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Method for manufacturing lactide with polyhydroxy lactic acid oligomer

A polyhydroxylactic acid and oligomer technology, applied in organic chemistry and other directions, can solve problems such as hindering the normal progress of the degradation reaction

Inactive Publication Date: 2008-01-23
NANJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This theory explains the reason why the polymer tends to be stable after acetylation of the hydroxyl terminal because the electron-withdrawing acetyl group will block the switching state and hinder the normal progress of the degradation reaction.

Method used

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  • Method for manufacturing lactide with polyhydroxy lactic acid oligomer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0013] Add 68g of L-lactic acid (88% aqueous solution), 1.2g of 1,4-butanediol and 0.3g of stannous octoate into a three-necked bottle equipped with mechanical stirring, place it in an oil bath at 100°C, and slowly evacuate to 40mmHg, water evaporates, maintain the vacuum state, gradually raise the temperature to 180°C, react for 6 hours, the molecular weight can reach 6600. The heating mantle was changed and the temperature was raised to 220° C., and the vacuum was pumped to 3 mmHg. The pyrolysis reaction was completed in 40 minutes, and 46 g of crude lactide was collected, with a yield of 93%.

Embodiment 2

[0015] Add 100g of D,L-lactic acid (85% aqueous solution), 2.4g of 1,3-propanediol and 0.7g of stannous chloride into a three-necked bottle equipped with mechanical stirring, place it in an oil bath at 100°C, and slowly evacuate When it reached 70mmHg, some water evaporated, and the vacuum state was maintained, and the temperature was gradually raised to 180°C, and the reaction was carried out for 8 hours, and the molecular weight could reach 3800. Replace the heating mantle and raise the temperature to 220° C., vacuumize to 4 mmHg, and the thermal cracking reaction ends in about 1 hour. 61 g of light yellow crude lactide is collected, with a yield of 90%.

Embodiment 3

[0017] Add 100g of L-lactic acid (88% aqueous solution), 0.8g of ethylene glycol and 0.6g of zinc oxide into a three-necked bottle equipped with mechanical stirring, place it in an oil bath at 100°C, and slowly evacuate to 40mmHg, and some water will evaporate , maintain the vacuum state, gradually raise the temperature to 180°C, react for 8 hours, and the molecular weight can reach 10500. Replace the heating mantle and raise the temperature to 220° C., vacuumize to 4 mmHg, and the pyrolysis reaction ends in about 1.5 hours. Collect and obtain 59.5 g of pale yellow crude lactide, with a yield of 85%.

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Abstract

The objective of the invention is to provide a method for preparing the lactide, which is characterized in that: the terminal polyhydroxy lactic acid oligomer prepared by the multiple hydroxyl alcohol produces the lactide through thermal degradation. Compared with the method of gaining the lactide through pure lactic acid oligomer thermal degradation, the invention has faster pyrolysis rate of the reaction and higher product yield and can make the size of the oligomer molecular weight suitable for the widening of the range with the objective of high lactide yield.

Description

technical field [0001] The invention relates to a method for preparing lactide. Background technique [0002] Today, when sustainable development is advocated, polylactic acid (PLA) is one of the most researched biodegradable materials. Lactic acid, the initial raw material of polylactic acid, can be widely derived from natural products such as corn, sugar beet, and cellulose, so it can effectively alleviate the increasingly scarce petroleum resources; at the same time, polylactic acid products can be completely decomposed into CO by microorganisms in the natural environment. 2 and H 2 O, does not cause "white pollution", is a real bio-renewable polymer. [0003] The indirect ring-opening polymerization of lactide is one of the important methods for preparing polylactic acid. The current method for preparing lactide is usually to first prepare lactic acid into low molecular weight lactic acid oligomers, and then thermally degrade the lactic acid oligomers to obtain lactid...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D319/12
Inventor 刘晓宁魏荣卿刘迎
Owner NANJING UNIV OF TECH
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