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Metalloporphyrin catalyzed oxidation of chlorophenols

University of British Columbia

The use of water soluble, non-aggregating metalloporphyrins (meso-tetra(2,6-dichloro-3-sulphonatophenyl) porphyrin (TDCSPP) and meso-tetra(2,6-dichloro-3-sulfonatopheny1)-β-octachloroporphyrin (TDCS-(β-Cl₈P) coordinated with iron or manganese) as catalysts for the peroxide oxidation of chlorophenols were investigated. The relative rates of chlorophenol oxidation with respect to several variables (catalyst, pH, oxidant, and chlorophenol structure) were determined. The rate was found to be pseudo-first order in the catalyst. The oxidation was most efficient using the iron porphyrins, at pH < 4. The oxidation rate was dependent on the oxidant. In order of decreasing rate, meta-chloroperoxybenzoic acid > potassium monoperoxysulfate > hydrogen peroxide > t-butylhydroperoxide. The oxidation rate was strongly dependent on both the number and the position of chlorine substitution on the phenol. In order of decreasing rate, 2,4-dichlorophenol > 2,4,5-trichlorophenol > 2-chlorophenol ≈ 4-chlorophenol > 3,4-dichlorophenol ≈ 2,4,6-trichlorophenol > 2,3,4,6-tetrachlorophenol 2,3,5,6-tetrachlorophenol > 3-chlorophenol > 3,5-dichlorophenol ≈ 2,3,4,5-tetrachlorophenol. The structures of some of the catalyzed reactions were elucidated. Products of phenoxy radical coupling, and quinones are typical. The results are discussed in the context of the possible use of these metalloporphyrins for pollution remediation.

Thesis/Dissertation

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2008-09-10

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http://hdl.handle.net/2429/1834

Chemistry

University of British Columbia

UBCV

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