THEORETICAL STUDY OF THE REACTION AMBER ANHYDRIDE WITH BENZOCAINE

Possible reaction pathways of aminolysis of succinic anhydride by benzocaine — concerted and two-step — have been investigated by the density functional theory method (level ωB97M—V/ma-def2-QZVPP//r2SCAN-3c). For each mechanism three variants are considered: without catalysis, self-catalysis by the reagent molecule (benzocaine) and autocatalysis by the product (succinamide). Thermodynamic and activation parameters of all elementary stages in the gas phase are calculated. It is shown that different mechanisms are involved in the course of the reaction: at early stages, both concerted and two-stage pathways of self-catalysis can be realized with equal probability; as the product is formed, the preferred route of reaction becomes stage autocatalysis with the limiting first stage.