A new approach to aromatic substitution—para-specific alkylation of acetophenone by alkyl radicals in strongly acidic media

Abstract

Acetophenone in 25% oleum is substituted by various alkyl radicals specifically in the para-position. The radicals used include cyclohexyl, 3-chloro-1-methylpropyl, 3-bromo-1-methylpropyl, 4-chloro-1-methylbutyl, 4-bromo-1-methylbutyl, 5-bromo-1-methylpentyl, 5-acetoxy-1-methylpentyl, 3-carboxy-1-methylpropyl, 4-carboxy-1-methylbutyl and 5-carboxy-1-methylpentyl. They were all generated by hydrogen atom abstraction at the radical position by dimethylaminium radicals, generated in turn from protonated dimethylchloramine and ferrous sulphate. Yields were generally poor to moderate but utilised simple conditions and cheap reagents.