Preparation method of 2-aminobiphenyl compound

Abstract

The invention discloses a preparation method of a 2-aminobiphenyl compound, which comprises the following steps: adding a substituted 2-nitro-1, 2, 3, 6-tetrahydro-1, 1 '-biphenyl compound, a toluene organic solvent, a polymerization inhibitor and a noble metal supported catalyst into a reaction kettle, introducing hydrogen at a first reaction temperature, and reacting at a second reaction temperature to obtain the 2-aminobiphenyl compound. And heating to a second reaction temperature, and carrying out a hydrogen transfer reaction to obtain the target product 2-aminobiphenyl compound. According to the method, dehydrogenation aromatization and reduction of nitryl into amino can be synchronously completed, tedious operations such as material transfer and solvent replacement are avoided, the yield reaches 90.5%-94.8%, and the method has the advantages of being low in cost, easy to operate, small in pollution, suitable for large-scale industrial production and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of organic compound preparation and relates to a method for preparing 2-aminobiphenyl compounds. Background Art

[0002] 2-Aminobiphenyl compounds are an important class of pesticide intermediates. For example, 4-chloro-2-aminobiphenyl is a key intermediate in the synthesis of boscalid, with a CAS registration number of 1204-44-0. Boscalid is a new nicotinamide fungicide developed by BASF of Germany. Its generic name is boscalid, also known as nicobifen, and its test number is BAS510. It is a mitochondrial respiration inhibitor and a succinate dehydrogenase inhibitor (SDHI). It works by inhibiting succinate coenzyme Q reductase (also known as complex II) on the mitochondrial electron transport chain. Its mechanism of action is similar to that of other amide and benzamide fungicides. It is mainly used to control powdery mildew, gray mold, various rots, brown rot and root rot. It is active against almost all types of fungal diseases and is also effective against bacteria resistant to other agents. 3',4',5'-Trifluoro-2-aminobiphenyl is an important intermediate for the synthesis of flupyroxad. Flupyroxad (obtained the ISO pesticide common name: Fluxapyroxad in April 2015, trade name: Xemium) is a succinate dehydrogenase inhibitor fungicide developed by BASF. Flupyroxad is a mitochondrial respiration inhibitor, a succinate dehydrogenase inhibitor (SDHI). SDHI fungicides inhibit the succinate dehydrogenase of pathogens, interfere with mitochondrial respiration, and cause the pathogens to be unable to synthesize energy normally, and then die of exhaustion, thereby achieving the purpose of preventing and controlling diseases. In 2012, BASF launched flupyroxad, which is used in grains, soybeans, corn and rapeseed in America and Europe. BASF Co., Ltd. has applied for patent protection in my country, which is valid until 2026.

[0003] There are many reports on the synthesis methods of 2-aminobiphenyl compounds, and the synthesis routes can be roughly divided into: Suzuki coupling reaction route, Grignard reaction route, aromatic radical coupling reaction route, Diels-Alder cyclization reaction route and other synthesis routes.

[0004] There are many related research reports on the synthesis of 2-aminobiphenyl compounds via the Suzuki coupling reaction route, which mainly focus on the selection of raw materials and the optimization of ligands. For example, Yue Hang et al. [CN104478726A, 2015-04-01] used 2-chloronitrobenzene and disubstituted phenylboronic acid in the presence of a non-phosphine ligand catalyzed by Pd / C to carry out a Suzuki coupling reaction with a high yield. However, the preparation of the raw material disubstituted phenylboronic acid in this method requires the use of a Grignard reaction, which has the disadvantages of harsh synthesis conditions, high safety risks, and a large amount of "three wastes". Wang Jie et al. [CN109912425A, 2019-06-21] used p-chlorophenylboric acid as the main raw material and synthesized 4-chloro-2-aminobiphenyl via Suzuki reaction, which has the advantages of high yield and mature technology, but the disadvantages are also obvious: the cost of raw materials such as p-chlorophenylboric acid is high, and the synthesis methods of p-chlorophenylboric acid include organic lithium reagent method, Grignard reagent method and palladium-catalyzed oxyborylation method. The organic lithium reagent method and Grignard reagent method are mainly used in industry. The organic lithium reagent method produces p-chlorophenylboric acid with high product quality, followed by the Grignard reagent method. Both methods have difficulties such as harsh synthesis conditions, high safety risks, and large amounts of "three wastes", resulting in high production costs of p-chlorophenylboric acid.

[0005] Cheng Chuanjie et al. [Pesticides, 2016, 55(2):96-98] obtained 4′-chloro-2-aminobiphenyl by coupling aniline and p-chlorophenylhydrazine under 30% hydrogen peroxide oxidation. This route is short and does not use precious metal palladium-based precious metal-supported catalysts and p-chlorophenylboronic acid raw materials, but the yield is only 50.7%, and a large amount of aniline is used to improve the selectivity of aromatic radical coupling, which does not meet the requirements of industrialization.

[0006] A. Cote et al. [CN102348675B, 2014-10-01] reported a cycloaddition synthesis route: using p-chlorobenzaldehyde as the raw material, 4′-chloro-2-aminobiphenyl was obtained through five steps of Herry reaction, Diels-Alder cyclization reaction, halogenation, elimination oxidation, and hydrogenation reduction. This route avoids the costly Suzuki reaction, but the total yield is low (31.2%), the product purity is only 93%, and the raw materials used are of various types, the operation is cumbersome, the post-processing is difficult, and there are many "three wastes", making industrial production difficult. Shao Yutian et al. [CN106103404B, 2017-11-24] improved on this basis: using 2-nitroarylethylene and substituted 1,3-butadiene as raw materials, reacting at 60-160°C and 0.2-4.0MPa in one step to obtain 2-aminobiphenyl compounds, 2-nitrobiphenyl compounds or their mixtures, and then reducing to prepare 2-aminobiphenyl compounds. This scheme reduces the number of reaction steps, but the yield is low, the raw materials are not easy to obtain, and it is difficult to apply industrially.

[0007] As the relevant patents of SDHI fungicides such as boscalid, bixafen, and flupyracopyram expire one after another, in order to break the monopoly and reduce the cost of using such products, it is necessary to study the synthesis process of its key intermediate 2-aminobiphenyl compounds, improve product yield, reduce production costs and environmental pollution, and enhance corporate competitiveness. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a preparation method of 2-aminobiphenyl compounds with high yield, low cost, easy operation, less pollution and suitable for large-scale industrial production.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions.

[0010] A method for preparing a 2-aminobiphenyl compound comprises the following steps:

[0011] Adding a substituted 2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl compound, a toluene organic solvent, a polymerization inhibitor and a noble metal-supported catalyst into a reaction kettle, introducing hydrogen at a first reaction temperature of 50° C. to 90° C., then heating to a second reaction temperature of 180° C. to 290° C. to perform a hydrogen transfer reaction, and after the reaction, obtaining a target product, a 2-aminobiphenyl compound;

[0012] The chemical structural formula of the substituted 2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl compound is as follows:

[0013]

[0014] Among them, R 1 , R 2 and R 3 Each is independently selected from hydrogen, fluorine, chlorine, bromine, hydroxyl, alkyl or alkoxy, the alkyl is selected from methyl, ethyl, propyl or isopropyl, and the alkoxy is selected from methoxy, ethoxy, propoxy, isopropoxy or benzyloxy.

[0015] The method of the present invention uses the same solvent in a one-pot method to complete multiple-step reactions. The main reaction process is shown in formula (1), and dehydrogenation aromatization and nitro hydrogenation reduction can be achieved simultaneously.

[0016]

[0017] In the above-mentioned method for preparing 2-aminobiphenyl compounds, preferably, the mass ratio of the toluene organic solvent to the substituted 2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl compound is 2-5:1; and the toluene organic solvent is at least one of toluene, xylene and mesitylene.

[0018] In the above-mentioned method for preparing 2-aminobiphenyl compounds, preferably, the mass ratio of the inhibitor to the substituted 2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl compound is 0.001-0.01:1; the inhibitor is at least one of hydroquinone, 2,6-di-tert-butyl-p-cresol, acetophenone and methylhydroquinone.

[0019] In the above-mentioned method for preparing 2-aminobiphenyl compounds, preferably, the mass ratio of the noble metal-supported catalyst to the 2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl compound is 0.005 to 0.05:1.

[0020] In the above-mentioned method for preparing 2-aminobiphenyl compounds, preferably, the mass fraction of the precious metal in the precious metal-loaded catalyst is 1% to 10%; the precious metal-loaded catalyst includes at least one of an activated carbon-loaded palladium catalyst, an activated carbon-loaded platinum catalyst, an activated carbon-loaded rhodium catalyst, an alumina-loaded palladium catalyst, an alumina-loaded platinum catalyst and an alumina-loaded rhodium catalyst.

[0021] In the above-mentioned method for preparing 2-aminobiphenyl compounds, preferably, the time for introducing hydrogen at the first reaction temperature is 1 hour to 3 hours.

[0022] In the above-mentioned method for preparing 2-aminobiphenyl compounds, preferably, the molar ratio of the hydrogen introduced at the first reaction temperature to the substituted 2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl compound is 0.95-1.05:1.

[0023] In the above-mentioned method for preparing 2-aminobiphenyl compounds, preferably, the time of the hydrogen transfer reaction is 3h to 10h.

[0024] In the above-mentioned method for preparing 2-aminobiphenyl compounds, preferably, post-treatment is performed after the reaction is completed, and the post-treatment includes cooling, filtering, desolventizing and recrystallization, and the recrystallization uses n-hexane, cyclohexane, n-heptane or petroleum ether as solvent.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] The preparation method of the invention uses substituted 2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl compounds as raw materials and hydrogen as a hydrogen source, realizes simultaneous completion of dehydrogenation aromatization and reduction of nitro groups to amino groups, avoids tedious operations such as material transfer and solvent replacement, and has the advantages of high yield, low cost, easy operation, less pollution, and suitability for large-scale industrial production requirements.

[0027] The method of the invention provides a new preparation route for 2-aminobiphenyl compounds, realizes the one-pot method of using the same solvent to complete multi-step reactions, significantly reduces the amount of raw materials, effectively avoids tedious operations such as complex post-treatment and material transfer, has good reaction selectivity, is simple to operate, produces less "three wastes", and is conducive to industrial production.

[0028] The preparation method of the invention has high product yield, and the total yield reaches 90.5% to 94.8%. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with specific preferred embodiments, but the protection scope of the present invention is not limited thereby. The materials and instruments used in the following embodiments are all commercially available.

[0030] Example 1

[0031] A method for preparing 2-aminobiphenyl compounds of the present invention, specifically the synthesis of 3',4',5'-trifluoro-2-aminobiphenyl, comprises the following steps:

[0032]

[0033] 78.74 g (98%, 0.3 mol) of 3',4',5'-trifluoro-2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl, 157.48 g of toluene, 0.08 g of hydroquinone and 0.39 g of activated carbon-supported palladium catalyst were added to a 1000 mL autoclave, wherein the mass fraction of palladium in the activated carbon-supported palladium catalyst was 5%. The mixture was replaced with nitrogen three times and heated to 50° C. Within 3 h, 0.57 g of hydrogen was introduced. After the introduction of hydrogen was stopped, the temperature was continued to rise to 180° C. The reaction was kept warm for 10 h. After cooling, filtering and desolventizing, the mixture was recrystallized with n-hexane to obtain 61.43 g of a white solid, which was the target product 3',4',5'-trifluoro-2-aminobiphenyl. The content of 3',4',5'-trifluoro-2-aminobiphenyl was determined by liquid chromatography external standard method to be 98.65%, with a yield of 90.5%.

[0034] Example 2

[0035] A method for preparing 2-aminobiphenyl compounds of the present invention, specifically the synthesis of 3',4',5'-trifluoro-2-aminobiphenyl, comprises the following steps:

[0036] 78.74 g (98%, 0.3 mol) of 3',4',5'-trifluoro-2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl, 236.21 g of toluene, 0.24 g of 2,6-di-tert-butyl-p-cresol and 0.79 g of activated carbon-supported platinum catalyst were added to a 1000 mL autoclave, wherein the mass fraction of platinum in the activated carbon-supported platinum catalyst was 10%. The mixture was replaced with nitrogen three times and heated to 55° C. Within 2.5 h, 0.6 g of hydrogen was introduced, and the temperature was continued to rise to 200° C. after the introduction of hydrogen was stopped. The reaction was kept warm for 8 h, and the mixture was cooled, filtered, desolvated, and recrystallized from cyclohexane to obtain 61.82 g of a white solid, which was 3',4',5'-trifluoro-2-aminobiphenyl. The content of 3',4',5'-trifluoro-2-aminobiphenyl was determined by liquid chromatography external standard method to be 98.79%, and the yield was 91.2%.

[0037] Example 3

[0038] A method for preparing a 2-aminobiphenyl compound of the present invention, specifically the synthesis of 3',4',5'-trifluoro-2-aminobiphenyl, comprises the following steps:

[0039] 78.74 g (98%, 0.3 mol) of 3',4',5'-trifluoro-2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl, 314.95 g of toluene, 0.39 g of acetophenone and 1.18 g of activated carbon-supported rhodium catalyst were added to a 1000 mL autoclave, wherein the mass fraction of rhodium in the activated carbon-supported rhodium catalyst was 1%. The mixture was replaced with nitrogen three times and heated to 60° C. Within 2 h, 0.63 g of hydrogen was introduced. After the introduction of hydrogen was stopped, the temperature was continued to rise to 220° C. The reaction was kept warm for 6 h. After cooling, filtering and desolventizing, the mixture was recrystallized with n-heptane to obtain 62.08 g of a white solid, which was 3',4',5'-trifluoro-2-aminobiphenyl. The content of 3',4',5'-trifluoro-2-aminobiphenyl was determined by liquid chromatography external standard method to be 99.12%, with a yield of 91.9%.

[0040] Example 4

[0041] A method for preparing a 2-aminobiphenyl compound of the present invention, specifically the synthesis of 3',4',5'-trifluoro-2-aminobiphenyl, comprises the following steps:

[0042] 78.74 g (98%, 0.3 mol) of 3',4',5'-trifluoro-2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl, 393.69 g of xylene, 0.55 g of methylhydroquinone and 1.57 g of alumina-supported palladium catalyst were added to a 1000 mL autoclave, wherein the mass fraction of palladium in the alumina-supported palladium catalyst was 5%. The mixture was replaced with nitrogen three times and heated to 65° C. Within 1.5 h, 0.57 g of hydrogen was introduced, and the temperature was continued to rise to 240° C. after the introduction of hydrogen was stopped. The reaction was kept warm for 4 h, and the mixture was cooled, filtered, desolvated, and recrystallized with petroleum ether to obtain 62.86 g of a white solid, which was 3',4',5'-trifluoro-2-aminobiphenyl. The content of 3',4',5'-trifluoro-2-aminobiphenyl was determined by liquid chromatography external standard method and was 98.64%, with a yield of 92.6%.

[0043] Example 5

[0044] A method for preparing 2-aminobiphenyl compounds of the present invention, specifically the synthesis of 3',4',5'-trifluoro-2-aminobiphenyl, comprises the following steps:

[0045] 78.74 g (98%, 0.3 mol) of 3',4',5'-trifluoro-2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl, 157.48 g of xylene, 0.71 g of hydroquinone and 1.97 g of alumina-supported platinum catalyst were added to a 1000 mL autoclave, wherein the mass fraction of platinum in the alumina-supported platinum catalyst was 3%. The mixture was replaced with nitrogen three times and heated to 70° C. Within 1 hour, 0.6 g of hydrogen was introduced. After the introduction of hydrogen was stopped, the temperature was continued to rise to 260° C. The reaction was kept warm for 3 hours. The mixture was cooled, filtered, desolvated, and recrystallized with n-hexane to obtain 64.17 g of a white solid, which was 3',4',5'-trifluoro-2-aminobiphenyl. The content of 3',4',5'-trifluoro-2-aminobiphenyl was determined by liquid chromatography external standard method and was 98.92%, with a yield of 94.8%.

[0046] Example 6

[0047] A method for preparing a 2-aminobiphenyl compound of the present invention, specifically the synthesis of 3',4'-difluoro-2-aminobiphenyl, comprises the following steps:

[0048]

[0049] 73.23 g (98%, 0.3 mol) of 3',4'-difluoro-2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl, 219.69 g of xylene, 0.73 g of 2,6-di-tert-butyl-p-cresol and 2.2 g of alumina-supported rhodium catalyst were added to a 1000 mL autoclave, wherein the mass fraction of rhodium in the alumina-supported rhodium catalyst was 1%. The mixture was replaced with nitrogen three times and heated to 75° C. Within 1 hour, 0.63 g of hydrogen was introduced. After the introduction of hydrogen was stopped, the temperature was continued to rise to 280° C. The reaction was kept warm for 4 hours. The mixture was cooled, filtered, desolventized, and recrystallized from cyclohexane to obtain 57.3 g of a white solid, which was 3',4'-difluoro-2-aminobiphenyl. The content of 3',4'-difluoro-2-aminobiphenyl was determined by liquid chromatography external standard method to be 98.84%, with a yield of 92%.

[0050] Example 7

[0051] A method for preparing a 2-aminobiphenyl compound of the present invention, specifically the synthesis of 3',4'-difluoro-2-aminobiphenyl, comprises the following steps:

[0052] 73.23 g (98%, 0.3 mol) of 3',4'-difluoro-2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl, 292.92 g of mesitylene, 0.22 g of acetophenone and 2.56 g of activated carbon-supported palladium catalyst were added to a 1000 mL autoclave, wherein the mass fraction of palladium in the activated carbon-supported palladium catalyst was 3%. The mixture was replaced with nitrogen three times and heated to 80° C. Within 1 hour, 0.57 g of hydrogen was introduced. After the introduction of hydrogen was stopped, the temperature was continued to rise to 290° C. The reaction was kept warm for 3 hours. The mixture was cooled, filtered, desolvated, and recrystallized with n-heptane to obtain 57.06 g of a white solid, which was 3',4'-difluoro-2-aminobiphenyl. The content of 3',4'-difluoro-2-aminobiphenyl was determined by liquid chromatography external standard method to be 99.05%, with a yield of 91.8%.

[0053] Example 8

[0054] A method for preparing a 2-aminobiphenyl compound of the present invention, specifically the synthesis of 4'-chloro-2-aminobiphenyl, comprises the following steps:

[0055]

[0056] 72.76 g (98%, 0.3 mol) of 4'-chloro-2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl, 363.8 g of mesitylene, 0.36 g of methylhydroquinone and 2.91 g of activated carbon-supported platinum catalyst were added to a 1000 mL autoclave, wherein the mass fraction of platinum in the activated carbon-supported platinum catalyst was 1%. The mixture was replaced with nitrogen three times and heated to 85° C. Within 1 hour, 0.6 g of hydrogen was introduced, and the temperature was continued to rise to 220° C. after the introduction of hydrogen was stopped. The reaction was kept warm for 6 hours, and the mixture was cooled, filtered, desolvated, and recrystallized with petroleum ether to obtain 55.9 g of a white solid, which was 4'-chloro-2-aminobiphenyl. The content of 4'-chloro-2-aminobiphenyl was determined to be 99.14% by liquid chromatography external standard method, and the yield was 90.7%.

[0057] Example 9

[0058] A method for preparing a 2-aminobiphenyl compound of the present invention, specifically the synthesis of 4'-chloro-2-aminobiphenyl, comprises the following steps:

[0059] 72.76 g (98%, 0.3 mol) of 4'-chloro-2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl, 218.28 g of toluene, 0.51 g of hydroquinone and 3.64 g of activated carbon-supported palladium catalyst were added to a 1000 mL autoclave, wherein the mass fraction of palladium in the activated carbon-supported palladium catalyst was 1%. The mixture was replaced with nitrogen three times and heated to 90° C. Within 1 hour, 0.63 g of hydrogen was introduced, and the temperature was continued to rise to 240° C. after the introduction of hydrogen was stopped. The reaction was kept warm for 4 hours, and the mixture was cooled, filtered, desolvated, and recrystallized with n-hexane to obtain 56.5 g of a white solid, which was 4'-chloro-2-aminobiphenyl. The content of 4'-chloro-2-aminobiphenyl was determined to be 98.95% by liquid chromatography external standard method, and the yield was 91.5%.

[0060] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as above in the preferred embodiment, it is not used to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention, still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a 2-aminobiphenyl compound, characterized in that: The following steps are involved: Adding a substituted 2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl compound, a toluene organic solvent, a polymerization inhibitor and a noble metal-supported catalyst into a reaction kettle, introducing hydrogen at a first reaction temperature of 50° C. to 90° C., then heating to a second reaction temperature of 180° C. to 290° C. to perform a hydrogen transfer reaction, and after the reaction, obtaining a target product, a 2-aminobiphenyl compound; The chemical structural formula of the substituted 2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl compound is as follows: Among them, R 1 , R 2 and R 3 Each is independently selected from hydrogen, fluorine, chlorine, bromine, hydroxyl, alkyl or alkoxy, the alkyl is selected from methyl, ethyl, propyl or isopropyl, and the alkoxy is selected from methoxy, ethoxy, propoxy, isopropoxy or benzyloxy.

2. The method for preparing 2-aminobiphenyl compounds according to claim 1, characterized in that: The mass ratio of the toluene organic solvent to the substituted 2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl compound is 2-5:1; the toluene organic solvent is at least one of toluene, xylene and mesitylene.

3. The method for preparing 2-aminobiphenyl compounds according to claim 1, characterized in that: The mass ratio of the polymerization inhibitor to the substituted 2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl compound is 0.001-0.01:1; the polymerization inhibitor is at least one of hydroquinone, 2,6-di-tert-butyl-p-cresol, acetophenone and methylhydroquinone.

4. The method for preparing 2-aminobiphenyl compounds according to claim 1, characterized in that: The mass ratio of the noble metal supported catalyst to the substituted 2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl compound is 0.005-0.05:

1.

5. The method for preparing 2-aminobiphenyl compounds according to claim 4, characterized in that: The mass fraction of the precious metal in the precious metal-loaded catalyst is 1% to 10%; the precious metal-loaded catalyst comprises at least one of an activated carbon-loaded palladium catalyst, an activated carbon-loaded platinum catalyst, an activated carbon-loaded rhodium catalyst, an alumina-loaded palladium catalyst, an alumina-loaded platinum catalyst and an alumina-loaded rhodium catalyst.

6. The method for preparing a 2-aminobiphenyl compound according to any one of claims 1 to 5, characterized in that: The time for introducing hydrogen at the first reaction temperature is 1 h to 3 h.

7. The method for preparing a 2-aminobiphenyl compound according to any one of claims 1 to 5, characterized in that: The molar ratio of the hydrogen introduced at the first reaction temperature to the substituted 2-nitro-1,2,3,6-tetrahydro-1,1'-biphenyl compound is 0.95-1.05:

1.

8. The method for preparing 2-aminobiphenyl compounds according to any one of claims 1 to 5, characterized in that: The time of the hydrogen transfer reaction is 3h to 10h.

9. The method for preparing a 2-aminobiphenyl compound according to any one of claims 1 to 5, characterized in that: After the reaction is completed, post-treatment is performed, which includes cooling, filtering, desolventizing and recrystallization. The recrystallization uses n-hexane, cyclohexane, n-heptane or petroleum ether as solvent.

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