Preparation method of 2-amino-4-nitrophenol

Abstract

The invention provides a preparation method of 2-amino-4-nitrophenol, which comprises the steps of (1) dissolving 2-aminophenol in a solvent to react with concentrated sulfuric acid to generate 2-aminophenol sulfate, and passivating an amino group; (2) carrying out nitration reaction on the generated 2-aminophenol hydrogen sulfate and a mixed acid of concentrated sulfuric acid and concentrated nitric acid, and selectively nitrating at the 4 position to obtain 2-amino-4-nitrophenol; and (3) finally, processing the 2-amino-4-nitrophenol crude product into a 2-amino-4-nitrophenol refined product. According to the method provided by the invention, the defects of poor selectivity of sulfide, hydrazine hydrate or palladium carbon and the like can be avoided; and the preparation method provided by the invention is simple to operate, and the prepared product is good in appearance, good in quality and high in yield and has a good industrial prospect.

Description

technical field [0001] The invention relates to the technical field of chemical industry, in particular to a preparation method of 2-amino-4-nitrophenol. Background technique [0002] 2-amino-4-nitrophenol, also known as 2-hydroxy-5-nitroaniline, is an important organic chemical synthesis intermediate, widely used in reactive black ACE, neutral black BL, neutral black BRL, Neutral black BGL, antihypertensive drug acebutolol, 2-butyl-6-nitroindole and other important chemical products are being produced. [0003] The preparation methods of 2-amino-4-nitrophenol mainly include electrochemical synthesis and chemical synthesis. Due to factors such as high production costs and lack of electrochemical facilities, electrochemical synthesis does not yet have the level of industrialization. About chemical synthesis There are many reports on the preparation of 2-amino-4-nitrophenol. [0004] The U.S. patents whose publication numbers are US2464194 and US4115652 disclose the selectiv...

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Problems solved by technology

[0004] The U.S. patents whose publication numbers are US2464194 and US4115652 disclose the selective reduction of 2,4-dinitrophenol into 2-amino-4-nitrophenol with sodium sulfide as a reducing agent. The working environment and products produced by this process all have Odor of sulfides, low product yield, high production cost, huge amount of foul-smelling and difficult-to-treat wastewater

[0005] The Chinese patents whose publication numbers are CN105801432 and CN105801440 disclose the use of hydrazine hydrate as a reducing agent and the combination of ferric chloride hexahydrate / activated carbon as a catalyst to selectively reduce 2,4-dinitrophenol to 2-amino-4-nitrophenol 2-nitro-4-aminophenol, 2,4-diaminophenol and other impurities are generated in this process. At the same time, hydrazine hydrate is a highly toxic compound, highly corrosive, and expensive, so it is not suitable for fine chemical industry mass production use

[0006] The Chinese patent with the publication number CN1793107 discloses that 5-nitro-2-methoxyaniline is used as the main raw material, 70% to 99% acetic acid is used as the solvent, and 40% hydroiodic acid is used as the catalyst to synthesize 2-amino-4- Nitrophenol, the energy consumption of this method is high, the waste water containing hydroiodic acid is difficult to treat and the price of the main raw material 5-nitro-2-methoxyaniline is high, the market supply is insufficient, and it is not suitable for industrialization

[0007] The Chinese patent whose publication number is CN106928071 discloses the selective reduction of 2,4-dinitrophenol to 2-amino-4-nitrophenol with palladium carbon as a reducing agent, but the selectivity is not high, and there is 2-nitro-4 Production of impurities such as -aminophenol and 2,4-diaminophenol

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