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Method for preparing lactide

A lactide and lactic acid technology, applied in the chemical field, can solve the problems of low lactide yield, achieve the effect of avoiding process, improving yield and purity, and avoiding high temperature cracking

Inactive Publication Date: 2004-04-14
上海高分子材料研究开发中心
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention provides a kind of preparation method for the raw material lactide of synthetic polylactic acid for solving the low problem of lactide productive rate, and its steps are as follows:

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] Add 600g of 88% D, L-lactic acid into a 1L three-necked bottle equipped with a thermometer, and place it in an oil bath, and the temperature rises to 120°C. After that, some water will evaporate, and the water output will slow down after about 3 hours. The temperature of the system continued to rise, and slowly evacuated to 100mmHg. After 2 hours, the temperature rose to 150°C to obtain 519g of high-purity oligomeric lactic acid; transfer the obtained 519g of oligomeric lactic acid into a Add 1.5L of toluene and 1.03g of antimony trioxide to the 3L reaction kettle of the molecular sieve packing drying tower, pass nitrogen gas, and reflux. After 6 hours, no water droplets are formed in the water separator, and the drying tower is opened at this time. Piston, continue to reflux for 24 hours, then distill off toluene, distill under reduced pressure under nitrogen atmosphere, oil bath temperature is 175 ° C, vacuum degree is 5 mmHg, collect fractions at 155-158 ° C, and obta...

Embodiment 2

[0016] The experimental device and conditions are the same as in Example 1, with L-lactic acid instead of D, L-lactic acid, the vacuum degree is 5mmHg, and the fraction is collected at 154-158°C to obtain 297g of white L-lactide with a purity of 96%, which is the theoretical yield 71.5%.

Embodiment 3

[0018] The experimental device is the same as that of Example 1, with 600 g of 98% glycolic acid instead of D, L-lactic acid, and 4-methyl-2-pentanone instead of toluene, with a vacuum of 5 mmHg, and collecting fractions at 148-152 ° C to obtain glycolide 268 g, 65% of theoretical yield.

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PUM

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Abstract

The invention refers to a method for producing lactide. The character lies in: under the protection of inert gas, the invention uses instillation to eliminate the water in lactic acid, then uses an azeotropic solvent which can make the condensation reaction advantage to generate lactide, the solvent is good solvent to lactide and the bad solvent to lactic acid polymer, the solvent flows back in the protection of inert gas continuously, make the lactic acid is condensed into lactide, then decompression distillation is carried on, through recrystallization there gets the high purity lactide.

Description

[technical field] [0001] The invention relates to the field of chemistry, in particular to a method for preparing lactide. [technical background] [0002] Polylactic acid is a synthetic polymer compound that is completely biodegradable. Since the raw material lactic acid can be produced by fermentation of agricultural products, it is considered to be a sustainable and environmentally friendly compound. And because polylactic acid has good biocompatibility, the intermediate product of metabolism in the body is lactic acid, the normal metabolite of sugar, and the final metabolites are carbon dioxide and water. Therefore, polylactic acid has broad research and application prospects as the mechanism material of drug controlled release system, surgical suture, tissue engineering scaffold material and bone repair material. [0003] Generally, there are two routes for the preparation of polylactic acid, namely direct polycondensation method and ring-opening polymerization method....

Claims

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Application Information

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IPC IPC(8): C07D319/12
Inventor 陈国荣钟伟杜强国杨玉良
Owner 上海高分子材料研究开发中心
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