Patent ID: 8178725

Claim:
A method for separating and collecting an optically active amino acid amide from an aqueous solution containing the optically active amino acid amide and an optically active amino acid by a process utilizing a difference in solubility between the optically active amino acid amide and the optically active amino acid in an organic solvent, which comprises Changing the aqueous solution to an organic solvent solution by azeotropic distillation with an organic solvent or by dehydration-concentration followed by addition of an organic solvent under such a condition that a ratio (C/A) of the total equivalent (C) of cations to the total equivalent (A) of anions contained in the aqueous solution falls within a range indicated by the following numerical formula (1), 1−0.05 X<C/A< 1+0.05 X (1) wherein X is 1 when the aqueous solution is not desalted and X is 10 when the aqueous solution is desalted; and A and C exclude the equivalent of the optically active amino acid amide and optically active amino acid, hydrogen ions and hydroxide ions, and anions and cations that are distilled away during azeotropic distillation or dehydration-concentration, and performing solid-liquid separation of an organic solvent phase containing the resultant optically active amino acid amide from a precipitated solid phase containing the optically active amino acid, wherein the optically active amino acid amide is L-amino acid amide represented by the following chemical formula (1), wherein R represents a C 1-4 lower alkyl group, a phenyl group, or a benzyl group, and wherein the optically active amino acid is D-amino acid represented by the following chemical formula (2), wherein R represented a C 1-4 lower alkyl group, a phenyl group, or a benzyl group.