Kinetic study of some reactions related to the Mn(II)-catalyzed bromate-saccharide oscillating reactions

In the stirred batch experiment, the Mn(II)-catalyzed bromate-saccharide reaction in aqueous H₂SO₄ or HClO₄ solution exhibits damped oscillations in the concentrations of bromide and Mn(II) ions. Peculiar multiple oscillations are observed in the system with arabinose or ribose. The apparent second-order rate constants of the Mn(III)-saccharide reactions at 25°C are (0.659, 1.03, 1.76, 2.32, and 6.95) M^?1 s^?1 in 1.00 M H₂SO₄ and (4.69, 7.51, 10.2, 13.5, and 36.2) M^?1 s^?1 in (2.00–4.00) M HClO₄ for (glucose, galactose, xylose, arabinose, and ribose), respectively. At 25°C, the observed pseudo-first-order rate constant of the Mn(III)-Br^? reaction is k_obs = (0.2 ± 0.1) Br^?] + (130 ± 5)Br^?]² + (2.6 ± 0.1) × 10³Br^?]³ + (1.2 ± 0.2) × 10⁴Br^?]⁴ s^?1 and the rate constant of the Br₂? Mn(II) reaction is less than 1 × 10^?4 M^?1 s^?1. The second-order rate constants of the Br₂-saccharide reactions are (3.65 ± 0.15, 11.0 ± 0.5, 4.05, 12.5 ± 0.7, and 2.62) × 10^?4 M^?1 s^?1 at 25°C for glucose, galactose, xylose, arabinose, and ribose, respectively.