Synthesis, characterization and catalytic oxidation of ethylbenzene over “neat” and host (nanocavity of zeolite-Y)/guest (tetraza tetraone macrocyclic copper(II) complexes) nanocomposite materials (HGNM)

Abstract

Copper(II) complexes of [12]aneN4: 1,4,7,10-tetraazacyclododecane-2,3,8,9-tetraone; [14]aneN4: 1,4,8,11-tetraazacyclotetradecane-2,3,9,10-tetraone; Bzo2[12]aneN4: dibenzo-1,4,7,10-tetraazacyclododecane-2,3,8,9-tetraone and Bzo2[14]aneN4: dibenzo-1,4,8,11-tetraazacyclotetradecane-2,3,9,10-tetraone have been encapsulated in the nanopores of zeolite-Y by the in situ one pot template condensation reaction. Copper(II) complexes with azamacrocyclic ligand were entrapped in the nanocavity of zeolite-Y by a two-step process in the liquid phase: (i) adsorption of [bis(diamine)copper(II)]; [Cu(N-N)2]-NaY; in the supercages of the zeolite, and (ii) in situ condensation of the copper(II) precursor complex with diethyloxalate. The new host guest nanocomposite materials (HGNM) have been characterized by FTIR, DRS and UV–Vis spectroscopic techniques, XRD and elemental analysis, as well as nitrogen adsorption. The “neat” and encapsulated complexes exhibited good catalytic activity in the oxidation of ethylbenzene at 333 K, using tert-butyl hydroperoxide (TBHP) as the oxidant. Acetophenone was the major product though small amounts of o- and p-hydroxyacetophenones were also formed revealing that C–H bond activation takes place both at benzylic and aromatic ring carbon atoms. Ring hydroxylation was more over the “neat” complexes than over the encapsulated complexes.