Oxo-vanadium(IV) Schiff base complex supported on modified MCM-41: a reusable and efficient catalyst for the oxidation of sulfides and oxidative S-S coupling of thiols

Oxo-vanadium(IV) Schiff base complex supported on MCM-41 as an organic-inorganic hybrid heterogeneous catalyst was synthesized with post-grafting of MCM-41 with 3-aminoropropyltrimethoxysilane and subsequent reaction with 3,4-dihydroxybenzaldehyde and then complexation with oxo-vanadium acetylacetonate salt. The catalyst was analysed using a series of characterization techniques such as Fourier transform infrared spectroscopy, small-angle X-ray diffraction, nitrogen absorption isotherm, transmission electron microscopy and thermogravimetric analysis. The data collected provided evidence that the vanadium complex was anchored onto MCM-41. High catalytic activity of this catalyst was observed in the oxidation of various sulfides and thiols (into sulfoxides and disulfides, respectively) with urea hydrogen peroxide as oxidant in high to excellent yields and selectivity under mild conditions. The heterogeneous catalyst could be recovered easily and reused several times without significant loss in catalytic activity and selectivity. Copyright (c) 2015 John Wiley & Sons, Ltd.