Kinetics and Mechanism of Oxidation of Formic Acid by Chromium(VI). Inhibition by Manganese(II) Ion

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Title:Kinetics and Mechanism of Oxidation of Formic Acid by Chromium(VI). Inhibition by Manganese(II) Ion
Creators:
Arias, Conchita
Perez-Benito, Joaquin F.
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 57, 9, pp. 1821-1835

Abstract

Experiments have been done to clarify the mechanism of the chromium(VI)-formic acid reaction in aqueous perchloric acid media, both in the absence and in the presence of manganese(II) ion. Two mechanisms are proposed, one for slightly acid solutions (<i>I</i>) and the other for strongly acid ones (<i>II</i>). Both mechanisms are first order in both oxidant and reductant, but they differ in the order to hydrogen ion (1 for mechanism <i>I</i> and 3 for mechanism <i>II</i>). The activation energy for mechanism <i>I</i> (60.4 ± 0.9 kJ mol<sup>-1</sup>) is considerably higher than that for mechanism <i>II</i> (41.2 ± 0.4 kJ mol<sup>-1</sup>). The rate-controlling steps proposed for mechanisms <i>I</i> and <i>II</i> are the H<sub>2</sub>CrO<sub>4</sub>-HCOOH and HCrO<sub>3</sub><sup>+</sup>-HCOOH<sub>2</sub><sup>+</sup> reactions, respectively. Mechanism <i>I</i> is inhibited by manganese(II) ion, but mechanism <i>II</i> is not, which suggests that mechanism <i>I</i> involves Cr(IV) as an intermediate, whereas mechanism <i>II</i> does not.

Title:Kinetics and Mechanism of Oxidation of Formic Acid by Chromium(VI). Inhibition by Manganese(II) Ion
Creators:
Arias, Conchita
Perez-Benito, Joaquin F.
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:57
Number:9
Page Range:pp. 1821-1835
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19921821UNSPECIFIED
ID Code:3846
Item Type:Article
Deposited On:06 Feb 2009 16:46
Last Modified:06 Feb 2009 15:47

Citation

Arias, Conchita; Perez-Benito, Joaquin F. (1992) Kinetics and Mechanism of Oxidation of Formic Acid by Chromium(VI). Inhibition by Manganese(II) Ion. Collection of Czechoslovak Chemical Communications, 57 (9). pp. 1821-1835. ISSN 0010-0765

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