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5-fluoro-2-nitrophenol preparation method

A technology of nitrophenol and difluoronitrobenzene is applied in the field of preparation of 5-fluoro-2-nitrophenol, can solve the problems of unfavorable industrial operation, low conversion rate of synthesis method, long reaction time and the like, and achieves the reaction time Short, easy to operate, no side effects

Active Publication Date: 2018-04-20
LIER CHEM CO LTD +1
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Problems solved by technology

[0009] The technical problem to be solved in the present invention is that the conversion rate of the existing synthetic method is low, and the reaction time is long, which is unfavorable for industrial operation

Method used

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preparation example Construction

[0025] The preparation method of 5-fluoro-2-nitrophenol comprises the following steps:

[0026] a) 2,4-difluoronitrobenzene and NH 3 Reaction to obtain 5-fluoro-2-nitroaniline;

[0027] b) Dissolving 5-fluoro-2-nitroaniline in sulfuric acid aqueous solution first, then adding sodium nitrite aqueous solution dropwise to the above aqueous solution at 0°C-10°C, and then reacting at 0°C-10°C for 0.5-1h, Then within 1~2h, the temperature was raised to 90~95°C for 1h.

[0028] As a preferred solution of the present invention, in the preparation method of the above-mentioned 5-fluoro-2-nitrophenol, the NH described in step a) 3 For concentrated ammonia.

[0029] In the preparation method of the above-mentioned 5-fluoro-2-nitrophenol, the NH described in step a) 3 The molar ratio to 2,4-difluoronitrobenzene is 2~4:1. Preferably, the NH 3 The molar ratio to 2,4-difluoronitrobenzene is 2.1~2.5︰1.

[0030] In the above-mentioned preparation method of 5-fluoro-2-nitrophenol, the re...

Embodiment 1

[0038] Synthesis of embodiment 1 5-fluoro-2-nitroaniline

[0039] Add 127.5 g of concentrated ammonia water into a 500 mL reaction flask, and add 159 g (1 mol) of 2,4-difluoronitrobenzene at room temperature. Start stirring, and slowly raise the temperature to 40°C for 3 hours. After the raw materials disappeared in the central control analysis, it was cooled to 5-10°C under stirring to crystallize, and 152.9 g of 5-fluoro-2-nitroaniline was obtained by filtration, with a yield of 98%.

Embodiment 2

[0040] Example 2 Synthesis of 5-fluoro-2-nitroaniline

[0041] Add 180g of water into a 500mL reaction flask, and add 159g (1mol) of 2,4-difluoronitrobenzene at room temperature. Turn on the stirring, feed 42.5 g of ammonia gas at 35-40°C, and then keep it warm for 3 hours. After the raw materials disappeared in the central control analysis, it was cooled to 5-10°C under stirring to crystallize, and 153.2 g of 5-fluoro-2-nitroaniline was obtained by filtration, with a yield of 98.5%.

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Abstract

The invention belongs to the field of organic synthesis, and particularly relates to a 5-fluoro-2-nitrophenol preparation method. In the prior art, the existing synthesis method has disadvantages of low conversion rate and long reaction time so as not to easily achieve industrial operation. A purpose of the present invention is to solve the technical problem in the prior art. The technical schemeis to provide a 5-fluoro-2-nitrophenol preparation method, which comprises: a) carrying out a reaction on 2,4-difluoronitrobenzene and NH 3 to obtain 5-fluoro-2-nitroaniline; and b) carrying out a reaction on the 5-fluoro-2-nitroaniline under the actions of sulfuric acid and sodium nitrite to obtain the 5-fluoro-2-nitrophenol. According to the present invention, the 5-fluoro-2-nitrophenol preparation method has advantages of good selectivity, almost no side reaction, high yield, short reaction time, simple operation and easy industrialization.

Description

technical field [0001] The invention belongs to the field of organic synthesis, and in particular relates to a preparation method of 5-fluoro-2-nitrophenol. Background technique [0002] 5-Fluoro-2-nitrophenol is a key intermediate for the synthesis of fine chemicals such as the herbicide fluorentrafen, and the synthetic routes reported in the literature mainly include: [0003] (1) m-fluorophenol nitration method [0004] [0005] This method is reported in patent WO2009035407, etc., but this method is not of high industrial value due to the high price of m-fluorophenol, many by-products during nitration, and low yield. [0006] (2) 2,4-difluoronitrobenzene hydrolysis method [0007] [0008] Patents such as US5227535 have reported this method, in which 2,4-difluoronitrobenzene is hydrolyzed by strong inorganic bases such as NaOH and KOH, and then acidified to obtain the target product. This method is widely used because of its simple operation and high yield. How...

Claims

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Application Information

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IPC IPC(8): C07C201/12C07C205/26
CPCC07C201/12C07C209/10C07C205/26C07C211/52
Inventor 晏三军任杰林洪兵蒋涛
Owner LIER CHEM CO LTD
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