Method for reducing aromatic nitro compound into aromatic amine compound
阅读说明：本技术 一种芳香类硝基化合物还原成芳香胺类化合物的方法 (Method for reducing aromatic nitro compound into aromatic amine compound ) 是由 王超 刘宇轩 李昌志 肖建良 张涛 薛东 汤卫军 于 2019-12-05 设计创作，主要内容包括：本发明公开了一种芳香类硝基化合物还原成芳香胺类化合物的方法,在惰性或空气氛围下,以水为溶剂,异丙醇作为氢源,磷酸钾或碳酸钠作为碱,在铑催化剂的作用下,将芳香类硝基化合物在110～130℃反应,得到芳香胺类化合物。本发明操作简单,绿色环保,减少环境污染,反应产率高,可以放大到克级规模制备胺类化合物,催化剂活性高且可循环利用,工业化生产成本低。(The invention discloses a method for reducing aromatic nitro compounds into aromatic amine compounds, which comprises the step of reacting the aromatic nitro compounds at 110-130 ℃ under the action of a rhodium catalyst in an inert or air atmosphere by using water as a solvent, isopropanol as a hydrogen source and potassium phosphate or sodium carbonate as an alkali. The method has the advantages of simple operation, environmental protection, environmental pollution reduction, high reaction yield, high catalyst activity, cyclic utilization and low industrial production cost, and can be used for preparing the amine compound on a gram-scale.)
1. a method for reducing aromatic nitro compounds into aromatic amine compounds is characterized in that: under the inert or air atmosphere, reacting an aromatic nitro compound shown as a formula I at 110-130 ℃ by taking water as a solvent, isopropanol as a hydrogen source and potassium phosphate or sodium carbonate as alkali under the action of a rhodium catalyst to obtain an aromatic amine compound shown as a formula II;
wherein R represents H or C attached to any one or two positions of o, m, p or n of nitro1～C4Alkyl radical, C1～C3Any one or two of alkoxy, methylthio, amino, hydroxyl, piperazinyl and cyano;
the structural formula of the rhodium catalyst is shown as follows:
in the formula R1Represents any one of H, amino, hydroxyl, carboxyl, phenyl, 4-methoxyphenyl, 4-trifluoromethylphenyl, 2,4, 6-trimethoxyphenyl, 2-naphthyl and 9-anthryl.
2. The method of reducing an aromatic nitro compound to an aromatic amine compound according to claim 1, wherein: the R is1Represents 4-methoxyphenyl or hydroxy.
3. The method of reducing an aromatic nitro compound to an aromatic amine compound according to claim 1, wherein: the addition amount of the rhodium catalyst is 0.25-2% of the molar amount of the aromatic nitro compound.
4. The method of reducing aromatic nitro compounds to aromatic amine compounds of claim 3, wherein: the addition amount of the rhodium catalyst is 0.5 to 1 percent of the molar amount of the aromatic nitro compound.
5. The method of reducing an aromatic nitro compound to an aromatic amine compound according to claim 1, wherein: the addition amount of the isopropanol is 15-30 times of the molar amount of the aromatic nitro compound.
6. The method of reducing aromatic nitro compounds to aromatic amine compounds of claim 5, wherein: the addition amount of the isopropanol is 20-25 times of the molar amount of the aromatic nitro compound.
7. The method of reducing an aromatic nitro compound to an aromatic amine compound according to claim 1, wherein: the addition amount of the potassium phosphate or the sodium carbonate is 5 to 100 percent of the molar amount of the aromatic nitro compound.
8. The method of reducing an aromatic nitro compound to an aromatic amine compound according to claim 7, wherein: the addition amount of the potassium phosphate or the sodium carbonate is 10 to 30 percent of the molar amount of the aromatic nitro compound.
Technical Field
The invention belongs to the technical field of nitro reduction, and particularly relates to a method for reducing an aromatic nitro compound into an aromatic amine compound.
Background
Aromatic amine compounds are important intermediates for dye synthesis, cosmetics, rubber chemicals, pharmaceuticals and agrochemicals. The aromatic amine compound is mainly obtained by reducing aromatic nitro compounds. The aromatic nitro compound reduction system is more, and mainly comprises: (1) conventional Fe/HCl or Sn/HCl systems can give products with nitro groups reduced to amino groups. (2) Subject group of Matthias Beller (J.Am. chem. Soc.2011,133, 12875-12879) 2011 reported Fe (BF)4)2·6H2O as a catalyst, [ P (CH)2CH2PPh2)3As the phosphorus ligand, formic acid is used as a hydrogen source, and a product of reducing the nitro group into the amino group can be obtained under the conditions of 40 ℃ and ethanol as a solvent. (3) The Doherty project group (Catal. Sci. Technol.,2018,8, 1454-1467) reported PdNP @ PPh in 20182PEGPIILP as catalyst, hydrogen (70psi) or sodium borohydride as hydrogen source, water asSolvent to obtain the product with nitro reduced into amino. (4) The Oliver kappa topic group (Angew. chem. int. Ed.2012,51,10190-3As catalyst, in N2H4·H2And the nitro is reduced into amino by taking O as a hydrogen source and methanol as a solvent. (5) The shouchen Sun project group (ACS Catal.2014,4,1777-3·BH3As hydrogen source, ethanol and water are used as solvent to obtain the product of reducing nitro into amino. (6) The Sabuj Kundu topic group (RSC adv.,2016,6, 100532-100545) was reported in 2016 as [ RuCl ]2(p-cymene)]2As a catalyst, under the condition of 110 ℃ and isopropanol as a hydrogen source, a product with nitro reduced into amino can be obtained. In summary, the reported systems for reducing nitro groups have the following disadvantages: Fe/HCl or Sn/HCl systems generate a lot of waste, and the post-treatment is troublesome; some systems require high-pressure hydrogen, which is not easy to operate; some systems require the use of formic acid to emit the greenhouse gas carbon dioxide; some systems use relatively expensive hydrazine hydrate or NH3·BH3As a source of hydrogen; when cheap isopropanol is used as a hydrogen source (RSC adv, 2016,6, 100532-.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects of the method, and provide a method for synthesizing an aromatic amine compound by reducing nitro in an aromatic nitro compound with water as a solvent and isopropanol as a hydrogen source in the presence of a catalyst.
The technical scheme for solving the technical problems is as follows: under the inert or air atmosphere, reacting an aromatic nitro compound shown as a formula I at 110-130 ℃ by taking water as a solvent, isopropanol as a hydrogen source and potassium phosphate or sodium carbonate as alkali under the action of a rhodium catalyst to obtain an aromatic amine compound shown as a formula II;
wherein R represents H or C attached to any one or two positions of o, m, p or n of nitro1～C4Alkyl radical, C1～C3Any one or two of alkoxy, methylthio, amino, hydroxyl, piperazinyl and cyano.
The structural formula of the rhodium catalyst is shown as follows:
in the formula R1Represents any of 4-methoxyphenyl (catalyst 1a), 2,4, 6-trimethoxyphenyl (catalyst 1b), phenyl (catalyst 1c), 4-trifluoromethylphenyl (catalyst 1d), 2-naphthyl (catalyst 1e), 9-anthryl (catalyst 1f), H (catalyst 1g), amino (catalyst 1H), hydroxyl (catalyst 1i), carboxyl (catalyst 1j), preferably 4-methoxyphenyl or hydroxyl.
In the method, the addition amount of the rhodium catalyst is 0.25-2% of the molar amount of the aromatic nitro compound, and the addition amount of the rhodium catalyst is preferably 0.5-1% of the molar amount of the aromatic nitro compound.
In the method, the addition amount of the isopropanol is 15-30 times of the molar amount of the aromatic nitro compound, and preferably the addition amount of the isopropanol is 20-25 times of the molar amount of the aromatic nitro compound.
In the above method, the amount of potassium phosphate or sodium carbonate added is 5 to 100% of the molar amount of the aromatic nitro compound, and preferably 10 to 30% of the molar amount of the aromatic nitro compound.
The invention has the following beneficial effects:
compared with the prior art, the method has the advantages of simple operation, environmental protection, environmental pollution reduction, high reaction yield, capability of preparing amine compounds on a gram-scale, high catalyst activity, cyclic utilization and low industrial production cost.
Detailed Description
The present invention is further illustrated in detail below with reference to examples, but the scope of the present invention is not limited to these examples.