The Friedel-Crafts acylation is an organic reaction used to convert an aryl compound and an acyl halide or anhydride to an aryl ketone using a Lewis acid catalyst (such as AlCl3). The reaction begins with the Lewis acid abstracting the halide (or carboxylate) from the acyl halide (or ester) to form an electrophilic acylium cation and a tetrasubstituted aluminum anion. The aromatic compound then attacks the acylium ion via an electrophilic aromatic substitution (SEAr) to give a cationic product with loss of aromaticity. Deprotonation with the aluminum anion results in the final aryl ketone and regeneration of the Lewis acid catalyst.
Ador, E.; Crafts, J. Ber. Dtsch. Chem. Ges. 1877, 10, 2173–2176.