Unlock instant, AI-driven research and patent intelligence for your innovation.

Method for purifying 4-cyanopyridine by combining chemical recrystallization and physical separation

A technology of cyanopyridine and physical separation, applied in the direction of organic chemistry, can solve problems such as difficult separation, pipeline blockage, etc., and achieve the effect of easy operation and simple method

Active Publication Date: 2019-03-08
韩农黑龙江化工有限公司
View PDF5 Cites 0 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The present invention aims to solve the problem that 3-cyanopyridine and 4-cyanopyridine have similar boiling points, are difficult to separate, and are easily sublimated during vacuum distillation to directly cause pipeline blockage. The cyanopyridine method

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Method for purifying 4-cyanopyridine by combining chemical recrystallization and physical separation
  • Method for purifying 4-cyanopyridine by combining chemical recrystallization and physical separation
  • Method for purifying 4-cyanopyridine by combining chemical recrystallization and physical separation

Examples

Experimental program
Comparison scheme
Effect test

specific Embodiment approach 1

[0025] Specific implementation mode 1: This implementation mode utilizes the method of combining chemical recrystallization and physical separation to purify 4-cyanopyridine, and the specific steps are as follows:

[0026] Step 1: Chemical recrystallization: Dissolve the crude 4-cyanopyridine in a mixed solvent of petroleum ether and n-butanol. After cooling, a solid precipitates out. After the solid is filtered, washed and dried, 4-cyanopyridine with a purity >99% is obtained. base pyridine; then the liquid part is decompressed and recovered to the solvent to obtain a residue;

[0027] Step 2: Physical separation: heat the residue of step 1 to 50-70°C, after the system is transparent, cool it down to 30-45°C naturally, keep it warm for 1-3 hours, solids are precipitated, and the solids are obtained by filtration;

[0028] Step 3: Repeat the operation of Step 1 once for the solid obtained in Step 2 to obtain 4-cyanopyridine with a purity >99%;

[0029] Finally, the 4-cyanopyr...

specific Embodiment approach 2

[0030] Specific embodiment two: the difference between this embodiment and specific embodiment one is that the crude product of 4-cyanopyridine to be purified in step one is a mixture of 4-cyanopyridine and 3-cyanopyridine, wherein 4-cyanopyridine The mass percentage content is 75%~92%. Others are the same as in the first embodiment.

specific Embodiment approach 3

[0031] Specific embodiment three: the difference between this embodiment and specific embodiment one is that the crude product of 4-cyanopyridine to be purified in step one is a mixture of 4-cyanopyridine and 3-cyanopyridine, wherein 4-cyanopyridine The mass percentage content is 80%~90%. Others are the same as in the first embodiment.

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

The invention discloses a method for purifying 4-cyano pyridine by combination of chemical recrystallization and physical separation, relates to a method for purifying the 4-cyano pyridine, and aims to solve the problem that 3-cyano pyridine and the 4-cyano pyridine are near in boiling point, difficult to separate and easy to sublimate during rectification under vacuum so as to directly cause pipeline blockage. The method is as follows: 1, dissolving crude 4-cyano pyridine in a petroleum ether and n-butanol mixed solvent, cooling to precipitate a solid, then filtering, washing and drying; then recovering the solvent in the liquid to obtain a remainder; 2, heating the remainder, cooling and thermally insulating to precipitate a solid, and filtering to obtain the solid; and 3, repeating operation of the step 1 once on the solid, and finally collecting 4-cyano pyridine obtained by the step 1 and the step 3 to obtain the purified 4-cyano pyridine. The method is simple and easy to operate, a qualified product with the purity of more than 99% can be obtained, and the total extraction rate is up to 92%-99%. The method is used for purifying the 4-cyano pyridine.

Description

technical field [0001] The invention relates to a method for purifying 4-cyanopyridine. Background technique [0002] 4-cyanopyridine is an important fine chemical intermediate, which is used to prepare pharmaceutical and pesticide intermediates such as isonicotinic acid and isoniazid. 4-picoline is the only raw material for preparing 4-cyanopyridine, but the price of 4-picoline with a purity >97% is relatively high, so 4-picoline containing about 10% of 3-picoline is often used in production 4-cyanopyridine was prepared by methylation reaction using base pyridine as raw material. However, the boiling points of 3-picoline and 4-picoline differ only by 0.7°C, so it is difficult to separate them, and thus a mixture of 4-cyanopyridine and 3-cyanopyridine is obtained. Both 3-cyanopyridine and 4-cyanopyridine are easily sublimable substances, and their boiling points differ by 5°C, which directly cause pipeline blockage during vacuum distillation. Contents of the invention...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Patents(China)
IPC IPC(8): C07D213/84
CPCC07D213/84
Inventor 由君李美美刘波熊欣邢丽丹
Owner 韩农黑龙江化工有限公司