| 摘要 |
PURPOSE:To obtain the titled compound having improved hue and high quality in high yield, by adjusting the pH of a reaction solution obtained by optical resolution with acylase, dissolving the deposited titled compound, heat-treating the resultant solution with activated carbon, separating the liquid from the solid, and crystallizing the titled compound. CONSTITUTION:Sodium salt of N-acetyl-D,L-phenylalanine is optically resolved by acylase in an aqueous medium to give a reaction solution, and a pH adjustor, e.g. liquid ammonia or gaseous ammonia, is added thereto to adjust the pH to >=9.0, preferably 9.0-11.0. The adjusted reaction solution is then heated to 65-80 deg.C to dissolve L-phenylalanine deposited in the reaction therein. Activated carbon is added thereto, and the reaction solution is kept for 0.5-5hr to separate the liquid from the solid by filtration, etc. The resultant filtrate is then concentrated (preferably at 50-60 deg.C internal temperature under reduced pressure) to give 5-30wt% L-phenylalanine concentration, and the pH is adjusted to about a neutral value to crystallize and separate the L-phenylalanine.
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