Synthesis of N‐acyl amino acids and correlation of structure with surfactant properties of their sodium salts

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, N‐lauroyl leucinate exhibited optimum properties and compared well with sodium lauryl sulfate (SLS). Among the salts of Nα‐lauroyl amino acids, Nα‐lauroyl lysinate was found comparable to SLS. Salts of Nα‐lauroyl condensates of leucine, tryptophan, phenylalanine and proline showed good wetting ability; proline also displayed high calcium ion tolerance. Salts of N‐lauroyl tyrosine and phenylalanine exhibited good foaming ability. N‐Lauroyl aspartate showed inferior properties compared to SLS in spite of having an additional carboxylic group.