Kinetics and Mechanism of the Aminolysis of Thiophenyl Cyclohexanecarboxylates

摘要

The aminolysis reaction of carbonyl compounds is one of the most extensively investigated subjects in mechanistic organic chemistry. In this type of reaction, a non-linear Bronsted-type plot showing a break from a large (β = 0.8 -1.0) to a small (β = 0.1 - 0.3) rate dependence on basicity of the attacking amine is often obtained at pK_o as the basicity of nucleophile is increased. The break at pK_o where k_(-1) = k2 has been attributed to a change in the rate-determining step from breakdown (k2) to formation (k1) of atetrahedral intermediate, T~±, in the reaction path, eq. (1), where X, Y and Z are the substituents in the nucleophile, substrate and leaving group, respectively.