Friedel-Crafts alkylation

Schematic of the Friedel-Crafts alkylation. Reagents: aromatic compound, alkyl halide, Lewis acid catalyst, AlCl3. Product: substituted aromatic compound.

The Friedel-Crafts alkylation is an organic reaction used to convert an aryl compound and an alkyl halide to a substituted aromatic compound using a Lewis acid catalyst (such as AlCl3). The reaction begins with the Lewis acid abstracting the halide from the alkyl halide to form an electrophilic alkyl cation and a tetrasubstituted aluminum anion. The aromatic compound then attacks the alkyl cation via an electrophilic aromatic substitution (SEAr) to give a cationic product with loss of aromaticity. Deprotonation with the aluminum anion results in the final aromatic product and regeneration of the Lewis acid catalyst.[1]


Mechanism of the Friedel-Crafts alkylation.


Crafts, J. M.; Friedel, C. J. Chem. Soc. 1877, 32, 725–725.

Other Alkylation Reactions: