Oxidative Degradation of Polychlorinated Phenols Catalyzed by Metallosulfophthalocyanines

Abstract

Abstract2,4,6‐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.