Preparation of Optically Active Amphoteric Surfactants and Their Surface and Antimicrobial Properties

Abstract

Racemic and optically active amphoteric surfactants, N-substituted amino acids and amino sulfates derivatives were prepared to determine relationship of physico-chemical relations of chiral isomers with chemical structures among chiral isomers. Amphoterics possess a 1-phenylethyl group as the hydrophobic chiral center. The racemates showed no difference with optically active isomers with respect to capacity for lowering surface tension and cmc. The influence of the long alkyl chain length of the hydrophobic group on cmc was essentially the same as that of other types of surfactants governed by Traube's rule, while the influence of chain length between the two hydrophilic groups could not be determined exactly. The pH of the solution affected the solubility of amphoterics and an aqueous solution of the amino acid derivative surfactants became turbid below pH 4 in acidic condition.The amphoterics were also tested for antimicrobial activity against bacteria and fungi. The hydrophobic long alkyl group significantly influenced antimicrobial activity more than the chiral isomerism. N-Dodecylated homologues were confirmed to be more antimicrobial than N-decylated homologues.