Electrophilic Aromatic Substitution - Illustrative Reactions

Illustrative Reactions

The most widely practiced example of this reaction is the ethylation of benzene.

Approximately 24,700,000 tons were produced in 1999. In this process, solid acids are used as catalyst to generate the incipient carbocation. All other electrophilic reactions of benzene are conducted on much smaller scale, they are valuable routes to key intermediates. The nitration of benzene is achieved via the action of the nitronium ion as the electrophile.

Aromatic sulfonation of benzene with fuming sulfuric acid gives benzenesulfonic acid.

Aromatic halogenation of benzene with bromine, chlorine or iodine gives the corresponding aryl halogen compounds catalyzed by the corresponding iron trihalide.

The Friedel-Crafts reaction can be performed either as an acylation or as an alkylation. Typically aluminium trichloride is used, but almost any strong Lewis acid can be successful. For the acylation reaction a stoichiometric amount of aluminum trichloride must be used instead of simply a catalytic amount.