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Glycollic acid purification method, glycollic acid crystal and application thereof

A purification method and technology of glycolic acid, applied in the purification of glycolic acid, the application of glycolic acid crystals, the field of glycolic acid crystals, can solve the problems of high content of low polymer, high chroma, low purity of glycolic acid crystals, etc. Recovery rate, effect of reducing chroma

Pending Publication Date: 2021-04-13
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The purpose of the present invention is to provide a method for purifying glycolic acid in order to overcome the problems of high temperature in the concentration process of the aqueous glycolic acid solution in the prior art, low purity of the obtained glycolic acid crystals, high polymer content in the product, and high chroma And glycolic acid crystals and applications thereof, the glycolic acid crystals prepared by the method provided by the invention have high purity and low polymer content

Method used

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Embodiment approach

[0040]According to a preferred embodiment of the invention, the concentration of less than 70 wt% aqueous ethanol is a aqueous solution of 0.1 to 35 wt% ethanol acid, and the molecular distillation is a two-stage molecule distillation in series.

[0041]Preferably, the two-stage molecular distillation of the series comprises: (1) aqueous 0.1-35 wt% aqueous solution of aqueous solution is concentrated into a concentration of at least 10% by weight and a concentration of from 35 wt% to less than 70% by weight of a concentration of at least 10% by weight and a concentration of from 70% by weight of a concentration of at least 10% by weight and a concentration of from 35 wt% to less than 70% by weight of the concentration of at least 10% by weight and a concentration of from 35 wt% to less than 70 wt%; (2) The aqueous solution of ethanol acid aqueous concentration of 35 wt% to less than 70 wt% was concentrated to 70-90 wt% ethanol acid aqueous solution by distillation of the second stage m...

Embodiment 1

[0055]1) 5 wt% ethanol acid aqueous 5 wt% ethanol acid solution from the ethanolate hydrolyzate is concentrated into 36 wt% aqueous solution of ethanol, wherein the conditions of the first grade molecular distillation include: the distillation temperature is 65 ° C, the pressure is 2000Pa The condensation temperature is -5 ° C, the scraper rotation speed is 500 rpm;

[0056]2) The 36 wt% ethanol aqueous solution was concentrated to 70 wt% ethanol aqueous solution by distillation of the second stage, and the polymer content <0.3 wt%, wherein the conditions of the secondary molecular distillation include: the distillation temperature is 50 ° C, the pressure is 5500Pa The condensation temperature is -5 ° C, the scraper rotation speed is 500 rpm;

[0057]3) The aqueous 70 wt% ethanol acid aqueous solution was crystallized at -20 ° C, and then the solid-liquid separated, gave a purity of the ethanol acid crystal of 99.9 wt%, and the polymer content was <0.1% by weight.

Embodiment 2

[0059]1) 5 wt% ethanol acid aqueous solution of the ethanolic acid process from chlorocetic acid is concentrated into 39 wt% ethanol aqueous solution by distillation of the first stage molecule, wherein the conditions of the first grade molecule distillation include: the distillation temperature is 75 ° C, and the pressure is 2800Pa, the condensation temperature is -10 ° C, the scraper rotation speed is 500 rpm;

[0060]2) The 39 wt% ethanol aqueous solution was concentrated into 85 wt% ethanol aqueous solution by distillation of the second stage molecule, the polymer content <0.5 wt%, wherein the conditions of the secondary molecular distillation include: the distillation temperature is 60 ° C, the pressure is 7000Pa The condensation temperature is 0 ° C, the scraper rotational speed is 500 rpm;

[0061]3) The aqueous 85 wt% ethanol acid aqueous solution was crystallized at -15 ° C, and then the solid-liquid separated, the purity of the ethanol acid crystal was 99.8 wt%, and the polymer ...

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Abstract

The invention relates to the technical field of glycolic acid purification, and discloses a glycolic acid purification method, a glycolic acid crystal and application thereof. The method comprises the following steps of: (1) concentrating a glycollic acid aqueous solution of which the concentration is lower than 70wt% into a 70-90wt% glycollic acid aqueous solution by molecular distillation; and (2) crystallizing the 70-90wt% glycollic acid aqueous solution obtained in the step (1), and carrying out solid-liquid separation to obtain a glycollic acid crystal and a glycollic acid mother solution. The purity of the glycollic acid crystal obtained by the method provided by the invention is as high as 99.9 wt%, and the polymer content is less than 0.1 wt%. The glycollic acid crystal obtained by the method is applied to the fields of organic synthesis, medicines and cosmetics.

Description

Technical field[0001]The present invention relates to the field of ethanolic acid purification techniques, and more particularly to a purification method of ethanolic acid and an application of a ethanolic acid crystal and a ethanolate crystal obtained by the purification process.Background technique[0002]Glycolic acid (also known as acetic acid) is an important fine chemical and organic intermediate, widely used in personal care, textile, industrial production, especially pharmaceutical engineering materials and degradable materials, etc., so that glycolic acid demand increase yearly.[0003]Production methods of glycolic acid include hydrochloride, formaldehyde, cyanide, aldehyde catalytic dismissal, oxalic acid electrolytic reduction method, bioferder, oxalate, hydrogenate, but in gase acid Most of the crystals will undergo the concentrated crystallization steps of ethanol acid aqueous solutions. The conventional method of moisture in the aqueous solution of the ethanol is essentia...

Claims

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Application Information

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IPC IPC(8): C07C51/43C07C51/44C07C59/06A61K8/365
CPCC07C51/43C07C51/44A61K8/365
Inventor 王誉蓉宋海峰龚海燕
Owner CHINA PETROLEUM & CHEM CORP
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