Concurrent chlorination and carboxylation of aromatic hydrocarbons with thallium(III) chloride tetrahydrate in carbon tetrachloride

Abstract

In contrast to aromatic bromination with TlBr₃·4H₂O, the reaction of lower aromatic hydrocarbons (C₆–C₈) with molten TlCl₃·4H₂O in boiling carbon tetrachloride afforded the corresponding benzoic acids together with the expected chlorinated aromatic compounds. At lower temperatures, carboxylation was considerably favoured. Possible mechanisms for chlorination and carboxylation have been discussed.