Correlation of the Rates of Solvolysis of 4-Morpholinecarbonyl Chloride Using the Extended Grunwald-Winstein Equation

摘要

The rates of solvolysis of 4-morpholinecarbonyl chloride (MPC) have measured at 35.0 °C in water, D2O, CH3OD, and in aqueous binary mixtures of acetone, ethanol, methanol, and 2,2,2-trifluoroethanol. An extended (two-term) Grunwald-Winstein equation correlation gave sensitivities towards changes in solvent nucleophilicity and solvent ionizing power as expected for a dissociative S_N2 and/or S_N1 (ionization) pathway. For nine solvents specific rates were determined at two additional temperatures and higher enthalpies and smaller negative entropies of activation were observed, consistent with the typical dissociative S_N2 or S_N1 (ionization) pathway. The solvent deuterium isotope effect values for the hydrolysis of MPC of k_(H2O)/k_(D2O) = 1.27 and for the methanolysis of MPC of k_(MeOH)/k_(MeOD) = 1.22 are typical magnitudes of the S_N1 or ionization mechanism.