POSSIBILITY OF A CYCLIC MECHANISM FOR ACID-CATALYZED ESTER HYDROLYSIS

The rates of hydrolysis of protonated ethyl benzoate and ethyl acetate in 12-79% sulfuric acid and the carbonyl oxygen-18 exchange of ethyl acetate have been found to be linearly dependent on the square of the activity of water. The observed kinetic dependence for hydrolysis and exchange was rationalized by hydrogen-bonded cyclic transition states consisting of protonated ester and two water molecules. The rates of hydrolysis of protonated ester were calculated from the observed concentration of protonated ester and ordinary rates of hydrolysis. © 1968, American Chemical Society. All rights reserved.