Reactions of Aromatic Compounds

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Friedel-Crafts Alkylation Discovered in 1877 by French chemist Charles Friedel and his American collaborator James Crafts, this alkylation reaction (one introducing an alkyl group) and the related acylation reaction (one introducing an acyl group) are among the most useful synthetic reactions. Alkylation of an Arene + R-X AlCl 3 Alkyl halide Alkylbenzene R + HX This reaction requires a Lewis acid catalyst, typically aluminum chloride, AlCl 3. Many variations of the Friedel-Crafts alkylation reaction have been developed. All proceed by similar mechanisms.
A Mechanism for the Alkylation Reaction The Lewis acid catalysts generally required in Friedel-Crafts reactions promote formation of strong electrophiles. (1) Generation of the Electrophile R-Cl: : : Lewis base + AlCl 3 Lewis acid + R-Cl-AlCl 3 : : - Complex With 1 o halides, the complex itself, acting as an R + transfer agent, reacts with the arene. With 2 o and 3 o alkyl halides, dissociation to carbocation intermediates seems to occur, and the resulting R + species react with the arene. + R-Cl-AlCl 3 : : - R + + AlCl - 4
Page 1 and 2: Chapter 15 Reactions of Aromatic Co
Page 3 and 4: Examples of Electrophilic Aromatic
Page 5 and 6: Step 2: Deprotonation of the Areniu
Page 7 and 8: Halogenation of Benzene Halogenatio
Page 9 and 10: Mechanism: Step 1: Electrophilic At
Page 11 and 12: Iodination of Benzene Direct iodina
Page 13 and 14: Mechanism of Nitration (1) Generati
Page 15 and 16: Sulfonation of Benzene Benzene reac
Page 17: (4) Acid-Base Equilibrium :O: S O:
Page 21 and 22: Evidence for Carbocation Intermedia
Page 23: 2) Alcohols alkylate arenes in the

Reactions of Aromatic Compounds

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