| 摘要 |
PROBLEM TO BE SOLVED: To provide a method by which the objective dicarboxylic acid (I) can be deposited and produced without sticking thereof to the wall surface, etc., of a reaction vessel even when an aqueous solution of a 1,3-dibenzyl-2-oxo-imidazolidine-4,5-dicarboxylic acid alkali metal salt (II) is reacted with an acid without adding a chlorinated hydrocarbon thereto. SOLUTION: The aqueous solution of the 1,3-dibenzyl-2-oxo-imidazolidine-4,5-dicarboxylic acid alkali metal salt of formula (II) is reacted with the acid while maintaining≥65°C temperature to deposit the 1,3-dibenzyl-2-oxo-imidazolidine-4,5-dicarboxylic acid of formula (I). For example, the aqueous solution contains the dicarboxylic acid alkali metal salt of formula (II) in an amount of 0.2-0.4 mol based on 1 kg. The aqueous solution is a reaction mixture prepared by reacting bis-benzylamino-succinic acid of formula (III) with phosgene in the presence of an alkali metal hydroxide in water. The acid is a mineral acid and the reaction mixture after reacting the aqueous solution with the acid has pH≤7. COPYRIGHT: (C)2004,JPO
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