Preparation and Surface Active Properties of Alkali Salts of N-Perfluorooctanoylamino Acids

Abstract

Ethyl perfluorooctanoate was reacted at 30°C for 2h in ethanol with ethyl ester of amino acid (glycine, α- and β-alanine) to prepare N-perfluorooctanoylamino acid ester. The esters thus prepared were saponified to form the desired surface active agents by atidification with hydrochloric acid and successive neutralization with alkali hydroxides. The aqueous solution of these surfactants were subjected to the determination of surface tension, critical micelle concentration, Krafft point, wettability and oil repellency according to the conventional methods. Generally, the glycine derivatives were only slightly soluble in water showing higher Krafft points and poor surface activities. The α-alanine derivatives showed lower Krafft point due to the presence of methyl side chain and superior wettability to other amino acid derivatives. The β-alanine derivatives exhibited significant surface tension depression and in the case of K salt the surface tension was depressed to 15dyn/cm.