Amino acid Schiff base complex catalyst for effective oxidation of olefins with molecular oxygen

Abstract

The amino acid Schiff base manganese complex (Sal–Phe–Mn) was prepared with l-phenylalanine, salicylaldehyde and Mn(OAc) 2·4H 2O. The ligand and the complex were characterized by the infrared spectra, small area X-ray photoelectron spectroscopy, and ICP-AES. In the presence of the manganese complex, cyclohexene was effectively oxidized by molecular oxygen without reductant. The major products of the reaction were 2-cyclohexen-1-ol (–OH), 2-cyclohexen-1-one (CO) and 2-cyclohexen-1-hydroperoxide (–OOH), which was different with typical oxidation of cyclohexene. The influence of reaction temperature and additive for oxidation had been studied. The selectivity of 2-cyclohexen-1-hydroperoxide varied with reaction time and different additives. The mechanism of cyclohexene oxidation had also been discussed.