A method for increasing the yield of 3,6-dichloro-2-hydroxybenzoic acid

A technology of hydroxybenzoic acid and dichlorophenol, applied in the directions of carboxylate preparation, organic chemistry, etc., can solve the problems of not taking into account phenol, long reaction time, unsatisfactory effect, etc., reducing the reaction time and improving the yield per pass , the effect of saving the reaction cost

Inactive Publication Date: 2011-12-28
EAST CHINA UNIV OF SCI & TECH +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0013] In fact, although the existing technology is improving the dichlorosalicylic acid production process from different aspects, it does not take into account the carboxylation reaction to generate phenol
The usual treatment method is to dissolve the generated phenol in an organic solvent after the reaction is over, and recycle it as a raw material after separation and recovery, but the oil phase after recovery often contains tar compone

Method used

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  • A method for increasing the yield of 3,6-dichloro-2-hydroxybenzoic acid
  • A method for increasing the yield of 3,6-dichloro-2-hydroxybenzoic acid
  • A method for increasing the yield of 3,6-dichloro-2-hydroxybenzoic acid

Examples

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Example Embodiment

[0036] Example 1

[0037] Weigh 86g 2,5-dichlorophenol (95%) in a 1000ml four-necked flask and dissolve it in 34.3g KOH (90%) and 28.27ml H 2 In O, add 500ml of xylene as a solvent to mix evenly, heat up and heat to dehydrate until almost no moisture is evaporated, take the potassium phenate suspension to measure the moisture, when the moisture is less than 0.1%, it can be transferred to the high-pressure reactor and the high-pressure reaction is turned on The inlet valve of the kettle enters CO 2 Exhaust the air in the kettle, continue to ventilate for 10 minutes and empty it, heat up the high-pressure reactor, turn on the stirring at the same time, and pour CO into the kettle 2 , Carry out a carboxylation reaction, the reaction temperature and pressure are controlled at 160°C and 8 MPa, and the reaction time is 4hr. After the carboxylation is completed, pass cooling water into the autoclave cooling tube. When the system is cooled to 100°C, add 50g of 40% KOH aqueous s...

Example Embodiment

[0038] Example 2

[0039] Take 405 g (95%) of 2,5-dichlorophenol, add an aqueous KOH solution (176 g KOH, 180 ml H2O), and perform dehydration in 500 ml xylene solvent. The procedure is the same as in Example 1. Then it was transferred to an autoclave for a carboxylation reaction, the reaction temperature was 140° C., the pressure was 6 MPa, and the reaction time was 6 h. After cooling, add KOH aqueous solution (90gKOH, 90mlH 2 O) Perform azeotropic dehydration, and then add 70g of Na 2 CO 3 Carry out carboxylation reaction, and then continue to introduce CO 2 The second carboxylation was carried out in 10 minutes, and the second carboxylation conditions were also 140°C, 6MPa, and the reaction time was 6hr. After the secondary carboxylation reaction is completed, add 300ml of cooling water to lower the system temperature to 100°C, stir evenly, take the water phase after layering, and then add a 30% mass fraction hydrochloric acid aqueous solution to the water phase ...

Example Embodiment

[0040] Example 3

[0041] Weigh 86g 2,5-dichlorophenol (95%) in a 1000ml four-necked flask and dissolve it in 34g KOH (90%) and 25.5ml H 2 In O, heat and dehydrate in 300ml of toluene until almost no moisture is evaporated. Take a sample of the phenate suspension to measure the moisture. When the moisture is less than 0.1%, it can be transferred to the autoclave. Open the inlet valve of the autoclave. Enter CO 2 Exhaust the air in the kettle, continue to ventilate for 10 minutes and empty it, heat up the high-pressure reactor, turn on the stirring at the same time, and pour CO into the kettle 2 , Carry out a carboxylation reaction, the reaction temperature and pressure are controlled at 140°C and 6 MPa, and the reaction time is 6hr. After carboxylation is completed, pass cooling water into the cooling tube of the autoclave, and then add 70g of 40% KOH aqueous solution to the autoclave, and react while stirring until all the by-product dichlorophenol is converted into ph...

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Abstract

The invention belongs to a production technology of a dicamba intermediate, and relates to a method for preparing 3,6-dichloro-2-hydroxy benzoic acid by reacting 2,5-dichlorophenols salt with carbon dioxide in an organic solvent,the technology for increasing Kolbe-Schmitt carboxylation reaction yield by a secondary salt forming comprises the following steps: (1) preparing the raw material phenates and dehydrating; (2) performing a primary carboxylation reaction to the raw material phenates; (3) performing a salt forming and dehydration to by-product dichlorophenols; (4) carrying out a carboxylation reaction; (5) refining. Experiments show that the yield of 6-dichloro-2-hydroxybenzoic acid can reach 68.4%-70.5% after the secondary carboxylation, The method for increasing yield of 3,6-dichloro-2-hydroxybenzoic acid is capable of solving the unfavorable influence of dichlorophenols generated by the reaction, raising the reaction yield, minimizing the reaction time and saving the production cost.

Description

technical field [0001] The invention belongs to the production process of dicamba intermediates, and relates to a method of using 2,5-dichlorophenate and CO in an organic solvent 2 The key technology of reaction preparation 3,6-dichloro-2-hydroxybenzoic acid. Background technique [0002] 3,6-dichloro-2-hydroxybenzoic acid is 3,6-dichlorosalicylic acid, English name 3,6-Dichlorosalicylic Acid, structural formula: [0003] 水杨酸 [0004] 3,6-dichloro-2-hydroxybenzoic acid is an intermediate for the preparation of the pesticide herbicide dicamba (3,6-dichloro-2-methoxybenzoic acid), and can also be used for the preparation of chemiluminescent agent intermediate 3, Organic chemicals such as 5,6-trichlorosalicylic acid. Dicamba (Banvel, dicamba), a kind of benzoic acid series herbicide firstly developed by American Bezier Chemical Company (now merged by Swiss Sandoz Company). With the prohibition and restricted use of chlorsulfuron-methyl and metsulfuron-methyl prepa...

Claims

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Application Information

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IPC IPC(8): C07C65/05C07C51/02
Inventor 程振民储消和颜星星余中宝蒋亦文陈明伟艾荣华
Owner EAST CHINA UNIV OF SCI & TECH
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