The lactam‐amino acid equilibria for ethylpyrrolidone and polyvinylpyrrolidone

Abstract

Abstract The lactam‐amino acid equilibria of N ‐ethylpyrrolidone and poly‐ N ‐vinylpyrrolidone were studied in dilute aqueous solutions and in n ‐butanol at 100°C. and compared with earlier investigations of similar systems. It was found that with in the intermediate p H range the lactam is the predominant form. Below and above certain critical acid and alkaline p H values increasing amounts of amino acid will be formed. It has been shown that these critical p H values are closely related to p K 1 and p K 2 of the corresponding amino acid. The polymeric lactam PVP is more resistant against hydrolysis than the low molecular lactams. This effect is due to the polyampholyte character of the polymeric amino acid formed in the course of the hydrolysis reaction.