PURPOSE: To obtain the titled compound useful as a raw material of pharmaceuticals, etc., in high yield, by concentrating an L-phenylalanine-containing solution obtained by the optical resolution with an acylase in an aqueous medium, increasing the pH of the solution, heat-treating in the presence of activated carbon, separating into solid and liquid, and adjusting the pH of the liquid.
CONSTITUTION: The Na salt of N-acetyl-D,L-phenylalanine is subjected to the optical resolution reaction with an acylase in an aqueous medium, and the reaction liquid is concentrated until the concentration of L-phenylalanine in the liquid reaches 10W40wt%. The pH of the concentrated solution is raised to preferably 10W12, and the solution is heated at 50W90°C to dissolve the L-phenylalanine precipitated in the concentrated solution. The solution is then added with 5W 10wt% activated carbon based on the theoretical production amount of L-phenylalanine, maintained at the above temperature for 0.5W5hr, and separated into solid and liquid. The pH of the obtained filtrate is adjusted to nearly neutral state (preferably to 7W8pH), and the objective compound is crystallized and separated from the filtrate.
EFFECT: A high-quality L-phenylalanine especially having excellent color-tone can be produced.
MIYAHARA TOORU
MATSUMOTO TOSHIO
SAKAGUCHI AKIO
NITSUTA KAZUNARI
