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

Hydrogen peroxide (H2O2) 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 H2O2 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 [CH3(n-C8H17)(3)N][H2PO4] and [Et3NH][H2PO4] with Na2WO4 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 H2O2 and 0.5 M K2SO4 in pH 5 water, with no added cosolvent. Results were validated with authentic electrochemically produced H2O2, demonstrating the practical applicability of this approach.