Unusual kinetic role of a water-soluble iron(III) porphyrin catalyst in the oxidation of 2,4,6-trichlorophenol by hydrogen peroxide
✍ Scribed by Gábor Lente; James H. Espenson
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 106 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0538-8066
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✦ Synopsis
Abstract
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.