Mechanistic insight into the aerobic oxidation of benzyl alcohol catalyzed by the CuII–TEMPO catalyst in alkaline water solution

Abstract

Density functional theory (DFT) calculations have been performed to investigate the benzyl alcohol oxidation to acetaldehyde by a Cu^II/L–TEMPO (L: bis[2-N-(4-fluorophenyl)-pyrrolylcarbaldimide]) catalyst system in alkaline water solution. The catalytic cycle consists of catalyst activation, substrate oxidation and catalyst regeneration parts. Four pathways (path A, path B, path C and path D) for the catalyst activation step are considered. The rate-determining steps are proton transfer in these pathways. Moreover, water participation plays a major role in the proton transfer step. In consideration of the high concentration of the solvent water, path C and path D are supposed to be competitive during the reaction, with path D more favourable.