Prediction of Ester Hydrolysis Utilizing Results of Reaction Analysis

Abstract

Hydrolysis reaction is one of the major sources of degradants in the biodegradation test of Chemical Substance Control Law in Japan. We intended to add a new insight into the biodegradation prediction using activation energies of hydrolysis reaction. By applying Ingold's Aac2 and Bac2 mechanisms of ester hydrolysis, we made calculation of activation energies for the mechanisms using both MOPAC PM3 and DFT calculations and compared the calculated values with experimental data of those esters. And we developed prediction method of hydrolysis activation energy with combined use of MOPAC and DFT. We tried to use residual percentage after 28 days, calculated from predicted activation energies, as a measure of hydrolysis with threshold from water solubility. A resulting residual percentage data was compared to the hydrolysis estimation in the biodegradation test and it was found that the method shows the comparable performance with commercial software. Especially, our method showed successful performance to indicate the esters not to be hydrolyzed.