Unlock instant, AI-driven research and patent intelligence for your innovation.

Method for purifying crude cyclic ester

A purification method and technology of cyclic esters, which are applied in the field of purification of crude cyclic esters, can solve the problems of complex purification process, poor purification effect, high energy consumption, etc., and achieve the effects of increasing yield, reducing energy consumption, and reducing the number of operations

Inactive Publication Date: 2021-07-20
CHINA SHENHUA COAL TO LIQUID & CHEM CO LTD +1
View PDF0 Cites 0 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a method for the purification of crude cyclic esters, which has the advantages of simple process and low energy consumption, in order to overcome the problems of complex crude cyclic ester purification process, high energy consumption and poor purification effect in the prior art. And the advantages of good purification effect

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Method for purifying crude cyclic ester

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] (1) Mix crude glycolide with recrystallization solvent I ethyl acetate and recrystallization solvent II ethanol, and perform one recrystallization to obtain glycolide crystals, wherein the volume ratio of ethyl acetate and ethanol is 1:0.5; In the obtained glycolide crystal, the content of reaction solvent nitrobenzene is 0.1wt%, the content of free acid acetic acid is 0.4wt%, the content of oligomer polyglycolic acid is 0.9wt%, and the content of recrystallization solvent is 1.2wt%. wt%, the content of glycolide is 97.4wt%;

[0045] (2) Glycolide crystals are transported into a cyclic ester melting tank to form molten glycolide under normal pressure and 86° C., and flush into nitrogen to seal to prevent the oxidation of molten glycolide; The molten material enters the evaporator from the top of the wiped film evaporator for variable temperature evaporation, wherein the pressure of the wiped film evaporator is 2kPaA, the low temperature evaporation temperature at the up...

Embodiment 2

[0048] (1) recrystallize crude lactide and recrystallization solvent I butyl acetate once to obtain lactide crystals, wherein, in the obtained lactide crystals, the content of the reaction solvent dimethylformamide is 0.16wt% , the content of free acid acetic acid is 0.56wt%, the content of oligomer polylactic acid is 0.88wt%, the content of recrystallization solvent is 1.1wt%, and the content of lactide is 97.3wt%;

[0049] (2) Lactide crystals are transported into a cyclic ester melting tank, and molten lactide is formed under normal pressure and 102° C., and then flushed into nitrogen to seal to prevent the oxidation of lactide in the molten state; The molten material enters the evaporator from the top of the wiped film evaporator for variable temperature evaporation, wherein the pressure of the wiped film evaporator is 20kPaA, the low temperature evaporation temperature at the upper part of the heat exchange tube of the wiped film evaporator is 104°C, and the residence time...

Embodiment 3

[0052] (1) Mix crude lactide with recrystallization solvent I methyl acetate and recrystallization solvent II isopropanol, and perform one recrystallization to obtain lactide crystals, wherein, recrystallization solvent I methyl acetate and recrystallization solvent The volume ratio of II isopropanol is 1:0.8; In the lactide crystal obtained, the content of reaction solvent dimethylformamide is 0.13wt%, the content of free acid acetic acid is 0.1wt%, and the content of oligomer polylactic acid The content is 0.8wt%, the content of recrystallization solvent is 0.9wt%, and the content of lactide is 98.07wt%;

[0053] (2) Transport the lactide crystals to the cyclic ester melting tank, form the molten lactide under the condition of normal pressure and 98° C., and rush into the nitrogen seal to prevent the oxidation of the lactide in the molten state; The molten material enters the evaporator from the top of the wiped film evaporator for variable temperature evaporation. The press...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

The present invention relates to the technical field of cyclic ester purification, and discloses a crude cyclic ester purification method, which comprises: carrying out recrystallization on crude cyclic ester to obtain a cyclic ester crystal, melting the cyclic ester crystal, and carrying out variable temperature evaporation and sedimentation operation to obtain the refined cyclic ester. According to the purification method of the crude cyclic ester, provided by the invention, the recrystallized cyclic ester crystal is melted and then subjected to variable-temperature evaporation and sedimentation operation, so that impurities in the cyclic ester crystal can be removed on the premise of reducing the decomposition of the cyclic ester as much as possible, and therefore, the refined cyclic ester with the purity of 99.2 wt% or above and the yield of 99% or above is obtained.

Description

technical field [0001] The invention relates to the technical field of purification of cyclic esters, in particular to a method for purifying crude cyclic esters. Background technique [0002] Cyclic esters (glycolide, lactide, etc.) are generally synthesized by high-temperature methods. Taking lactide as an example: lactic acid is dehydrated and condensed into polylactic acid oligomers, and polylactic acid is cyclized to form acrylic acid under the action of a catalyst. lactide, and then use distillation to extract lactide vapor from the reaction system, and then cool at 60°C-85°C to obtain crude lactide. [0003] Among them, the lactide vapor extracted from the reaction system by distillation contains, in addition to gaseous lactide, a part of incompletely reacted reactant lactic acid, intermediate product polylactic acid, reaction solvent and water, etc., so it is called crude lactide. The presence of impurities will affect the product performance of cyclic esters, so c...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
IPC IPC(8): C07D319/12
CPCC07D319/12
Inventor 吴勇许朝阳尹甜吴金华
Owner CHINA SHENHUA COAL TO LIQUID & CHEM CO LTD