Abstract
The kinetic behavior of the autocatalytic oxidation of hemin by acidic bromate was studied spectrophotometrically. The reaction was shown to differ significantly from both the acidic decomposition and the direct bromination of hemin. The dependence of its maximal rate on the reactant concentrations was established as v = k[hemin]^0.8^[BrO^−^~3~][H^+^]^1.2^. The value of the net rate constant was determined at two different ionic strengths. In the reaction path BrO^.^~2~ radicals rather than elementary bromine play a crucial role. A mechanism is presented which takes into account the results of bromate chemistry as described for the Belousov–Zhabotinsky (BZ) reaction completed with the appropriate steps of hemin. On the basis of the suggested mechanism, model calculations were carried out which allowed to give an estimation for the rate constant of the reaction between hemin and BrO^.^~2~ radicals. The results of computations account for the main experimental features of the reaction. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 503–509, 2006