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Method for purifying 2,3-dichloropyridine

A dichloropyridine and crude product technology, which is applied in the field of purification of organic compound 2,3-dichloropyridine, can solve the problems of inability to purify by rectification, high operation requirements, low yield, etc., and achieve no safety hazard, simple operation, The effect of high recovery rate

Inactive Publication Date: 2018-10-19
江西扬帆新材料有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In actual production, some batches in the chlorination section produced more impurity 2,3,6-trichloropyridine due to some factors, which affected the purity of 2,3-dichloropyridine
Due to the azeotrope between 2,3-dichloropyridine and 2,3,6-trichloropyridine, distillation cannot purify
Literature (Fine Chemical Intermediates, 2008,38(5):19-21) was purified by recrystallization from aqueous methanol solution, but the yield of 2,3-dichloropyridine was only 66.9%, and the purity was only 98.3%
Moreover, organic solvents have potential safety hazards and have high requirements for operation.

Method used

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  • Method for purifying 2,3-dichloropyridine
  • Method for purifying 2,3-dichloropyridine
  • Method for purifying 2,3-dichloropyridine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Embodiment 1, a kind of method for purifying 2,3-dichloropyridine, carries out following steps successively:

[0023] 1), add 100g of 2,3-dichloropyridine crude product into the reaction kettle (the crude product contains 95wt% 2,3-dichloropyridine, and the rest is 2,3,6-trichloropyridine), that is, the crude product contains 0.64mol 2,3-dichloropyridine; add 80ml of 36.5wt% concentrated hydrochloric acid (0.96mol HCl), heat to 80°C with stirring, react for 30min, and separate liquids while hot to obtain oil phase and water phase.

[0024] 2), take the aqueous phase obtained in step 1), first add about 90ml of lye (30wt% sodium hydroxide solution) until the pH is 10;

[0025] Then heat to boiling, carry out steam distillation, collect cuts (100~103 ℃ cuts), stop distillation after the cuts are cooled to room temperature and there is no solid precipitation anymore. The fraction was filtered, and the filter cake was vacuum-dried at 30° C. to constant weight to obtain 90 ...

Embodiment 2～ Embodiment 7

[0027] Change the amount of hydrochloric acid added, reaction temperature, and reaction time in Example 1, and the rest of the content is equal to Example 1, and Examples 2 to 7 are obtained respectively. The specific content is shown in Table 1 below.

[0028] Table 1

[0029]

[0030]

[0031] Compared with Example 1, Example 7 uses more hydrochloric acid, and 2,3-dichloropyridine reacts more with it, so that the recovery rate of 2,3-dichloropyridine is increased, but too much hydrochloric acid The impurity 2,3,6-trichloropyridine is also reacted with it, resulting in a decrease in the purity of 2,3-dichloropyridine.

[0032] Embodiment 8~embodiment 12, change the acid in embodiment 1, that is, change into 36.5wt% sulfuric acid solution, perhaps change into phosphoric acid, formic acid, acetic acid, p-toluenesulfonic acid, replace the concentrated hydrochloric acid in embodiment 1 , the molar weight remains unchanged, still 0.96mol; the rest of the content is the sam...

Embodiment 19-25

[0044] Examples 19-25. Change the purity of 2,3-dichloropyridine and the amount of hydrochloric acid in Example 1, and the rest of the content is the same as Example 1 to obtain Examples 19-25. The specific content is shown in Table 4 below.

[0045] Table 4

[0046]

[0047]

[0048] It can be seen from Examples 19-25 that when 2,3-dichloropyridine exceeds 50 wt%, the method of the present invention can be used for better purification, and when 2,3-dichloropyridine is less than 50 wt%, the amount of acid used is less than 2, The recovery rate of 3-dichloropyridine is low, and the purity of 2,3-dichloropyridine will be low if more acid is used, which is not suitable for further purification.

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Abstract

The invention discloses a method for purifying 2,3-dichloropyridine. The method comprises the following steps: 1) placing crude 2,3-dichloropyridine into a reaction kettle, adding acid, then heating for reacting at 60 to 100 DEG C for 0.2-1 hour under the stirring condition, and separating obtained reaction liquid in a hot state to obtain an oil phase and a water phase; 2) adding alkali into the water phase obtained in the step 1) to regulate the pH to 8 to 12, then heating to boiling, performing steam distillation, collecting fractions of 100 to 103 DEG C, filtering the fractions, and dryinga filter cake to obtain 2,3-dichloropyridine. The method has the advantages of simple operation steps, high recovery rate of 2,3-dichloropyridine, high purity (purity of greater than or equal to 99.5percent by weight) and lower purification cost.

Description

technical field [0001] The invention relates to a method for purifying an organic compound 2,3-dichloropyridine. Background technique [0002] 2,3-Dichloropyridine is an important pharmaceutical and pesticide intermediate. At present, 3-aminopyridine is used as raw material in industry, and it is prepared by chlorination, diazotization and Sandmeyer reaction. In actual production, some batches in the chlorination section produced more impurity 2,3,6-trichloropyridine due to certain factors, which affected the purity of 2,3-dichloropyridine. Due to the azeotrope between 2,3-dichloropyridine and 2,3,6-trichloropyridine, it cannot be purified by rectification. Literature (Fine Chemical Intermediates, 2008, 38(5): 19-21) was purified by recrystallization from aqueous methanol solution, but the yield of 2,3-dichloropyridine was only 66.9%, and the purity was only 98.3%. Moreover, organic solvents have potential safety hazards and have high requirements for operation. Therefore...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/61
CPCC07D213/61
Inventor 樊彬张哲明陶明陈育亮吕雪皓廖祖态
Owner 江西扬帆新材料有限公司
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