Organic reactions in ionic liquids: A simple highly regioselective or regiospecific substitutions of benzotriazole

In the absence of any added base in ionic liquids [Bmim][BF₄], benzotriazole replaces the halogen atom of an α-halogenated ketone or α-halogenated carboxylic ester to give the corresponding N-1-substituted benzotriazole as the only isomer, and 1-chloro-2,4-dinitrobenzene reacted similarly with benzotriazole to afford the N-1-substituted benzotriazole in a good yield. Alkyl halides reacted regioselectively to afford the N-1-alkylbenzotriazole in ratios of more than 15 to 1 over the N-2-isomer.