Nucleophilicity in dimethylsulfoxide

Although the nucleophilicities of anions in protic solvents have been fairly extensively examined quantitatively, a parallel study has not been made in dipolar aprotic solvents. In this study the nucleophilicities of various anions in pure DMSO with respect to the displacement of tosylate from n-propyl tosylate have been examined. The activation parameters for this reaction with Cl-, Br-, and I- as nucleophiles in various DMSO-H2O mixtures have also been determined. As a complementary study the solvolysis of t-butylchloride in various DMSO-H[lowered 2]O solvent mixtures has been determined. In the initial phase of this work, the displacement of tosylate from methyl tosylate by the halide ions in DMSO-H[lowered 2]O mixtures at 30[degrees]C was studied.