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Polymer supported peroxotantalate based heterogeneous catalysts served as highly efficient, selective and recyclable catalysts for alkene epoxidation and sulfide oxidation with green oxidant aqueous H2O2 under mild reaction conditions.

An efficient and eco-compatible route for the selective oxidation of a variety of thioethers to the corresponding sulfoxide or sulfone with 30% aqueous H 2 O 2 in water, using newly synthesized peroxoniobium (pNb) complexes as catalysts, is described. The catalysts with formulas Na 2 [Nb(O 2 ) 3 (arg)]·2H 2 O (arg = arginate) (NbA) and Na 2 [Nb(O 2 ) 3 (nic)(H 2 O)]·H 2 O (nic = nicotinate) (NbN) have been synthesized from the reaction of sodium tetraperoxoniobate with 30% H 2 O 2 and the respective organic ligand in an aqueous medium, and these have been comprehensively characterized by elemental analysis, spectral studies (FTIR, Raman, 1 H NMR, 13 C NMR and UV-vis), EDX analysis and TGA-DTG analysis. The density functional theory (DFT) method has been used to investigate the structure of the synthesized pNb complexes. The catalysts are physiologically safe and can be reused for at least six reaction cycles without losing their activity or selectivity. The oxidation is chemoselective for sulfides or sulfoxides leaving the CC or alcoholic moiety unaffected. The developed methodologies, apart from being high yielding and straightforward, are completely free from halogen, organic co-solvent, or co-catalysts.

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