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Synthetic method for 3,6-dichloro-2-hydroxybenzoic acid

A technology of hydroxybenzoic acid and hydroxybenzoate, which is applied in the field of synthesis of 3,6-dichloro-2-hydroxybenzoic acid, can solve the problems of difficult realization and high requirements, and reduce reaction cost and production cost effect

Inactive Publication Date: 2013-04-03
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the existing technology, the yield of this reaction is about 45%. To increase the yield, the requirements for technological production are very high, and it is difficult to realize in industry

Method used

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  • Synthetic method for 3,6-dichloro-2-hydroxybenzoic acid

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Embodiment 1, a kind of synthetic method of 3,6-dichloro-2-hydroxybenzoic acid, carries out following steps successively:

[0028] 1) Dissolve 73g (0.415mol) 2,5-dichlorophenol (95% purity) in 24.8g (0.381mol) KOH (86% purity) and 40ml water in a 1000ml three-necked flask, then add Mix 480ml of xylene as a solvent evenly, heat up to 142~145°C, dehydrate with a water separator until almost no water is evaporated, and obtain 2,5-dichlorophenoxide potassium solution.

[0029] 2) Transfer the potassium 2,5-dichlorophenate solution obtained in the above step 1) to the autoclave, then add 32g of potassium chloride, and fill the autoclave with CO 2 To 3Mpa, after being stabilized, empty the air, and continue the same operation for 3 times, so as to fully replace the air in the kettle; then fill with CO 2 to 5Mpa ， and heating; finally, control the reaction temperature to 145° C. and the reaction pressure to 6 Mpa to carry out the carboxylation reaction, and the reaction time...

Embodiment 2

[0031] Embodiment 2, a kind of synthetic method of 3,6-dichloro-2-hydroxybenzoic acid, carries out following steps successively:

[0032] 1) Dissolve 146g (0.83mmol) 2,5-dichlorophenol (95%) in 98gKOH (0.84mol) aqueous solution (48% concentration) in a 1000ml three-necked flask, and then add 640ml xylene as Mix the solvent evenly, heat up to 142~145°C, dehydrate with a water separator until almost no water evaporates, and obtain 2,5-dichlorophenoxide potassium solution.

[0033] 2) Transfer the potassium 2,5-dichlorophenate solution obtained in the above step 1) to the autoclave, then add 63g of potassium chloride, and use CO 2 After fully replacing the air in the kettle, carry out the carboxylation reaction. The controlled temperature is 145°C, the pressure is 6Mpa, and the reaction time is 12h. After the reaction, a reaction product containing potassium 3,6-dichloro-2-hydroxybenzoate was obtained.

[0034] 3) After cooling the reaction product containing potassium 3,6-dic...

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Abstract

The invention discloses a synthetic method for 3,6-dichloro-2-hydroxybenzoic acid, which sequentially comprises the following steps: 1) salifying 2,5-dichlorophenol, 2) performing carboxylation, and 3) performing refinement, wherein according to Step 2), a 2,5-dichlorophenol saline solution is transferred into a high-pressure reactor, a catalyst is added, CO2 is supplied for high-pressure carboxylation reaction, a reaction product containing 3,6-dichloro-2-hydroxybenzoic acid salt is obtained, and the catalyst is potassium chloride; and according to Step 3), an alkaline solution is added after the reaction product is cooled to a room temperature, pH is adjusted to 11-13, an aqueous phase is obtained after layering, an acid solution is added to the aqueous phase, the pH is adjusted to 1-3, and after vapor distillation is performed and 2,5-dichlorophenol is recovered, suction filtration and drying are performed, and 3,6-dichloro-2-hydroxybenzoic acid is obtained. 3,6-dichloro-2-hydroxybenzoic acid synthesized with the method has the characteristics of low cost and higher yield.

Description

technical field [0001] The invention belongs to a dicamba intermediate production process and relates to a synthesis method of 3,6-dichloro-2-hydroxybenzoic acid. Background technique [0002] 3,6-dichloro-2-hydroxybenzoic acid, 3,6-dichlorosalicylic acid, English name 3,6-Dichlorosallicylic Acid, structural formula: [0003] . [0004] 3,6-dichloro-2-hydroxybenzoic acid is an intermediate in the preparation of the pesticide herbicide dicamba (3,6-dichloro-2-methoxybenzoic acid). Dicamba is a benzoic acid series herbicide first developed by the former American Siebel Chemical Company. With the prohibition and restricted use of chlorsulfuron and metsulfuron-methyl preparations, the demand for dicamba will increase, and the market prospect is promising. At present, the global sales volume of dicamba is about 15,000 t / year, and its production is mainly concentrated in Germany's BASF company and Switzerland's Sandoz company. In China, it is mainly Zhejiang Shenghua Biotech ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C65/05C07C51/15
Inventor 章国林陈俊倪航程俞永平
Owner ZHEJIANG UNIV
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