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Unusual kinetic role of a water‐soluble iron(III) porphyrin catalyst in the oxidation of 2,4,6‐trichlorophenol by hydrogen peroxide
Author(s) -
Lente Gábor,
Espenson James H.
Publication year - 2004
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.20018
Subject(s) - chemistry , hydrogen peroxide , porphyrin , catalysis , chloride , substrate (aquarium) , inorganic chemistry , peroxide , photochemistry , kinetic energy , organic chemistry , oceanography , physics , quantum mechanics , geology
The oxidation of 2,4,6‐trichlorophenol (TCP) to 2,6‐dichloro‐1,4‐benzoquinone (DCQ) by hydrogen peroxide using iron(III) meso‐tetra(4‐sulfonatophenyl) porphine chloride, Fe(TPPS)Cl, as a catalyst was studied with stopped‐flow UV–vis spectrophotometry and potentiometry using a chloride ion selective electrode. The observations are interpreted by a three‐step kinetic model: the initial reaction of the catalyst with the oxidant (Fe(TPPS) + + H 2 O 2 → Cat′) produces an active intermediate, which oxidizes the substrate (Cat′ + TCP → Fe(TPPS) + + DCQ + Cl − ) in the second step. The third step is the transformation of the catalyst into a much less active form (Cat′ → Cat″) and is responsible for the unusual kinetic phenomena observed in the system. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36:449–455, 2004.