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Method for synthesizing optically pure lactide by composite catalysis method

A composite catalyst and lactide technology, applied in the direction of organic chemistry and the like, can solve the problems of high lactide temperature, high energy consumption, long time, etc., and achieve the effects of high cost, low optical purity, and improved selectivity

Pending Publication Date: 2022-07-22
长兴电子(苏州)有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] This case is a cyclic process for synthesizing optically pure lactide using a composite catalyst composed of organoguanidine and organotin, which can solve the problem of easy racemization or high temperature and time in the synthesis of lactide using a single catalyst in the prior art. Long, high energy consumption disadvantages

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  • Method for synthesizing optically pure lactide by composite catalysis method
  • Method for synthesizing optically pure lactide by composite catalysis method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] The present embodiment provides a kind of preparation method of pure L-lactide, and this preparation method is as follows:

[0043] In a 1000mL three-necked flask, add 800g of L-lactic acid (chemical content 98.5%, moisture content 1.5%), 20g of D-sorbitol, 0.08g of creatinine (0.01%wt compared to L-lactic acid), 0.08 g of stannous octoate (0.01% wt compared to L-lactic acid), dehydrated by heating at 16 torr, 60-80 °C, dehydration for 2 h; 80-175 °C, dehydration for 10 h.

[0044]The molecular weight of the lactic acid oligomer was monitored to be between 1000 and 2000 Da. Then, the vacuum degree of the system was increased to 1.2 torr, and the temperature was increased to 200 °C for cracking, and the cracking was carried out for 3 hours to obtain 660 g of crude L-lactide. The crude product was filtered under reduced pressure to obtain 160 g of filtrate.

[0045] About 500 g of the white solid obtained from the filter cake was placed in a 1000 mL beaker, and 300 g of ...

Embodiment 2

[0053] The present embodiment provides a kind of preparation method of pure L-lactide, and this preparation method is as follows:

[0054] In a 5000mL three-necked flask, add 4000g of L-lactic acid (chemical content 98.5%, moisture content 1.5%), 100g of D-sorbitol, 0.4g of creatinine (0.01%wt compared to L-lactic acid), 0.4 g of stannous octoate (0.01%wt compared to L-lactic acid) was dehydrated by heating at 25torr, 60-80°C, dehydration for 3h; 80-175°C, dehydration for 10h.

[0055] The molecular weight of the lactic acid oligomer was monitored to be between 1000 and 2000 Da, and then the vacuum degree of the system was increased to 2.0 torr, and the temperature was increased to 200° C. for cracking for 5 hours to obtain 3300 g of crude L-lactide. The crude product was filtered under reduced pressure to obtain 820 g of filtrate.

[0056] The obtained filter cake about 2480g of white solid was placed in a 5000mL beaker, and 1600g of 5% Na was added. 2 CO 3 The aqueous sol...

Embodiment 3

[0064] The present embodiment provides a kind of preparation method of pure D-lactide, and this preparation method is as follows:

[0065] In a 1000mL three-necked flask, add 800g of L-lactic acid (chemical content 98.5%, moisture content 1.5%), 20g of D-sorbitol, 0.08g of creatinine (0.01%wt compared to D-lactic acid), 0.08 g of stannous octoate (0.01%wt compared to D-lactic acid) was dehydrated by heating at 15torr, 60-80°C, dehydration for 2h; 80-175°C, dehydration for 10h.

[0066] The molecular weight of the lactic acid oligomer was monitored to be between 1000 and 2000 Da, then the vacuum degree of the system was increased to 1.0 torr, and the temperature was increased to 200 °C for cracking for 3 hours to obtain 640 g of crude D-lactide. The crude product was filtered under reduced pressure to obtain 135 g of filtrate.

[0067] About 505 g of the white solid obtained from the filter cake was placed in a 1000 mL beaker, and 300 g of 5% Na was added. 2 CO 3 The aqueous...

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Abstract

The invention provides a method for synthesizing optically pure lactide by a composite catalysis method. The method comprises the following steps: adding a composite catalyst consisting of organic guanidine and organic tin into lactic acid under a first heating condition, and reacting at normal pressure; under a second heating condition, carrying out reduced pressure reaction under a first pressure, and carrying out dehydration polycondensation to synthesize a lactic acid oligomer; under a third heating condition, collecting distilled crude lactide under a second pressure under reduced pressure; and carrying out reduced pressure suction filtration on the crude lactide to obtain a filtrate and a filter cake, washing the filter cake, and carrying out vacuum drying to obtain the optically pure lactide. The method provided by the invention solves the problem that lactide is easy to racemize when only stannous octoate is used for catalytic synthesis; moreover, the use of the (oligomer) molecular weight control agent to reduce the carbonization of lactide at high temperature is beneficial to the proceeding of cracking reaction.

Description

technical field [0001] The invention belongs to the technical field of organic materials, and relates to a method for synthesizing optically pure lactide by a composite catalytic method, in particular to a method for synthesizing optically pure lactide by using an organic guanidine and organic tin composite catalytic method. Background technique [0002] Biodegradable plastics are divided into bio-based biodegradable plastics and petrochemical-based biodegradable plastics according to the source of raw materials. At present, the petrochemical-based biodegradable plastic PBAT and the bio-based biodegradable plastic polylactic acid (PLA) are the most highly industrialized, and lactide is the key raw material for synthesizing PLA. [0003] Lactide (C 6 H 8 O 4 ), white needle-like, melting point 93~95℃, boiling point 216℃, molecular weight 144, easily soluble in chloroform, ethanol, insoluble in water. Lactide can be divided into three types: L-lactide, D-lactide, and meso-...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D319/12
CPCC07D319/12C07B2200/07
Inventor 张燕飞卓胜池钱俊宇
Owner 长兴电子(苏州)有限公司
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