Preparation method of lactide

A lactide and lactic acid technology, applied in the direction of organic chemistry, can solve the problems of high synthesis cost, increased production efficiency, disadvantages, etc., and achieve the effects of simple and environmentally friendly production process, less environmental pollution, and low reaction temperature

Inactive Publication Date: 2018-10-02
CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In addition, the patent (CN101891733B) uses a titanium-based catalyst to catalyze the direct synthesis of lactide from lactate by transesterification; however, compared with lactic acid, the synthesis cost of lactate is high, which is not conducive to increasing production efficiency

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[0021] The invention provides a method for preparing lactide, which can be realized by those skilled in the art by referring to the content of this article and appropriately improving the process parameters. In particular, it should be pointed out that all similar substitutions and modifications are obvious to those skilled in the art, and they all belong to the protection scope of the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously make changes or appropriate changes and combinations to the method and application herein without departing from the content, spirit and scope of the present invention to realize and apply the present invention Invent technology.

[0022] The invention provides a method for preparing lactide, comprising:

[0023] In the presence of H-beta molecular sieve, the lactic acid is heated and reacted under reduced pressure to obtain lactide; the ...

Embodiment 1

[0041] 2 grams of H-beta molecular sieve (SiO 2 :Al 2 o 3 Molar ratio 25:1), 2 grams of lactic acid (concentration 105%) were added to the reaction flask. The reaction flask was placed in an oil bath at a temperature of 130° C. and continuously stirred; at the same time, vacuum distillation was carried out. After 4 hours of reaction, no product distilled out of the reaction flask, and lactide was obtained in the condenser, and the lactide yield was 27%.

Embodiment 2

[0043]1 gram of H-beta molecular sieve (Si:Al molar ratio 12.5:1) and 4 grams of lactic acid (concentration 105%) were added to the reaction flask. The reaction bottle was kept stirring in an oil bath with a temperature of 120°C; at the same time, vacuum distillation was carried out with a vacuum degree of 300 Pa. After 4 hours of reaction, no product distilled out of the reaction bottle, and lactide was obtained in the condenser tube, and the lactide yield was 51 %.

[0044] The result is as figure 1 as shown, figure 1 GC-MS figure for the lactide prepared in Example 2 of the present invention; figure 2 The mass spectrum of lactic acid at a retention time of 4.263 minutes in the GC-MS diagram of lactide prepared in Example 2 of the present invention; image 3 The mass spectrum of racemic lactide at the retention time of 6.377 minutes in the GC-MS chart of the lactide prepared in Example 2 of the present invention; Figure 4 It is the mass spectrum of L-lactide with a ret...

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Abstract

The invention provides a preparation method of lactide. The method comprises the following step: lactic acid is subjected to a heating reaction under reduced pressure in presence of an H-beta molecular sieve, and lactide is obtained, wherein the reaction pressure is 50-1500 Pa. With adoption of the method adopting vacuum and heating, lactic acid reaction is catalyzed by the H-beta molecular sieve,synthesis of lactide from lactic acid is finished directly, lactide with high optical purity (higher than 96%) is obtained, and the defects of long technological process and high reaction temperaturecaused by the that that oligomerization and high-temperature pyrolysis are needed in the conventional lactide are overcome. No organic solvent is used in the whole preparation process, only wastewater is produced during preparation, and little environmental pollution is caused; the reaction temperature is low, repeated catalysis is realized through hydrolysis of a lactic acid oligomer, the H-betamolecular sieve can be recycled, and the preparation process is simple and environmentally friendly and has potential large-scale application prospect.

Description

technical field [0001] The invention relates to the technical field of organic synthesis, in particular to a method for preparing lactide. Background technique [0002] With the development of society and economy, petroleum-based non-degradable plastics are used more and more widely; at the same time, various types of waste generated are increasingly polluting the natural environment; in addition, the demand for general-purpose plastics on non-renewable petroleum resources has affected sustainable development of mankind. The development of biodegradable plastics based on biomass to replace traditional petroleum-based plastics has become a research focus in the field of polymer materials. Polylactic acid is a bio-based degradable polymer polyester material with high mechanical strength and good processing performance, suitable for extrusion, injection molding, blister and other processing methods; it can be degraded into carbon dioxide in the natural environment after being ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D319/12
CPCC07D319/12
Inventor 项盛边新超陈学思
Owner CHANGCHUN INST OF APPLIED CHEMISTRY - CHINESE ACAD OF SCI
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