Polymer-supported Schiff base complexes in oxidation reactions

Polymer-supported Schiff base complexes of metal ions show high catalytic activity in comparison to their unsupported analogues. The catalytic activity of metal complexes of different types of Schiff base was analyzed and presented in this review. The manganese(III) Schiff base complexes exhibited high catalytic activity in the oxidation of alkenes and alkanes both in homogeneous and heterogeneous conditions. Similarly, the Schiff base complexes of iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) ions have been used as catalysts in the epoxidation of cyclohexene and oxidation of phenol. Polymer-supported iron(III) Schiff base complexes have demonstrated higher activity than unsupported and polymer-supported Schiff base complexes of other metal ions. Similarly, the polymer-supported salen complexes of ruthenium(Ill), iron(Ill) and Schiff base complexes of molybdenum carbonyls have been used successfully as catalysts in the oxidation of cyclo-octene. The oxidation of styrene, limonene, stilbene. benzene and its alkyl derivatives, adamantane, benzyl alcohol, etc. was catalyzed significantly by polymer-supported Schiff base complexes of different metal ions. The recyclability of polymer-supported Schiff base complexes has also been evaluated and presented in this review. The thermal and moisture stability of polymer-supported Schiff base complexes is responsible for their high activities in reactions involving high temperatures. (C) 2009 Elsevier B.V. All rights reserved.