Kinetics and Mechanisms of the Reduction of Chromium(VI) by 2-Mercaptoethanesulfonic Acid in Aqueous Solution: Difference in the Mechanistic Process of Reduction with Noncarboxylate Thiols
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Dwight C. Ramdon
Abstract
The kinetics of the reaction of chromium(VI) with 2-mercaptoethanesulfonic acid (MESA) has been studied spectrophotometrically at wavelength, 435 nm, and ionic strength, I, of 0.50 mol dm-3 (NaClO4) over the ranges: 16.0 < θ < 29.5 °C, 2.6 < pH < 7.1 (citric acid-phosphate buffer), [Cr(VI)]T = 2.0 χ 10-4 mol dm-3, 1.0 χ 10-2 < [MESA]T < 4.0 χ 10-2 mol dm-3. The reaction occurs giving clear indication of the formation of an intermediate, which is assumed to be a typical Cr(VI)-thioester. The decay of the thioester then occurs via a series of electron transfer reactions to give Cr(III). The formation and decay rates of this intermediate have been investigated kinetically and a detailed mechanism for the overall reaction proposed. Experimental data were fitted to rate equations derived from this mechanism. The specific rate constants and corresponding activation parameters were also deduced. The results show that MESA without carboxylate groups, react differently when compared to other thiols having such groups present. This confirms the participating role of carboxylate groups in the formation of the Cr(VI)-thioester. The catalytic effect of added Zn2+ was investigated and its overall role in the reaction of Cr(VI) with MESA was explained.
© 2014 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- Kinetics and Mechanism of the Reaction of Ninhydrin with Chromium(III)-tryptophan Complex in Absence and Presence of Surfactants
- Site of Bond Breaking in mer-(Dihapto-[60]fullerene) (Dihapto-1,2-Bis-(DiphenyIphosphino)ethane Tricarbonyl Tungsten(0)
- Kinetic and mechanistic studies of mono(terpyridine)- to bis(terpyridine)-nickel(II) complex formation reactions involving a range of substituted 2,2′:6′,2″-terpyridine ligands: an investigation of π-stacking interactions in outer-sphere complexes.
- Kinetics and mechanism of reaction of α-picolinic acid with dichloro-{2-(arylazo)- heterocycle}palladium(II) complexes
- Simulation of Complex Chemical Kinetics
- Kinetics and Mechanisms of the Reduction of Chromium(VI) by 2-Mercaptoethanesulfonic Acid in Aqueous Solution: Difference in the Mechanistic Process of Reduction with Noncarboxylate Thiols
- Salt Effects on Reactivity for Substitution Reactions of Pentacyanoferrate(II) Complexes
- Substitution of aqua ligands from ds-[Pt(en)(H2O)2](ClO4)2 and cis-[Pt(dmen)(H2O)2](ClO4)2 (en = ethylenediamine, dmen = Ν,Ν′-dimethylethylenediamine) by glutathione (reduced) (GSH) in aqueous medium - A Kinetic And Mechanistic Study.
- Synthesis, Characterisation and Dissociation of a Glycinate Bridged Trinuclear Co(III)-Cu(II)-Co(III) Complex
- Notes for Contributors. Inorganic Reaction Mechanisms (IRM)
