Application of the Grunwald–Winstein equation to the solvolysis of the 2-adamantyl p-(trimethylammonio)benzenesulfonate (amsylate) cation. Absence of significant perturbation by a remote positive charge

Abstract

The solvolyses of 2-adamantyl p-(trimethylammonio)benzenesulfonate (amsylate) trifluoromethanesulfonate (1) in 37 pure and binary solvents proceed more rapidly than the corresponding solvolyses of 2-adamantyl toluene p-sulfonate (2-AdOTs) used to establish the Y_OTs scale, and a Hammett σ value for a p-NMe₃⁺ group of 0.77 ± 0.05 (in ethanol at 25 °C) is indicated. Despite the leaving group from 1 being a zwitterion, an excellent Grunwald–Winstein correlation with Y_OTs values is observed, with an m value of 0.92 ± 0.02 (correlation coefficient of 0.990). The appreciable solubility of amsylates in highly aqueous solvents suggests that 1 would be a good substitute substrate for establishing Y_OTs values for such solvents, in which 2-AdOTs is only very sparingly soluble.