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Preparation method of 2-chloro-5-nitropyridine

A technology of nitropyridine and propoxypyridine, which is applied in the field of preparation of 2-chloro-5-nitropyridine, can solve the problems of high price, potential safety hazard, and low yield of direct nitration, and achieves controllable reaction temperature, Improvement of yield and reduction of side reactions of isomers

Pending Publication Date: 2022-01-28
BENGBU CHINA SYNCHEM TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Among them: the first step is that the amino group in 2-aminopyridine has an ortho-para substitution effect, and there will be isomers (2-amino-3-nitropyridine) in direct nitration, which needs to be purified and then proceeded further, often directly nitrated to obtain relatively low rate
The second step is diazotization by sodium nitrite, and then hydrolyzed to obtain 2-hydroxy-5-nitropyridine. If it is produced on a large scale, there will be a greater safety hazard
[0009] The used raw material 2-chloro-5-pyridine boric acid of this synthetic method and reagent two (trifluoroacetoxy group) iodobenzene are all expensive, do not have economic effect

Method used

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  • Preparation method of 2-chloro-5-nitropyridine
  • Preparation method of 2-chloro-5-nitropyridine
  • Preparation method of 2-chloro-5-nitropyridine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032]

[0033] Under the protection of nitrogen, add 56.8g (0.50mol) of 2-chloropyridine and 400mL of isopropanol to the reaction flask, raise the temperature to 80-85°C, add 54.0g (0.55mol) of potassium isopropoxide in batches, and then raise the temperature to reflux React for 2 hours, evaporate a large amount of isopropanol by concentration under reduced pressure, add 5% acetic acid aqueous solution to adjust pH = 6.4-6.9, continue to concentrate under reduced pressure and evaporate isopropanol, the materials are separated, the water layer is extracted with a small amount of dichloromethane, and combined The organic phase was distilled under reduced pressure at 80-100°C to collect a fraction of 2-isopropoxypyridine 64.1g, yield 93.4%, GC: 99.6%. 1 HNMR (400MHz, CDCl 3 ):8.12-8.10(m,1H),7.51-7.49(m,1H),6.78-6.69(m,2H),5.29-5.26(m,1H),1.35-1.32(m,6H).

Embodiment 2

[0035]

[0036] Under the protection of nitrogen, add 56.8g (0.5mol) 2-chloropyridine and 400mL isopropanol to the reaction flask, raise the temperature to 80-85°C, add 49.2g (0.60mol) sodium isopropoxide in batches, and then raise the temperature to reflux React for 2 hours, evaporate a large amount of isopropanol by concentration under reduced pressure, add 5% acetic acid aqueous solution to adjust pH = 6.4-6.9, continue to concentrate under reduced pressure and evaporate isopropanol, the materials are separated, the water layer is extracted with a small amount of dichloromethane, and combined The organic phase was distilled under reduced pressure at 80-100°C to collect a fraction of 2-isopropoxypyridine 63.6g, yield 92.7%, GC: 99.7%.

Embodiment 3

[0038]

[0039] Under the protection of nitrogen, add 6.86g (0.05mol) 2-isopropoxypyridine and 350mL concentrated sulfuric acid to the reaction flask and mix, slowly add 5.25g (0.06mol) 72% nitric acid dropwise at 20-25°C, and then heat up to 75- React at 80°C for 0.5 hours. After the reddish-brown color appears, control the temperature at 75-85°C, and simultaneously add 54.9g (0.4mol) 2-isopropoxypyridine and 39.4g (0.45mol) 72% concentrated nitric acid dropwise, and react at this temperature for 2 hours . Cool down to room temperature, pour into ice water, extract with MTBE, wash the organic phase with saturated sodium bicarbonate and water, then concentrate under reduced pressure, add n-heptane to beat the temperature, filter to obtain 5-nitro-2-isopropoxypyridine 73.5 g, yield 89.7%, HPLC: 98.9%. 1 HNMR (400MHz, CDCl 3 ):9.25-9.23(m,1H),8.45-8.43(m,1H),6.96-6.94(m,1H),5.37-5.34(m,1H),1.36-1.34(m,6H).

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Abstract

The invention discloses a preparation method of 2-chloro-5-nitropyridine, and belongs to the technical field of organic synthesis. The preparation method comprises the following steps: taking 2-chloropyridine as a raw material, and carrying out nucleophilic substitution on the 2-chloropyridine and sodium / potassium isopropoxide to obtain 2-isopropoxy pyridine; then reacting in a concentrated sulfuric acid / nitric acid system to obtain 5-nitro-2-isopropoxy pyridine; then carrying out deprotection in the presence of boron trichloride to obtain 2-hydroxy-5-nitropyridine; and finally, reacting with phosphorus oxychloride to obtain the 2-chloro-5-nitropyridine. According to the invention, raw materials are convenient and easy to obtain, the operation process is simple and convenient, nitration conditions are relatively mild, isomers are few, dangerous diazotization operation is avoided in the process, and the total yield of the four-step reaction can reach 65-68%.

Description

technical field [0001] The invention relates to a preparation method of 2-chloro-5-nitropyridine, which belongs to the technical field of organic synthesis. Background technique [0002] 2-Chloro-5-nitropyridine (2-Chloro-5-nitropyridine), CAS: 4548-45-2, is an important intermediate in the pesticide and pharmaceutical industries, such as an important intermediate for the synthesis of certain antibiotic drugs Body, wherein anti-Aureococcus antibiotics have the effects of strengthening the heart, anti-virus, sterilization and anti-arrhythmia. [0003] The nitro group on the pyridine ring has properties similar to halogens and can be substituted by nucleophiles. In addition, the introduction of halogen into the pyridine ring can increase the polarity of the molecule, and through the conversion of halogen, derivatives containing other substituents can be prepared or their properties can be changed. The synthetic method of 2-chloro-5-nitropyridine is mainly: [0004] Literatu...

Claims

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Application Information

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IPC IPC(8): C07D213/61
CPCC07D213/61Y02P20/584
Inventor 刘洪强杨忆魏佳玉朱克明王松松
Owner BENGBU CHINA SYNCHEM TECH CO LTD
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