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A method for preparation of 2-amino-5-chloro-pyridine

A technology of aminopyridine and pyridine, which is applied in the field of fine organic synthesis to achieve the effects of less pollution, low cost and mild reaction conditions

Inactive Publication Date: 2017-02-22
ANHUI UNIVERSITY OF TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is: using sodium hypochlorite and hydrochloric acid solution composition as chlorinating agent, provide a kind of chlorinated aminopyridine preparation method with low cost, little pollution and easy operation

Method used

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  • A method for preparation of 2-amino-5-chloro-pyridine

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Experimental program
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Embodiment 1

[0021] In a 250ml three-necked flask, add 0.053mol (5.00g) of 2-aminopyridine, and place it in a water bath at 10°C. Under continuous stirring, after adding 0.11 mol of 13% (mass concentration, the same below) NaClO solution, 0.3 mol of 36% (mass concentration, the same below) hydrochloric acid was slowly added dropwise. After reacting at a constant temperature of 10°C for 2h, the temperature was raised to 25°C to continue the reaction for 4h. Finally, the reaction was terminated by cooling down to 10°C with ice water.

[0022] Adjust the above reaction solution to pH>8 with 5mol / L NaOH solution, filter and separate, wash with deionized water, and extract the filtrate and washing liquid with dichloroethane solvent to recover 2-aminopyridine and its chloride. The solid precipitate obtained by filtration and the dichloroethane extract were combined, dissolved in 10% dilute hydrochloric acid, and filtered. The filtrate was adjusted to pH=4 with 5 mol / L NaOH solution, extracted ...

Embodiment 2

[0024] In a 250ml three-necked flask, add 0.053mol (5.00g) of 2-aminopyridine, and place it in a water bath at 10°C. Under continuous stirring, after adding 0.16 mol of 8% NaClO solution, 0.3 mol of 25% hydrochloric acid was slowly added dropwise. After reacting at a constant temperature of 10°C for 2h, the temperature was raised to 25°C to continue the reaction for 4h. Finally, the reaction was terminated by cooling down to 10°C with ice water.

[0025] Adjust the above reaction solution to pH>8 with 5mol / L NaOH solution, filter and separate, wash with deionized water, and extract the filtrate and washing liquid with dichloroethane solvent to recover 2-aminopyridine and its chloride. The solid precipitate obtained by filtration and the dichloroethane extract were combined, dissolved in 10% dilute hydrochloric acid, and filtered. The filtrate was adjusted to pH=4 with 5 mol / L NaOH solution, extracted with dichloroethane solvent, and 5.75 g of the reaction product was obtaine...

Embodiment 3

[0027] In a 250ml three-necked flask, add 0.053mol (5.00g) of 2-aminopyridine, and place it in a water bath at 10°C. Under continuous stirring, after adding 0.11 mol of 13% NaClO solution, 0.25 mol of 36% hydrochloric acid was slowly added dropwise. After reacting at a constant temperature of 10°C for 2h, the temperature was raised to 25°C to continue the reaction for 4h. Finally, the reaction was terminated by cooling down to 10°C with ice water.

[0028] Adjust the above reaction solution to pH>8 with 5mol / L NaOH solution, filter and separate, wash with deionized water, and extract the filtrate and washing liquid with dichloroethane solvent to recover 2-aminopyridine and its chloride. The solid precipitate obtained by filtration and the dichloroethane extract were combined, dissolved in 10% dilute hydrochloric acid, and filtered. The filtrate was adjusted to pH=4 with 5 mol / L NaOH solution, extracted with dichloroethane solvent, and 5.58 g of the reaction product was obtai...

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Abstract

The invention provides a method for preparation of 2-amino-5-chloro-pyridine and belongs to the technical field of fine organic synthesis. 2-amino-5-chloro-pyridine is prepared by adopting 2-aminopyridine as a raw material and using hydrochloric acid and sodium hypochlorite for an oxidative chlorination reaction. The method mainly includes the following steps: at 10 DEG C, slowly and dropwise adding a certain amount of concentrated hydrochloric acid in a mixed solution of 2-aminopyridine and NaClO, conducting a reaction at constant temperature for 2 hours, increasing the temperature to 25 DEG C for continuing the reaction for 4 hours, regulating the pH of a reaction product, extracting the reaction product with dichloroethane, and conducting separation to obtain 2-amino-5-chloro-pyridine. The yield of 2-amino-5-chloro-pyridine is up to 72%. The method has the advantages that the cheap NaClO solution generated by chlorination of tail gas by chlorine gas and hydrochloric acid are used as chlorinating agents, the cost is thus reduced, and the comprehensive utilization of resources is achieved; the reaction conditions are mild, direct use of chlorine gas is avoided, safety is high, and pollution is little.

Description

technical field [0001] The invention belongs to the technical field of fine organic synthesis, in particular to a preparation method of chlorinated aminopyridine, in particular to a preparation method of 2-amino-5-chloro-pyridine. Background technique [0002] Chlorinated aminopyridine compounds are important "three-drug" intermediates, which are mainly used in the synthesis of important chemical products such as medicines, pesticides, and dyes. For example, 3-amino-2-chloropyridine and its derivatives are important intermediates of the antiulcer drug pirenzepine, and 4-amino-2-chloropyridine can be used to synthesize plant growth regulator KT-30, 2-amino -5-chloropyridine can be used to prepare important drugs such as new quinolone DW-116 after fluorination. At the same time, due to the advantages of high efficiency, low toxicity, and easy decomposition in the environment, pyridine insecticides have broad application prospects in the synthesis of pesticides. [0003] Due ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/73
CPCC07D213/73
Inventor 王知彩侍洋庆水恒福雷智平任世彪
Owner ANHUI UNIVERSITY OF TECHNOLOGY
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