Biphasic Selective Oxidation of Cyclohexene with Dilute Aqueous Hydrogen Peroxide Using Phase Transfer Catalysts

Abstract

Hydrogen peroxide (H 2 O 2 ) can be produced electrochemically as a replacement for conventional anthraquinone oxidation routes. From a sustainability perspective, it would be best to use it in chemical applications without further purification or added cosolvents. Here, cyclohexene oxidation is carried out with dilute (0.08−0.25 M) aqueous H 2 O 2 containing sulfate salts as a probe of the direct use of electrochemically produced oxidants. As catalysts, tungsten and molybdenum salts were combined with ammonium and imidazolium phase transfer agents. A mixture of [CH 3 (n-C 8 H 17 ) 3 N][H 2 PO 4 ] and [Et 3 NH][H 2 PO 4 ] with Na 2 WO 4 resulted in 95% overall yield of cyclohexene oxidation products� cyclohexene oxide (80%) and cyclohexene-1,2-diol (15%)�using a solution of 0.25 M H 2 O 2 and 0.5 M K 2 SO 4 in pH 5 water, with no added cosolvent. Results were validated with authentic electrochemically produced H 2 O 2 , demonstrating the practical applicability of this approach.