Purifying method of 2, 3-dichloropyridine

A technology of dichloropyridine and purification method, applied in 2 fields, can solve problems such as differences in detection methods, lack of industry standards or national standards, differences in detection conclusions, etc., and achieve the effect of complete separation

Active Publication Date: 2013-07-10
SHANDONG TIANXIN CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] There are currently two liquid chromatography methods in China for the detection of 2,3-dichloropyridine. The main reason is that the detection wavelength is different: one is detected at a wavelength of 265nm, and the response value to the impurity 2,3,6-trichloropyridine Therefore, the content of the product detected by this method is above 99%; the second type is detected at a wavelength of 235nm, and the response value to the impurity 2,3,6-trichloropyridine is high, and the main content is above 95%. ; Therefore, the same 2,3,-dichloropyridine sample is

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0018] Example 1

[0019] Dissolve 100 grams of crude 2,3-dichloropyridine (main content 72%, content of 2,3,6-trichloropyridine 25%) in 100 grams of methanol, and then add 11.7 grams of a 40% aqueous solution of monomethylamine, A liquid reaction system is formed; the liquid reaction system is reacted at a temperature of 20°C and stirring conditions; a sample is taken from the liquid reaction system, and the sample is detected by liquid chromatography. If the impurity content in the sample is greater than 0.5%, continue The liquid phase reaction system is allowed to react, and then a sample is drawn for liquid chromatography detection. Once the impurity content in the sample is detected to be less than 0.5%, the reaction is terminated. After the reaction, the product solution is prepared, and then the product solution is cooled to -10°C, the crystalline product is fully analyzed, and 85 grams of crystalline product is obtained by suction filtration. The crystalline product is ad...

Example Embodiment

[0020] Example 2

[0021] Dissolve 100 grams of crude 2,3-dichloropyridine (main content 72%, content of 2,3,6-trichloropyridine 25%) in 100 grams of methanol, and add 16.99 grams of dimethylamine aqueous solution with a concentration of 40%. A liquid reaction system is formed; the liquid reaction system is reacted at a temperature of 90℃ and stirring conditions; a sample is taken from the liquid reaction system, and the sample is detected by liquid chromatography. If the impurity content in the sample is greater than 0.5%, continue The liquid phase reaction system is allowed to react, and then a sample is drawn for liquid chromatography detection. Once the impurity content in the sample is detected to be less than 0.5%, the reaction is terminated. After the reaction, the product solution is prepared, and then the product solution is cooled to 25°C, the crystalline product is fully analyzed, and 65 grams of crystalline product is obtained by suction filtration. The crystalline pr...

Example Embodiment

[0022] Example 3

[0023] Dissolve 100 grams of crude 2,3-dichloropyridine (main content 72%, content of 2,3,6-trichloropyridine 25%) in 100 grams of ethanol, and then add 9.44 grams of hydrazine hydrate aqueous solution with a concentration of 80% to form Liquid reaction system; make the liquid reaction system react at a temperature of 40℃ and stirring conditions; take a sample from the liquid reaction system and use liquid chromatography to detect the sample. If the impurity content in the sample is greater than 0.5%, continue to use The liquid reaction system reacts, and then a sample is drawn for liquid chromatography detection. Once the impurity content in the sample is detected to be less than 0.5%, the reaction is terminated. After the reaction, the product solution is prepared, and then the product solution is cooled to 5°C, the crystalline product is fully analyzed, and 88 grams of crystalline product is obtained by suction filtration. The crystalline product is added to...

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Abstract

The invention discloses a purifying method of 2,3-dichloropyridine. The purifying method comprises the following steps of: mixing a crude 2, 3-dichloropyridine product, a treating agent and an organic solvent to form a liquid phase reaction system, and enabling the liquid phase reaction system to react at the temperature of 20-90DEG C; extracting a sample from the liquid phase reaction system, detecting the sample by using liquid chromatography under the detection conditions that the wavelength is 235nm and the volume ratio of methanol to water in a moving phase is 70:30, and when the content of 2,3,6-trichloropyridine in the sample is less than 0.5 percent, ending the reaction, or continuously reacting; and preparing a product solution after the reaction is ended, then cooling the product solution so that a crystallized product is sufficiently separated out, carrying out solid-liquid separation to obtain the crystallized product, adding the crystallized product to water so as to form a dispersed system, adjusting the pH of the dispersed system to be 1-4 by using inorganic acid, and filtering the dispersed system to obtain solid matters, namely the purified 2, 3-dichloropyridine.

Description

technical field [0001] The invention relates to a method for purifying 2,3-dichloropyridine. Background technique [0002] 2,3-Dichloropyridine is a key intermediate in the synthesis of the pesticide chlorantraniliprole, and its content directly determines the selectivity of subsequent reactions and the quality of the final product chlorantraniliprole. If the 2,3-dichloropyridine produced by domestic manufacturers is detected by liquid chromatography under the detection conditions of wavelength 235nm and mobile phase methanol:water=70:30, its main content is greater than 95%, and the main impurity content is 2- 4%. [0003] The impurity is mainly 2,3,6-trichloropyridine. 2,3,6-trichloropyridine is the result of excessive chlorination during the synthesis of 2,3-dichloropyridine. It is difficult to completely avoid it during the synthesis process. The presence of 2,3,6-trichloropyridine leads to a decrease in product selectivity in subsequent processes, high viscosity of in...

Claims

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Application Information

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IPC IPC(8): C07D213/61
Inventor 赵庭栋闫晓红刘杰单美青魏军波
Owner SHANDONG TIANXIN CHEM
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