Inhibition of chemical oscillations by bromide ion in the Briggs–Rauscher reaction

The addition of bromide ions to the component solutions of the Briggs– Rauscher oscillating system produces a variety of phenomena, depending on the sequence of the addition and on the initial bromide concentration. If the addition is made some minutes after the mixing of H₂O₂ and acidic IO₃⁻ and before adding malonic acid and Mn²⁺ ions, the oscillations last for five or six cycles, then suddenly ceases. If the addition is made immediately after the mixing of H₂O₂ and acidic IO₃⁻ and before adding malonic acid and Mn²⁺ ions, the oscillations do not start at all. The addition of bromide ions to an actively oscillating BR reaction causes a rapid suppression of the oscillations. Our observations may be accounted for by a mechanism involving the IBr species. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 641–646, 1998