Transesterification Mechanism in Pharmaceutical Intermediate (SLT-methylester) Synthetic Process Using Potassium Carbonate as Catalyst

摘要

The reaction field and rate-determing step of the transesterification of SLT-allylester allyl (5-chloro-2-oxo-1,3-benzothiazol-3(2H)-yl) acetate with methanol to form SLT-methylester in dichloromethane using potassium carbonate (K_2CO_3) as a catalyst were investigated. The reaction rate in solid-liquid phase was 45 times higher than that in homogenous liquid phase, which indicates that the reaction takes place almost exclusively on the surface of K_2CO_3 particles and the reaction of the surface of K_2CO_3 is rate-determining step. In addition, by changing the order of supplying the reactants and catalyst into the reactor, it was found that the occurrence of an induction period for the reaction in the solid-liquid phase was caused by the combination of methanol with K_2CO_3.