 Friedel-Crafts reaction

A Friedel-Crafts reaction introduces an alkyl or acyl group onto an aromatic ring by electrophilic aromatic substitution, commonly with activation by a Lewis acid. Alkylation and acylation are related reaction families but have different intermediate chemistry.

An alkylation pathway can involve carbocation-like rearrangements and can promote repeated substitution. An acylation transfers an acyl group through an activated electrophile, often described using an acylium ion, and its carbonyl substituent generally deactivates the product toward further substitution. These differences explain why the two variants are not interchangeable methods of adding a carbon substituent.