title: Chlorination of the β-triketone herbicides tembotrione and sulcotrione: Kinetic and mechanistic study, transformation products identification and toxicity.
abstract: The fate of tembotrione (TBT) and sulcotrione (SCT) during chlorination was investigated in this work. Chlorination kinetics of TBT and SCT were studied by using a continuous-flow reactor in the pH range 2-12 with an excess of total chlorine. Second-order reaction was observed and rate constants of 9.69 (±0.15) × 10(3) M(-1)s(-1) for TBT and 9.48 (±0.62) × 10(3) M(-1)s(-1) for SCT were obtained at pH 7. Intrinsic rate constants for the elementary reactions of chlorine species with neutral and deprotonated forms of TBT and SCT were also calculated, leading to the conclusion that the reaction between hypochlorous acid and the deprotonated form of the pesticide is predominant at neutral pH. Several degradation products during chlorination of TBT and SCT were identified by LC-MS/MS and a reaction pathway was proposed. Chlorine initially reacted on the α-carbon of the three carbonyl functional groups. This reaction initiated the well-known haloform reaction and produced chloroform as end-product. Molar yields of 0.99 mol CHCl3/mol and 0.91 mol CHCl3/mol were obtained for TBT and SCT, respectively at pH 7. Moreover, a toxicity evaluation using Vibrio fischeri was carried out to study the toxicity pattern during TBT and SCT chlorination. An increase in toxicity was observed but it could not be clearly assigned to the identified byproducts.
authors: Institut de Chimie des Milieux et des Matériaux de Poitiers IC2MP, UMR 7285 CNRS Université de Poitiers - Equipe Eaux, Géochimie Organique, Santé - 1 rue Marcel Doré, TSA 41105, 86073 Poitiers Cedex 9, France.
authors: Alice
authors: A
authors: Tawk
authors: Institut de Chimie des Milieux et des Matériaux de Poitiers IC2MP, UMR 7285 CNRS Université de Poitiers - Equipe Eaux, Géochimie Organique, Santé - 1 rue Marcel Doré, TSA 41105, 86073 Poitiers Cedex 9, France.
authors: Marie
authors: M
authors: Deborde
authors: Institut de Chimie des Milieux et des Matériaux de Poitiers IC2MP, UMR 7285 CNRS Université de Poitiers - Equipe Eaux, Géochimie Organique, Santé - 1 rue Marcel Doré, TSA 41105, 86073 Poitiers Cedex 9, France.
authors: Jérôme
authors: J
authors: Labanowski
authors: Institut de Chimie des Milieux et des Matériaux de Poitiers IC2MP, UMR 7285 CNRS Université de Poitiers - Equipe Eaux, Géochimie Organique, Santé - 1 rue Marcel Doré, TSA 41105, 86073 Poitiers Cedex 9, France. Electronic address: herve.gallard@univ-poitiers.fr.
authors: Hervé
authors: H
authors: Gallard
mesh_terms: D048908:Aliivibrio fischeri / Q000187:drug effects; D002713:Chlorine / Q000737:chemistry*; D003512:Cyclohexanones / Q000737:chemistry* / Q000633:toxicity; D004202:Disinfectants / Q000737:chemistry; D054879:Halogenation; D006540:Herbicides / Q000737:chemistry* / Q000633:toxicity; D006863:Hydrogen-Ion Concentration; D006997:Hypochlorous Acid / Q000737:chemistry; D007700:Kinetics; D008698:Mesylates / Q000737:chemistry* / Q000633:toxicity; D013450:Sulfones / Q000737:chemistry* / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000633:toxicity; D018508:Water Purification / Q000379:methods*
chemical_list: D003512:Cyclohexanones; D004202:Disinfectants; D006540:Herbicides; D008698:Mesylates; D013450:Sulfones; D014874:Water Pollutants, Chemical; D002713:Chlorine; C079906:sulcotrione; D006997:Hypochlorous Acid; C585552:tembotrione
keywords: Chlorination; Chloroform; Kinetic; Sulcotrione; Tembotrione; β-triketones