Molybdenum complex-catalysed epoxidation of unsaturated fatty acids by organic hydroperoxides

Abstract

The catalytic activity of the molybdenum catalysts, molybdenum naphthenate, Mo(CO) 6, H 2[Mo 2O 4(ox) 2(H 2O) 2]·4H 2O·Me 2CO, Mo(O) 2(acac) 2, and [Mo(O) 2(SAP)(EtOH)], was investigated in the reaction of oleic acid epoxidation by organic hydroperoxides. A new highly efficient and selective system for the epoxidation of unsaturated aliphatic acids was developed with tert-butyl hydroperoxide ( t-BuOOH) and the [Mo(O) 2(SAP)(EtOH)] complex. The epoxidation reaction of oleic acid shows 86.8% selectivity to 9,10-epoxystearic acid at 67% conversion of t-BuOOH. Routine kinetic measurements were performed to determine the reaction orders with respect to t-BuOOH and the catalyst. They are 1.00±0.05 and 0.51±0.05, respectively. The activation energy and enthalpy, E a=99±4 kJ mol −1 and Δ H=96±4 kJ mol −1, were calculated from the temperature dependences. The results allowed us to propose a reaction mechanism whose outline is consistent with the generally accepted mechanism of the catalytic epoxidation of olefins by organic hydroperoxides.