Novel Two-Phase Catalysis with Organometallic Compounds for Epoxidation of Vegetable Oils by Hydrogen Peroxide

A series of new organometallic catalysts for epoxidized vegetable oils using H2O2 in a biphasic system were investigated. The effect of reaction parameters such as the amount of hydrogen peroxide, reaction time and temperature in the epoxidation of soybean oil are discussed in detail. A selectivity of 83.8% was obtained in 4 h at 60 A degrees C, when [(C18H37)(2)N(CH3)(2)](3){PO4[WO(O-2)(2)](4)} was used as the catalyst. When methyltrioxorhenium (MTO), imidazole and CH3CN were used as the catalyst, adduct, and solvent respectively, a selectivity of 99.90% was achieved in 4 h at 20 A degrees C. The catalytic system was used for the epoxidation of other oils, whose results showed it was active in the epoxidation of long-chain unsaturated compounds. Furthermore, the reaction of H2O2 with methyltrioxorhenium was studied by UV-Vis spectroscopy, which revealed the active peroxorhenium complexes formed during the reaction. Epoxidation of these oils with organometallic compounds occurred through the interactions between the oils unsaturated sites HOMO pi(C-C) and the unoccupied peroxo sigma*(O-O) orbital.