Solvent Effects on the Solvolysis of Benzyl <i>p</i>-Toluenesulfonates

Abstract

Abstract Solvolysis rates of benzyl p-toluenesulfonate were determined in a wide variety of solvents. The solvent effects were analyzed based on the Winstein–Grunwald equation. The solvent effect on benzyl solvolysis failed to give a single linear correlation with the 2-adamantyl YOTs parameter. The lower response to the solvent polarity and the pattern of dispersion for each binary solvent series can be qualitatively interpreted in terms of nucleophilic solvent assistance. The Winstein–Grunwald analysis gave m = 0.67 and l = 0.36, but with less satisfactory precision. The use of the polarity scale Yneo derived from 2-methyl-2-phenylpropyl solvolysis in place of YOTs gave an improved correlation. A solvent polarity scale Yneo is better applicable to benzyl solvolysis than 2-adamantyl-based YOTs, since the former is compatible with the entire π-delocalization of cationic charge between aryl ring and the reaction center in the transition state.