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Method for preparing 2-fluoro-4-nitrophenol

A technology for nitrophenol and nitrosophenol, which is applied in the field of preparation of 2-fluoro-4-nitrophenol, can solve the problems of unsatisfactory yield, high separation difficulty and high production cost, and achieves reduction of production cost and high production cost. Simple process, easy to refine effect

Inactive Publication Date: 2006-10-25
YETAI FINE CHEM INST CHANGZHOU CITY
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  • Abstract
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AI Technical Summary

Problems solved by technology

[0002] The methods usually used to prepare 2-fluoro-4-nitrophenol mainly include the following two methods: one preparation method uses 2-fluorophenol as a raw material and obtains it through nitration. Isomers, one is the product 2-fluoro-4-nitrophenol, and the other is the by-product 2-fluoro-6-nitrophenol, which is very difficult to separate, resulting in a very low yield, generally less than 30%, so high production cost
Another preparation method is to use 2-fluorophenol as raw material, nitrosation in the presence of sulfuric acid, and then oxidize with nitric acid to obtain 2-fluoro-4-nitrophenol, but the yield is not ideal, only about 60%

Method used

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preparation example Construction

[0010] A preparation method of 2-fluoro-4-nitrophenol is characterized in that the following steps are adopted:

[0011] a), nitrosation reaction: 2-fluorophenol is used as raw material, and nitrosated in the presence of dilute hydrochloric acid to generate 2-fluoro-4-nitrosophenol. The concentration of dilute hydrochloric acid is 15-20%, preferably 15%; the nitrosation reagent is alkali metal nitrite or nitrite, preferably sodium nitrite; the nitrosation reaction temperature is -5-5°C, preferably 0°C.

[0012] b) Oxidation reaction: oxidize 2-fluoro-4-nitrosophenol with dilute nitric acid to prepare 2-fluoro-4-nitrophenol. The concentration of dilute nitric acid used is 15-55%, preferably 30%.

Embodiment 1

[0014] Add 500ml of 15% hydrochloric acid to a 1L three-necked flask equipped with a stirrer, a thermometer and two dropping funnels, cool to 0°C, and simultaneously add 1mol of 35% sodium nitrite solution and 0.67mol of 2-fluoro Phenol, the dropwise addition time is 45 minutes, continue to keep warm for 1 hour after the dropwise addition is completed, and filter the water.

[0015] Put the filter cake into a 500ml three-neck flask, pour 1.2 mol of 30% dilute nitric acid at about 5°C, mix well and then gradually heat up to 40°C, keep it warm for 1 hour, cool and filter to obtain the crude product with a content of about 98%, ethanol Recrystallized, the content is 99.5%, and the yield is about 90%.

Embodiment 2

[0017] Add 500ml of 30% hydrochloric acid to a 1L three-neck flask equipped with a stirrer, a thermometer and two dropping funnels, cool to 0°C, and simultaneously add 1mol of 35% sodium nitrite solution and 0.67mol of 2-fluoro Phenol, the dropwise addition time is 45 minutes, continue to keep warm for 1 hour after the dropwise addition is completed, and filter the water.

[0018] Put the filter cake into a 500ml three-necked flask, pour 1.2 mol of 30% dilute nitric acid at about 5°C, mix well and then gradually heat up to 40°C, keep it warm for 1 hour, cool and filter to obtain the crude product, ethanol recrystallization, yield About 80%.

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Abstract

This invention relates to chemical product preparation method, especially 2- fluorin-4-nitrophenol preparation method. First is nitrosation reaction, 2-fluoropenol is material, it nitrosation generates 2-fluorin-4-nitrosophenol. Muriate acid concentration is 15-20 percent, first select 15 percent, nitrosation solvent is nitrous acid metal salt or nitrous acid ester, and sodium nitrate is first selected. The reaction temperature is -5-5 degrees centigrade, 0 degree centigrade is first selected. Second is oxidizing reaction, dilute nitric acid is used to oxidize 2-fluorin-4-nitrosophenol to make 2-fluorin-4-nitrophenol. The dilute nitric acid concentration is 15-55 percent, 30 percent is first selected. Its preparation technique is simple, very few isomers is generated during nitrosation, yield can reach 90 percent, its polishin is also easy, purity can reach more than 99.5 percent, cost is reduced.

Description

technical field [0001] The invention relates to a preparation method of chemical products, in particular to a preparation method of 2-fluoro-4-nitrophenol. Background technique [0002] The methods usually used to prepare 2-fluoro-4-nitrophenol mainly include the following two methods: one preparation method uses 2-fluorophenol as a raw material and obtains it through nitration. Isomers, one is the product 2-fluoro-4-nitrophenol, and the other is the by-product 2-fluoro-6-nitrophenol, which is very difficult to separate, resulting in a very low yield, generally less than 30%, so Production costs are high. Another preparation method uses 2-fluorophenol as raw material, nitrosation in the presence of sulfuric acid, and then oxidation with nitric acid to obtain 2-fluoro-4-nitrophenol, but the yield is not ideal, only about 60%. Contents of the invention [0003] In order to overcome the shortcoming of low yield of the existing preparation of 2-fluoro-4-nitrophenol, the pres...

Claims

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Application Information

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IPC IPC(8): C07C201/14C07C205/26
Inventor 柳建华
Owner YETAI FINE CHEM INST CHANGZHOU CITY
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