Photodechlorination of octachlorodibenzothiophene and octachlorodibenzofuran: Comparison of experimental degradation pathways with degradation pathways predicted by DFT.

Photodechlorination of octachlorodibenzothiophene and octachlorodibenzofuran: Comparison of experimental degradation pathways with degradation pathways predicted by DFT. Research Abstract Details 

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Photodechlorination of octachlorodibenzothiophene and octachlorodibenzofuran: Comparison of experimental degradation pathways with degradation pathways predicted by DFT. Abstract Text:

Polychlorodibenzothiophenes (PCDTs) are sulfur analogues of polychlorodibenzofurans (PCDFs) and have been detected in environmental samples. We used density functional theory calculations (Gaussian 98W) to predict the photodechlorination pathways of octachlorodibenzothiophene (OCDT) and octachlorodibenzofuran (OCDF) in hexane, and we compared the predicted pathways with those observed during UV irradiation experiments. OCDT and OCDF were observed to degrade through first-order dechlorination processes, and the rate constant for OCDT was less than one-third that for OCDF. The main experimental photodechlorination pathways of OCDT and OCDF led to hexachlorinated and tetrachlorinated congeners, respectively; that is, the photodechlorination pathway of OCDT differed from that of OCDF. On the assumption that the dechlorination mechanisms involved radical reactions, we used DFT calculations to estimate bond-dissociation energies and single-point energies of OCDT and OCDF and their dechlorinated congeners, and we used the resulting information, along with hypotheses regarding the rate-controlling step of the degradations, to predict theoretical degradation pathways. We propose that reaction of dechlorinated radicals with a hydrogen donor was the rate-controlling step for OCDT and that C-Cl bond dissociation by UV light was the rate-controlling step for OCDF.

Photodechlorination of octachlorodibenzothiophene and octachlorodibenzofuran: Comparison of experimental degradation pathways with degradation pathways predicted by DFT. Publishing Authors By Initials

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Photodechlorination of octachlorodibenzothiophene and octachlorodibenzofuran: Comparison of experimental degradation pathways with degradation pathways predicted by DFT. Journal Published:

PUBLICATION TYPE: Journal Article

Journal: Chemosphere

VOLUME: 73

Page Numbers: 1005-10

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ISSN: 0045-6535

DAY: 26

MONTH: 07

YEAR: 2008

Photodechlorination of octachlorodibenzothiophene and octachlorodibenzofuran: Comparison of experimental degradation pathways with degradation pathways predicted by DFT. Information

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LANGUAGE: eng

NlmUniqueID: 320657

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AFFILIATION: Department of Chemical Engineering, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei, Tokyo 184-8588, Japan.

Country: England

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