Effects of Ce(III) and Mn(II) on the Dushman reaction and simulations of the Briggs–Rausher reaction

The Dushman reaction (reduction of iodate by iodide) is a subsystem of the Briggs–Rausher oscillating reaction. We show that the previously observed effects of Ce(III) and Mn(II) on the kinetics of the Dushman reaction are mainly ionic strength effects. The observed decrease of the rate constant of the Dushman reaction when the ionic strength increases and the formation of the ion pairs MnSO4(aq) and CeSO4 + explain quantitatively our kinetic results. We also show why the original mechanism of the Briggs–Rausher reaction must be revised and propose a variant of the mechanism proposed in 2002 by Furrow, Cervellati and Amadori. This variant establishes a relationship with the reduction of iodate by high concentrations of hydrogen peroxide and the non-catalyzed BR reaction.