Elucidating active species and mechanism of the direct oxidation of benzene to phenol with hydrogen peroxide catalyzed by vanadium-based catalysts using DFT calculations

The mechanism by which benzene is converted to phenol through hydroxylation, catalyzed by vanadium in CH3CN is explored at the B3LYP(IEF-PCM)//B3LYP/6-311G(2d,2p) level. Three candidate catalysts are used to simulate the catalytic cycle. The solvent effectively reduces the free energy barriers of the C-H bond activation step. The binuclear vanadium species is predicted to be the main form of the operative catalyst. The cooperative role of the two vanadium centres and the dynamic charge distribution of the binuclear vanadium species are found to increase the catalytic activity. The conservation of aromaticity for the phenyl ring in the benzene or phenyl ligand is essential for the benzene hydroxylation.