Epoxidation of methyl oleate with hydrogen peroxide. The use of Ti-containing silica solids as efficient heterogeneous catalysts

Titanium-silica catalysts, obtained by grafting titanocene dichloride onto mesoporous silica (MCM-41 and MCM-48) and onto nanosized pyrogenic silica, were tested in the epoxidation of methyl oleate using aqueous hydrogen peroxide. All titanium-containing materials, combined with the slow addition of hydrogen peroxide, showed good catalytic activity and comparable behaviour in terms of conversion, selectivity and yield of methyl epoxystearate, notwithstanding the morphology and the texture of the silica support. By optimizing the reaction conditions (especially, the catalyst to substrate ratio), high yields up to 91% in epoxide were obtained for Ti/MCM-41 with a high stereoselectivity (80%) for the cis-epoxide. The formation of the cis/trans-epoxide and the nature of the catalytic reaction pathway are also discussed.