| Abstract |
The effect of microwave and mechanochemical ball milling energy inputs was studied for the peroxidative oxidation (with aqueous H2O2) of cyclohexane to cyclohexanol and cyclohexanone, over CoCl2 and/or V2O5 dispersed (m scale) catalysts. A maximum total yield of cyclohexanol and cyclohexanone of 43\% after 1 h of reaction at 30 degrees C, in acetonitrile and under microwave irradiation (5 W), was achieved over the CoCl2-V2O5 (3:1) catalyst prepared by ball milling. Cyclohexanol is the main final product with a selectivity of up to 93\% over cyclohexanone. Conducting the oxidation reaction under microwave irradiation under the same conditions but without any mechanochemical treatment of the catalyst prior to use resulted in a lower total yield of 30\% with a lower selectivity (69\%) towards cyclohexanol over cyclohexanone. The sole application of mechanochemical treatment for the catalyst preparation and the catalytic oxidation of cyclohexane allowed to reach yields of 29\% after 1 h of reaction, at room temperature, without microwave irradiation and any additive and in the absence of any organic solvent. Ball milling is shown to provide a convenient, solvent-free method to disperse these solid catalysts and to promote the above cyclohexane oxidation, although, in the latter case, not so effectively as microwave irradiation. |
