Switchable Selectivity during Oxidation of Anilines in a Ball Mill

A solvent free method for the direct oxidation of anilines to the corresponding azo and azoxy homocoupling products by using a planetary ball mill was developed Various oxidants and grinding auxiliaries were tested and a variety of substituted anilines were investigated It was possible to form chemoselectively either azo, azoxy, or the nitro compounds from re action of aromatic anilines The selectivity of the solvent-free reaction is switchable by applying a combination of oxidant and grinding auxiliary Furthermore, a comparison with other methods of energy input (microwave classical heating, and ultrasound) high lighted the advantages of the ball mill approach and its high energy efficiency