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Abstract
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Epoxides are the key starting materials for a wide variety of products, and the epoxidation of alkenes is one of the most widely studied reactions in organic chemistry. The importance of epoxides arises mainly from their ring opening reactions. Catalytic oxidation of olefins in the presence of transition metal complexes is one of the important methods for preparing epoxides. Copper complexes are active catalysts for epoxidation of olefins in the presence of various oxidants. On the other hand, coordination chemistry of transition metals containing Schiff base ligands is one of the important and interesting research fields in inorganic chemistry. In the present paper we report synthesis, characterization and catalytic activity of two new Cu(II) complexes obtained from the reaction of Cu(NO3)2·3H2O with methyl cabarzate based N- and O-donor ligands (Scheme 1). The ligands and complexes were characterized by elemental analysis, spectroscopic methods (FT-IR, UV–vis), and single crystal X-ray diffraction analysis. X-ray studies revealed that the hydrazone ligands are coordinated to the Cu(II) ion as a tridentate N- and O-donor ligand. These complexes were used as catalyst precursor for oxidation of cyclooctene as representative substrate of olefins in the presence of hydrogen peroxide (H2O2) as a green oxidant. The effect of various parameters on the catalytic activity of complexes including the amount of the catalyst, temperature and solvent were studied. The results showed these complexes are active and selective catalysts for oxidation of cyclooctene
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