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Purification method of 4-cyanopyridine

A cyanopyridine and purification method technology, applied in the direction of organic chemistry, can solve the problems of unfavorable storage and transportation, poor drying effect, long processing time, etc., and achieve the effect of facilitating storage and transportation, shortening time and improving yield

Pending Publication Date: 2022-05-27
ANHUI RUIBANG BIOLOGICAL SCI & TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to provide a method for removing 4-cyanopyridine in the drying process of recrystallized 4-cyanopyridine wet product, which takes a long time to process, the drying effect is not good, and it is not conducive to storage and transportation in the production process. Pyridine Moisture Method

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Take 500g of pyridine mixture (95% of 4-cyanopyridine content, 0.3% of 3-cyanopyridine content, 0.1% of 3-methylpyridine and toluene content each), first according to the mass ratio of pyridine mixture and water 1:2 pyridine mixture and water mixed, stirred at a temperature of 60 °C to dissolve, while stirring while cooling to 20 °C, continue to stir the crystallization, centrifuge centrifuge at low speed (speed 1500 rpm), to give 420g 4-cyanopyridine wet product (4-cyanopyridine content of 95%, The moisture content is 4%), and the crystallization mother liquor is applied until the next recrystallization.

[0026] Take 4-cyanopyridine wet product 200.1g, it is mixed with toluene 33g, added to the rotary evaporator, vacuumed to -0.03MPa, heated to 158 °C, rotary evaporation 3.5h, at this time, the quality of the solution in the collection bottle reached 36.2g, no longer changed; stop spinning steaming, collect the material (4-cyanopyridine content of 97%, toluene content of ...

Embodiment 2

[0028]Take Example 1 recrystallization prepared 4-cyanopyridine wet product (4-cyanopyridine content of 95%, moisture content of 4%) 200g, it and toluene 32.4g mixed, added to the rotary evaporator, vacuum to -0.04MPa, heated to 158 °C, rotary evaporation 3.5h, at this time, the mass of the solution in the collection bottle reaches 36g, no longer changes; stop spinning steaming, collect the material (4-cyanopyridine content is 97%, toluene content is 2%, The moisture content is 0.01%, the 3-cyanopyridine content is 0.01%, 3-methylpyridine is not detected), the material is white powder; the material is placed in a fume hood for 4h, the remaining toluene is evaporated at room temperature, the material is collected, and the finished 4-cyanopyridine is 190.1g, the moisture content in the 4-cyanopyridine finished product is 0.01%, the content of 4-cyanopyridine is detected by liquid chromatography is 99.9%, the 3-cyanopyridine is 0.05%, and other impurities are not detected.

Embodiment 3

[0030] Take Example 1 recrystallization prepared 4-cyanopyridine wet product (4-cyanopyridine content of 95%, moisture content of 4%) 200g, and toluene 48g mixed, added to the rotary evaporator, vacuumed to -0.04MPa, heated to 158 °C, rotary evaporation 3.5h, at this time, the quality of the solution in the collection bottle reaches 36g, no longer unchanged; stop spinning, collect the material (4-cyanopyridine content is 97%, toluene content is 2%, The moisture content is 0.01%, the 3-cyanopyridine content is 0.01%, 3-methylpyridine is not detected), the material is white powder; the material is placed in a fume hood for 4h, the remaining toluene is evaporated at room temperature, the material is collected, and the finished 4-cyanopyridine is 190.7g, the moisture content of the 4-cyanopyridine finished product is 0.01%, the content of 4-cyanopyridine is detected by liquid chromatography is 99.9%, the 3-cyanopyridine is 0.01%, and other impurities are not detected.

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Abstract

The invention discloses a purification method of 4-cyanopyridine. The purification method comprises the following steps: recrystallizing a pyridine mixture to obtain a 4-cyanopyridine wet product; adding toluene according to a mass ratio of water to toluene in the 4-cyanopyridine wet material of 1: 2-1: 6, and mixing; and carrying out vacuum rotary evaporation at the pressure of 0-0.04 MPa and the temperature of 150-170 DEG C until no liquid is evaporated, thereby obtaining the 4-cyanopyridine product. According to the method, moisture in a 4-cyanopyridine wet material is removed by utilizing an azeotropic method of toluene and water, residual toluene in the material is removed by utilizing the volatile property of toluene, a high-purity 4-cyanopyridine finished product is finally obtained, the purity of the 4-cyanopyridine is as high as 99.9%, the moisture content is only 0.01%, and meanwhile, the yield of the 4-cyanopyridine is also increased. According to the method, the time of the whole drying process is greatly shortened; and the 4-cyanopyridine finished product is white powder, thereby being beneficial to storage and transportation in the production process.

Description

Technical field [0001] The present invention relates to a purification method of 4-cyanopyridine. Background [0002] 4-Cyanopyridine is mainly used as a pharmaceutical and pesticide intermediate, is a white to light yellow needle-like crystal, with a characteristic odor, its melting point is 88 °C, and the boiling point under atmospheric pressure is 196 °C. [0003] At present, the production method of 4-cyanopyridine is mainly: under the action of the catalyst, the 3-methylpyridine is reacted with ammonia to generate 3-cyanopyridine and by-products mixed with pyridine, and the 3-cyanopyridine and mixed pyridine are separated by the difference in boiling point; the mixed pyridine is then recrystallized to obtain 4-cyanopyridine. The specific recrystallization method is: the mixed pyridine is mixed with water, the water bath is heated until the material is safely dissolved, and then reduced to room temperature, and the whole process is kept at a uniform speed of stirring; and the...

Claims

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Application Information

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IPC IPC(8): C07D213/84
CPCC07D213/84
Inventor 李玉山杨竞成齐勇韩洋
Owner ANHUI RUIBANG BIOLOGICAL SCI & TECH CO LTD
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