Dynamics and Mechanism of Bromate Oscillators with 1,4-Cyclohexanedione

Abstract

Experimental and numerical studies of the temporal behavior of the acidic bromate-1,4-cyclohexanedione batch reaction in the presence of Ce(SO 4 ) 2 , MnSO 4 , or Ru(bipy) 3 SO 4 catalyst are reported. With increasing concentration of catalyst and at [H 2 SO 4 ] e 1 mol/dm 3 these systems show the following bifurcation sequences: uncatalyzed oscillations f clock reaction (with excitability) f catalyzed oscillations, while at [H 2 SO 4 ] g 1.5 mol/dm 3 the sequence is uncatalyzed oscillations f catalyzed oscillations. A chemical mechanism based on kinetic measurements of some component reactions is suggested and used to simulate the experimentally found bifurcation sequences and the monotonic and nonmonotonic recovery of the system after perturbation of the excitable state. A reduced model for the bromate-CHD-catalyst system is developed and analyzed.

CO2 production in the bromate‐1,4‐cyclohexanedione oscillatory reaction

“…This product distribution was essentially identical in catalyzed and non-catalyzed reactions at 90 8C. In a manner consistent with an earlier mechanistic investigation, [10] our experiments show no ring-opening products in the reaction between ferriin and CHD at elevated temperature.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] While in most of the bromate-cyclic compound oscillators the oscillatory behavior is short-lived when studied in a batch system, [1,2] over 200 oscillation peaks have been achieved in the closed bromate-1,4-cyclohexanedione (CHD). [3] The long lasting oscillatory dynamics, coupled with the absence of gas production, has made the bromate-CHD reaction a new popular model system for the investigation of nonlinear spatial-temporal dynamics, [13][14][15] an important behavior that has been encountered in a variety of systems ranging from physical to biological systems.…”

Transient complex oscillations in a closed chemical system with coupled autocatalysis

“…22,29 According to these existed models, the following reactions take place: where Q ͑1,4-benzoquinone͒ is the oxidation product of hydroquinone and is not involved in further reactions. 22,29 According to these existed models, the following reactions take place: where Q ͑1,4-benzoquinone͒ is the oxidation product of hydroquinone and is not involved in further reactions.…”

“…In comparison to externally perturbed nonlinear media, which have been explored extensively in the last two decades, [9][10][11][12][13][14][15][16][17][18] behaviors of intrinsically coupled chemical systems have not been well understood. The protocol we investigated in this study is introducing hydroquinone into the classical BZ reaction, in which, according to the mechanism proposed for the 1,4-cyclohexanedione ͑1,4-CHD͒-bromate oscillator, [20][21][22] hydroquinone competes with ferroin to react with brominedioxide radicals and thus builds up coupled autocatalytic processes. 19 Their investigation demonstrates that a small perturbation could induce dramatic changes in the reaction behavior when applied directly to the nonlinear feedbacks.…”

Self-Organized Traveling Chemo-Hydrodynamic Fingers Triggered by a Chemical Oscillator

“…This rules out that convection is due to double diffusion triggered by a larger amount of fast diffusive protons in the lower layer. A difference in diffusivity between the oxidized and reduced forms of the catalyst independently of the oscillatory mechanism is also excluded because convection appears as well using the uncatalyzed Bromate-CHD oscillator, 29 which oscillates even in the absence of the catalyst. Convective fingers are then present in the Schlieren view even if the absence of a color change due to the absence of ferroin does not allow one to follow the concentration dynamics.…”