Surface-induced stirring effects in the manganese-catalyzed Belousov-Zhabotinskii reaction with a mixed hypophosphite/acetone substrate in a batch reactor

Abstract

Tschuikow-Roux, E.; Rauk, A. J. Phys. Chem. 1991, 95,9832. (b) Chen, Y.; Rauk, A.; Tschuikow-Roux, E. J. Phys. Chem. 1991, 95.9900. (1 5) Pople, J. A.; Head-Gordon, M.; Fox, D. J.; Raghavachari, K.; Curtis, (16) Corbett, P.; Tarr, A. M.; Whittle, E.A manganese-catalyzed Belousov-Zhabotinskii (BZ) reaction with a mixed hypophosphite/acetone substrate was found to be remarkably sensitive to stirring in a batch reactor. The reaction d a t e d in a container with a gas/liquid interface (either air or nitrogen). However, when the reaction was stirred in a sealed flask with no interface, the system remained in the reduced state. When the slow stirring (about 100 rpm) was stopped, a pink color from Mn(II1) was observed to ascend from the Teflon-coated stir bar. When a glass stir bar was used, the system would oxidize much more slowly than with the Teflon one. A possible mechanism is considered in which bromine loss to the gas phase is crucial for oscillation. In the sealed system, oxidation occurs when the stirring is stopped because bromine can adsorb to the surface of the Teflon, allowing local oxidation which spreads throughout the system.

Transient complex oscillations in a closed chemical system with coupled autocatalysis

“…Here, the initial concentration of H 2 Q is 0.015M, while all other reaction conditions are identical to those used in Fig. 38,39 Gas exchange such as O 2 absorption and/or Br 2 loss in a reactor with an open surface has also been considered as an important factor. A dramatic decrease in the frequency of oscillation can be seen; especially the frequency of the first several peaks ͑about 8 min per peak͒ is significantly slower than that in Fig.…”

Mechanism and Phenomenology of an Oscillating Chemical Reaction

“…Other than purging the system with an inert gas, stirring may physically remove Br 2 from the system [101,102]. Bromine might also be removed chemically, as demonstrated by Noszticzius, Rastogi and others in the mixed organic substrate systems involving oxalic, tartaric or mandelic acids with acetone or some other ketones [103][104][105].…”

“…Ouyang et al suggested several "bubble-free" systems suitable for studying pattern formation, including the manganese-catalysed hypophosphate (H 2 PO 2 -)-acetone system, but had limited success in finding appropriate conditions for oscillations [109]. Pojman et al demonstrated that the ability of these dual-catalyst systems to display oscillations is extremely sensitive to the stirring rate, suggesting that the escape of bromine into the gas phase still plays an important role [102]. Recently, Orbán et al [110] proposed a hypophosphate-acetone-dual catalyst system that displays oscillations over a reasonable range of concentrations and has the added advantage of long-lived behaviour in batch, without the production of gaseous or solid by-products.…”

Effect of mixed methyl ketones on the catalyzed resorcinol based oscillatory reaction at different temperatures

“…cyclohexanone [15] and acetone [16] in wide range of concentrations of the substrates have been reported, but the effect of binary mixtures of ketones (mixed ketones) on BZ system containing aromatic compounds as the main substrate has not been studied till date. Although, it is reported that oscillations exhibit remarkable change with ketones, e.g., increasing or decreasing the concentration of acetone causes the concentration of Br 2 to be either very low or else high [17].…”