NEW MATERIAL:Optically active phenylalanine monosodium pentahydrate crystal.

USE: Since the compound has excellent selectivity to separate the impurities originated from a fermentation liquid or synthesized liquid, it is used for the efficient selection of tyrosine which is especially difficult to remove among the impurities originated from the fermentation liquid, by crystallizing the impurity in the process for separating phenylalanine from the fermentation liquid or synthesized liquid.

PREPARATION: The optically active phenylalanine monosodium monohydrate crystal is converted to the optically active phenylalanine monosodium pentahydrate crystal by keeping the crystal at about ≤9pH and a temperature below the transition temperature between the optically active phenylalanine monohydrate crystal and the optically active phenylalanine monosodium pentahydrate crystal and above the freezing point of the liquid. The transition temperature between the optically active phenylalanine monosodium monohydrate crystal and that of the pentahydrate crystal in a pure system (in water) is about 12°C.