Surfactant control of the ortho/para ratio in the bromination of anilines. 3

Article abstract of DOI:10.1016/0040-4020(95)01067-X

We report the bromination of N,N-dimethylaniline in aqueous suspension of cetylpyridinium tribromide, cetylquinuclidinium tribromide, laurylquinuclidinium tribromide, cetyltributylammonium tribromide, cetyldimethyl-2-hydroxyethylammonium tribromide, 1,2-bis(cetyl-N,N-dimethylammonium)ethane tribromide, 1,3-bis(cetyl-N,N-dimethylammonium)propane tribromide, 1,4-bis(cetyl-N,N-dimethylammonium)butane tribromide, (2S,3S)-2,3-dimethoxy-1,4-bis(N-cetyl-N,N-dimethylammonium)butane tribromide. The nature of the head groups of the surfactant, as well as the length of the hydrophobic chain, influence the regioselectivity of the reaction and permits a hypothesis on the structure of the aggregates.