6 Diastereomers 6 7 Meso Compounds 6 8 Enantiomeric Resolution 6 9 Ghiral Molecules without Asymmetric 6 10 6 17 6 12 231 234 235 235 238 239 241 242 246 249 Atoms Conformational Stereoisomers A Stereoisomers Interconvefied by Internal Rotations B Asymmetric Nitrogen Amine Inversion 7 xl 251 253 253 255 Drawing Structures That Contain Three Dimensional lnformation 257 The Postulation of Tetrahedral Carbon 2s9 Key ldeas in Chapter 6 Additional Problems 263 253 cYcHc coMPouNDs STEREOCHEMISTRY OF REACTIONS 7 1 Relative Stabilities of the Monocyclic Alkanes 7 2 Conformations of Gyclohexane 268 268 269 A The Chair Conformation B Interconversion of Chair Conformations 273 C Boat and Twist Boat Conformations 274 269 xtl CONTENTS 7 3 Monosubstituted Gyclohexalres Gonformational Rnalysis 7 4 Disu 7 5 bstituted Gyclohexanes 281 A Cis Trans Isomerism in Disubstituted Cyclohexanes B Conformational Analysis C Use of Planar Structures for Cyclic Compounds 281 D Stereochemical Consequences of the Chair Interconversion 285 Gyclopentar Gyclobutane and Gyclopropane 288 283 284 A