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Method for refining pyromellitic dianhydride

A technology of pyromellitic dianhydride and crude anhydride, which can be used in sustainable manufacturing/processing, organic chemistry, climate sustainability, etc., and can solve problems such as low quality, uneven particle size, and low yield

Active Publication Date: 2022-08-05
JIANGSU ZHENGDAN CHEM IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0012] Its shortcomings are: the purity of crude anhydride in the market is 92-98%; the purity of refined anhydride is about 99.5%, and the yield is about 80%.
The existing gas phase capture method, sublimation method or recrystallization method have the problems of low quality, low yield and uneven particle size

Method used

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  • Method for refining pyromellitic dianhydride
  • Method for refining pyromellitic dianhydride
  • Method for refining pyromellitic dianhydride

Examples

Experimental program
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Effect test

Embodiment 1

[0028] First, add a mixed solvent of 3 parts of acetone and 1 part of acetonitrile (in a ratio of 3:1 by weight) to the reaction vessel, and start stirring; then add 0.5 part of 98% crude anhydride (crude anhydride and mixed solvent in a ratio of 1:8 by weight) ) into the reaction vessel, continue to heat up and reflux until the crude anhydride is basically dissolved, and the reflux temperature is 65 ° C; then hot filtration to remove insoluble impurities;

[0029] At 65°C, the air containing 3.5vt% ozone was fed into the filtrate for oxidation, and kept for 30min, and the amount of air fed was 60-80 times / hour of the solvent volume; then 1 / 2 of the weight of the solvent was distilled out; then The remaining mother liquor was cooled to 20°C, the cooling rate was 1°C / min, and the stirring rate was controlled at 135r / min until the crystals were precipitated; then the crystalline material was filtered through a vacuum dryer, the vacuum degree was maintained at 0.08-0.09MPa, and th...

Embodiment 2-1

[0035] 92% crude anhydride was used instead, and others were the same as in Example 1.

Embodiment 2-2

[0037] 95% crude anhydride was used instead, and others were the same as in Example 1.

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Abstract

The invention discloses a method for refining pyromellitic dianhydride in the field of chemical production, which comprises the following steps: dissolving, filtering, oxidizing, distilling, crystallizing, filtering and drying to obtain a target product, during dissolving, acetone and acetonitrile are prepared into a mixed solvent according to the weight ratio of (2-4): 1, and the weight ratio of crude anhydride to the mixed solvent is 1: (4-12); during oxidation, ozone-containing air is introduced into the filtrate for oxidation; according to the invention, the reflux temperature lower than the boiling point of acetonitrile can be realized, so that the refining energy consumption is reduced. Ozone is introduced to oxidize methyl carboxylic acid impurities into corresponding aromatic acid, and other aromatic diacid and trianhydride are easily dissolved in acetone and acetonitrile, so that during crystallization, the aromatic acid and trianhydride cannot be separated out and enter pyromellitic dianhydride, a pure product of the pyromellitic dianhydride is white, the obtained pyromellitic dianhydride is low in impurity content, the product quality is improved, and the production cost is reduced. Meanwhile, the purification energy consumption is low; the refined anhydride finished product has the characteristics of good purity, high melting point, high yield and uniform granularity.

Description

technical field [0001] The invention relates to a method for purifying pyromellitic dianhydride, in particular to obtaining refined pyromellitic dianhydride through an oxidation-crystallization method from crude pyromellitic dianhydride, belonging to the technical field of chemical industry. Background technique [0002] Pyromellitic dianhydride, referred to as homoanhydride, the English abbreviation is PMDA. Anhydride is an important organic chemical raw material. Homo anhydride is an important raw material for the production of polyimide resins and films, matting agents, plasticizers, epoxy resin curing agents, polyester resin cross-linking agents, phenolic resin stabilizers, etc. Polyimide is a new material with high temperature resistance, low temperature resistance, radiation resistance, impact resistance and excellent electrical and mechanical properties. It has important uses that cannot be replaced by other engineering plastics in the aerospace and electromechanical...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D493/04
CPCC07D493/04Y02P20/10
Inventor 曹翠琼曹丹李江华庄建李峻高俊唐莹王福曹正国
Owner JIANGSU ZHENGDAN CHEM IND CO LTD
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