Minimal bromate reaction mechanisms

We studied the autocatalytic minimal bromate reaction, which can be oscillatory, but was studied in a bistable regime. A proposed mechanism for this reaction, and participating species, are listed in Table 10.1. 

Table 10.1. Reaction mechanism for the minimal bromate reaction, from (5)...

For the first purpose we choose a chemical reaction system with some ionic species, as for example the minimal bromate reaction, for which we presented some experiments in Chap. 10. The system may be in equilibrium or in a nonequilibrium stationary state. An ion selective electrode is inserted into the chemical system and coimected to a reference electrode. The imposition of a current flow through the electrode coimection drives the chemical system (CS) away from its initial stationary state to a new stationary state of the combined chemical and electrochemical system (CCECS), analogous to driving the CS away from equilibrium in the same maimer. A potential difference is generated by the imposed current, which consists of a Nernstian term dependent on concentrations only, and a non-Nernstian term dependent on the kinetics. We shall relate the potential difference to the stochastic potential for this we need to know the ionic species present and their concentrations, but we do not need to know the reaction mechanism of the chemical sj tem, nor rate coefficients. 

While work of this type has focused primarily on chlorite systems, several new bromate oscillators, simpler in their chemistry and mechanism than the BZ system, have also been discovered. The first of these, the "minimal" bromate oscillator (Orbln, De Kepper and Epstein, [22] ) consists of bromate, bromide and either cerous or manganous ions flowed into the CSTR. It is essentially the BZ reaction with malonic acid replaced by an input of bromide (which in the batch reaction is generated by a... 

With the single exception of the chlorite-bromate-reductant systems [14], for which a mechanism has been developed by joining the NFT model [26] with THOMPSON S [42] mechanism for the BrOj -ClOo reaction, no mechanism has been published for any chlorite oscillator. In Table 2, we give a recently developed mechanism [43] for the minimal chlorite-iodide oscillator. Of special significance is the fact that it contains no radical species, but rather the binuclear intermediate CIO,. Calculations with this mechanism give excellent agreement with a wide variety of experimental results. One example is given in Fig. 5. 

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