An Additional Negative Feedback Loop in the Classical Belousov-Zhabotinsky Reaction: Malonyl Radical as a Second Control Intermediate

Article abstract of DOI:10.1021/j100344a011

Reactions of malonyl radicals with inorganic bromine species (oxidation numbers -1 to +5) of the Belousov-Zhabotinsky (BZ) reaction are investigated in 1 M sulfuric acid medium by electron spin resonance spectroscopy in continuous-flow experiments.A very high reaction rate is found for BrO2^. (k₇ ca. 5*1E9 M^-1 s^-1), followed by Br2 and HOBr (k₉ < 1.5*1E8 M^-1 s^-1 and k₈ < 1*1E7 M^-1 s^-1, respectively).At high concentrations acidic bromate and bromide have some effect too, but this is probably due to indirect reactions.The results indicate that malonyl radical plays an important role as a second control intermediate besides bromide ion in the oscillatory mechanism of the BZ reaction.