THE HA ACIDITY FUNCTION AND THE MECHANISM OF AMIDE HYDROLYSIS IN HYDROCHLORIC ACID

Abstract

Values of the HA acidity function have been determined for 0–35% hydrochloric acid using a set of amide indicators. The indicator pK values agree with those previously obtained in sulfuric acid. The HA scale decreases less steeply than H0 in the high concentration region, but the difference between the two functions is less marked than in sulfuric acid. The reasons for this are discussed. The values of HA have been combined with available rate and water activity data to obtain information about the mechanism of amide hydrolysis. Eleven sets of rate data, consisting of 64 rate constants obtained under a variety of experimental conditions, give similar hydration parameters for this reaction. The temperature dependence of hydration parameters is discussed.