A method for preparing tetracarboxylic acid with regular crystal shape

A tetracarboxylic acid and crystal technology, which is applied in the field of monomer synthesis of special engineering plastics, can solve problems affecting the quality of polyimide products, and achieve the effects of increasing safety, good dispersion, and improving the degree of acidification

Active Publication Date: 2021-10-22
WANHUA CHEM GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Actual studies have shown that when tetracarboxylic acid crystals have a special regular shape, they are easy to filter and separate, which also shows that their purity is very high, and the rate of dehydration into anhydride is also relatively fast, which will briefly affect the quality of polyimide products.

Method used

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  • A method for preparing tetracarboxylic acid with regular crystal shape
  • A method for preparing tetracarboxylic acid with regular crystal shape
  • A method for preparing tetracarboxylic acid with regular crystal shape

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] In a reactor with a spherical condenser and a fractionation column with a reflux ratio controller, slowly and continuously add 24 wt% of bisphenol A type diether to 140 g of 98 wt % concentrated sulfuric acid at a temperature of 60 ° C Aqueous solution of tetra-substituted sodium salt of tetracarboxylic acid (bisphenol A type bis-ether tetra-substituted sodium salt of tetracarboxylic acid 225.4g (molecular weight 608), water 700g), the temperature of the whole process of adding is 100°C, and the time of adding is 30min. A dispersed granular solid gradually formed under stirring.

[0045] When the amount of bisphenol A type diether tetracarboxylic acid tetrasubstituted sodium salt solution is 35% of the total amount, 1.47 g of sorbitan lauryl ester is added at one time, and 293 g of acetonitrile is added to the system, and the addition time is 10 minutes , after adding acetonitrile, keep the acetonitrile in a continuous total reflux state. Continue to slowly add the aqueo...

Embodiment 2

[0047] In a reactor with a spherical condenser and a fractionation column with a reflux ratio controller, slowly and continuously add 25 wt% of hydroquinone-type bis- Aqueous solution of tetra-substituted sodium ether tetracarboxylic acid (hydroquinone-type bis-ether tetra-substituted sodium salt 233g (molecular weight: 526), ​​water 700g), the temperature of the whole process is 105°C, and the time of adding is 40min. A dispersed granular solid gradually formed under stirring.

[0048] When the hydroquinone-type bis-ether tetracarboxylic acid tetra-substituted sodium salt solution was added in an amount of 50% of the total amount, 2.10 g of nonylphenol polyoxyethylene ether was added at one time, and 350 g of acetonitrile was added to the system, and the addition time was 15 minutes. After adding acetonitrile, keep the acetonitrile in a continuous total reflux state. Continue to slowly add the aqueous solution of hydroquinone type bis-ether tetracarboxylic acid tetra-substit...

Embodiment 3

[0051] In a reactor with a spherical condenser and a fractionation column with a reflux ratio controller, slowly add 20 wt% of hydroquinone-type bis-ether four Aqueous solution of tetrasubstituted sodium salt of formic acid (175 g of tetrasubstituted sodium salt of hydroquinone type bisether tetracarboxylic acid, 700 g of water), the temperature of the whole process of adding drops is 70°C, and the time of adding drops is 45 minutes. A dispersed granular solid gradually formed under stirring.

[0052] When the hydroquinone-type bis-ether tetracarboxylic acid tetra-substituted sodium salt solution was added in an amount of 30% of the total amount, 8.4 g of Rubrakine A was added at one time, and 210 g of acetonitrile was added to the system, and the addition time was 20 minutes. After adding acetonitrile, Keep acetonitrile under continuous total reflux. Continue to slowly add the aqueous solution of hydroquinone type bis-ether tetracarboxylic acid tetra-substituted sodium salt ...

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Abstract

The invention provides a method for preparing tetracarboxylic acid with regular crystal shape, comprising the steps of: a) adding dropwise an aqueous solution of tetracarboxylic acid tetrasubstituted alkali metal salt into a high-concentration hot inorganic acid aqueous solution to generate tetracarboxylic acid solid; b) when When the added amount of the aqueous solution of tetracarboxylic acid tetrasubstituted alkali metal salt reaches 30-50% of the total amount, add a dispersant and an organic solvent with a boiling point of 50-100°C to the system; c) continue to carry out the acidification reaction and then separate the organic solvent; d) After the separation of the organic solvent is completed, the temperature of the system is lowered to 60-80° C., and then filtered, washed, and dried to obtain a tetracarboxylic acid solid. The solid is observed under an optical microscope, and it can be seen that the appearance is regular-shaped crystals.

Description

technical field [0001] The invention relates to a method for preparing regular-shaped tetracarboxylic acid crystals, and belongs to the technical field of special engineering plastic monomer synthesis. Background technique [0002] Triphenylene ether tetracarboxylic acid, biphenyl tetracarboxylic acid, bisphenol A diether tetracarboxylic acid, biphenyl diphenol diether tetracarboxylic acid, monoether tetracarboxylic acid, thioether tetracarboxylic acid, etc. are polyimide monomers - dianhydride important intermediates. The purity and shape of tetracarboxylic acid will directly affect the method of its dehydration into anhydride and the purity of the dianhydride product. [0003] Although the structures and synthesis methods of various tetracarboxylic acids are different, they have something in common, that is, most of them are prepared by acidification of four-substituted alkali metal salts of tetracarboxylic acids. However, due to the structural characteristics of differe...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C51/42C07C65/24C07C65/34C07C63/331
CPCC07B2200/13C07C51/42C07C65/24C07C65/34C07C63/331
Inventor 张鑫李旭峰孙一峰仇伟陈海波
Owner WANHUA CHEM GRP CO LTD
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