Application of the Extended Grunwald-Winstein Equation to the Solvolyses of Phenyl Methanesulfonyl Chloride in Aqueous Binary Mixtures

摘要

This report shows the rates of solvolyses for phenyl methanesulfonyl chloride (C6H5CH2SO2Cl, I) in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, acetone, 2,2,2-trifluroethanol (TFE) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) are reported. Three representative solvents, studies were made at several temperatures and activation parameters were determined. The thirty kinds of solvents gave a reasonably precise extended Grunwald-Winstein plot, coefficient (R) of 0.954. The sensitivity values (l = 0.61 and m = 0.34, l/m = 1.8) of phenyl methanesulfonyl chloride (I) were smaller than those obtained for benzenesulfonyl chloride (C6H5SO2Cl, II; l = 1.01 and m = 0.61) and 2-propanesulfonyl chloride ((CH3)2CHSO2Cl, III; l = 1.28 and m = 0.64). As with the two previously studied solvolyses, an S_n2 pathway with somewhat ionization reaction is proposed for the solvolyses of I. The activation parameters, ΔH~≠ and ΔS~≠, were determined and they are also in line with values expected for a bimolecular reaction mechanism. The kinetic solvent isotope effect of 2.34 in CH3OH/CH3OD is in accord with a bimolecular mechanism, probably assisted by general-base catalysis.