| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject compound in a high purity and a high yield, by subjecting a specific amount of an alkaline acqueous solution of crude phenylenedioxydiacetic acids, to an acid dipping at a specific temperature, and thereafter, by thermal insulation thereof at a specific temperature. SOLUTION: This compound is obtained by subjecting >=10 wt.% of an alkaline acqueous solution of a crude phenylenedioxydiacetic acid consisting mainly of a phenylenedioxydiacetic acid of formula I (R is a halogen, carboxyl or a <=4C hydrocarbon; n is 0-3), namely containing pref. about >=80 wt.%, more pref. about >=90 wt.%, calculated as solid content, to acid dipping at a temp. of 0 to 50 deg.C, using a mineral acid, and thereafter, by thermal insulation thereof at a temp. of 80 to 110 deg.C. The alkaline acqeous solution of the crude phenylenedioxydiacetic acid can be obtained, for example, by etherification of a dihydroxybenzene of formula II (e.g. resorcinol) with a haloacetic acid (e.g. monochloroacetic acid) in an alkaline acqueous solution (e.g. an acqueous sodium hydroxide solution).
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