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2, 3-dichloropyridine preparation method

A technology of dichloropyridine and dicarboxamide pyridine, which is applied in the field of preparing 2,3-dichloropyridine, can solve the problems of high toxicity of dichloromethane, potential safety hazards, and difficulty in recycling, and achieve low production cost and high product yield. Efficiency and quality, stable and safe response

Active Publication Date: 2016-03-16
SHANDONG TIANXIN CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

During the chlorination reaction of the 2-position of the pyridine ring by 3-aminopyridine and hydrogen peroxide, a side reaction of chlorination of the 6-position of the pyridine ring will occur. Exhaust emissions
Although the method disclosed in the Chinese patent document of CN102432528A has simple process and high yield, hydrogen gas is used in the reaction process, which has potential safety hazards, and the metal catalysts are mostly noble metals, and the cost is relatively high
Although the method of catalytic transfer hydrogenation in the Chinese patent document of CN103145609A has avoided the potential safety hazard caused by the use of hydrogen, and the process is simple and the yield is high, but the metal catalyst is palladium, and the cost is still relatively high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] (1) Keep the temperature at 5-20℃, add 330kg of 2,3-dimethylamide pyridine to 1320kg of purified water, stir until the 2,3-dimethylamide pyridine is completely dissolved, and then add 30% mass fraction dropwise successively 533.3kg of sodium hydroxide aqueous solution and 3132.6kg of sodium hypochlorite aqueous solution with a mass fraction of 9.5%. The temperature and stirring conditions of 5~20℃ are maintained during the dripping process. The dripping time is controlled within 3h. After the dripping is completed, the temperature is raised to 80~100℃, keep stirring for 2h to make the reaction fully proceed. After the reaction is completed, add hydrochloric acid to adjust the pH of the system to 7 to remove excess sodium hydroxide, and distill under reduced pressure to remove the water in the system to obtain 2,3-di Crude aminopyridine.

[0026] (2) Add the crude 2,3-diaminopyridine obtained in step (1) to 1944.5 kg of hydrochloric acid with a mass fraction of 30%, and add...

Embodiment 2

[0029] (1) Keep the temperature at 5-20℃, add 330kg of 2,3-dimethylamide pyridine to 1980kg purified water, stir until the 2,3-dimethylamide pyridine is completely dissolved, and then dropwise add 46% mass fraction successively 609.8kg of potassium hydroxide aqueous solution and 3234.8kg of sodium hypochlorite aqueous solution with a mass fraction of 11.5%. The temperature and stirring conditions of 5~20℃ are maintained during the dripping process. The dripping time is controlled within 3h. After the dripping is completed, the temperature is raised to 80~100℃, keep for 2h under stirring to make the reaction fully proceed. After the reaction is completed, add hydrochloric acid to adjust the pH of the system to 5-6 to remove excess sodium hydroxide, and distill under reduced pressure to remove the water in the system to obtain 2,3 -Crude diaminopyridine.

[0030] (2) Add the crude 2,3-diaminopyridine obtained in step (1) to 2878.4 kg of hydrochloric acid with a mass fraction of 38%...

Embodiment 3

[0033] (1) Keep the temperature at 5-20℃, add 330kg of 2,3-dimethylamide pyridine to 1320kg of purified water, stir until the 2,3-dimethylamide pyridine is completely dissolved, and then dropwise add 35% mass fraction successively 457.1kg of sodium hydroxide aqueous solution and 2834.3kg of sodium hypochlorite aqueous solution with a mass fraction of 10.5%. The temperature and stirring conditions of 5-20℃ are maintained during the dripping process. The dripping time is controlled within 3h. After the dripping is completed, the temperature is raised to 80~100℃, keep for 2h under stirring to make the reaction fully proceed. After the reaction is completed, add hydrochloric acid to adjust the pH of the system to 4~5 to remove excess sodium hydroxide, and distill under reduced pressure to remove the water in the system to obtain 2,3 -Crude diaminopyridine.

[0034] (2) Add the crude 2,3-diaminopyridine obtained in step (1) to 1767.8 kg of hydrochloric acid with a mass fraction of 33%...

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Abstract

The present invention discloses a 2, 3-dichloropyridine preparation method comprising the following steps: (1) 2,3-dimethylamide pyridine is dissolved in water, then a caustic soda aqueous solution and a sodium hypochlorite aqueous solution are successively added, after the addition is completed, the mixture is heated for full reaction, after the reaction is completed, the system is adjusted to be neutral or acidic by use of hydrochloric acid, and water is removed by distillation to obtain a 2,3-diaminopyridine crude product; (2) the 2,3-diaminopyridine crude product is dissolved in hydrochloric acid, a catalyst is added, then a sodium nitrite aqueous solution is added dropwise, after the addition is complete, the2,3-diaminopyridine crude product is completely reacted, and after the reaction is completed, a 2, 3-dichloropyridine crude product is obtained by distillation; and (3) the 2, 3-dichloropyridine crude product is added into an organic solvent for complete dissolving, then cooled for recrystallization, crystals are filtered off and dried to obtain a 2, 3-dichloropyridine finished product. The method avoids the problem of very low tendency for side effects of 2-site chlorination, the production process is simple, the reaction is smooth and steady, production cost is low, product yield is high, and product purity is high.

Description

Technical field [0001] The present invention relates to a method for preparing 2,3-dichloropyridine. Background technique [0002] 2,3-Dichloropyridine is an important fine chemical intermediate, widely used in the fields of medicine and pesticides, and has a large market demand. In recent years, there have been many studies on 2,3-dichloropyridine at home and abroad. The reported preparation methods of 2,3-dichloropyridine mainly include the following. [0003] The Chinese patent document with publication number CN103570609A discloses that 3-carboxamidepyridine (nicotinamide) is used as the starting material, Hofmann degradation is performed to obtain 3-aminopyridine, water is distilled, dichloromethane is extracted, and hydrochloric acid is used. After stripping, react with hydrogen peroxide to obtain a hydrochloric acid solution of 2-chloro-3-aminopyridine, and then undergo diazotization and Sandmeier reaction to obtain 2,3-dichloropyridine. During the chlorination reac...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/61
CPCC07D213/61
Inventor 赵奔腾张通慈玉印邢晓华刘迎石锡攀
Owner SHANDONG TIANXIN CHEM
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