Kinetics of the reaction of methyl iodide with sulfite and thiosulfate ions in aqueous solution

The rate of reaction of methyl iodide with sulfite ion is determined. In addition, the rate of reaction of methyl iodide with thiosulfate ion is reexamined and the rate of reaction of methyl iodide with bisulfite ion is estimated. A pronounced effect of ionic strength on the reaction rate in the methyl iodide – sulfite ion system is observed, this effect does not occur in the methyl iodide – thiosulfate ion system. The second order reaction rate constant and activation energy for the reaction of methyl iodide with the respective nucleophiles are: SO32−, 4.4 × 10−2M−1 s−1, 18.6 kcal mole−1; HSO3−, 1 × 10−3M−1 s−1, 18.4 kcal mole−1; and S2O32− 3.1 × 10−2M−1 s−1, 19.4 kcal mole−1.