Synthesis and characterization of optically active surfactants derived from phenylalanine and leucine

Two optically active cationic surfactants, (2S)-N-hexadecyl-N, N-dimethyl-( 1-hydroxy-3-phenylpropyl)-2-ammonium chloride 1 and (2S)-N-hexadecyl-N,N-di methyl-(l-hydroxy-4-methylpentyl)-2-ammonium chloride 2, have been selected and synthesized for use as enantioselective micellar catalysts in aqueous media. Their surface and aggregation behavior has been investigated at 298 K using surface tension and light scattering studies, which revealed that b oth molecules associate at low concentrations to produce micellar aggregate s. Interestingly, although the area per molecule occupied by the surfactant s at the air-water interface (43.6 Angstrom (2) for 1 and 54.6 Angstrom (2) for 2) is similar to that of related cationic surfactants, their aggregati on number (23 for 1 and 19 for 2) is much smaller, perhaps reflecting the i nfluence of the size or homochiral nature of the head group in the packing of the micelle. (C) 2001 Academic Press.