Catalytic activity of anchored vanadyl complexes

Vanadyl complexes anchored to polymers are effective as catalysts in the oxidation of sulfoxide to sulfone by tert-butyl hydroperoxide. To study the effect of ligand bound to vanadium in such catalytic reactions, vanadyl complexes of salicylaldoxime (a), 3-2(thenoyl-1,1,1-trifluoroacetone) (b) and (o-phenylene-bis-salicylimine) (c) were anchored to polymers and the effectiveness of the catalysts in the oxidation of dimethylsulfoxide and diphenylsulfoxide by tert.-butylhydroperoxide was investigated. The order of catalytic activity was a ≈ b > c in both cases. In the homogeneous systems using the same complexes, the order of catalytic activity was found to be b > c > a. The polymeric beads isolated at the end of oxidation reaction were used for successive runs and the catalytic activity was similar in the first three cycles. The results are discussed on the basis of structural features of the ligands and the reactants.