Large Solvent‐Dependent Rate Enhancement of Autocatalytic Hydrolysis of Alkyl and Aryl Thiosulfates

The hydrolysis of alkyl and aryl thiosulfates (Bunte salts), to produce the corresponding thiol and bisulfate ion, is autocatalytic in the absence of added acid and proceeds at greatly accelerated rates in organic solvents at room temperature relative to the same reaction in aqueous solution. Kinetics studies of the hydrolysis of n-hexadecyl thiosulfate and p-nitrophenyl thiosulfate allowed the determination of the associated rate constants. Control experiments indicate that the enhancement of the rate was not due to the preconcentration of the reactant and the bisulfate catalyst within reverse micelles. Rather, it appears to be related to the properties of the solvent and differences in solvation of the reactant, product, and/or transition state. High-throughput measurements of the induction periods across a reaction population were fit well by a Gaussian function.