Aqueous phenol oxidation catalysed by molybdenum and tungsten carbonyl complexes

The catalytic activities of the complexes, Cp'M(CO)(3)X (Cp'=Cp (eta(5)-C5H5), Cp* (eta(5)-C5Me5); M = Mo, W; X=Cl, CH3) and Mo(CO)(6) have been examined for the oxidation of phenol (37.6 g/L) using H2O2 as oxidant in aqueous solution. Among them, CpMo(CO)(3)Cl and CpMo(CO)(3)(CH3) showed the highest catalytic activity. Conversion of phenol at 55 degrees C is more than 80% after 24 h when water is used as solvent and the ratio of catalyst:phenol:H2O2 is 1:50:200. The main oxidation products observed in solution are oxalic acid and catechol, together with trace amount of p-benzoquinone and maleic acid. Under similar conditions, binary Mo(CO)(6) catalyses phenol oxidation giving hydroquinone and p-benzoquinone as main products. (C) 2010 Elsevier B.V. All rights reserved.