Simulations of the iodide ion perturbed uncatalyzed Belousov-Zhabotinskii oscillator with 1-hydroxy-4-(2-(methylamino)propyl)benzene

Györgyi, László; Varga, Margit; Kőrös, E.; Field, Richard J.; Ruoff, Peter

doi:10.1021/j100344a027

Cited by 24 publications

(20 citation statements)

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“…These mechanisms neglect bromoderivatives of the initial reductant as a source of bromide, despite the fact that the oxidation of these bromoderivatives is believed to deliver most of the Br -in the catalyzed BZ reaction. An alternative mechanism for the UBO 20 suggests that bromoderivatives of the organic substrate provide the source of Br -. Our experiments show that prebromination of CHD diminishes, and can practically eliminate, the induction period.…”

Section: Discussionmentioning

confidence: 99%

Bromate−1,4-Cyclohexanedione−Ferroin Gas-Free Oscillating Reaction. 1. Basic Features and Crossing Wave Patterns in a Reaction−Diffusion System without Gel

et al. 1996

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We present a study of the bromate-1,4-cyclohexanedione-ferroin oscillating reaction in both well-stirred and reaction-diffusion systems. We investigate the dependence of the system dynamics on the initial reagent concentrations, with the initial concentration of ferroin varied from 0 to 5 × 10 -3 M, and show that the system behaves like a typical BZ oscillator if the concentration of ferroin exceeds 5 × 10 -5 M. We demonstrate spontaneous formation of spiral waves and transverse wave fronts in quasi-two-dimensional systems and formation of crossing wave patterns in thin layers of solution open to air. IntroductionThe Belousov-Zhabotinsky (BZ) reaction-diffusion system is perhaps the most commonly employed tool for experiments on chemical waves and pattern formation. [1][2][3][4][5][6][7] The ferroincatalyzed reaction with malonic acid as the initial reductant has been the most frequently used BZ system for this purpose. An important drawback of this reaction is the production of carbon dioxide, which results in the formation of bubbles that disturb the reaction-diffusion patterns and make it difficult to conduct lengthy experiments in either batch or open reactors. Attempts have been made to develop gas-free versions of the BZ reaction. 8 Unfortunately, these variants do not generate the range of chemical wave behavior found in the ferroin-malonic acid BZ reaction. Recently, showed that target patterns develop in the bromate-1,4-cyclohexanedione-ferroin reaction-diffusion system without formation of bubbles. They used ferroin at a concentration of 5 × 10 -4 M and considered it to be only an indicator, implying that the reaction is an uncatalyzed bromate oscillator (UBO). [9][10][11][12] Here we present further results related to both the uncatalyzed and the ferroin-catalyzed systems. We study the dependence of the system dynamics on the initial reagent concentrations, with that of ferroin varied from 0 to 5 × 10 -3 M, and show that the system behaves like a typical BZ oscillator if the concentration of ferroin exceeds 5 × 10 -5 M.The absence of bubbles and precipitate makes the present system an excellent tool for experiments on chemical waves and patterns. We demonstrate spontaneous formation of spiral waves and transverse wave fronts in quasi-two-dimensional systems and the formation of crossing wave patterns in thin layers of solution open to air.Some preliminary mechanistic considerations are also suggested. Experimental SectionMaterials. Stock solutions of 1.0 M NaBrO 3 (Janssen Chimica, 99+%), 0.3 M 1,4-cyclohexanedione (abbreviated as CHD) (Aldrich, 98%) dissolved in 1.0 M H 2 SO 4 by stirring the solution on a hot plate (40-50°C) for about 30 min, 0.025 M ferroin (prepared from the calculated amount of FeSO 4 ‚7H 2 O (Fisher, certified) and 1,10-phenanthroline (Aldrich, 99+%)), 0.2 M NaBr (Fisher, certified), and 1.0-10.0 M H 2 SO 4 were used to prepare the working solutions.Apparatus and Procedures. Batch experiments with the bromate-CHD and the bromate-CHD-ferroin systems were performed in a thermosta...

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Section: Discussionmentioning

confidence: 99%

Bromate−1,4-Cyclohexanedione−Ferroin Gas-Free Oscillating Reaction. 1. Basic Features and Crossing Wave Patterns in a Reaction−Diffusion System without Gel

et al. 1996

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“…5 In later years, an extended mechanism 6 was suggested, and also, reduced models were published in the literature. 7 Generally, UBOs are composed of an aromatic (mostly a phenol or an aniline derivative), bromate ion, and sulfuric acid.…”

Section: Introductionmentioning

confidence: 99%

The 1,4-Cyclohexanedione−Bromate−Acid Oscillatory System. 3. Detailed Mechanism

Szalai

Kőrös

1998

J. Phys. Chem. A

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1,4-Cyclohexanedione (CHD) in its reaction with acidic bromate undergoes aromatization and one of the main resulting products 1,4-dihydroxybenzene (H2Q) is further oxidized and brominated to 1,4-benzoquinone and bromoorganics. The kinetics of H2Q formation, of the reaction of CHD and Br2, as well as of the reaction between H2Q and bromate ion, were followed spectrophotometrically. The latter reaction exhibited Landolt (clock)-type dynamics. On the basis of our earlier analytical and present kinetic investigations, a detailed mechanistic model has been suggested that could well simulate the temporal oscillations of the title system. H2Q plays an essential role in the mechanism and is responsible for the unusual behavior (200−300 oscillations) of this chemical oscillator. We pointed to the relation that may exist between the CHD−bromate−acid system and those reported as oscillatory Landolt-type reactions [e.g., I − S − Fe(CN ].

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“…The oxidation of safranine results in the formation of a transient intermediate, probably an oxime (SB), followed by further oxidation 11, 16. During the oxidation involving bromine and hypobromous acid, formation of brominated aromatics as transient intermediates in oxidation reactions involving bromine are well known 15–17, 18. Such brominated intermediates form a temporary sink for bromine to delay the generation of bromide.…”

Section: Resultsmentioning

confidence: 99%

Kinetics and simulations of reaction between safranine‐O and acidic bromate and role of bromide therein

Jonnalagadda

Shezi

Gollapalli

2002

Int J of Chemical Kinetics

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Safranine-O, a dye of the phenazinium class, was found to exhibit intricate kinetics during its reaction with bromate at low pH conditions. Under conditions of excess concentrations of acid and bromate, safranine-O (SA + ) initially depleted very slowly (k = (3.9 ± 0.3) × 10 −4 M −3 s −1 ) but after an induction time, the reaction occurred swiftly. Bromide exhibited a dual role in the reaction mechanism, both as an autocatalyst and as an inhibitor. The added bromide increased the initial rate of depletion of SA + , but delayed the transition to rapid reaction. The overall stiochiometric reaction was found to be 6SA + + 4 BrO 3 − = 6SP + 3N 2 O + 3H 2 O + 6H + + 4Br − , where SP is 3-amino-7-oxo-2,8-dimethyl-5-phenylphenazine. The fast kinetics of the reaction between aqueous bromine and safranine-O (k = (2.2 ± 0.1) × 10 3 M −1 s −1 ) are also reported in this paper A 17-step mechanism, consistent with the overall reaction dynamics and supported by simulations, is proposed and the role of various bromo and oxybromo species is also discussed.

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Simulations of the iodide ion perturbed uncatalyzed Belousov-Zhabotinskii oscillator with 1-hydroxy-4-(2-(methylamino)propyl)benzene

Cited by 24 publications

References 0 publications

Bromate−1,4-Cyclohexanedione−Ferroin Gas-Free Oscillating Reaction. 1. Basic Features and Crossing Wave Patterns in a Reaction−Diffusion System without Gel

Bromate−1,4-Cyclohexanedione−Ferroin Gas-Free Oscillating Reaction. 1. Basic Features and Crossing Wave Patterns in a Reaction−Diffusion System without Gel

The 1,4-Cyclohexanedione−Bromate−Acid Oscillatory System. 3. Detailed Mechanism

Kinetics and simulations of reaction between safranine‐O and acidic bromate and role of bromide therein

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