Microwave-promoted mono-N-alkylation of aromatic amines in water: a new efficient and green method for an old and problematic reaction

A greener improvement to direct mono-N-alkylation of aromatic amines by alkyl halides was achieved using microwave irradiation in water without any catalyst. The reaction was carried out in water at 150 °C with twice the amount of the appropriate alkyl halide and without any catalyst. This synthetic procedure works very well with a variety of arylamines and in a satisfactory way also with deactivated amines; it allows only mono-N-alkylated products to be obtained and it is chemoselective in the presence of more than one functional group. The reaction is efficient, rapid and clean. The described method could be a useful synthetic way to achieve alkylarylamines avoiding the use of organic solvents and catalysts or additives.