Cooxidation of formic acid and oxalic acid by chromium(VI) in aqueous acid media: a kinetic study

2001 ◽  
Vol 2001 (8) ◽  
pp. 334-335 ◽  
Author(s):  
Asim K. Das ◽  
Aparna Roy ◽  
Bidyut Saha ◽  
Mahua Das
Keyword(s):  
Oxalic Acid ◽  
Formic Acid ◽  
Kinetic Study ◽  
Acid Media ◽  
Aqueous Acid ◽  
Chromium Vi

Micellar Effect on the Catalytic Co-Oxidation of Dimethyl Sulfoxide and Oxalic Acid by Chromium(VI) in Aqueous Acid Media: A Kinetic Study

2005 ◽  
Vol 30 (3) ◽  
pp. 215-226 ◽  
Author(s):  
Bidyut Saha ◽  
Monirul Islam ◽  
Asim K. Das
Keyword(s):  
Electron Transfer ◽  
Oxalic Acid ◽  
Dimethyl Sulfoxide ◽  
Ternary Complex ◽  
Single Step ◽  
Experimental Conditions ◽  
Acid Media ◽  
Aqueous Acid ◽  
Chromium Vi ◽  
Micellar Effect

The CrVI oxidation of a mixture of dimethyl sulfoxide (DMSO) and oxalic acid (OXH2) in aqueous acid media occurs much faster than that of either of the two substrates alone (DMSO reacts extremely slowly under the experimental conditions). In the mixture, both substrates undergo oxidation simultaneously in a ternary complex of CrVI through a three electron transfer step (i.e. CrVI → CrIII), two electrons from DMSO and one electron from oxalic acid. Hitherto there has been a debate regarding the existence of a 3e transfer in a single step. The micellar effect may be considered as a probe for 3e transfer in a single step.

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

1992 ◽  
Vol 57 (9) ◽  
pp. 1821-1835 ◽  
Author(s):  
Conchita Arias ◽  
Joaquin F. Perez-Benito
Keyword(s):  
Formic Acid ◽  
The Other ◽  
Hydrogen Ion ◽  
Acid Solutions ◽  
Acid Media ◽  
First Order ◽  
Chromium Vi ◽  
Acid Reaction ◽  
Aqueous Perchloric Acid ◽  
Mechanism Of Oxidation

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) and the other for strongly acid ones (II). Both mechanisms are first order in both oxidant and reductant, but they differ in the order to hydrogen ion (1 for mechanism I and 3 for mechanism II). The activation energy for mechanism I (60.4 ± 0.9 kJ mol-1) is considerably higher than that for mechanism II (41.2 ± 0.4 kJ mol-1). The rate-controlling steps proposed for mechanisms I and II are the H2CrO4-HCOOH and HCrO3+-HCOOH2+ reactions, respectively. Mechanism I is inhibited by manganese(II) ion, but mechanism II is not, which suggests that mechanism I involves Cr(IV) as an intermediate, whereas mechanism II does not.

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