| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a cyclic dimeric ester economically and efficiently from an α-hydroxycarboxylic acid oligomer. ! SOLUTION: The method for producing a cyclic dimeric ester of an α-hydroxycarboxylic acid by depolymerizing an α-hydroxycarboxylic acid oligomer comprises: allowing a specific hydroxyl group-containing compound to reside beforehand in a reaction system set at 0.1 kPa to 5 kPa and 160°C to 230°C; continuously supplying an α-hydroxycarboxylic acid oligomer obtained by direct dehydration condensation of an α-hydroxycarboxylic acid or some oligomer into the reaction system; reacting the hydroxyl group-containing compound and the α-hydroxycarboxylic acid oligomer in the reaction system in the presence of a depolymerization catalyst; and continuously distilling off from the reaction system a cyclic α-hydroxycarboxylic acid dimer derived from the α-hydroxycarboxylic acid oligomer, and a cyclic hydroxycarboxylic acid dimer derived from a reaction product |
