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

Abstract

Abstract In the stirred batch experiment, the Mn(II)‐catalyzed bromate‐saccharide reaction in aqueous H 2 SO 4 or HClO 4 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 H 2 SO 4 and (4.69, 7.51, 10.2, 13.5, and 36.2) M −1 s −1 in (2.00–4.00) M HClO 4 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) × 10 3 [Br − ] 3 + (1.2 ± 0.2) × 10 4 [Br − ] 4 s −1 and the rate constant of the Br 2 Mn(II) reaction is less than 1 × 10 −4 M −1 s −1 . The second‐order rate constants of the Br 2 ‐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.