Potassium permanganate absorbed on copper(II) sulfate pentahydrate oxidizes aniline into azobenzene under heterogenous conditions. Azoxybenzene is a minor by-product. Under solventless reaction conditions, the oxidation does not take place owing to predominant complex formation between copper(II) and aniline. The influence of the nature of the solvent as well as the replacement of copper(II) sulfate pentahydrate by several other inorganic salt hydrates on the potassium permanganate promoted oxidation of aniline is described.
