Illustrated Glossary of Organic Chemistry

Friedel-Crafts alkylation: An electrophilic aromatic substitution reaction in which a hydrogen atom bonded to an aromatic ring is substituted by an alkyl group. In the traditional version of the reaction, a molecule containing a benzene ring is reacted with an alkyl chloride and AlCl₃ (a Lewis acid) to form an alkylated benzene ring.

In this Friedel-Crafts alkylation reaction, benzene reacts with methyl chloride in the presence of AlCl₃ to form toluene (methylbenzene).