Synthesis and characterization of some novel transition metal Schiff base complexes encapsulated in zeolite Y: effective catalysts for the selective oxidation of benzyl alcohol

Abstract

The synthesis of Co(II), Ni(II) and Cu(II) complexes of 2-[(2-hydroxy-phenylimino)-methyl]-4-(4-chloro-3-nitro-phenylazo)-phenol (H2L) in the supercages of zeolite Y by the flexible ligand method has been described. These complexes ([M complex]-NaY) have been characterized by spectroscopic (electronic and FT-IR) studies, XRD, TGA, BET and elemental analysis. These encapsulated transition metal complexes have been used as heterogeneous catalysts for the selective oxidation of benzyl alcohol, and the reactivity of these heterogeneous catalysts was compared with corresponding homogeneous catalysts. Furthermore, reaction conditions have been optimized by considering the type of solvent, type and amount of catalyst, type and concentration of oxidant, temperature and time. Also, the kinetic effects of reaction were studied at four different temperatures (25, 40, 60 and 80 °C). The encapsulated Cu(II) complex was found to be more active than the other corresponding complexes for the oxidation of benzyl alcohol. These catalysts were very stable and can be reused for more than three times.