Kinetics of formation of 4-thiazolidinones by cyclocondensation reaction of Schiff bases and thioglycolic acid

Kinetics of formation of 4-thiazolidinone by cyclocondensation of Schiff bases (SB) and thioglycolic acid (TGA) have been studied. The reaction shows first order dependence both on SB and TGA concentrations; it follows an overall second order kinetics. The reaction is catalyzed by toluene-4-sulfonic acid (TSA). The influence of a neutral salt, namely, sodium perchlorate, dielectric constant and temperature on the rate of reaction has been studied. Thermodynamic and kinetic parameters are evaluated. The order of reactivity of substituted SB is explained. A suitable mechanism is proposed. The activation parameters are consistent with the proposed mechanism.