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Elsner, M. ; McKelvie, J.* ; Lacrampe Couloume, G.* ; Sherwood Lollar, S.*

Insight into Methyl tert-Butyl Ether (MTBE) Stable Isotope Fractionation from Abiotic Reference Experiments.

Environ. Sci. Technol. 41, 5693-5700 (2007)
DOI PMC
Open Access Green as soon as Postprint is submitted to ZB.
Methyl group oxidation, SN2-type hydrolysis, and SN1-type hydrolysis are suggested as natural transformation mechanisms of MTBE. This study reports for the first time MTBE isotopic fractionation during acid hydrolysis and for oxidation by permanganate. In acid hydrolysis, MTBE isotopic enrichment factors were C = -4.9” ± 0.6” for carbon and H = -55” ± 7” for hydrogen. Position-specific values were C,reactive position = -24.3” ± 2.3” and H,reactive position = -73” ± 9”, giving kinetic isotope effects KIEC = 1.025 ± 0.003 and KIEH = 1.08 ± 0.01 consistent with an SN1-type hydrolysis involving the tert-butyl group. The characteristic slope of 2Hbulk/13Cbulk bulk,H/ bulk,C = 11.1 ± 1.3 suggests it may identify SN1-type hydrolysis also in settings where the pathway is not well constrained. Oxidation by permanganate was found to involve specifically the methyl group of MTBE, similar to aerobic biodegradation. Large hydrogen enrichment factors of H = -109” ± 9” and H,reactive position = -342” ± 16” indicate both large primary and large secondary hydrogen isotope effects. Significantly smaller values reported previously for aerobic biodegradation suggest that intrinsic fractionation is often masked by additional non-fractionating steps. For conservative estimates of biodegradation at field sites, the largest values reported should, therefore, be used.
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Publication type Article: Journal article
Document type Scientific Article
Corresponding Author
ISSN (print) / ISBN 0013-936X
e-ISSN 1520-5851
Quellenangaben Volume: 41, Issue: 16, Pages: 5693-5700 Article Number: , Supplement: ,
Publisher ACS
Publishing Place Washington, DC
Non-patent literature Publications
Reviewing status Peer reviewed