Sulfur Isotope Effects in the Hydrogen Ion Decomposition of Thiosulfate

Sulfur isotope effects in the decomposition of thiosulfate have been studied. There are two distinct intermolecular isotope effects and these have been used to examine various mechanisms for the reaction. By use of the theory of competing isotope reactions the thiosulfate decomposition mechanisms of La Mer and Davis have been shown to predict isotope effects not in accord with experiment, while a simple bimolecular three-centered reaction has been shown to predict sulfur and sulfite isotope effects in good agreement with the experimentally determined values of 1.9% and 0.9%.