Photocatalytic oxidation of aromatic aldehydes with Co(II)tetra-(benzoyloxyphenyl)porphyrin and molecular oxygen

Illuminated with 450 W high pressure mercury lamp (HPML), the oxidation of aromatic aldehydes was investigated with molecular oxygen in the presence o f Co(II)[meso-tetra(benzoyloxy-phenyl) porphyrin] (CoTBCOPP). The oxygen up take was measured during the reaction process. Under the mild condition (30 degrees C, 1 atm O-2), the oxidation reactions occurred without consumptio n of reducing agent. It was observed that CoTBCOPP could catalyze the oxida tion of aromatic aldehydes by reversibly binding molecular oxygen. The effe cts of the concentrations of catalyst and substrate in the oxidation reacti on system were studied, meanwhile the factor of solvents was discussed in d etail. The induction period was greatly shortened by raising the temperatur e of oxidation system or adding hydrogen dioxide. However, low dioxygen abs orbed and the long induction period were obtained when imidazole was added as the fifth ligand. (C) 1999 Elsevier Science B.V. All rights reserved.