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Elsner, M. ; Cwiertny, D.M.* ; Roberts, L.* ; Sherwood Lollar, B.*

1,1,2,2-Tetrachloroethane Reactions with OH-, Cr(II), Granular Iron, and a Copper-Iron Bimetal: Insights from Product Formation and Associated Carbon Isotope Fractionation.

Environ. Sci. Technol. 41, 4111-4117 (2007)
DOI PMC
Open Access Green möglich sobald Postprint bei der ZB eingereicht worden ist.
Despite widespread implementation of zero-valent iron remediation schemes, the manner and order of chemical bond cleavage in iron-mediated organohalide transformations remains imperfectly understood. We present insights from carbon isotope fractionation for the dehalogenation of 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA) and 1,1,1-trichloroethane (1,1,1-TCA) by various reactants. Elimination of HCl by OH- gave isotope fractionation in 1,1,2,2-TeCA of = -25.6”, KIEC = 1.02 to 1.03 per carbon center, consistent with a concerted (E2) mechanism. In contrast, 1,1,1-TCA reduction by Cr(II), Fe(0), and Cu-plated iron (Cu/Fe) resulted in = -13.6” to -15.8” indicating the initial involvement of a single C-Cl bond (KIEC 1.03). 1,1,2,2-TeCA reduction by Cr(II), Fe(0), and Cu/Fe yielded = -18.7”, -19.3”, and -17.0”, respectively. In the two latter cases, depletion of the minor product TCE by 26” indicated its formation via nonreductive dehydrohalogenation. The major 1,1,2,2-TeCA reduction products, cis- and trans-DCE, differed by 2.3” ± 1.0” in Cr(II) systems, but were equivalent in Fe(0) and Cu/Fe systems. In contrast, the ratio of cis-DCE to trans-DCE concentration was 2.5 for reduction with Cr(II) and Fe(0), but ~3.8 with Cu/Fe. Complementary isotope and concentration data therefore suggest differences in the transition state geometry and/or reaction intermediates in each reductant system.
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Publikationstyp Artikel: Journalartikel
Dokumenttyp Wissenschaftlicher Artikel
Korrespondenzautor
ISSN (print) / ISBN 0013-936X
e-ISSN 1520-5851
Zeitschrift Environmental Science & Technology
Quellenangaben Band: 41, Heft: 11, Seiten: 4111-4117 Artikelnummer: , Supplement: ,
Verlag ACS
Verlagsort Washington, DC
Nichtpatentliteratur Publikationen
Begutachtungsstatus Peer reviewed
Institut(e) Institute of Groundwater Ecology (IGOE)