Synthesis and Properties of the Substituted Guanidine Type Amphoteric Surfactants

Abstract

N-Substituted guanidine-type amphoteric surfactants containing carboxylate or sulfonate groups were synthesized by reactions of N-alkylated guanidine and acrylonitrile or propanesultone, followed by hydrolysis with hydrochloric acid. The surface active properties of their aqueous solutions were noted to depend on alkyl chain length, types of anionic groups and the number of methyl groups introduced into the guanidino group. The solubility of amphoteric surfactants containing the N-methylated guanidino group increased in proportion to the degree of N-methylation. It was found that surface tension of guanidino amphoterics could be lowered easily and effectively over a wide pH range.