| Abstract |
The cis-dioxidomolybdenum(VI) complexes [MoO2(L-1)] (1), [MoO2(L-2)]center dot MeOH (2) and [MoO2(L-3)] (3) were prepared by reaction of [MoO2 (acac)(2)] with the corresponding aroylhydrazone Schiff base H2L1 = 2,3-dihydroxybenzylidene-2-hydroxybenzohydrazide, H3L2 = 2,3-dihydroxybenzylidene- benzohydrazide and H2L3 = (3,5-di-tert-butyl-2-hydroxybenzylidene)-2-hydroxybenzohydrazide, respectively. The catalytic activities of these complexes towards cyclohexane (CyH) oxidation were examined and compared in CH3CN, ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF6]), supercritical carbon dioxide (SC-CO2), and SC-CO2/[bmim][PF6] mixed solvent. The yields in the ionic liquid (IL) are always higher than in CH3CN. A very high selectivity towards cyclohexanol is obtained in the SC-CO2 medium with all three complexes. The catalyst can be recycled with full preservation (3 cycles) of its activity in the SC-CO(2 )and SC-CO2/IL media. (C) 2017 Published by Elsevier B.V. |
