Effect of fluorine substitution on the rate for ester hydrolysis: estimation of the hydrolysis rate of perfluoroalkyl esters

To investigate the fluorine substitution effect on the rate for ester hydrolysis, the energies of the tetrahedral intermediates, as well as those of the reactants and products, were evaluated with ab initio calculations. The CBS-4 and CBS-Q energies suggested significant acceleration of the hydrolysis rate of fluoro-substituted esters: not only the trifluoromethyl group in the acyl portion of esters but also that in the alcohol portion will accelerate significantly the ester hydrolysis rate as compared to non-substituted counterparts. This implies that perfluoroalkyl esters resulting from the atmospheric degradation of hydrofluoroethers (HFEs) will be rather unstable even in almost neutral hydrolytic conditions.