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[Chemical Knowledge]：Production process and preparation method of p-aminophenol

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P-aminophenol, also known as diaminophenol, is an organic compound with a chemical formula of C12H11NO. It is a functional chemical and is widely used in medicine, dyes, coatings and other fields. This article will introduce the production process and preparation method of p-aminophenol.

1. production process

At present, the production process of aminophenol mainly has the following kinds:

1. Direct amination method: the reaction of phenol and ammonia to generate aminophenol. The molar ratio of phenol to ammonia in the reaction feed should be 1:2.

2. meta-amination method: the reaction of styrene and nitric acid to generate m-nitrostyrene, and then hydrogenation reduction of m-nitrostyrene to obtain m-aminostyrene. Subsequent hydrolysis with excess carbon dioxide produces p-aminophenol.

3. reductive amination method: phenol is reacted with sodium nitrite to produce m-nitrophenol, which is then reduced to m-aminophenol. Subsequent hydrolysis with excess carbon dioxide produces p-aminophenol.

Among the above three production processes, the direct amination method is simple and has wide applicability, but the purity of the reaction product is low; the meta-amination method and the reductive amination method have higher product purity, but the process is complex.

2. preparation method

1. direct amination method

reaction raw materials for phenol and ammonia, the molar ratio of 1:2. The phenol and ammonia are thoroughly mixed, heated to 67-71°C, and allowed to stand for 6-8 hours to obtain the product p-aminophenol. The reaction process is as follows:

C6H5OH 2NH3 → C6H3(NH2)2OH

2. The meta-amination method

the reaction of styrene and nitric acid to produce meta-nitrostyrene; then the meta-nitrostyrene is hydrogenated and catalytically reduced to obtain meta-aminostyrene. Finally, m-aminostyrene is hydrolyzed with excess carbon dioxide to produce p-aminophenol. The reaction process is as follows:

① C6H5CH = CH2 HNO3 → C6H4(NO2)-CH = CH2 H2O

② C6H4(NO2)-CH = CH2 H2 → C6H4(NH2)-CH = CH2

③ C6H4(NH2)-CH = CH2 CO2 H2O → C6H3(NH2)2OH CH2O

3. Nitrous Acid Reaction of Phenol
by
; the m-nitrophenol is then reduced to m-aminophenol. Finally, m-aminophenol is hydrolyzed to produce p-aminophenol. The reaction process is as follows:

① C6H5OH HNO2 → C6H4(NO2)OH H2O

② C6H4(NO2)OH 6[H] → C6H4(NH2)OH 2 H2O

③ C6H4(NH2)OH CO2 H2O → C6H3(NH2)2OH CH2O