caa a22 4500 37887117X CHVBK 20180305123409.0 cr unu---uuuuu 161128e20030101xx s 000 0 eng 10.1515/irm-2003-0106 doi (NATIONALLICENCE)gruyter-10.1515/irm-2003-0106 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 [Elektronische Daten] [Dwight C. Ramdon, Donovan A. Dixon, Tara P. Dasgupta] 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 reduction kinetics nationallicence chromium(VI) nationallicence 2-mercaptoethanesulfonic acid nationallicence thioester nationallicence Ramdon Dwight C. aut Dixon Donovan A. aut Dasgupta Tara P. aut BioInorganic Reaction Mechanisms De Gruyter 5/1(2003-01-01), 47-58 2191-2483 5:1<47 2003 5 irm https://doi.org/10.1515/irm-2003-0106 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1515/irm-2003-0106 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ramdon Dwight C. aut NATIONALLICENCE 700 1- Dixon Donovan A. aut NATIONALLICENCE 700 1- Dasgupta Tara P. aut NATIONALLICENCE 773 0- BioInorganic Reaction Mechanisms De Gruyter 5/1(2003-01-01), 47-58 2191-2483 5:1<47 2003 5 irm CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter