Reusable Metal Bound Polystyrene-Anchored Thiophene-2-carboxaldehyde Catalysts for Efficient Oxidation of Benzyl Alcohol

Cross-linked amino-polystyrene was reacted with thiophene-2-carboxyldehyde followed by the reaction with different metal salts [Cu(II), Mn(II), V(IV), Fe(III) and Ni(II)] to form new heterogeneous polystyrene-anchored catalysts. The structures of the immobilized catalysts were established on the basis of CHNS, DRS, FTIR, AAS, EDX and EPR techniques. The catalytic activity of polystyrene-anchored catalysts was estimated for the oxidation of benzyl alcohol using tert-butyl hydroperoxide and hydrogen peroxide as oxidants. The influence of different reaction parameters like temperature, time, oxidant and the quantity of catalyst on the oxidation were investigated. Under optimized condition, the results show that TBHP as an oxidant provides 90% conversion with the nickel catalyst. The copper catalyst, when used with TBHP, demonstrated the highest selectivity for benzaldehyde, reaching 98%. Under optimal conditions, the catalysts can be reused four times without considerable loss in its activity.