Structure of proton disolvates formed in the acid hydrolysis of ethyl formate and methyl acetate

By the density functional method (B3LYP/6-31++G(d,p)) optimal structures of proton hetero and homo disolvates involving water molecules, ethyl formate, methyl acetate and products of their hydrolysis are calculated. The data on the structure of these ions and the strength of their H bonds are analyzed together with the results of a similar calculation previously performed for methyl formate. It is shown that in proton solvation by two molecules present in the solution during the hydrolysis of ethyl formate, methyl acetate, and methyl formate stable (X…H…X)+ or (X…H…Y)+ particles form. Structural and energy parameters of their O…H…O bridges obey the same regularities and are mainly determined by a difference in the proton affinity of X and Y molecules. Calculation results are compared to the data of a number of experimental studies of the acid hydrolysis of esters.