Oscillating iodine clock

Briggs, T. and Rauscher, W. (1973). An oscillating iodine clock. J. Chem. Educ., 50,... 

B An Oscillating Iodine Clock (Briggs-Rauscher Reaction)... 

IIIB) Dutt, A. K., Banerjee, R. S. Oscillating Iodine Clock Reaction in Presence of Chloride 1981-2 Ions. J. Indian Chem. Soc. 58, 717-719... 

Briggs and Rauscher discovered an oscillating reaction which is identified as an iodine clock. It resembles the iodate-hydrogen peroxide reaction of Bray (1921), and has some of the elements of the reaction of Belousov, see Section III.C. The chemicals involved are ... 

Bromate and iodate salts are prepared on a much smaller scale than chlorates. Under appropriate conditions, these ions undergo oscillating chemical reactions known as chemical clocks. The best known clock reaction is observed when an acidified solution of sodium sulfite (Na2S03) is mixed with an excess of iodate in the presence of starch indicator. After a suitable induction period allowing for sodium sulfite reduction of iodate to iodide [Eq. (44)], the blue, starch-iodine color periodically appears and disappears as the iodide is oxidized to iodine [Eq. (45)], and the iodine is reduced back to iodide [Eq. (46)]. 

The kinetics of the batch reaction between chlorine(III) and iodine species has now been documented. It is known that chloride ion accelerates the decomposition of Cl(III) in acid media. It is natural to speculate on the effect bromine species would have on Cl(III). Would the system Cl(III)-Br oscillate Would it "clock" What reaction would occur when Cl(III) and Br2 are mixed Would mechanistic analysis require postulation of BrC102 type intermediates To find out, we mixed Cl(III) with Br in flow and batch, and reacted Br2 (and Br3 ) with Cl(III) in batch. 

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