On the basis of elementary chemical considerations, it is shown that proton-producing redox reactions of oxyanions are expected to be autocatalytic and to manifest propagating acidity fronts. The conditions of proton production in redox reactions are established and verified experimentally by the reactions of S2032-, S4062-, S2042-, S032-, S2062-, and N2H5+ with Br03~, I03", C103", C102", and S2082-. Twenty new propagating acidity front reactions have been discovered among the possible combinations of these reactions.

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The kinetics of the reaction between BrO 3Ϫ and sulfite was studied by measuring the concentrations of [Br Ϫ ] and [H ϩ ] both in buffered and in unbuffered solutions. A mechanism was applied for simulation of the experimental observations. Rate constants k ϭ 1 and were determined for the following reactions: Rate constant k 1 was obtained directly from the experimental results on unbuffered reactions, where Reaction (1) was predominant. Rate constant k 2 was obtained by computer fitting of [Br Ϫ ] to the experimental values for buffered reactions, where the rate of Reaction (2) was about four times higher than that of Reaction (1).

The cobaltous acetate-catalyzed autoxidation of benzaldehyde in acetic acid has been investigated and the nature and the mechanism of the oxidation at high cobaltous concentration (1.2-5 x M) has been studied in detail. The induction period appearing at the beginning of the limiting rate region is explained by the inhibition brought about by the cobaltous ions. The inhibiting effect of the transition metal ions studied has been shown to be due to their electronic structure. The limiting rate of oxidation at high cobalt concentrations could be explained on the basis of the steady-state concentration of perbenzoic acid produced by the catalyst.

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