Oxidation of Thioglycolic Acid and Glutathione by (trans-Cyclohexane-1,2-diamine-N,N,N',N'-tetraacetato)manganate(III) in Aqueous Media

Article abstract of DOI:10.1039/DT9940000841

The kinetics of the electron-transfer reactions of the manganese(III) complex of trans-cyclohexane-1,2-diamine-N,N,N',N'-tetraacetate (cdta(4-)) with two thiols thioglycolic acid and glutathione has been investigated at 30 deg C in aqueous media in the range pH 2.0-10.33 with varying reductant concentrations at constant ionic strength, I = 0.20 mol dm^-3 (NaClO4).The reactions are first order both in complex and reductants and follow the general rate law, -d/dt = k_obs = k.Both the reactions have been assumed to proceed via an inner-sphere mechanism with support for this coming from the observation of a rapid initial increase in absorption followed by a slower decay.This indicates the formation of an inner-sphere associated species which decomposes unimolecularly leading to the transfer of the electron from the thiol to the oxidant.Additional support for this mechanism comes from a comparison of the water-exchange rate of (1-) with the higher limit of the electron-transfer rates.The pH-rate profiles are bell-shaped curves and were successfully modelled by fitting the experimental data to a computer-fitted program thereby evaluating the reactivity of all the reacting species of the reductants.

Full text of DOI:10.1039/DT9940000841

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