To provide a method for producing an optically active amino acid having a high optical purity of at least ≥99% or its hydrochloride.
In this method for producing an optically active amino acid having high optical purity or its hydrochloride by crystallization from an optically active amino acid containing an optical isomer, crystallization of an optically active substance is carried out in pH region exhibiting an isoelectric point by utilizing pH dependence of convergence of mutual solubility between optical isomers and then, pH of recovered mother liquid is lowered to ≤1 and crystallization is carried out or crystallization of the optically active substance which excessively exists at pH of mother liquid of ≤1 is carried out and the recovered mother liquid is crystallized by neutralization at pH near isoelectric point and a solution of an amino acid having optical purity of convergence of mutual solubility of optical isomer is recovered as the mother liquid and pH of mother liquid is lowered to ≤1 and crystallized at a prescribed concentration.
IRINO SHIGEAKI (JP)
TOKUDA AKIRA (NL)
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