The kinetics and mechanism of the oxidation of pyruvate ion by hypochlorous acid

Mónika Galajda, Tímea Fodor, Mihály Purgel, I. Fábián

Research output: Contribution to journalArticle

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Abstract

The oxidation of pyruvic acid by hypochlorous acid was studied in the pH 1.0-11.0 range. The main path in the redox process is the reaction between the pyruvate ion and HOCl. It was shown that the reaction is second order in both reactants and kHOCl = 2.17 ± 0.04 M-1 s-1 (I = 1.0 M (NaClO4), T = 25.0 °C) with ΔH≠HOCl = 34.6 ± 1.2 kJ mol-1 and ΔS≠HOCl = -120.3 ± 3.6 J mol-1 K-1 for this reaction step. The relatively large negative entropy of activation is consistent with an O atom-transfer mechanism. DFT calculations support this conclusion by predicting a concerted rearrangement of the activated complex which includes the reactants and the solvent water molecule. It was also confirmed that the hydration of pyruvic acid has a significant contribution to the observed kinetic features under acidic conditions. The hydration reaction is a proton catalyzed process and the pseudo-first-order rate constant can be interpreted by considering the protolytic and hydration equilibria of pyruvic acid. The rate constants were determined for the non-catalytic and the proton catalyzed paths: kh0 = 0.24 ± 0.01 s-1 and kh1 = 5.5 ± 0.2 M-1 s-1.

Original languageEnglish
Pages (from-to)10512-10520
Number of pages9
JournalRSC Advances
Volume5
Issue number14
DOIs
Publication statusPublished - 2015

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Hypochlorous Acid
Pyruvic Acid
Hydration
Ions
Oxidation
Kinetics
Acids
Protons
Rate constants
Discrete Fourier transforms
Entropy
Chemical activation
Atoms
Molecules
Water

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Chemistry(all)

Cite this

The kinetics and mechanism of the oxidation of pyruvate ion by hypochlorous acid. / Galajda, Mónika; Fodor, Tímea; Purgel, Mihály; Fábián, I.

In: RSC Advances, Vol. 5, No. 14, 2015, p. 10512-10520.

Research output: Contribution to journalArticle

Galajda, Mónika ; Fodor, Tímea ; Purgel, Mihály ; Fábián, I. / The kinetics and mechanism of the oxidation of pyruvate ion by hypochlorous acid. In: RSC Advances. 2015 ; Vol. 5, No. 14. pp. 10512-10520.
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