Lactic Acid → Hydroxyacetic acid--2-hydroxypropanoic acid (1/1)

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Reaction Steps

The lactide obtained in Example 2 (10 g) and glycolide (10 g) were put into a 100-ml reaction vessel equipped with a stirrer and a nitrogen-introducing tube. After substitution of nitrogen gas was carried out three times, the temperature was raised to 150°±5° C., and the mixture was molten over 3 hours with stirring. To the resulting mixture was added 0.4 g of synthetic light aluminum silicate (Tomita Pharmaceutical Co., Ltd.), and the temperature was raised to 195°±5° C. The pressure was reduced gradually to 20 mmHg over 30 minutes, followed by stirring for 3 hours. After the pressure was reduced gradually to 1 mmHg over 30 minutes, the mixture was stirred at 195°±5° C. for 7 hours to give lactic acid-glycolic acid copolymer in the molten state. The product was cooled to room temperature to give 11.50 g of light brown copolymer. The weight-average molecular weight of this copolymer was 65,000.

Provenance & Evidence