Magnetically separable nanocatalyst for selective oxidation of sulfides to sulfoxides

A molybdenum complex, [MoO2Cl2 (DMSO) 2], was immobilized on Schiff base magnetic Fe3O4@SiO2 nanoparticles by covalent linkage. First, superparamagnetic Fe3O4 nanoparticles were prepared by the coprecipitation method [1]. Secondly, the surface of Fe3O4 was encapsulated with silica in order to increase the functionality and stability of nanoparticles. Then, the Fe3O4 nanoparticles were surface-modified with 3-aminopropyltriethoxysilane (APTS) which introduced -NH2 on to the surface of support [1]. After functionalization by APTS, free amino groups on the surface can react with many different carbonyl compounds to form Schiff base ligand. For preparation of Fe3O4@SiO2/Schiff base, Fe3O4@SiO2-NH2 nanoparticles were reacted with dialdehyde and then reacted with the MoO2Cl2 (DMSO) 2 complex to synthesize Mo (VI) nanocatalyst.The resulting nanocatalyst are used as an efficient and recyclable catalyst for the selective oxidation of sulfides to corresponding sulfoxides using urea hydrogen peroxide as the oxidant. The characterization of catalyst was carried out by means of TGA, SEM, TEM, VSM, elemental analysis, FT-IR and Raman microprobe techniques.