The effect of structural variation in fatty acid and amino acid moieties on surfactant properties of sodium salts of N-acyl condensates of amino acids was investigated. Pure N-acyl leucines and N-lauroyl condensates of different amino acids were synthesized and neutralized. Among the N-acyl leucinates, Nlauroyl leucinate exhibited optimum properties and compared well with sodium lauryl sulfate (SLS). Among the salts of N~-lauroyl amino acids, N~-lauroyl lysinate was found comparable to SLS. Salts of Nalauroyl condensates ofleucine, tryptophan, phenylalanine and proIine showed good wetting ability; proline also displayed high calcium ion tolerance. Salts of Nlauroyl tyrosine and phenylalanine exhibited good foaming ability. N-Lauroyl aspartate showed inferior properties compared to SLS in spite of having an additional carboxylic group.KEY WORDS: N-acyl leucines, N-lauroyl amino acids, structure vs surfactant properties.

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643 DiethanolRmides (DEA) of proteins possess nonionic skincompatible, biodegradable, surfactant and antibacterial properties. The DEA of dipeptides are, however, too hydrophilic to be effective surfactants. Hence, DEA of N-lauroyl dipeptides were synthesized and their surfactant and antibacterial properties were correlated with the structures of Amino acid moieties. N-Lauroyl condensates of five simple Amluo acids were coupled with the cop responding Amino acid methyl esters and the resulting products were condensed with diethanolamine in the presence of sodium methoxide to yield DEA of N-lauroyl dipeptides. The DEA of N-lauroyl glycine dipeptide showed surfactant properties comparable to lauroyl diethanol-Rmlde. The thiol group in the cysteine derivative exerted an unfavorable effect on surfactant properties. The isobutyl side chain in the leucine derivative contributed greatly to the antibacterial activity when compared to the other amino acid derivatives studied. KEY WORDS: Diethanolamides of N-lauroyl dipeptides, structure vs. surfactant and antibacterial properties.