A Study of the Kinetics of Aliphatic Ester Saponification.

Abstract This investigation is a systematic study of the effect upon saponification velocity of substitution of the phenyl and various alkyl groups in the acyl component of ethyl esters of monobasic aliphatic acids.The experimental course of such saponification follows the kinetic expression for second order reactions, - d(ester) /dt = k(ester) (base). (1)The specific reaction rate constant, k, is a suitable index for comparing the reactivities of different esters. It may, for theoretical reasons, be expressed k = PZ e -E/RT (2)E, the activation energy, is the minimum energy the reacting molecules must possess for reaction to occur. 2 is the collision number; it varies only slightly with temperature and for a given medium has essentially the same value for all esters. P, a steric factor, is usually less than unity and accounts for the fact that not every collision between sufficiently activated reactant molecules is necessarily fruitful. Changes in reaction velocity, then, may be due to the effect of a substituent on either or both P and E.