Nucleophilic Substitution Reactions of Phenyl Dithioacetates with Pyridines in Acetonitrile

초록

The kinetics of reactions between Z-phenyl dithioacetates with X-pyridines are investigated in acetonitrile at 60.0→. The Bronsted plots obtained for the pyridinolysis of phenyl dithioacetates are curved, with the center of curvature at ~4.5(pKa). The Bronsted plots for these nucleophilic reactions show a change in slope from a large (bx=0.78 ? 0.90) to a small (bx=0.35 ? 0.36) value, which can be attributed to a change in the rate-determining step from the breakdown to formation of a tetrahedral intermediate in the reaction path as the basicity of the pyridine nucleophile increases.