A kind of continuous production process of 3,6-dichlorosalicylic acid

A technology of dichlorosalicylic acid and production process, which is applied in the field of intermediates for synthesizing herbicide dicamba, can solve the problems of low production efficiency and product yield, harsh water content requirements, and high equipment investment costs, and achieves reduction of side reactions. The effect of reducing the generation of high temperature and high pressure reactors and reducing equipment investment costs

Active Publication Date: 2018-09-25
SICHUAN FOURSTAR BIOTECH RANDD CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The present invention aims to solve the problems in the existing production of 3,6-dichlorosalicylic acid that the water content of the reaction system is harsh, there is a lot of tar, the investment cost of equipment is high, the production efficiency and the product yield are low, and a 3,6-dichlorosalicylic acid is provided. The continuous production process of dichlorosalicylic acid can reduce the stringent requirements on the water content of the reaction system, reduce coking, reduce equipment investment costs, and high-efficiency, continuous production

Method used

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  • A kind of continuous production process of 3,6-dichlorosalicylic acid
  • A kind of continuous production process of 3,6-dichlorosalicylic acid
  • A kind of continuous production process of 3,6-dichlorosalicylic acid

Examples

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Embodiment 1

[0045] A continuous production process of 3,6-dichlorosalicylic acid includes the following process steps:

[0046] A. Stir and mix the xylene solution of potassium 2,5-dichlorophenate, anhydrous potassium carbonate powder, and dispersant in the batching kettle to obtain a slurry;

[0047] B. The slurry in step A is pumped into the carbon dioxide absorption tank through a metering pump, the carbon dioxide gas source is turned on, and the carbon dioxide gas is absorbed, and then the slurry is pumped through the metering pump into the high-pressure reaction section for reaction. The high-pressure reaction section includes the reaction Pipes and mixers installed on the reaction pipes;

[0048] C. The slurry reacted in the high-pressure reaction section enters the pressure relief discharge section, which includes a pressure relief valve, a buffer tank, a condenser, an acidification kettle, and a filter press which are connected in sequence. The pressure valve enters the buffer tank afte...

Embodiment 2

[0050] A high-pressure continuous reaction system for the production of 3,6-dichlorosalicylic acid, comprising a batching tank 1, a carbon dioxide absorption tank 2, a high-pressure reaction section, and a pressure-relief discharging section connected in sequence; the high-pressure reaction section includes a reaction The pipeline 3 and the mixer 4 arranged on the reaction pipeline 3, the pressure relief discharging section includes a pressure relief valve 5, a buffer tank 6, a condenser 7, an acidification kettle 8 and a filter press 9 connected in sequence.

[0051] The batching tank 1 is connected to the carbon dioxide absorption tank 2 through a metering pump, the carbon dioxide absorption tank 2 is connected to the high-pressure reaction section through a metering pump, and the high-pressure reaction section is connected to the pressure relief valve 5 through the The buffer tank 6 is connected, the buffer tank 6 is connected to one end of the condenser 7, the other end of the...

Embodiment 3

[0060] On the basis of Example 1:

[0061] Preferably, in step A, the preparation process of the potassium 2,5-dichlorophenol is: under the protection of nitrogen, dissolving 2,5-dichlorophenol in xylene to obtain 2,5-dichlorophenol The xylene solution of phenol, and then the potassium hydroxide aqueous solution was added dropwise to the xylene solution of 2,5-dichlorophenol under stirring. After the dropwise addition is completed, heat to boiling, distill, and measure the moisture content of the distilled xylene to reach At 200ppm, stop the distillation, and then lower the temperature to 20°C to obtain potassium 2,5-dichlorophenolate solution.

[0062] Preferably, in step A, carbon dioxide gas is introduced into the batching kettle for protection after batching.

[0063] Preferably, in step A, the mass ratio of the potassium 2,5-dichlorophenate, xylene, anhydrous potassium carbonate powder, and dispersant is 1:4:0.5:0.01.

[0064] Furthermore, the dispersant is one or a mixture of t...

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Abstract

The invention relates to a continuous production process of 3,6-dichlorosalicylic acid, and belongs to the technical field of the synthesis of a herbicide dicamba intermediate. A specific continuous production process and a specific continuous production system are adopted, harsh requirements on the water content of a reaction system can be lowered, coking is reduced, equipment investment cost is lowered, efficiency is high, and continuous production is realized. The process disclosed by the invention lowers the harsh requirements on the water content of the reaction system, can meet reaction requirements if the water content is below 2000ppm, and has the advantages of high once through yield, high selectivity and little coking. When the process disclosed by the invention is adopted, the yield is above 55%, and the selectivity is above 96%.

Description

Technical field [0001] The present invention relates to a production process for the synthesis of key intermediates of dicamba. More specifically, the present invention relates to a continuous production process of 3,6-dichlorosalicylic acid, which belongs to the middle of the synthetic herbicide dicamba Physical technology field. Background technique [0002] Usually, the process of synthesizing 3,6-dichlorosalicylic acid adopts a kettle-type reaction, and the reaction device is an autoclave, that is, under alkaline conditions, 2,5-dichlorophenol forms phenate, and then the solvent brings water to the system to contain 50ppm water. Next, transfer to the autoclave, add potassium carbonate catalyst, and pass CO 2 Carry out the carboxylation reaction to generate 3,6-dichlorosalicylate, and then add the water layer to the reaction mixture, add acid to the water phase product for acidification, and separate and recover unreacted 2,5-dichlorophenol by steam distillation. Filtering an...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C51/15C07C65/05
CPCC07C51/15C07C65/05
Inventor 彭琼黄印朱槽陈笑宽李滔刘虎王长江杨露张安邦张弦张华王蕾
Owner SICHUAN FOURSTAR BIOTECH RANDD CORP
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