| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for economically and efficiently producing anα-hydroxycarboxylic dimeric cyclic ester from the correspondingα- hydroxycarboxyllc acid oligomer, and to provide a method for economically and efficiently purifying a crudeα-hydroxycarboxylic acid dimeric cyclic ester. SOLUTION: The method for producing and purifying the subject compound is as follows: (1) a mixture comprising anα-hydroxycarboxylic acid oligomer and at least one kind of high-boiling polar organic solvent 230-450 deg.C in boiling point is heated under normal or reduced pressures at such a temperature as to depolymerize the oligomer, (2) the oligomer is dissolved in the solvent until the remaining rate of the oligomer in the melt phase comes to <=0.5wt.%, (3) the heating is further continued at the above temperature to depolymerize the remaining oligomer, (4) the dimeric cyclic ester produced is distilled out together with the high-boiling polar organic solvent, and (5) the aimed dimeric cyclic ester is recovered from the distillate.
|
