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Hydrolysis of mefenpyrdiethyl: An analytical and DFT investigation.

Anal. Bioanal. Chem. 398, 2325-2334 (2010)
DOI
Open Access Green möglich sobald Postprint bei der ZB eingereicht worden ist.
The hydrolysis of the herbicide safener mefenpyrdiethyl (1-(2, 4-dichlorophenyl)-4, 5-dihydro-5-methyl-1H-pyrazole-3,5-dicarboxylic acid diethyl ester) was investigated in aqueous solutions in the pH range from 2 to 9 and the temperature range from 298 to 323 K. The kinetics of hydrolysis were pseudo first order and were found to be strongly pH and temperature dependent. While near-constant in acidic medium, the hydrolysis rates strongly increased in alkaline pH, and total hydrolysis was observed at pH 11. Two main hydrolysis products, mefenpyrethyl (monoester) and mefenpyr (dicarboxylic acid) were isolated by ultrahigh-pressure liquid chromatography (UHPLC) and characterized using high-resolution Fourier transform ion cyclotron resonance mass spectroscopy (ICR-FT/MS) as well as H-1, C-13 and 2D NMR analyses. Additionally, a density functional theory (DFT) investigation explained the stability of the pesticide at pH 7 and the high reactivity of the pesticide in alkaline medium. The key nucleophilic reaction partner is hydroxyl ions instead of neutral water molecules. Furthermore, the calculated activation barrier for hydrolysis in alkaline medium is in agreement with the extrapolated and experimentally determined activation barrier at pH 14.
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Publikationstyp Artikel: Journalartikel
Dokumenttyp Wissenschaftlicher Artikel
Korrespondenzautor
Schlagwörter Mefenpyrdiethyl; Hydrolysis; Kinetics; Hydrolysis products; OPTIMIZING LARGE MOLECULES; GEOMETRY OPTIMIZATION; ITERATIVE SUBSPACE; ABIOTIC HYDROLYSIS; IMPROVED ALGORITHM; DIRECT INVERSION; AQUEOUS-SOLUTION; DEGRADATION; SOIL; PESTICIDES
ISSN (print) / ISBN 1618-2642
e-ISSN 1618-2650
Quellenangaben Band: 398, Heft: 5, Seiten: 2325-2334 Artikelnummer: , Supplement: ,
Verlag Springer
Verlagsort Heidelberg
Nichtpatentliteratur Publikationen
Begutachtungsstatus Peer reviewed
Institut(e) Institute of Ecological Chemistry (IOEC)