Contents 15-9 Electronic Configurations of the allyl radical.cation.and Anion 680 15-10 Sx2 Displacement Reactions of Allylic Halides and Tosylates 681 15-11 The Diels-Alder Reaction 682 Key Mechanism:The Diels-Alder Reacticn 682 15-12 The Diels-Alder as an Example of a Pericyclic Reaction 691 15-13 Ultraviolet Absorption Spectroscopy 694 Chapter 15 Glossary 701 Study Problems 703 16 AROMATIC COMPOUNDS 707 16-1 Introduction:The Discovery of Benzene 707 16-2 The Structure and Properties of Benzene 707 16-3 The Molecular Orbitals of Benzene 711 16-4 The Molecular Orbital Picture of Cyclobutadiene 714 16-5 Aromatic.Antiaromatic,and Nonaromatie Compounds 716 16-6 Htickel's Rule 716 Molecular Orbital Derivation of Huckel's Rule 718 16-9 Aromatic Tons 719 Aromatic Compounds 72 f 16-1 Fused He 16.13 s734 16-14 Physical Pro ies of ber e and Its De ivatives 736 16-15 Spe d73 Chapter 16 Glossary 740 Study Problems 742 17 REACTIONS OF AROMATIC COMPOUNDS 75 17- Aromat Nitration of Be n of Benzene 757 17-5 Nitration of Toluene:The Effect of Alkyl Substitution759 17-6 Activating.Ortho.Para-Directing Substituents 761 Summary:Activating,Ortho.Para-Directors 764 17-7 Deactivating.Meta-Directing Substituents 765 Summary:Deactivating.Meta-Directors 768 17-8 Halogen Substituents:Deactivating.but Ortho.Para-Directing 768 Summary:Directing Effects of Substituents 770 179 Effects of Multiple Substi uents on Electrophilic 17-10 The EriedeL-Cr 17-11 The Friedel-Crafts Acy 777 son of Friedel-Crafts Alkylation and Aeylation 780 17-12 Nucleophilic Aromatic Substitution 78215-9 Electronic Configurations of the Allyl Radical, Cation, and Anion 680 15-10 SN2 Displacement Reactions of Allylic Halides and Tosylates 681 15-11 The Diels-Alder Reaction 682 Key Mechanism: The Diels-Aider Reaction 682 15-12 The Diels-Alder as an Example of a Pericyclic Reaction 691 15-13 Ultraviolet Absorption Spectroscopy 694 Chapter 15 Glossary 701 Study Problems 703 16 AROMATIC COMPOUNDS 707 16-1 Introduction: The Discovery of Benzene 707 16-2 The Structure and Properties of Benzene 707 16-3 The Molecular Orbitals of Benzene 711 16-4 The Molecular Orbital Picture of Cyclobutadiene 714 16-5 Aromatic, Antiaromatic, and Nonaromatic Compounds 716 16-6 Htickel's Rule 716 16-7 Molecular Orbital Derivation of Htickel's Rule 718 16-8 Aromatic Ions 719 16-9 Heterocyclic Aromatic Compounds 725 16-10 Polynuclear Aromatic Hydrocarbons 729 16-11 Aromatic Allotropes of Carbon 731 16-12 Fused Heterocyclic Compounds 733 16-13 Nomenclature of Benzene Derivatives 734 16-14 Physical Properties of Benzene and Its Derivatives 736 16-15 Spectroscopy of Aromatic Compounds 737 Chapter 16 Glossary 740 Study Problems 742 17 REACTIONS OF AROMATIC COMPOUNDS 751 17-1 Electrophilic Aromatic Substitution 751 Key Mechanism: Electrophilic Aromatic Substitution 752 17-2 Halogenation of Benzene 753 17-3 Nitration of Benzene 755 17-4 Sulfonation of Benzene 757 17-5 Nitration of Toluene: The Effect of Alkyl Substitution 759 17-6 Activating, Ortho, Para-Directing Substituents 761 Summary: Activating, Ortho, Para-Directors 764 17-7 Deactivating, Meta-Directing Substituents 765 Summary: Deactivating, Meta-Directors 768 17-8 Halogen Substituents: Deactivating, but Ortho, Para-Directing 768 Summary: Directing Effects of Substituents 770 17-9 Effects of Multiple Substituents on Electrophilic Aromatic Substitution 770 17-10 The Friedel-Crafts Alkylation 773 17-11 The Friedel-Crafts Acylation 777 Summary: Comparison of Friedel-Crafts Alkylation and Acylation 780 17-12 Nucleophilic Aromatic Substitution 782 Contents xiii