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Preparation method of 2-fluoro-3-chloro-5-(trifluoromethyl)pyridine

A technology for trifluoromethylpyridine and crude trifluoromethylpyridine is applied in the field of preparation of 2-fluoro-3-chloro-5 trifluoromethylpyridine, and can solve the problems of difficult separation, serious pollution, high toxicity and the like , to achieve the effect of improving product purity, simple post-processing and low production cost

Inactive Publication Date: 2018-04-24
内蒙古佳瑞米精细化工有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] U.S. Patent No. 4,567,273 has reported that 2,3-dichloro-5-trichloromethylpyridine is used as a raw material, and HgF 2 , HgO, HgCl 2 , AgF, etc. as activators, with HF as fluorinating agent, under low temperature reaction, to obtain 2-fluoro-3-chloro-5 trifluoromethylpyridine, the method uses HgF 2 , HgO, etc. as activators, high toxicity, serious pollution, and difficult industrial production technology
[0004] It is reported in China that KF is used as the fluorinating agent. KF is dehydrated and activated by reflux with solvent, and a phase transfer catalyst is added. The yield is about 90%, and the purity is 98%. However, there are nearly 2% impurities in the product, and the separation is difficult. This method is very difficult. Obtain high-purity 2-fluoro-3-chloro-5-trifluoromethylpyridine

Method used

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  • Preparation method of 2-fluoro-3-chloro-5-(trifluoromethyl)pyridine

Examples

Experimental program
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Effect test

Embodiment 1

[0034] 1. In a 200 mL autoclave, add 23.0 g (0.1 mol) of 2,3,-dichloro-5-trichloromethylpyridine, close the lid, fill with nitrogen gas at 10.0 MPa to maintain the pressure for 5 hours, and test the reactor for leaks. After confirming that there is no gas leakage in the reaction kettle, vent the pressure in the kettle. Then the reaction kettle was placed in an ice-salt bath for cooling, when the temperature in the kettle dropped to below -5°C, anhydrous HF40.0g (~2.0mol) was filled into the kettle, and the reaction system was heated to 180 under stirring conditions. ℃, incubated for 12h.

[0035] 2. After the reaction is completed, the temperature is lowered to 25°C, and the reaction kettle is replaced with nitrogen for half an hour (the replaced gas is passed into a 10% aqueous sodium hydroxide solution for neutralization and absorption), and the reaction pressure is poured into a 250mL round-bottomed flask. , 70 g (~1.0 mol) of 25% ammonia solution was added, and the reacti...

Embodiment 2

[0038] The temperature of the reaction system in Example 1 was changed to 200° C., and other operating conditions including post-treatment steps were the same as those in Example 1. 15.6 g of 2-fluoro-3-chloro-5-trifluoromethylpyridine product was obtained, and the content of 2-fluoro-3-chloro-5-trifluoromethylpyridine in the product was 98.65% (GC) by analysis, Yield 95.12%.

Embodiment 3

[0040] The ammoniation reaction temperature in Example 1 was changed to 50° C., and other operating conditions including post-treatment steps were the same as those in Example 1. 14.8 g of 2-fluoro-3-chloro-5-trifluoromethylpyridine product was obtained, and the content of 2-fluoro-3-chloro-5-trifluoromethylpyridine in the product was 98.88% (GC) by analysis, Yield 90.24%.

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Abstract

The present invention discloses a preparation method of 2-fluoro-3-chloro-5-(trifluoromethyl)pyridine, and belongs to the technical field of organic synthesis. The method comprises the following steps: firstly, taking 2,3-dichloro-5-(trichloromethyl)pyridine as a raw material to synthesize 2-fluoro-3-chloro-5-(trifluoromethyl)pyridine through one-step direct fluorination; then adding an aminationreagent to the obtained reaction solution to remove front impurities of the 2-fluoro-3-chloro-5-(trifluoromethyl)pyridine; washing an oil layer with water; and carrying out reduced pressure distillation on the washed oil layer to obtain the high-purity 2-fluoro-3-chloro-5-(trifluoromethyl)pyridine. The preparation method provided by the invention has simple process and low production cost, and issuitable for industrial production.

Description

Technical field: [0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a preparation method of 2-fluoro-3-chloro-5 trifluoromethylpyridine. Background technique: [0002] 2-Fluoro-3-chloro-5-trifluoromethylpyridine is an important chemical intermediate raw material and a key intermediate for the synthesis of new fungicide fluazinam and herbicide fenflufop. Its application value and market The prospects are very promising. [0003] U.S. Patent US4567273 reported using 2,3-dichloro-5-trichloromethylpyridine as raw material, using HgF 2 , HgO, HgCl 2 , AgF, etc. are activators, and HF is used as a fluorinating agent. Under the low temperature reaction, 2-fluoro-3-chloro-5 trifluoromethyl pyridine is obtained. This method adopts HgF 2 , HgO, etc. are activators, with high toxicity, serious pollution, and difficult industrial production technology. [0004] There are reports in China that KF is used as a fluorinating agent, KF ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/61
CPCC07D213/61
Inventor 司永利王克勇柯有胜王小军张树田
Owner 内蒙古佳瑞米精细化工有限公司
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