The Belousov-Zhabotinsky Reaction
The reaction involves the oxidation of an organic species (malonic acid) from an acidified bromate solution, in the presence of a metal ion catalyst. Different metal ions have been used, with the Ce(III)/Ce(IV) and [Fe(II)phen)]2+/[Fe(III)phen)]3+ being more common. The history of this reaction begins in 1951 when Boris Belousov1, a Soviet biophysicist, was looking for an inorganic analogue of the biochemical Krebs cycle. He noticed that the colour of a mixture consisting of bromate and cerium ions with citric acid in sulfuric acid switched repeatedly between colourless [Ce(III)] and pale yellow [Ce(IV)] with a period of a minute or so. The reaction had shown oscillating behaviour. The results were published but no one paid any attention because it was thought that chemical oscillations where thermodynamically impossible. It was Anatol Zhabotinsky2 who began to study and modified the initial "recipe" by changing citric acid with malonic acid and employing a different catalyst (ferroin-ferriin). He characterised much of the chemistry and showed that, in an unstirred system, the reaction gave rise to target patterns3. The Belousov-Zhabotinsky (BZ) reaction became widely known to the west at a conference on biological and biochemical oscillators in 1968 at Prague4. The BZ reaction is one of the most studied oscillating chemical systems, yet its reaction mechanism is not yet fully understood.
- B. P. Belousov (1958). Sb. Ref. Radiats. Med.Medgiz, Moscow, 1959, p 145. The early history of the BZ reaction is described in: A. T. Winfree (1984). J. Chem. Educ., 61, 661.
- A. M. Zhabotinsky (1964). Proc. Acad. Sci., USSR, 157, 392.
- A. T. Winfree (1978). Prog. Theor. Chem., 4, 1.
- B. Chance, E. K. Pye, A. K. Ghosh, B. Hess (eds) (1973). Biological and Biochemichal Oscillators. Academic Press, New York.