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Method for preparing 2,4-dimethylbenzoic acid by using carbon dioxide carboxylation process

A technology of dimethyl benzoic acid and carbon dioxide, which is applied in the preparation of carboxylate salts, chemical instruments and methods, and the preparation of organic compounds. It can solve the problems of harsh reaction conditions, many by-products, and complicated processes, and achieve mild reaction conditions. , environmental friendliness and low cost of raw materials

Inactive Publication Date: 2013-09-25
TAISHAN MEDICAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] All of these synthetic routes have the disadvantages of relatively harsh reaction conditions, many reaction steps, complicated process and many by-products.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Put 100g of m-xylene and 20g of aluminum trichloride catalyst into the reaction kettle, start stirring, continuously add carbon dioxide gas into the reaction kettle, keep the pressure inside the kettle at 0.4MPa, keep the reaction temperature at 25°C, and react for 9 hours. After the reaction is completed, add about 10 g m-xylene and 15 g dilute hydrochloric acid to the reactant, keep the temperature below 30° C., stir for 20 minutes, and let stand to separate layers. Adjust the pH value of the organic phase to about 11 with alkali, let it stand, separate the water phase, add dilute hydrochloric acid to adjust the pH value to 2-3, and precipitate a large amount of white powder. Filter and dry to obtain the product 2,4-dimethylbenzoic acid.

Embodiment 2

[0019] Put 100g of m-xylene and 25g of aluminum trichloride catalyst into the reaction kettle, start stirring, continuously add carbon dioxide gas into the reaction kettle, keep the pressure inside the kettle at 0.3MPa, keep the reaction temperature at 30°C, and react for 7 hours. After the reaction is completed, add about 10 g m-xylene and 15 g dilute hydrochloric acid to the reactant, keep the temperature below 30° C., stir for 20 minutes, and let stand to separate layers. Adjust the pH value of the organic phase to about 11 with alkali, let it stand, separate the water phase, add dilute hydrochloric acid to adjust the pH value to 2-3, and precipitate a large amount of white powder. Filter and dry to obtain the product 2,4-dimethylbenzoic acid.

Embodiment 3

[0021] Put 100g of m-xylene and 30g of aluminum trichloride catalyst into the reaction kettle, start stirring, continuously add carbon dioxide gas into the reaction kettle, keep the pressure inside the kettle at 0.5MPa, keep the reaction temperature at 35°C, and react for 6 hours. After the reaction is completed, add about 10 g m-xylene and 15 g dilute hydrochloric acid to the reactant, keep the temperature below 30° C., stir for 20 minutes, and let stand to separate layers. Adjust the pH value of the organic phase to about 11 with alkali, let it stand, separate the water phase, add dilute hydrochloric acid to adjust the pH value to 2-3, and precipitate a large amount of white powder. Filter and dry to obtain the product 2,4-dimethylbenzoic acid.

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Abstract

The invention discloses a method for preparing 2,4-dimethylbenzoic acid by using a carbon dioxide carboxylation process. The method comprises the following steps of: (1) orderly adding m-xylene and an aluminium trichloride catalyst according to a certain ratio in a reaction kettle with a stirring function, and sealing the reaction kettle; (2) leading carbon dioxide gas to the reaction kettle, replacing air and starting the stirring function, pressurizing to 0.2-0.7Mpa, and keeping the temperature at 25-40 DEG C to react for 5-10 hours; (3) adding a reactant to the m-xylene and diluted hydrochloric acid after reaction is finished, keeping below 30 DEG C to agitate for 20 minutes, stewing and layering; (4) adjusting pH value of an organic phase to about 11 by alkali, standing, and separating the water phase, adding the diluted hydrochloric acid to adjust the pH value to 2-3, separating out a lot of white powder, filtering and drying to obtain the product 2,4-dimethylbenzoic acid, wherein the mass ratio of the m-xylene to the aluminium trichloride catalyst is 1 to (0.10-0.35).

Description

technical field [0001] The invention belongs to the technical field of fine chemical production, in particular to a method for preparing 2,4-dimethylbenzoic acid by carbon dioxide carboxylation. Background technique [0002] 2,4-Dimethylbenzoic acid is an intermediate for the preparation of acylphosphine oxides, which are new photoinitiators and are widely used. It can also be used as an intermediate for dyes, insecticides, and medicines, and has a large market at home and abroad. [0003] The 2,4-dimethylbenzoic acid synthetic method of bibliographical information has following several: [0004] (1) m-xylene and oxalyl chloride are reacted under the catalysis of aluminum trichloride, and then hydrolyzed to obtain; [0005] (2) m-xylene is obtained by addition of carbon dioxide after bromination and Grignard reaction; [0006] (3) It can be obtained by acylation reaction between m-xylene and chloroacetyl chloride, followed by haloform reaction and then acidification. [...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C63/04C07C51/15
Inventor 曹晓群葛燕青陈震
Owner TAISHAN MEDICAL UNIV
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