Perchlorate esters. Part 3. Correlation of the rates of reaction of arenesulphonate ions with methyl perchlorate in acetonitrile

Abstract

Second-order rate coefficients for the reactions of acetonitrile solutions of tetra-n-butylammonium benzenesulphonate and seven meta- and para-substituted derivatives with methyl perchlorate, at 0.3°, lead to a Hammett ρ value (–1.10 ± 0.04) essentially identical to those previously reported for reactions with other powerful methylating agents. When silver ion is substituted for tetra-n-butylammonium ion, the second-order rate coefficients become concentration dependent and the fall off with increasing salt concentration can be rationalised on the basis of only free anions being reactive. The calculated degrees of dissociation are applied to the previously studied silver-ion assisted reaction of silver toluene-p-sulphonate with methyl iodide.