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Lactide synthesis method

A synthesis method and technology of lactide, applied in the direction of organic chemistry, can solve the problems of poor optical purity, expensive catalyst, difficult to apply mechanically, etc., achieve high yield, reduce production cost, and be environmentally friendly

Active Publication Date: 2021-08-10
YANGZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

There are disadvantages such as poor optical purity, low yield, expensive catalyst and difficult application.

Method used

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  • Lactide synthesis method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Into a 250 ml round bottom flask was added 100 g lactic acid, 0.3 g copper triflate, 1.5 g polyselenide. Build a vacuum distillation device (with a vent valve to adjust the vacuum in the system), under 100 mm Hg pressure, mechanical stirring (400 rpm), heat to 140 ° C for polymerization, and keep warm for 4 hours, polymerization The water produced by the reaction is removed by a distillation unit. Completely close the purge valve, increase the vacuum of the system, and gradually raise the temperature of the system to 185° C. for cracking under the pressure of 15 mm Hg, collect the distilled components to obtain the product lactide. The yield is 89%, and the optical purity is 98.6%.

Embodiment 2

[0021] Only change the kind of copper salt, other conditions are the same as Example 1, research the effect of using different copper salt catalysts, the results are shown in Table 1:

[0022] Table 1 Comparison of the effects of different copper salt catalysts

[0023]

[0024] The above results show that the copper salt catalyst significantly affects the product yield, but has little effect on the optical purity. Among them, copper salts with electron-withdrawing groups have the best effect, such as copper trifluoromethanesulfonate and copper trifluoroacetate.

Embodiment 3

[0026] Only the usage amount of copper salt was changed, other conditions were the same as Example 1, and the effect of using different dosages of copper salt was studied, and the results are shown in Table 1.

[0027] Table 2 Comparison Table of Effect Test of Different Copper Salt Dosage

[0028]

[0029] The above results show that the amount of copper salt has little effect on the optical purity of the product, but has a significant effect on the yield, and the effect is best when the amount reaches 0.3%. Continue to increase the dosage, and can not improve the yield.

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Abstract

The invention discloses a lactide synthesis method, and belongs to the technical field of chemical production. The method comprises the following steps: mixing lactic acid, a copper salt and a polyselenide catalyst, carrying out a polymerization reaction, then carrying out a cracking reaction, distilling, and collecting fractions to obtain lactide. The synthesis method is relatively high in yield and high in optical purity of the product, and can be used for preparing high-quality polylactic acid. The catalyst is not inactivated after being recycled for multiple times, so that the catalyst cost can be greatly reduced, and the production cost of the product is reduced. The method can be used mechanically without separating the catalyst and can be developed into a continuous synthesis process, and apart from water, the whole production process is free of waste discharge and environment-friendly.

Description

technical field [0001] The invention belongs to the technical field of chemical production. Background technique [0002] Polylactic acid is a degradable material that is expected to replace traditional plastics and thus solve the problem of white pollution. There are two main methods for the synthesis of polylactic acid, one is the direct polymerization of lactic acid, and the other is the polymerization of lactide. Among them, the lactic acid direct polymerization method has problems such as complex catalytic system and easy corrosion of reaction equipment (the iron element dissolved in equipment corrosion will make the color of the polymer darker and affect the product phase). In addition, the water molecules removed during the polymerization of lactic acid will lead to changes in the structure of the material in the system, affecting the optical purity of the polymer, which may affect the mechanical properties of the prepared material. The lactide polymerization rule c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D319/12
CPCC07D319/12
Inventor 俞磊孟祥坤
Owner YANGZHOU UNIV