SOLVOLYSIS OF THE (P-METHOXYBENZYL)DIMETHYLSULFONIUM ION - DEVELOPMENT AND USE OF A SCALE TO CORRECT FOR DISPERSION IN GRUNWALD-WINSTEIN PLOTS

The specific rates of solvolysis of the (p-methoxybenzyl)dimethylsulfonium ion have been found to vary only modestly over a wide range of solvents and previous claims of a dependence on water nucleophilicity during hydrolysis are questioned. The variations in specific rate are somewhat greater than those previously recorded for the 1-adamantyldimethylsulfonium ion and the differences are used to establish values for an aromatic: ring parameter (I). Application of the, parameter removes dispersion from Grunwald-Winstein plots and the need to choose from within a matrix of similarity models, which are now recommended only as regards the leaving group. The requirements for a good similarity model are discussed in terms of the I parameter. It is shown that either a neglect of the term including I or an overcompensation when using;the alternative similarity model approach can be reflected as an apparent relationship between the specific rate and solvent nucleophilicity.