Microwave- and Ultrasound-Accelerated Green Oxidation of Alcohols by Potassium Permanganate absorbed on Copper(II) Sulfate Pentahydrate

The solvent-free potassium permanganate (KMnO4)–promoted oxidation of alcohols into the corresponding carbonyl derivatives has been examined in detail with respect to the importance of supporting materials and supporting irradiation. Secondary alcohols are oxidized very efficiently to the corresponding ketones at ambient temperature by KMnO4 absorbed on a fourfold molar amount of copper(II) sulfate pentahydrate. The reaction is accelerated considerably by ultrasonic irradiation and drastically by microwave irradiation. Under the latter conditions, also hydroquinone can be converted 100% into p-benzoquinone within 4.5 min. Benzylic alcohols are oxidized most efficiently to the corresponding benzaldehydes under heterogeneous reaction conditions.