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

A 90 wt % aqueous solution of L-lactic acid (90 g) and 10 g of glycolic acid were put into a reaction vessel equipped with a stirrer and a nitrogen-introducing tube. After substitution of nitrogen gas was carried out three times, the mixture was concentrated at 150° C. for 5 hours with stirring in a stream of nitrogen to give 50 g of lactic acid-glycolic acid oligomer. To the obtained oligomer was added 1.1 g of Baylith 5A with which sodium elution (381 ppm) had been observed. Then, the temperature was raised to 200° C., and the pressure was reduced gradually to 20 mmHg over 30 minutes. The mixture was stirred at 195±5° C. for one hour. 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 29.24 g of lactic acid-glycolic acid copolymer as a white solid. The weight-average molecular weight of this copolymer was 93,000.

1. customequipped with a stirrer
2. additiona nitrogen-introducing tube
3. concentrationthe mixture was concentrated at 150° C. for 5 hours

ORD record

ord-1b823580f66842cb8c1334972b4d196e

Source dataset

uspto-grants-1999_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05952455