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Preparation method for high purity 2-chlorine-3-aminopyridine hydrochloride

A technology of aminopyridine hydrochloride and aminopyridine, which is applied in the field of preparation of high-purity 2-chloro-3-aminopyridine hydrochloride, can solve the problems of high pH value control requirements, cumbersome operation, and difficult control, and achieve equipment The effect of low requirements, high product purity and convenient post-processing

Active Publication Date: 2012-07-18
ABA CHEM NANTONG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method is very cumbersome to operate, and the process requires high pH control, which is difficult to control. After treatment, the product has a purity of 94-98.6%, and still contains about 1.5-3% of 2,6-dichloro-3-aminopyridine

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Dissolve 18.8g (200mmol) of 3-aminopyridine in 110ml of hydrochloric acid, add 27.2g (240mmol) of 30% hydrogen peroxide dropwise at 0-5°C, make the reaction system react at 15-20°C for 3 hours, add 21g (40mmol) of 30% Sodium sulfite solution to obtain a mixture solution of 2-chloro-3-aminopyridine and 2,6-dichloro-3-aminopyridine.

[0026] Use 50% sodium hydroxide solution to adjust pH=4~5, keep the temperature <40°C, extract twice with 200ml ethyl acetate, combine the organic phases, dry with anhydrous sodium sulfate, cool the filtrate to 0~5°C, drop Add ethyl hydrogen chloride solution to adjust pH=1~2. After the addition, heat to 80-85°C and stir under reflux for 2 hours, cool to room temperature, continue to stir for 12 hours, filter, wash with a small amount of ethyl acetate, and dry under vacuum at 40°C to obtain 2-chloro-3-aminopyridine hydrochloride 28.5 g, yield 85%, purity 99.2%, containing 0.3% 2,6-dichloro-3-aminopyridine.

Embodiment 2

[0028] Dissolve 18.8g (200mmol) of 3-aminopyridine in 110ml of hydrochloric acid, add 27.2g (240mmol) of 30% hydrogen peroxide dropwise at 0-5°C, make the reaction system react at 15-20°C for 3 hours, add 21g (40mmol) of 30% Sodium sulfite solution to obtain a mixture solution of 2-chloro-3-aminopyridine and 2,6-dichloro-3-aminopyridine.

[0029] Use 50% sodium hydroxide solution to adjust pH=5~6, keep the temperature <40°C, extract twice with 200ml ethyl acetate, combine the organic phases, dry with anhydrous sodium sulfate, cool the filtrate to 0~5°C, drop Add hydrogen chloride isopropanol solution to adjust pH=1~2. After the addition, heat to 80-85°C and stir under reflux for 2 hours, cool to room temperature, continue to stir for 12 hours, filter, wash with a small amount of ethyl acetate, and dry under vacuum at 40°C to obtain 2-chloro-3-aminopyridine hydrochloride 27.5 g, yield 82%, purity 99.3%, containing 0.25% of 2,6-dichloro-3-aminopyridine.

Embodiment 3

[0031] Dissolve 18.8g (200mmol) of 3-aminopyridine in 110ml of hydrochloric acid, add 27.2g (240mmol) of 30% hydrogen peroxide dropwise at 0-5°C, make the reaction system react at 15-20°C for 3 hours, add 21g (40mmol) of 30% Sodium sulfite solution to obtain a mixture solution of 2-chloro-3-aminopyridine and 2,6-dichloro-3-aminopyridine.

[0032] Use 50% sodium hydroxide solution to adjust pH=5~6, keep the temperature <40°C, extract twice with 200ml methyl tert-butyl ether, combine the organic phases, dry with anhydrous sodium sulfate, and cool the filtrate to 0~5 °C, add hydrogen chloride isopropanol solution dropwise to adjust pH=1-2. After the addition, heat to 40-45°C and stir for 4 hours, cool to room temperature, continue to stir for 12 hours, filter, wash with a small amount of ethyl acetate, and dry under vacuum at 40°C to obtain 27.8g of 2-chloro-3-aminopyridine hydrochloride , 83% yield, 99.2% purity, containing 0.4% of 2,6-dichloro-3-aminopyridine.

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Abstract

The invention discloses a preparation method for high purity 2-chlorine-3-aminopyridine hydrochloride, which comprises choosing 3-aminopyridine as a raw material to be chloridized to obtain 2-chlorine-3-aminopyridine reaction liquid, adjusting a potential of hydrogen (pH) value, adopting an organic solvent to extract, dewatering extraction liquid to form the 2-chlorine-3-aminopyridine hydrochloride with hydrogen chloride, and stirring to crystallize at the appropriate temperature to achieve the 2-chlorine-3-aminopyridine hydrochloride with the purity >= 99%. Impurities of 2,6-dichloro-3-aminopyridine are smaller than or equal to 0.5%. the preparation method is simple in operation, little in equipment investment, low in cost, small in environment pollution and suitable for industrialization production.

Description

technical field [0001] The invention relates to a preparation method of a pharmaceutical intermediate and a pesticide intermediate, in particular to a preparation method of high-purity 2-chloro-3-aminopyridine hydrochloride. Background technique [0002] 2-Chloro-3-aminopyridine and its hydrochloride are important fine chemical products widely used in the fields of medicine and pesticides. [0003] It can be used to synthesize the anti-peptic ulcer drug pirenzepine. US 4749788 and EP 410148 respectively report that 2-chloro-3-aminopyridine can be used as an intermediate of anti-AIDS drugs. [0004] 2-Chloro-3-aminopyridine and its hydrochloride are also important raw materials for phthalamide insecticides represented by chlorantraniliprole. [0005] The preparation of 2-chloro-3-aminopyridine from 3-aminopyridine is usually obtained by chlorination of 3-aminopyridine under the action of hydrochloric acid and hydrogen peroxide or chlorine. WO 2005070888 and JP09227522 resp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/73
Inventor 江岳恒阙利民蔡彤
Owner ABA CHEM NANTONG
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