Kinetic study of the ferriin oxidation of malonic acid and its derivatives. Implication in the Belousov-Zhabotinsky reaction

Ferroin (Fe(phen)₃²⁺) behaves differently from Ce(III) or Mn(II) as a catalyst for the Belousov-Zhabotinsky reaction with malonic acid (MA) or methylmalonic acid (MeMA). The kinetics of the ferriin (Fe(phen)₃³⁺) oxidation of MA, MeMA, bromomalonic acid (BrMA), bromomethylmalonic acid (BrMeMA), dibromomalonic acid (Br₂MA), oxalic acid (OA), and bromide ion were studied under anaerobic or aerobic conditions. It was found that under anaerobic conditions the order of relative reactivities toward ferriin oxidation is Br₂MA > OA ≫ (MA, BrMA, MeMA, BrMeMA) whereas under aerobic conditions the order is BrMA > MeMA > Br₂MA > MA > OA > BrMeMA. Under anaerobic conditions, Ce(IV) is more reactive than ferriin in oxidizing OA, MA, BrMA, and MeMA whereas it is less reactive in oxidizing Br₂MA and Br^- ion. Simulations of kinetic data based on proposed mechanisms are also carried out.