| abstract |
(57) [Summary] [Purpose] Starting from an aqueous solution of glyoxal, Provided is a method for directly producing a free glycolic acid aqueous solution which is free from coloration by a simple method. [Structure] An aqueous solution of glyoxal having a concentration of 85% by weight or less is heated to 50 ° C. or more in the presence or absence of a catalyst, and the obtained reaction solution containing glycolic acid is converted into an acidic solution having a pH of 2 or less. A column in which a solid component present in the acidic solution is adjusted and filtered, and the obtained filtrate is packed with a porous body having a specific surface area of 500 m 2 / g or more and an average pore diameter of 200 Å or less. At a temperature of 40 ° C. or lower, the pH of the effluent is adjusted to 1 or higher, and the column is filled with a cation exchange resin, and the column is flowed at a temperature of 40 ° C. or lower. A method for producing a glycolic acid aqueous solution having the following hue. |