Kinetics of the Reaction of Cutch (Acacia catechu) with Sodium Sulphite in Tween-80 Micellar Environment

The rate constants and thermoydnamic activation parameters of the reactions of cutch tannins with Na₂SO₃ in the presence and absence of Tween-80 micelles were studied. Tween-80 micelles profoundly decelerated the reaction rate with the increase of temperature. High negative entropy of activation in presence of Tween-80 micelles suggest an overall organised transition state. The δ(ΔG*), the free energy difference between the reaction of cutch with Na₂SO₃ in aqueous environment and in Tween-80 micellar environment became less negative with increase of temperature from 60°C and became positive at 90°C presumably due to the instability of the micelles. The enthalpy entropy compensated each other. Microscopic measurements showed that the bigger size particles of cutch are formed in presence of Tween-80 micelles than in absence. Polvoxyethylated nonionic surfactant micelle is advantageous in solubilization of cutch tannins.