PROCESS FOR PRODUCING CYCLIC LACTIC ACID OLIGOMER HAVING TWO-FOLD POLYMERIZATION DEGREE

摘要

A process for producing a cyclic lactic acid oligomer having a degree of polymerization of 2m, characterized by (i) reacting a chain lactic acid oligomer having a degree of polymerization of m, which has m structure units derived from lactic acid (m is an integer of 2 to 30; the same applies hereinafter), with a carboxylic acid or derivative thereof which is represented by R<1>COX and (ii) subsequently cyclizing the resultant reaction product in an organic solvent at a temperature of 0 to 30°C. Thus, a cyclic lactic acid oligomer having a degree of polymerization of 2m, which is two times the degree of polymerization, m, of the chain lactic acid oligomer used as a starting material, can be selectively produced. Furthermore, a cyclic lactic acid oligomer mixture having a peculiar composition containing a major proportion of the cyclic lactic acid oligomer having a degree of polymerization of 2m can be obtained.