A series of N-acyl-amino-acids have been heretofore synthesized and used in cosmetics, washing agents and similar fields. With respect to the salts of N-acyl-β-alanines, many references are available but they reveal that the salts have no excellent surfactant properties.
The authors, however, synthesized various salts of N-acyl-N-alkyl-β-alanines, for investigation of their physical and surface active properties, and found that these compounds have much more excellent surface active properties than their precursor compounds and N-acyl sarcosinates. They are new surfactants.
N-acyl-N-alkyl-β-alanines and salts thereof were prepared by acylating N-alkyl-β-alanines and N-alkyl-β-alanine methyl esters in water or in an organic solvent in the presence of an organic alkali or caustic soda as a catalyst, wherein N-alkyl radical is a straight-chain or branched-chain of one to four carbon atoms with a fatty acid chloride or fatty acid, and acyl group is a saturated or unsaturated straight-chain radical of 10 to 18 carbon atoms.
N-acyl-N-alkyl-β-alanine salts thus obtained were purified by recrystallization and examined for their solubility in water and for surface active properties. It was found they exhibit various excel-lent properties including foaming, wetting and resisting to hard water. Of these compounds, N-methyl and N-ethyl derivatives, lauroyl and myristoyl derivatives exhibited most excellent surf ace activities in pH 67.
