A quantum chemical approach to the water assisted neutral hydrolysis of ethyl acetate and its derivatives

A quantum chemical approach to the neutral water assisted hydrolysis of eth yl acetate and its halogenated derivatives in the gas phase is presented. C alculations of a cluster containing one ester and two water molecules were accomplished with the progam Gaussian 94 at the semi-empirical AM1 and the ab initio RHF/3-21G and RHF/6-31 + G(d) computational levels. For each meth od the Gibbs energies of several key structures along the reaction path wer e calculated after full geometry optimization. For the proposed first react ion step a transition state with tetrahedral structure at the carbonyl carb on of the ester was found, thus corroborating experimental studies. The com puted Gibbs energy of activation of the first reaction reveals a similar in fluence of polar substituents on this reaction as found by experiments in t he liquid phase.