the catalytic efficiency of molybdenum(vi) complex supported on fe3o4@sio2 in oxidation of sulfides to sulfoxides

A molybdenum complex, [moo2cl2(dmso)2], was immobilized on schiff base magnetic fe3o4@sio2 nanoparticles by covalentlinkage. first, superparamagnetic fe3o4 nanoparticles were prepared by the coprecipitation method [1]. secondly, the surface offe3o4 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.due to the high catalytic activity and efficient recyclability of catalyst, it was selected to study the substrate scope in the catalytic oxidation of sulfides to sulfoxides (table). using catalyst, the oxidation of methylphenyl, ethylphenyl, diphenyl, dioctyl and diethyl sulfide resulted to the formation of corresponding sulfoxides in good yields (45-99%) and selectivities (91-100%). control experiments indicated that no oxidation occurred in the absence of either catalysts or oxidant. in the other words, the use of fe3o4@sio2, fe3o4@sio2-nh2 or fe3o4@sio2-sb nanoparticles in place of catalyst did not promote oxidation.