| 摘要 |
PROBLEM TO BE SOLVED: To provide a method capable of stably producing high purity phenylenedioxydiacetic acids from a mixture of phenylenedioxydiacetic acids represented by formula (1) (wherein, R is a halogen atom, a carboxy group or a 1-4C hydrocarbon group and n is an integer of 0-4) and an alkali aqueous solution. SOLUTION: The mixture of phenylenedioxydiacetic acids and the alkali aqueous solution is mixed with an acid to form crystals of the free acids of the phenylenedioxydiacetic acids which are, in turn, taken out at 35 deg.C or higher.
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