THE HYDROLYSIS OF ALIPHATIC NITRILES IN CONCENTRATED HYDROCHLORIC ACID SOLUTIONS

Abstract

Studies of nitrile hydrolysis in concentrated acid media have been extended to the hydrolysis of hydrocyanic acid, acetonitrile, and cyanoacetic acid in hydrochloric acid solutions of concentration 1 to 8.5 N. It appears that the hydrolysis of aliphatic nitriles in concentrated sulphuric and hydrochloric acids provides systems of consecutive, irreversible unimolecular reactions over the complete range knitrile[Formula: see text]kamide (more dilute acid) to knitrile[Formula: see text]kamide (highly concentrated acid), for a sufficient range of acid concentrations. The limit, knitrile[Formula: see text]kamide, is not attained in hydrobromic acid solutions. The nitriles studied here exhibit a large decrease in activation energy with increase of acid concentration, similar to that observed earlier for propionitrile. The magnitude of the variation of the Arrhenius parameters is specific for each nitrile. For the acetonitrile hydrolysis, the increase in rate with increase of acid concentration largely follows the accompanying activation energy decrease. The relative rates of hydrolysis of different nitriles, at given acid concentration, are not governed by differences in activation energy. The variation of activation energy is briefly discussed in relation to certain other factors.