Comparison of microwave and mechanochemical energy inputs in the catalytic oxidation of cyclohexane. Issue 25 (6th June 2018)

• Record Type: Journal Article
• Authors: Ribeiro, Ana P. C.; Alegria, Elisabete C. B. A.; Kopylovich, Maximilian N.; Ferraria, Ana M.; Botelho do Rego, Ana M.; Pombeiro, Armando J. L.
• Is Part Of: Dalton transactions. Volume 47:Issue 25(2018)
• Page Start: 8193
• Page End: 8198
• Publication Date: 2018-06-06
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c8dt00866c
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : The effect of microwave and mechanochemical ball milling energy inputs was studied for the peroxidative oxidation of cyclohexane, over CoCl2 and/or V2 O5 dispersed (μm scale) catalysts. Abstract : The effect of microwave and mechanochemical ball milling energy inputs was studied for the peroxidative oxidation (with aqueous H2 O2 ) of cyclohexane to cyclohexanol and cyclohexanone, over CoCl2 and/or V2 O5 dispersed (μm scale) catalysts. A maximum total yield of cyclohexanol and cyclohexanone of 43% after 1 h of reaction at 30 °C, in acetonitrile and under microwave irradiation (5 W), was achieved over the CoCl2 –V2 O5 (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.