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Preparation method of 2,5-dihydroxy terephthalic acid

A technology of hydroxyterephthalic acid and dialkoxybenzene is applied in the synthesis field of ortho-para-substituted dicarboxylic acid, can solve the problems of long reaction time, complicated separation, high pressure of the method, etc., and achieves high product yield, The effect of high purity and short cycle time

Inactive Publication Date: 2011-10-12
SHANDONG NON METALLIC MATERIAL RES INST
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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 preparing DHTA with mild reaction conditions and easy separation and operation to solve the problems of high pressure, violent reaction, long reaction time, complicated separation, low purity and low conversion rate in the existing DHTA preparation method

Method used

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  • Preparation method of 2,5-dihydroxy terephthalic acid
  • Preparation method of 2,5-dihydroxy terephthalic acid
  • Preparation method of 2,5-dihydroxy terephthalic acid

Examples

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Embodiment 1

[0030] This example provides a method for preparing DHTA with 1,4-dibromo-2,5-dimethoxybenzene as the initial raw material, metal magnesium and 1,4-dibromo-2,5-dimethoxybenzene The molar ratio of phenylbenzene was 2.3:1.

[0031] On a dry 250ml three-necked bottle, install a spherical condenser with a calcium chloride drying tube and a constant pressure dropping funnel, N 2 Under protection, add fresh magnesium shavings, add dropwise a mixture of 2.96g (0.01mol) 1,4-dibromo-2,5-dimethoxybenzene and 30ml anhydrous tetrahydrofuran through a constant pressure dropping funnel, the addition amount is about 1 / 10 of the total volume, put a small grain of iodine to initiate the reaction; control the temperature at (40-50) ° C, and continue to drop the remaining 1,4-dibromo-2,5-dimethoxybenzene / The tetrahydrofuran solution was continued to react for 30 min after the dropwise addition, and cooled to room temperature to obtain the Grignard reagent (A) of 1,4-dibromo-2,5-dimethoxybenzen...

Embodiment 2

[0036] This example provides a method for preparing DHTA with 1,4-dibromo-2,5-diethoxybenzene as the initial raw material, metal magnesium and 1,4-dibromo-2,5-diethoxy The molar ratio of base benzene is 2:1.

[0037] First, install a spherical condenser with a calcium chloride drying tube and a constant pressure dropping funnel on a dry 250ml three-necked bottle, N 2 Under protection, add fresh magnesium powder, a drop of 1,2-dibromoethane, dropwise add 9.69g (0.03mol) 1,4-dibromo-2,5-diethoxybenzene raw material and 60ml of anhydrous tetrahydrofuran mixed solution, control the temperature at (55-60) ° C, stir, dropwise, continue the reaction for 40min to obtain the Grignard reagent of 1,4-dibromo-2,5-diethoxybenzene (A ).

[0038] Then pour the Grignard reagent (A) into 0.1mol dry ice, and the solution quickly becomes milky white turbid. After the dry ice evaporates completely, filter, keep the filter cake, dissolve the gained filter cake with distilled water, add 45ml of 5...

Embodiment 3

[0042] This example provides a method for preparing DHTA with 1,4-diiodo-2,5-dipropoxybenzene as the initial raw material, metal magnesium and 1,4-diiodo-2,5-dipropoxy The molar ratio of phenylbenzene is 3:1.

[0043] In anhydrous butyl ether, iodine triggers, fresh magnesium bar reacts with 1,4-diiodo-2,5-dipropoxybenzene 4.46g (0.01mol) to obtain Grignard reagent, and dry CO 2 Gas reaction, with 15ml 20% H 2 SO 4 Acidification to obtain 2,5-dipropoxy terephthalic acid, at room temperature, 2,5-dipropoxy terephthalic acid is hydrolyzed in 20ml of 1mol / L boron tribromide in dichloromethane solution Propoxy to give the product DHTA. The operation process is the same as the first embodiment.

[0044] The yield of the product prepared in this embodiment is 85%, and the purity is 98.3%.

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Abstract

The invention belongs to the technical field of organic synthesis and relates to ortho-para substitution of an aromatic ring, in particular to a synthesis technology of ortho-para substituted dicarboxylic acid. A preparation method of 2,5-dihydroxy terephthalic acid, disclosed by the invention, comprises the following steps of: preparing a Grignard reagent, increasing a carbon chain, hydrolyzing, separating, purifying and the like by adopting a Grignard reaction mechanism based on 1,4-dihalo-2,5-dialkoxy benzene to obtain 2,5-dihydroxy terephthalic acid. The preparation method is implemented under a normal pressure condition and has the advantages of stability in reaction, short period, convenience in operation, easiness in controlling and high yield and purity of a product.

Description

1. Technical field [0001] The invention belongs to the technical field of organic synthesis, and relates to the ortho-para substitution of aromatic rings, in particular to the synthesis technology of ortho-para substituted dibasic carboxylic acids. 2. Background technology [0002] Hydroxybenzoic acid compounds can be used for a variety of valuable purposes, such as monomers for preparing polymers, and also intermediates in organic synthesis. Specifically, 2,5-dihydroxyterephthalic acid (2,5-Dihydroxyterephthalic acid, referred to as DHTA) can be used as an intermediate to produce medicines, colorants, fluorescent substances and organic light-emitting polymers with high solubility, etc. Useful monomers for high performance fibers such as fibers made from poly(2,5-dihydroxy-1,4-phenylenepyridodiimidazole) resins. [0003] [0004] 2,5-dihydroxyterephthalic acid existing preparation method general situation is as follows: [0005] (1) Sikkema mentioned in the patent US 60...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C65/05C07C51/02
CPCC07C51/15C07C65/05
Inventor 郭国建吴立军冀克俭毛如增柳洪超尤瑜升鲁毅
Owner SHANDONG NON METALLIC MATERIAL RES INST