| 摘要 |
To provide a method for purifying a fluorinated carboxylic acid having an etheric oxygen atom and its derivative, with small decomposition and inclusion of impurities. A liquid containing at least one member selected from the group consisting of a fluorinated compound represented by the following formula (1) and a fluorinated compound represented by the following formula (2) is held at a heating temperature of at most 150° C. and distilled: RFOR1COOH  (1) RFOR1COOR2  (2) RF is a linear or branched monovalent fluoroorganic group which may have an etheric oxygen atom in its main chain, R1 is a linear or branched bivalent organic group, and R2 is a linear or branched monovalent organic group. Further, the liquid is a liquid obtained from any of a waste liquid after an aqueous emulsion of a fluoropolymer is coagulated and the fluoropolymer is separated, an aqueous liquid obtained by cleaning an exhaust gas in a step of drying and/or a step of heat treatment of the separated fluoropolymer, and a liquid obtained by cleaning an anion exchange resin which has been brought into contact with the waste liquid or an aqueous dispersion obtained from the aqueous emulsion of the fluoropolymer, with an alkaline aqueous solution.
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