Complex rate law for the cerium(IV) oxidation of glycolic acid in the medium HClO4–Na2SO4–NaClO4

The kinetics of the cerium(IV) oxidation of glycolic acid have been studied in the medium HClO₄? Na₂SO₄? NaClO₄ at varying organic substrate (HL), hydrogen, and bisulfate ion concentrations at 25.0°C and ionic strength 2.0M. Under the experimental conditions used (0.03 ? H⁺] ? 0.5M; 0.02 ? HSO₄^?] ? 0.1M; 0.01 ? HL] ? 0.1M) the observed pseudo-first-order rate constant k_obs has been found to follow the complex expression where the values of the various constants have been estimated by a nonlinear least-squares method. According to this expression the oxidation process occurs significantly through three simultaneous pathways. Moreover three equilibria involving cerium(IV) and HSO₄^? (or SO₄^2?) ions are important from a kinetic point of view, whereas only two equilibria involving the corresponding complexes with the organic substrate are predominant.