Malonic acid Reactions

Lengyel I, Rabai G and Epstein I R Experimental and modelling study of oscillations in the chlorine dioxide-iodine-malonic acid reaction J. Am. Chem. See. 112 9104-10... 

Some of these chlorite oscillators exhibit particularly interesting or exotic phenomena. Batch oscillations in the absence of flow may be obtained in the systems numbered 3, 10 a and 13, while the chlorite-iodide-malonic acid reaction gives rise to spatial wave patterns as well. These latter, which are strikingly similar to those observed in the BZ reaction61 are shown in Fig. 12. Addition of iodide to the original chlorite-iodate-arsenite oscillator produces a system with an extremely complex phase diagram58, shown in Fig. 13, which even contains a region of tristability, three possible stable steady-states for the same values of the constraints. 

Malapradian oxidations by lO , 435 maleate ion, effect on HNCO+H2O, 287 malic acid, reaction+S20g , 473, 474 malonic acid, reaction+IO , 455, 456 manganese(Il), catalysis of decomposition of HzSOs, 338... 

Oscillating reactions In these coupled autocatalytic reactions, repeated undamped oscillations occur in concentrations of reactants. These reactions have been reviewed by Field. For example, in the cerium-catalyzed reaction of bromate with malonic acid, changes in concentration of bromide ion and in the Ce(rV)-Ce(III) ratio over several orders of magnitude occur repeatedly. These systems as yet are not well understood. For the bromate-malonic acid reaction a 10-step process for the mechanism has been proposed. ... 

For an application of Hopf bifurcations, we now consider a class of experimental systems known as chemical oscillators. These systems are remarkable, both for their spectacular behavior and for the story behind their discovery. After presenting this background information, we analyze a simple model proposed recently for oscillations in the chlorine dioxide-iodine-malonic acid reaction. The definitive reference on chemical oscillations is the book edited by Field and Burger (1985). See also Epsteinet al. (1983), Winfree (1987b) and Murray (1989). 

De Kepper, P., V. Castets, E. Dulos J. Boissonnade. 1991. Turing-type chemical patterns in the chlorite-iodide-malonic acid reaction. Physica 49D 161-69. 

Horvath, A.K., Dolnik, M., Zhabotinsky, A.M., Epstein, I.R. Kinetics of photoresponse of the chlorine dioxide-iodine-malonic acid reaction. J. Phys. Chem. A 104(24), 5766-5769... 

Rudovics, B., Barillot, E., Davies, P.W., Dulos, E., Boissonade, J., De Kepper, R Experimental smdies and quantitative modeling of Turing patterns in the (chlorine dioxide, iodine, malonic acid) reaction. J. Phys. Chem. A 103, 1790-1800 (1999). http //dx.doi.org/ 10.1021/jp983210v... 

Another set of pattern formation phenomena involve stationary, or Turing patterns (77), which arise in systems where an inhibitor species diffuses much more rapidly than an activator species. These patterns, which are often invoked as a mechanism for biological pattern formation, were first found experimentally in the chlorite-iodide-malonic acid reaction (72). Examples of typical spot and stripe patterns appear in Figure 3. Recently, experiments in reverse microemulsions have given rise not only to the waves and patterns described above, but to a variety of novel behaviors, including standing waves and inwardly moving spirals, as well (75). 

Figure 3. Turing patterns in the chlorite-iodide-malonic acid reaction. Dark areas show high concentrations of starch-triiodide complex. Each frame is approximately 1,3 mm square. Images courtesy of Patrick De Kepper,...

Noyes for bromate-malonic acid reaction and involves formation of BrOg radicals which oxidize the reduced metal complex. Silver(i) inhibition in the gallic acid reaction is observed, presumably by reduction of the Br present... 

Figure 3. Turing patterns in the chlorine dioxide-iodine-malonic acid reaction in an unstirred gel reactor. Initial concentrations [malonic acid] 1x1 (T M, [IJ = SxlOr M [CIOJ = Mfleft). I-5xlff M (right).

Figure 6.14 Patterns observed in the chlorite-iodide-malonic acid reaction in a Couette reactor. The CSTR composition, flow rate, and rotation rate are held fixed, except for chlorite composition in one CSTR, whieh serves as the bifurcation parameter. In each frame, the abscissa represents the position along the reactor and the ordinate represents time. The dark color results from the presence of the starch- triiodide complex. (Adapted from Ouyang et al., 1991.)...

Lengyel, I. Rabai, G. Epstein, I. R. 1990b. Experimental and Modeling Study of Oscillations in the Chlorine Dioxide-Iodine-Malonic Acid Reaction, J. Am. Chem. Soc. 7/2, 9104-9110. 

Perraud, J, J. Agladze, K. Dulos, E, De Kepper, P. 1992, Stationary Turing Patterns versus Time-Dependent Structures in the Chlorite-Iodide Malonic Acid Reaction, Physica A 188, 1-16. 

Figure 19.10 (a) Turing structure in a one-dimensional Brusselator model, (b) Turing structures observed in chlorite-iodide-malonic acid reaction in an acidic aqueous solution (Courtesy Harry L. Swinney). The size of each square is nearly 1 mm. 

An interesting example of oscillation in a chemical system has been described in the bromate-cerium(iv)-malonic acid reactions in sulphuric acid media. In a stirred acidic solution containing initially KBrOa, malonic acid, and cerium(iv) sulphate, the concentrations of the cerium(rv) and of bromide ion produced may be monitored potentiometrically using a tungsten and a bromide-ion-sensitive electrode, respectively, and have been shown to undergo marked repeated oscillations. A mechanism has been postulated in which both the overall chemical reactions and those responsible for the oscillations have been identified. In the conditions of malonic acid (0.1—0.5 mol 1 ), BrOj ( 0.06 mol 1 ), and Ce ( 10" mol 1 ) in 0.8M-sulphuric acid, there are three overall reactions,... 

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