Syntheses of Liquid Crystal Intermediates: 4-Alkylbenzoyl Chlorides

Acylation of seven alkyl- and four halobenzenes with oxalyl chloride-aluminum chloride, to give 4-substituted benzoyl chlorides in one step and free of positional isomers, was studied for variations in reactant ratios, temperatures and times. The addition of one equivalent of arene over sixty minutes to a 2 : 1 ratio of oxalyl chloride to aluminum chloride at 5° gave best results. Evidence was obtained for phosgene as the active reagent. The product acid chlorides are directly useful for and can be converted to a variety of other intermediates for syntheses of liquid crystalline materials.