Patent ID: 7812181
Filing Date: 2010-10-12
Classification: C07D

Abstract:
1. A process for producing glycolide, comprising the steps of: feeding a starting glycolic acid oligomer containing hydroxyl group-free impurity carboxylic acids (A) and nitrogen-containing compounds (B) selected from the group consisting of ammonia, ammonium salts, amines and amides repetitively and/or continuously into a depolymerization system containing an organic solvent, depolymerizing the glycolic acid oligomer under heating to produce glycolide, calculating an effective concentration (x+100y wt. %) of depolymerization-obstructing substances as a total of a concentration calculated as diglycolic acid (of x wt. %) of the hydroxyl group-free impurity carboxylic acids (A) and 100 times a concentration calculated as ammonia (of y wt. %) of the nitrogen-containing compounds (B), respectively, with respect to the starting glycolic acid oligomer in the depolymerization system, and controlling the depolymerization system to suppress the effective concentration (x+100y wt. %) to at most 15 wt. %.