Reaction of NN′-dimethylimidazolidine-2-thione with methyl iodide. Kinetic and thermodynamic aspects

Abstract

The reaction of NN′-dimethylimidazolidine-2-thione with methyl iodide followed simple second-order kinetics in polar solvents, whereas in less polar solvents the reverse process made a significant contribution to the overall rate. The solvent effects on the forward rate constant were linearly correlated with those on the rate of the reaction of tetramethylthiourea with methyl iodide. However, the reactions of two 1,2,4-triazole-3-thione derivatives with methyl iodide did not show any such correlations. From the volume changes and enthalpy changes measured, three transition state indices, (Δ₂V‡/Δ₂°), n_T, and α were determined in acetonitrile, ca. 0.28, 0.35, and 0.43, respectively.