A facile method for promoting activities of vanadium-schiftbase complex anchored on organically modified MCM-41 in epoxidation reaction

Abstract

An organic-inorganic hybrid heterogeneous catalyst (V-MCM-41) was synthesized by anchoring vanadium-schiffbase complex on chloropropyl modified mesoporous silica (CP-MCM-41). Characterization of the functionalized ordered two-dimensional mesoporous material by powder X-ray diffraction (XRD), N(2) adsorption-desorption, CP-MAS NMR spectroscopy ((13)C and (29)Si), Fourier transform infrared spectroscopy (FT-IR), diffuse-reflectance UV-vis spectroscopy, demonstrate the successful grafting of vanadium complex into the functionalized mesoporous silica. It is also observed that the mesostructure has not been destroyed in multistep synthetic procedure. We have performed the epoxidation reaction of various olefins using V-MCM-41 as the catalyst, hydrogen peroxide as the oxidant and sodium bicarbonate as the co-catalyst in acetonitrile solvent. The co-catalyst enhances the rate of reaction by many folds. The reaction requires minimum amount of H(2)O(2), short time period and most importantly occurs at room temperature. The heterogeneous catalyst can be recovered easily and reused many times without significant loss in catalytic activity and selectivity. (C) 2010 Elsevier B.V. All rights reserved.