Oxidation of cyclohexene with tert-butylhydroperoxide catalysted by host (nanocavity of zeolite-Y)/guest (Mn(II), Co(II), Ni(II) and Cu(II) complexes of N, N′-bis(salicylidene)phenylene-1,3-diamine) nanocomposite materials (HGNM)

Abstract

Transition metal (M = Mn(II), Co(II), Ni(II) and Cu(II)) complexes with tetradendate Schiff-base ligand; N, N′-bis(salicylidene)phenylene-1,3-diamine, H 2[sal-1,3-phen]; was entrapped in the nanocavity of zeolite-Y by a two-step process in the liquid phase: (i) adsorption of bis(salicylaldiminato)metal(II); [M(sal) 2]-NaY; in the supercages of the zeolite, and (ii) in situ Schiff condensation of the metal(II) precursor complex with the corresponding phenylene-1,3-diamine; [M(sal-1,3-phen)]-NaY. The new materials were characterised by several techniques: chemical analysis, spectroscopic methods (DRS, BET, FTIR and UV–vis), conductometric and magnetic measurements. Analysis of the data indicates that the M(II) complexes are encapsulated in the nanodimensional pores of zeolite-Y and exhibit different from those of the free complexes, which can arise from distortions caused by steric effects due to the presence of sodium cations, or from interactions with the zeolite matrix. The host–guest nanocomposite materials (HGNM); [M(sal-1,3-phen)]-NaY; catalyzes the oxidation of cyclohexene with tert-butylhydroperoxide (TBHP). Oxidation of cyclohexene with [M(sal-1,3-phen)] gave 2-cyclohexene-1-one, 2-cyclohexene-1-ol and 1-( tert-butylperoxy)-2-cyclohexene whereas, oxidation with [M(sal-1,3-phen)]-NaY resulted in the formation of 2-cyclohexene-1-one and 2-cyclohexene-1-ol. [Mn(sal-1,3-phen)]-NaY shows significantly higher catalytic activity than other catalysts.