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Preparation method of 2,3,5,6-tetrachloropyridine

A technology of tetrachloropyridine and pyridine, applied in the field of chemical synthesis, can solve the problems of lack of practicability, high reaction temperature, complicated post-processing, etc., and achieves good chlorination reaction selectivity, mild and fast reaction conditions, and good solvent adaptability. Effect

Inactive Publication Date: 2017-06-09
孙振铎 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the limitation of technical conditions at that time, the disadvantages of this method such as poor controllability, high reaction temperature, complex reaction products, and cumbersome post-treatment lead to its lack of practicability.
U.S. Patent No. 4,515,953 describes the process of preparing 2,3,5,6-tetrachloropyridine by liquid phase chlorination, but still cannot avoid the disadvantages of low yield and complex products

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Add 4.0g (50mmol) of pyridine to 20ml of carbon tetrachloride, cool to 0℃ with ice brine under the protection of nitrogen, keep the internal temperature below 20℃, add 10.3g (100mmol) of sulfur dichloride and 5ml of tetrachloride dropwise After the addition of the carbonization solution, heat to reflux (71°C), keep refluxing for 6h (reaction end temperature is 80°C), cool the reaction solution to room temperature, filter, and collect the filtrate (GC yield 71%). The filtrate was washed with 20% sodium hydroxide solution under ice brine cooling to neutrality, dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure. The concentrate was purified by column chromatography. The mobile phase was petroleum ether / ethyl acetate (9:1) , The solvent was removed under reduced pressure to obtain 2,3,5,6-tetrachloropyridine as a white solid. b.p.91℃; 1 H NMR(400MHz; CDCl3)δH 7.81(s, 1H, C=CH); 13 C NMR (400MHz, CDCl3): δC 146.0, 140.2, 129.7; MS: 217(...

Embodiment 2

[0023] Add 4.0g (50mmol) of pyridine to 20ml of carbon tetrachloride, cool to 0℃ with ice brine under the protection of nitrogen, and keep the internal temperature below 20℃. Add 15.5g (150mmol) of sulfur dichloride and 5ml of tetrachloride. After the addition of the carbonization solution, heat to reflux (71°C), keep refluxing for 6h (reaction end temperature is 80°C), cool the reaction solution to room temperature, filter, and collect the filtrate (GC yield 95%). The filtrate was washed with 20% sodium hydroxide solution under ice brine cooling to neutrality, dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure. The concentrate was purified by column chromatography. The mobile phase was petroleum ether / ethyl acetate (9:1) , The solvent was removed under reduced pressure to obtain 2,3,5,6-tetrachloropyridine as a white solid.

Embodiment 3

[0025] Add 4.0g (50mmol) pyridine to 20ml carbon tetrachloride, cool to 0℃ with ice brine under nitrogen protection, keep the internal temperature below 20℃, add 52.5g (500mmol) sulfur dichloride and 5ml tetrachloride dropwise After the addition of the carbonization solution, heat and raise the temperature to reflux (71°C), keep the reflux reaction for 6h (reaction end temperature is 80°C), cool the reaction solution to room temperature, filter, and collect the filtrate (GC yield 97%). The filtrate was washed with 20% sodium hydroxide solution under ice brine cooling to neutrality, dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure. The concentrate was purified by column chromatography. The mobile phase was petroleum ether / ethyl acetate (9:1) , The solvent was removed under reduced pressure to obtain 2,3,5,6-tetrachloropyridine as a white solid.

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PUM

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Abstract

The invention provides a preparation method of 2,3,5,6-tetrachloropyridine, comprising: mixing pyridine, a chlorinating agent and a solvent, and chlorinating for 6-8 hours to obtain the finished 2,3,5,6-tetrachloropyridine; to be specific, adding pyridine into a solvent, maintaining the reaction solution at 20 DEG C, dropwise adding sulfur dichloride, and heating for reflux reaction for 6-8 h after dropwise adding; cooling the reaction solution to room temperature, and filtering to remove solid; maintaining inner temperature not less than 10 DEG C, and dropwise adding 20% sodium hydroxide solution until the reaction solution is neutral; separating the solution, collecting organic phase, drying with anhydrous magnesium sulfate overnight, removing the solvent under reduced pressure, and purifying by column chromatography to obtain the 2,3,5,6-tetrachloropyridine. The preparation method has the advantages of good condition mildness, high reaction speed, and high selectivity; the 2,3,5,6-tetrachloropyridine prepared by using the preparation method has purity of >97%.

Description

Technical field [0001] The invention relates to a preparation method of 2,3,5,6-tetrachloropyridine, which belongs to the field of chemical synthesis. Background technique [0002] 2,3,5,6-Tetrachloropyridine is an important pesticide and pharmaceutical intermediate. It is widely used in the synthesis of low-toxic, high-efficiency insecticides chlorpyrifos, chlorpyrifos methyl and the herbicides chlorpyridine, triclopyr and other pesticides. . The preparation of 2,3,5,6-tetrachloropyridine is mainly through the following ways: liquid-phase chlorination, addition cyclization, and gas-phase catalytic chlorination. Summary of the invention [0003] The earliest reported synthesis method of 2,3,5,6-tetrachloropyridine dates back to 1898 (Journal of the Chemical Society, Vol. 73, 1898, 432-441). William used the liquid phase chlorination method to synthesize for the first time 2, 3,5,6-tetrachloropyridine. In this method, pyridine and 4 times the amount (weight ratio) of phosphorus ...

Claims

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Application Information

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IPC IPC(8): C07D213/61
CPCC07D213/61
Inventor 孙道鸣孙振铎陈浩楠
Owner 孙振铎
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