A kind of synthetic method of 2-chloro-5-trifluoromethylpyrazine

A technology of trifluoromethylpyrazine and synthetic method, which is applied in the direction of organic chemistry, can solve the problems of low product yield, low yield, long reaction steps, etc., and achieves easy-to-obtain raw materials, high yield, and simple process Effect

Active Publication Date: 2020-11-03
KINGCHEM LIAONING CHEMICAL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, a large amount of three wastes will be produced, and the reaction steps are longer, the yield is low, and the cost is high
[0005] Although hydrofluoric acid and sulfur tetrafluoride have been used as trifluoromethylation reagents, the low yield of products has always been a problem under the existing reaction conditions

Method used

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  • A kind of synthetic method of 2-chloro-5-trifluoromethylpyrazine
  • A kind of synthetic method of 2-chloro-5-trifluoromethylpyrazine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] In a 2L stainless steel autoclave, add 158.5g (1.0mol) of 5-chloropyrazine-2-carboxylic acid, cool down to 0-10°C, add 240g (12mol) of anhydrous hydrogen fluoride, and continue to cool down to -40°C, 238 g (2.2 mol) of sulfur tetrafluoride was introduced. Then slowly raise the temperature to 80-90°C, and keep it warm for 4 hours. After the reaction is completed, the reaction liquid is poured into ice water, neutralized with 10% sodium carbonate aqueous solution to pH = 7, the organic layer is separated, steam distilled, and the obtained product is rectified to obtain 2-chloro-5-tri Fluoromethylpyrazine 146g, content 99%, yield 80%. Its structural characterization is shown in the following data:

[0031] 2-Chloro-5-trifluoromethylpyrazine product structure confirmed: 1H-NMR (400MHz, CDCl3) σ: 8.74ppm (s, 1H); 8.70 (s, 1H).

Embodiment 2

[0033] In a 2L stainless steel autoclave, add 317g (2.0mol) of 5-chloropyrazine-2-carboxylic acid, cool down to 0-10°C, add 480g (24mol) of anhydrous hydrogen fluoride, continue to cool down to -40°C, and Add 476 (4.4mol) g of sulfur tetrafluoride. Then slowly raise the temperature to 75-80°C, and keep it warm for 6 hours. After the reaction is completed, the reaction liquid is poured into ice water, neutralized with 10% sodium carbonate aqueous solution to pH = 7, the organic layer is separated, steam distilled, and the obtained product is rectified to obtain 2-chloro-5-tri Fluoromethylpyrazine 329g, content 99%, yield 90%. Its structural characterization is shown in the following data:

[0034] 2-Chloro-5-trifluoromethylpyrazine product structure confirmed: 1H-NMR (400MHz, CDCl3) σ: 8.74ppm (s, 1H); 8.70 (s, 1H).

Embodiment 3

[0036] In a 2L stainless steel autoclave, add 317g (2.0mol) of 5-chloropyrazine-2-carboxylic acid, cool down to 0-10°C, add 300g (15mol) of anhydrous hydrogen fluoride, continue to cool down to -40°C, and Add 476 (4.4mol) g of sulfur tetrafluoride. Then slowly raise the temperature to 75-80°C, and keep it warm for 6 hours. After the reaction is completed, the reaction liquid is poured into ice water, neutralized with 10% sodium carbonate aqueous solution to pH = 7, the organic layer is separated, steam distilled, and the obtained product is rectified to obtain 2-chloro-5-tri Fluoromethylpyrazine 274g, content 99%, yield 75%. Its structural characterization is shown in the following data:

[0037] 2-Chloro-5-trifluoromethylpyrazine product structure confirmed: 1H-NMR (400MHz, CDCl3) σ: 8.74ppm (s, 1H); 8.70 (s, 1H).

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Abstract

The invention provides a method for synthesizing 2-chloro-5-(trifluoromethyl)pyrazine by using 5-chloro-pyrazine-2-carboxylic acid, anhydrous hydrogen fluoride and sulfur tetrafluoride. The method forsynthesizing 2-chloro-5-(trifluoromethyl)pyrazine has the advantages of simple technology, easily available raw materials, and high yield.

Description

technical field [0001] The invention relates to the field of pharmaceutical synthesis, in particular to a synthesis method of 2-chloro-5-trifluoromethylpyrazine. Background technique [0002] In the prior art, the synthesis of 2-chloro-5-trifluoromethylpyrazine is based on 5,6-diamino-4-hydroxypyrimidine sulfate and 1,1-dibromo-2,2,2-trifluoroacetone 2-amino-5-trifluoromethylpyrazine is obtained by condensation hydrolysis as a raw material; 2-hydroxy-5-trifluoromethylpyrazine is obtained by diazotization hydrolysis; and 2- Chloro-5-trifluoromethylpyrazine. The reaction formula is as follows: [0003] [0004] In the specific reaction process, in the first step, 5,6-diamino-4-hydroxypyrimidine sulfate and 1,1-dibromo-2,2,2-trifluoroacetone are used as raw materials, and the target product is obtained through a three-step reaction , Condensation hydrolysis, obtain 2-amino-5-trifluoromethylpyrazine yield 15%; The second step diazotization hydrolysis obtains 2-hydroxyl-5-t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D241/16
CPCC07D241/16
Inventor 李德刚王永灿付立民唐小凤齐悦孙杰杨阳张薇
Owner KINGCHEM LIAONING CHEMICAL CO LTD
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