Copper(II) complex of (±)trans-1,2-cyclohexanediamine azo-linked Schiff base ligand encapsulated in the nanocavity of zeolite-Y for the catalytic oxidation of olefins

Abstract

A Schiff base ligand derived from 2-hydroxy-5-(phenylazo)-benzaldehyde and (±)trans-1,2-cyclohexanediamine (H2L) and its corresponding Cu(II) complex (CuL) were synthesized and characterized by FT-IR, UV-Vis and 1H-NMR spectroscopy. The copper Schiff base complex was encapsulated in the nanopores of zeolite-Y (CuL-Y) by the flexible ligand method and its encapsulation was confirmed by different studies. The homogeneous and the corresponding heterogeneous catalysts were used for the oxidation of different alkenes with tert-butyl hydroperoxide. Under the optimized reaction conditions, the oxidation of cyclooctene, cyclohexene, styrene and norbornene catalyzed by CuL gave 89, 63, 46 and 13 % conversion, respectively. These olefins were oxidized efficiently with 50, 96, 95 and 92 % conversion, respectively, in the presence of CuL-Y. Comparison of the catalytic behavior of CuL and CuL-Y showed the higher catalytic activity and selectivity of the heterogeneous catalyst with respect to the homogenous one.