| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optically active N-carbonylamino acid ester capable of keeping high optical activity by carrying out phosgenation of an optically active amino acid ester salt at a specific temperature, heating up the resultant compound at a temperature higher than a reaction temperature in phosgenation while blowing an inert gas into the compound after finishing phosgenation and carrying out degasification. SOLUTION: (A) An optically active amino acid ester salt (e.g. L- phenylalanine methyl ester hydrochloride) is suspended in an organic solvent and phosgenation is carried out by blowing phosgene in an amount of 0.1-1 mol based on 1 mol amino acid ester per hr at <100 deg.C into the amino acid ester and (B) after finishing phosgenation, a temperature of the treated compound is gradually raised to a temperature higher by 10-100 deg.C than reaction temperature in phosgenation while blowing an inert gas (e.g. nitrogen, helium or neon) into the solution, preferably at a rate of 0.01 L/hr based on 1 L solution to remove hydrochloric acid content causing racemization together with excess content of phosgene.
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