Chemical Oscillations and Waves in the Catalyzed Bromate-Pyrocatechol Reaction

Long time series of temporal oscillations and wave formation are observed in the catalyzed bromate-pyrocatechol reaction conducted in a batch reactor, in which the induction time is insensitive to the presence of ferroin but is greatly shortened by Ce(III) or Mn(II). On the other hand, the number of oscillations is significantly increased by ferroin, while it is less sensitive to Ce(III) and Mn(II). The ferroin-catalyzed system also exhibits strong photosensitivity, in which illumination could quench the oscillatory behavior. A phase diagram illustrates that the oscillatory behavior of the studied system is more sensitive to the ratio of [pyrocatechol]/[bromate] than their absolute concentrations. Reactions conducted in a spatially extended medium show that the ferroin-catalyzed system supports a two-stage pattern formation with the wave activity surviving for up to 10 h.