Synthesis of Chemical Oscillations

In this chapter, we will examine how chemical oscillation can arise, in general, and how it is possible to create chemical reactions that are likely to show oscillatory behavior. In the next chapter, we will discuss how to take a chemical oscillator apart and analyze why it oscillates—the question of mechanism. We also look in detail there at the mechanisms of several oscillating reactions. 

In order to gain some insight into how oscillation might arise in a chemical system, we shall consider a very simple and general model for a reaction involving two concentrations, u and v. Two independent concentration variables is the 

Excitability is an important property in many biological systems, such as neurons, and it is also closely connected with traveling waves in chemical systems. Excitability has two important characteristics a threshold of excitation and a refractory period. The threshold is the minimum perturbation that will cause 

We have just seen that oscillation can arise in a two-variable system in which one variable changes significantly faster than the other and has relatively complex 

one way to design a chemical oscillator might be to look for systems that obey rate equations like eqs. (4.1). Let us ignore, for the moment, the question of where one might hope to find real systems that have the right kinetics and look first at a beautifully simple model that captures the essence of eqs. (4.1) and points us toward a way of designing real chemical oscillators. The model, proposed by Boissonade and De Kepper (1980), consists of two rate equations for the species x and y  

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Synthesis of Chemical Oscillations 79 Table 4.1 Chlorite-Based Chemical Oscillators in a CSTR... 

Many of the most remarkable achievements of chemical science involve either synthesis (the design and construction of molecules) or analysis (the identification and structural characterization of molecules). We have organized our discussion of oscillating reactions along similar lines. In the previous chapter, we described how chemists have learned to build chemical oscillators. Now, we will consider how to dissect an oscillatory reaction into its component parts—the question of mechanism. 

The typical Xx in condensed phases is no longer than 10 s. This is much longer than characteristic times of oscillation periods of atoms and molecules ( 10 to 10 s) but, on the other hand, much shorter than characteristic times that are necessary to detect stepwise chemical transformations (see following) in chemical synthesis, catalysis, and so on. 

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