Hydrolysis of amides. II. Substituent effects in dilute acid and alkali

Abstract

Energies and entropies of activation for the hydrolysis in dilute acid of six aliphatic amides are reported. These results, in conjunction with those of other workers, indicate the dilute acid hydrolysis of primary aliphatic amides to be governed by a combination of steric and hyperconjugative substituent effects and to be independent of polar effects. The reaction series is well correlated by the Taft-type equation                logk = 0.858 EC/S-0.493(n-3)+logk₀ in which EC/S denotes a pure steric substituent parameter and n is the number of α-hydrogens in the substituent. The alkaline hydrolysis of a similar series of amides is well correlated by the equation              log k = 2.05ø*+ 1.08 EC/S -O.743(n-3)+ log k_o.