Patent ID: 7199264

Claim:
A method for separating respective optical isomers from a mixture containing a pair of optical isomers of an amino acid derivative, in which one of hydrogen atoms of an amino group or an imino group of amino acid having at least one asymmetric carbon is N-substituted with an organic carbonyl group to form an N-substituted amino acid derivative, said method comprising: (A) preparing the above mixture, (B) mixing the above mixture with a hydrophilic compound having a different affinity to the respective optical isomers contained therein in an aqueous solution to form an aqueous solution or aqueous suspension containing the complex, (C) subjecting the aqueous solution or aqueous suspension containing the above complex to: (i) a condition whereby the pH is 3.5 or lower, or (ii) the coexistence thereof with a compound having a group which can be a counter ion for an ion originating in a charging group of the above amino acid derivative and a hydrophobic atomic group, whereby a difference in hydrophobicity is brought about between complexes of the respective optical isomers, and (D) separating the complexes of the respective optical isomers from each other by making use of such difference in the hydrophobicity by bringing the respective optical isomers into contact with a hydrophobic substance selected from the group consisting of a hydrophobic organic solvent or a solid fine particle having a hydrophobic surface, and further wherein: said N-substituted amino acid derivative is represented by Formula (I): wherein R 1 represents a non-substituted or substituted C 1-6 alkyl group, and the substituent used when substituted is selected from the group consisting of hydroxy, mercapto, methylthio, amino, mono- or dimethylamino, C 1-6 alkylcarbonylamino, C 1-6 alkyloxycarbonyl, amidinoamino, carboxy, C 1-6 alkyloxycarbonyl, carbamoyl, non-substituted or substituted phenyl, wherein the substituents in the case of substituted phenyl are the same or different and can be 1 to 3 halogen atoms, hydroxy, mercapto, methyl, trifluoromethyl or amino; one of R 2 and R 3 is a hydrogen atom, and the other represents alkoxycarbonyl, aralkyloxycarbonyl, aryloxycarbonyl, alkenyloxycarbonyl or acyl, said hydrophilic compound is selected from the group consisting of polysaccharides and derivatives thereof and optically active compounds of amino acid and derivatives thereof, and said hydrophobic atomic group is an alkyl group having 1 to 22 carbon atoms, which may have a substituent selected from the group consisting of hydroxyl group, nitro group and halogen atom, or an aryl group, which may have a substituent selected from the group consisting of hydroxyl group, nitro group and halogen atom.