Because of the low reactivity of the aromatic π bond nucleophile, however, the acyl chloride electrophile in a Friedel-Crafts acylation must be further activated with a Lewis acid reagent such as alum...Because of the low reactivity of the aromatic π bond nucleophile, however, the acyl chloride electrophile in a Friedel-Crafts acylation must be further activated with a Lewis acid reagent such as aluminum trichloride, which again serves to polarize the carbon-chlorine bond and increase the electrophilicity of the acyl carbon.
