Haloform Reaction

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Uwe Hartfiel - One of the best experts on this subject based on the ideXlab platform.

Lutz F Tietze - One of the best experts on this subject based on the ideXlab platform.

Herve Gallard - One of the best experts on this subject based on the ideXlab platform.

  • Chlorination of the beta-triketone herbicides tembotrione and sulcotrione: Kinetic and mechanistic study, transformation products identification and toxicity
    Water Research, 2015
    Co-Authors: Alice Tawk, Marie Deborde, Jérome Labanowski, Herve Gallard
    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) x 10(3) M(-1)s(-1) for TBT and 9.48 (+/- 0.62) x 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 a-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. (

  • Chlorination of the β-triketone herbicides tembotrione and sulcotrione: Kinetic and mechanistic study, transformation products identification and toxicity.
    Water research, 2015
    Co-Authors: Alice Tawk, Marie Deborde, Jérome Labanowski, Herve Gallard
    Abstract:

    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) × 103 M−1s−1 for TBT and 9.48 (±0.62) × 103 M−1s−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.

E Voss - One of the best experts on this subject based on the ideXlab platform.

Joan Bosch - One of the best experts on this subject based on the ideXlab platform.

  • Nucleophilic addition to chiral pyridinium salts: stereoselective synthesis of (−)-Na-methylervitsine
    Tetrahedron-asymmetry, 2003
    Co-Authors: M.-lluïsa Bennasar, Ester Zulaica, Yolanda Alonso, Joan Bosch
    Abstract:

    Abstract Chiral non-racemic 4-substituted 3,5-diacyl-1,4-dihydropyridines 8 are prepared by the regio- and diastereoselective addition of organocopper reagents to chiral pyridinium salt 2 , followed by acylation with trichloroacetic anhydride and subsequent Haloform Reaction. Additionally, (−)- N a -methylervitsine is synthesized by Reaction of the enolate derived from 2-acetylindole 9 with pyridinium salt 2 , followed by electrophile (Me 2 N + CH 2 I − )-induced cyclization and subsequent elaboration of the 16-methylene and (20 E )-ethylidene substituents.

  • Nucleophilic addition to chiral pyridinium salts: stereoselective synthesis of (-)-Na-methylervitsine
    Tetrahedron: Asymmetry, 2003
    Co-Authors: M.-lluïsa Bennasar, Ester Zulaica, Yolanda Alonso, Joan Bosch
    Abstract:

    Abstract Chiral non-racemic 4-substituted 3,5-diacyl-1,4-dihydropyridines 8 are prepared by the regio- and diastereoselective addition of organocopper reagents to chiral pyridinium salt 2 , followed by acylation with trichloroacetic anhydride and subsequent Haloform Reaction. Additionally, (−)- N a -methylervitsine is synthesized by Reaction of the enolate derived from 2-acetylindole 9 with pyridinium salt 2 , followed by electrophile (Me 2 N + CH 2 I − )-induced cyclization and subsequent elaboration of the 16-methylene and (20 E )-ethylidene substituents.

  • Synthesis of 4-functionalized aryl-3,5-diacyl-1,4-dihydropyridines
    Tetrahedron, 2002
    Co-Authors: M.-lluïsa Bennasar, Tomas Roca, Manuel Monerris, Cecilia Juan, Joan Bosch
    Abstract:

    Abstract The valuable N-unsubstituted 4-aryl-3,5-diacyl-1,4-dihydropyridines 12b–f , bearing an electron-withdrawing substituent at the benzene ring, have been synthesized by the copper-mediated addition of functionalized arylmagnesium reagents 2b–f to N-benzhydrylpyridinium salt 9 , followed by acylation with trichloroacetic anhydride and the subsequent Haloform Reaction and N-deprotection.

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