Kinetics and mechanism of the reaction of methyl iodide with silver perchlorate in nitromethane

Abstract

The initially homogeneous reaction of silver perchlorate with methyl iodide in nitromethane yields, together with a precipitate of silver iodide, ca. 80% methyl perchlorate, accompanied by an unidentified amorphous red solid. For a constant initial concentration of silver perchlorate, the initial reaction rate increases less than linearly with increasing initial methyl iodide concentration and the data can be analysed in terms of Michaelis–Menton type kinetics, strong evidence for the intermediate formation of an alkyl halide–silver ion complex. For a constant initial concentration of methyl iodide, the initial reaction rate increases more than linearly with increasing initial silver perchlorate concentration and the order in silver perchlorate increases from close to unity at low concentrations to ca. 2·7 at 0·22M. Added tetraethylammonium perchlorate leads to relatively modest rate increases and does not influence the distribution of products. Possible reaction mechanisms are discussed and related to previously proposed non-electrophilically assisted mechanisms for nucleophilic substitution.