A Kinetic Study of the Solvent Effect of Aquo-Dipolar Aprotic Organic-Solvent Systems on the Biochemical Efficiency of Caprate Ester

For studying the Solvent-effect of a dipolar aprotic solvent, DMSO on the biochemical efficiency of Caprate ester, the kinetics of alkali catalysed hydrolysis of Propyl caprate was carried out in aquo-DMSO solvent systems having different concentration of the organic component (DMSO) varying from 30 to 80% (v/v) at different temperatures ranging from 20 to 40°C The mumber of water molecules associated with the activated complex of the reaction were found to decrease from 1.339 to 0.324 and from this, it is inferred that DMSO acts as structure reformer of water converting its bulky form into dense form and it changes the mechanistic path way of the reaction from unimolecular to bimolecular. With gradual addition of DMSO to the reaction media, enthalpy of activation (ΔH*) and entropy of activation (ΔS*) were found increasing with simultaneous increase in free energy of activation (ΔG*). On the basis of this observation, it has been inferred that the enthalpy of activation enhances to greater extent than entropy of activation and initial state of the reaction is solvated and the transition state is desolvated, The Iso-composition activation energy (EC) values of the reaction were found to be enhancing from 102.11 kJ/mol to 130.53 kJ/mol with increasing concentration of DMSO in the reaction media. From this enhancement in EC it has been confirmed that the initial state of the reaction is solvated and its transition state is desolvated. From the depletion observed in iso-dielectric activation energy (ED) of the reaction with increase in D values of the reaction media, it is concluded that EC and ED values of the reaction are complementary to each other. From the numerical value of the iso-kinetic temperature of the reaction, which is evaluated to be 331.44, it is opined that there is strong and appreciable interaction between solvent and solute in water-DMSO reaction media.