Mechanistic study on thiacloprid transformation: Free radical reactions

Georgina Rózsa, László Szabó, Krisztina Schrantz, E. Takács, L. Wojnárovits

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Free radical induced oxidation/reduction mechanisms of the hazardous water contaminant thiacloprid have been unravelled using pulse radiolysis techniques involving transient spectral analysis and redox titration experiments. The [rad]OH-induced oxidation of thiacloprid proceeds with appreciable rate, the reaction rate constant has been determined to be kOH = 4.8 × 109 mol−1 L s−1. The [rad]OH attack leaves behind a rather complex free radical system consisting of ∼9% α-aminoalkyl radicals, ∼31% aminyl + aminium nitrogen centred radicals, ∼46% radicals at the sulfur and ∼14% hydroxycyclohexadienyl radical of the pyridyl moiety. Since ∼86% of radicals are formed on the key cyanoiminothiazolidine pharmacophore, [rad]OH is anticipated to be an appropriate candidate for inactivation of this biologically active pollutant. The one-electron reduction exerted by eaq occurs at a diffusion controlled rate. As a result of the eaq attack pyridinyl radical forms that takes part in subsequent protonation and dechlorination processes. The course of events is anticipated to lead to the destruction of another important part of the molecule in respect to insecticidal activity.

Original languageEnglish
Pages (from-to)17-25
Number of pages9
JournalJournal of Photochemistry and Photobiology A: Chemistry
Volume343
DOIs
Publication statusPublished - Jun 15 2017

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Keywords

  • Hydroxyl radical
  • Pulse radiolysis
  • Radical kinetics
  • Thiacloprid
  • Transient spectroscopy

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Physics and Astronomy(all)

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