Reduction of carboxylato bound chromium(V) by several reducing agents such as N2H4, NH2OH, Ti(III), Fe(II), VO2+, U(IV) formed part of earlier studies in which electron transfer to Cr(V) seems to occur through nitrogen or by inner or outer sphere path. In the chromium(V) oxidation of lactic acid, saturation kinetics has been observed and the association constant,K, evaluated from a double reciprocal plot, indicates weak interaction between reactants. In contrast, the reduction of Cr(V) by thiolactic acid exhibits total second order kinetics-first order with respect to each reactant. Probably the Crv-S bond is weaker than the Crv-O bond and electron transfer mediated through the sulphur system is facile. Under identical conditions Cr(VI) seems to be a better oxidant for lactic than for thiolactic acid.
Volume 134, 2022
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