Homogeneous oxidation of alcohols in water catalyzed with Cu(II)-triphenyl acetate/bipyridyl complex

A water-soluble mononuclear copper(II) complex, [Cu(OOCC(C6H5)(3))(C10H8H2)(H2O)](ClO4)(CH3OH) (triphenylacetic acid = HOOCC(C6H5)(3), 2-2'-bipyridyl (bipy) = C10H8N2) was synthesized and used as a catalyst precursor in the oxidation of primary (cinnamyl alcohol, benzyl alcohol, cyclohexanol, and 1-heptanol) and secondary alcohols (1-phenylethanol, 3-pentanol, and 2-octanol) to corresponding aldehydes, ketones, and acids. The complex exhibited high catalytic activity toward benzyl alcohol to benzaldehyde as one product (97% conversion in 6 h) and cinnamyl alcohol to benzaldehyde (91.5%) and cinnamaldehyde (6.6%), in 6 h reaction time with less catalyst loading (1 mol%) at a moderate temperature (70 degrees C). Water was used as a solvent and H2O3 as an oxidant for alcohol oxidation. Thus, the Cu(II)/H2O/H2O2 catalytic system could serve as an environmentally benign "green chemistry" alternative to oxidation methods in traditional organic solvents. (C) 2017 Elsevier Ltd. All rights reserved.