Oxidative degradation of polychlorinated phenols catalyzed by metallosulfophthalocyanines

2,4,6-trichlorophenol (TCP) is oxidized by potassium monopersulfate or hydrogen peroxide in the presence of iron or manganese tetrasulfonatophthalocyanines (FePcS or MnPcS) to yield not only the corresponding 2,6-dichloro-1,4-benzoquinone but also ring-cleavage products. Catalytic oxidation of the TCP ring by hydrogen peroxide is more efficient than by potassium monopersulfate, despite a slower substrate conversion, suggesting that different mechanisms are involved for these two catalytic systems: a metal-oxo mechanism for FePcS/KHSO5 and a metal-peroxo mechanism for FePcS/H2O2. Eight different final oxidation products and four quinone intermediates have been identified in the oxidation of TCP by the FePcS/H2O2 catalytic system. Chloromaleic acid is the main product of the oxidative ring cleavage. An iron-peroxo complex PcS-FeOOH is probably the active species responsible for the epoxidation of 2,6-dichloro-1,4-benzoquinone and the C-C bond cleavage of 3,5-dichloro-2-hydroxy-1,4-benzoquinone ring, both intermediates generated during the catalytic TCP degradation. The oxidation of pentachlorophenol (PCP) is also catalyzed by FePcS or MnPcS with KHSO5 or H2O2.