Preparation method of 2-amino-5-chlorobenzophenone

Abstract

The invention provides a preparation method of 2-amino-5-chlorobenzophenone, and relates to the technical field of medicine synthesis. The method comprises the following steps: dissolving 5-chloro-3-phenyl-2, 1-benzisoxazole in ethyl acetate, under the action of a composite catalyst, vacuumizing, introducing hydrogen for reaction until the content of 2-amino-5-chlorobenzophenone in a reaction liquid detected by HPLC (High Performance Liquid Chromatography) is not lower than 93%, carrying out filter pressing, collecting filtrate, carrying out reduced pressure distillation on the filtrate, and recrystallizing to obtain the 2-amino-5-chlorobenzophenone. Drying is carried out, such that 2-amino-5-chlorobenzophenone is obtained; the composite catalyst is a nitrogen-doped porous graphene loaded platinum monatomic catalyst. According to the method for preparing the 2-amino-5-chlorobenzophenone, Pt (at) NHG is adopted as the catalyst, the dosage is small, and the catalyst can be recycled and reused; compared with a traditional iron powder / acid reduction process, a large amount of metal waste residues and acid-containing waste water are not generated, and environment friendliness is achieved.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical synthesis technology, and in particular to a method for preparing 2-amino-5-chlorobenzophenone. Background Technology

[0002] 2-Amino-5-chlorobenzophenone and its derivatives are key intermediates in the synthesis of anti-insomnia, anti-anxiety, and antidepressant drugs such as diazepam, alprazolam, nitrazepam, and oxazepam, and are in widespread and continuous demand in the pharmaceutical industry. Currently, industrially, this intermediate is mainly prepared from 5-chloro-3-phenyl-2,1-benzisoxazole via a reduction reaction. Depending on the reduction system used, existing technologies mainly fall into three categories: First, metal reduction, which uses zinc or iron powder under acidic conditions. For example, Chinese patents CN104230727 and CN108250091 report iron powder / hydrochloric acid and iron powder / sulfuric acid systems, respectively, and Tetrahedron 2007, 63, 474 also reports an iron powder / acetic acid reduction method. Second, catalytic hydrogenation, which uses supported metal catalysts such as nickel and palladium under a hydrogen atmosphere. For example, Chinese patents CN107698453A, CN107827763A, CN10793587A, CN106083621A, CN106496050A, and CN113956168A all report hydrogenation processes using palladium / carbon or Raney nickel as catalysts. Third, rare earth reduction, such as Tetrahedron… The samarium diiodide reduction method reported in Lett. 2002, 43, 7001. However, the above methods all have significant drawbacks in industrial applications: the iron powder reduction system requires the use of metals in stoichiometric quantities, and the reaction generates a large amount of solid waste such as ferrous chloride and acidic wastewater, causing serious environmental pollution; in addition, the reaction requires heating, resulting in high energy consumption; in the catalytic hydrogenation method, Raney nickel is flammable and explosive, posing a significant safety hazard, while palladium / carbon catalysts, although highly active, have poor selectivity and are prone to dechlorination side reactions, generating structurally similar 2-aminobenzophenone impurities. These impurities have similar physicochemical properties to the target product, making separation difficult and seriously affecting product purity and yield; although samarium diiodide has good reduction selectivity, it is expensive and not suitable for large-scale industrial production.

[0003] Therefore, there is an urgent need to develop a new reduction process that is efficient, safe, environmentally friendly and cost-controllable to achieve the green and highly selective synthesis of 2-amino-5-chlorobenzophenone. Summary of the Invention

[0004] In view of this, the present invention proposes a method for preparing 2-amino-5-chlorobenzophenone, which uses 5-chloro-3-phenyl-5-chloro-3-phenylisoxazole and hydrogen as raw materials, and catalyzes the reduction of 2-amino-5-chlorobenzophenone with high selectivity under the catalysis of a platinum single-atom catalyst supported on nitrogen-doped porous graphene.

[0005] The technical solution of the present invention is achieved through the following steps:

[0006] This invention provides a method for preparing 2-amino-5-chlorobenzophenone, comprising the following steps:

[0007] 5-Chloro-3-phenyl-2,1-benzoxazole was dissolved in ethyl acetate. Under the action of a composite catalyst, the reaction was carried out under vacuum and then hydrogen was introduced. The 2-amino-5-chlorobenzophenone content in the reaction solution was not less than 93% as determined by HPLC. The filtrate was collected by pressure filtration, and the filtrate was recrystallized and dried after vacuum distillation to obtain 2-amino-5-chlorobenzophenone.

[0008] The composite catalyst is a platinum single-atom catalyst (Pt@NHG) supported on nitrogen-doped porous graphene.

[0009] Further, the mass ratio of the 5-chloro-3-phenyl-2,1-benzisoxazole, the ethyl acetate, and the composite catalyst is 1:4-6:0.005-0.03.

[0010] Furthermore, the hydrogen pressure is 0.1-0.5 MPa.

[0011] Furthermore, the reaction temperature is 20-50℃, and the reaction time is 1-3h.

[0012] Furthermore, in the nitrogen-doped porous graphene-supported platinum single-atom catalyst, the loading of platinum single atoms is 0.3-0.1%, the doping amount of nitrogen atoms is 5-10%, and the average pore size of the porous graphene is 2-5 nm.

[0013] Furthermore, the preparation of the nitrogen-doped porous graphene-supported platinum single-atom catalyst includes the following steps:

[0014] S1. Hydrogen peroxide solution and ammonia were added to the aqueous solution of graphene oxide, and a hydrothermal reaction was carried out to obtain nitrogen-doped porous graphene.

[0015] S2. Nitrogen-doped porous graphene was dispersed in water, potassium chloroplatinate was added, and the mixture was stirred in the dark. After filtration and drying, a platinum single-atom catalyst supported on nitrogen-doped porous graphene was obtained.

[0016] Furthermore, in step S1, the concentration of graphene in the graphene oxide aqueous solution is 1-20 mg / mL, the mass fraction of the hydrogen peroxide solution is 20-30%, and the mass fraction of the ammonia solution is 25-28%.

[0017] Furthermore, in step S1, the mass ratio of the graphene oxide dispersion, the hydrogen peroxide solution, and the ammonia water is 1:0.05-2:30.

[0018] When the ratio of hydrogen peroxide to ammonia is too low, the specific surface area of ​​the prepared catalyst decreases, and the catalyst activity decreases after metal loading. Conversely, when the ratio of hydrogen peroxide to ammonia is too high, the stability of the prepared catalyst decreases.

[0019] Furthermore, in step S1, the temperature of the hydrothermal reaction is 150-250℃, and the time is 4-24h.

[0020] Furthermore, in step S2, the mass concentration of the nitrogen-doped porous graphene dispersion is 1-10 mg / mL;

[0021] The mass ratio of the nitrogen-doped porous graphene to the potassium chloroplatinate is 1:0.03-0.1.

[0022] If the amount of potassium chloroplatinate added is too low, the metal content in the catalyst will be too low, resulting in poor catalytic performance. If the amount of potassium chloroplatinate added is higher than 0.1%, some metal cannot be fully loaded, increasing the cost of the catalyst.

[0023] The present invention provides a method for preparing 2-amino-5-chlorobenzophenone, which, compared with the prior art, has the following advantages:

[0024] Beneficial effects:

[0025] 1. The method for preparing 2-amino-5-chlorobenzophenone of the present invention uses Pt@NHG as a catalyst, which requires a small amount and the catalyst can be recycled and reused. Compared with the traditional iron powder / acid reduction process, it does not produce a large amount of metal waste and acidic wastewater, and is environmentally friendly.

[0026] 2. The method for preparing 2-amino-5-chlorobenzophenone of the present invention has excellent chemical selectivity compared with the problem of excessive reduction and dechlorination side reaction caused by commercial Pd / C catalysts. It can completely suppress the generation of dechlorination impurities such as 2-aminobenzophenone, significantly improve product yield and quality, and reduce the difficulty of subsequent separation and purification.

[0027] 3. The method for preparing 2-amino-5-chlorobenzophenone in this invention, compared with the synthetic route of commercial Pt / C catalysts, has high platinum dispersion in the form of single atoms on nitrogen-doped porous graphene support, resulting in high utilization of active sites, significantly improved catalytic efficiency, and the reaction can be completed in 1-2 hours, greatly shortening the reaction time.

[0028] 4. The preparation method of the present invention can be carried out at room temperature without heating, is safe to operate, has low energy consumption, which helps to reduce industrial operating costs. Moreover, the entire reaction system is stable, easy to operate, the catalyst is easy to separate and recover, has good reusability, and is suitable for large-scale continuous production. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a process route diagram for preparing 2-amino-5-chlorobenzophenone according to the present invention. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] The following provides an exemplary description of the specific reaction steps and detailed control parameters of the synthesis method. Unless otherwise specified, the main materials involved in the following examples are conventional commercial products or raw materials that can be prepared by existing known chemical methods.

[0033] Example 1

[0034] This embodiment provides a method for preparing 2-amino-5-chlorobenzophenone, comprising the following steps:

[0035] Step 1: Catalyst Preparation

[0036] Graphene oxide, hydrogen peroxide solution, and ammonia were added at a mass ratio of 1:0.5:30. 300 mL of a 6 mg / mL graphene oxide aqueous solution was placed in a 1000 mL polytetrafluoroethylene (PTFE) reactor liner. 6.67 mL of a 30% hydrogen peroxide solution and 400 mL of a 28% ammonia solution were added and mixed thoroughly. The resulting mixture was then placed in a hydrothermal reactor and hydrothermally reacted in a 220°C oven for 5 hours to obtain nitrogen-doped porous graphene (NHG). NHG and potassium chloroplatinate were then added at a mass ratio of 1:0.05. 300 mL of a 5 mg / mL NHG aqueous dispersion was prepared. Then, 50 mg of potassium chloroplatinate was added to the dispersion under an ice bath (0°C), and the mixture was stirred and reacted in the dark for 3 hours. After filtration and freeze-drying, 1478 mg of the Pt@NHG composite catalyst was obtained.

[0037] Step 2: Preparation of 2-amino-5-chlorobenzophenone

[0038] 200 g of 5-chloro-3-phenylbenzisoxazole was weighed and dissolved in 1400 mL of ethyl acetate. The solution was then transferred to a 2000 mL hydrogenation reactor. 1.0 g of Pt@NHG catalyst was added, and hydrogen gas was introduced to maintain a hydrogen pressure of 0.5 MPa. After reacting at room temperature for 1 h, a sample was taken, and the product content was found to be 94.9%. The reaction was stopped, the mixture was filtered, and the solvent was recovered by vacuum distillation of the filtrate, yielding a crude yellow solid, 2-amino-5-chlorobenzophenone. 1500 mL of 95% ethanol was added, and the mixture was heated until dissolved. Approximately 1000 mL of ethanol was then recovered by distillation. The remaining liquid was cooled to -10 °C with ice-salt water and stirred to crystallize, yielding a pale yellow solid product. The yellow solid was filtered, dried, and weighed, yielding 194.7 g of product, with a yield of 96.51% and a purity of 99.66%.

[0039] Example 2

[0040] This embodiment provides a method for preparing 2-amino-5-chlorobenzophenone, comprising the following steps:

[0041] Step 1: Catalyst Preparation

[0042] Graphene oxide, hydrogen peroxide solution, and ammonia were added at a mass ratio of 1:0.05:30. 300 mL of a 6 mg / mL graphene oxide aqueous solution was placed in a 1000 mL polytetrafluoroethylene (PTFE) reactor liner. 6.67 mL of a 3% (w / w) hydrogen peroxide solution and 400 mL of a 28% (w / w) ammonia solution were added and mixed thoroughly. The resulting mixture was then placed in a hydrothermal reactor and hydrothermally reacted in a 220°C oven for 4 hours to obtain nitrogen-doped porous graphene (NHG). NHG and potassium chloroplatinate were then added at a mass ratio of 1:0.05. 300 mL of a 5 mg / mL NHG aqueous dispersion was prepared. Then, 50 mg of potassium chloroplatinate was added to the dispersion under an ice bath (0°C), and the mixture was stirred and reacted in the dark for 3 hours. After filtration and freeze-drying, 1478 mg of the Pt@NHG composite catalyst was obtained.

[0043] Step 2: Preparation of 2-amino-5-chlorobenzophenone

[0044] 200 g of 5-chloro-3-phenylbenzisoxazole was weighed and dissolved in 1400 mL of ethyl acetate. The solution was then transferred to a 2000 mL hydrogenation reactor. 1.0 g of Pt@NHG catalyst was added, and hydrogen gas was introduced to maintain a hydrogen pressure of 0.1 MPa. After reacting at room temperature for 1 h, a sample was taken, and the product content was found to be 94.1%. The reaction was stopped, the mixture was filtered, and the solvent was recovered by vacuum distillation of the filtrate, yielding a crude yellow solid, 2-amino-5-chlorobenzophenone. 1500 mL of 95% ethanol was added, and the mixture was heated until it dissolved completely. Approximately 1000 mL of ethanol was then recovered by distillation. The remaining liquid was cooled to -10 °C with ice-salt water and stirred to crystallize, yielding a pale yellow solid product. The yellow solid was filtered, dried, and weighed, yielding 193.6 g of product, with a yield of 95.96% and a purity of 99.51%.

[0045] Example 3

[0046] This embodiment provides a method for preparing 2-amino-5-chlorobenzophenone, comprising the following steps:

[0047] Step 1: Catalyst Preparation

[0048] Graphene oxide, hydrogen peroxide solution, and ammonia were added at a mass ratio of 1:0.05:30. 300 mL of a 6 mg / mL graphene oxide aqueous solution was placed in a 1000 mL polytetrafluoroethylene (PTFE) reactor liner. 0.03 mL of a 30% hydrogen peroxide solution and 48 mL of a 28% ammonia solution were added and mixed thoroughly. The resulting mixture was then placed in a hydrothermal reactor and hydrothermally reacted at 150°C for 24 hours to obtain nitrogen-doped porous graphene (NHG). NHG and potassium chloroplatinate were then added at a mass ratio of 1:0.03. 300 mL of a 5 mg / mL NHG aqueous dispersion was prepared. 45 mg of potassium chloroplatinate was added to this dispersion under ice bath (0°C), and the mixture was stirred and reacted in the dark for 3 hours. After filtration and freeze-drying, 1452 mg of the Pt@NHG composite catalyst was obtained.

[0049] Step 2: Preparation of 2-amino-5-chlorobenzophenone

[0050] 200 g of 5-chloro-3-phenylbenzisoxazole was weighed and dissolved in 800 mL of ethyl acetate. The solution was then transferred to a 2000 mL hydrogenation reactor. 1.0 g of Pt@NHG catalyst was added, and hydrogen gas was introduced to maintain a pressure of 0.1 MPa. The reaction was carried out at 20 °C for 3 h. After 3 h, a sample was taken and the product content was found to be 94.1%. The reaction was stopped, the mixture was filtered, and the solvent was recovered by vacuum distillation of the filtrate, yielding crude 2-amino-5-chlorobenzophenone as a yellow solid. 1500 mL of 95% ethanol was added, and the mixture was heated until dissolved. Approximately 1000 mL of ethanol was then recovered by distillation. The remaining liquid was cooled to -10 °C with ice-salt water and stirred to crystallize, yielding a pale yellow solid product. The yellow solid was filtered, dried, and weighed, yielding 191.2 g of product, with a yield of 94.75% and a purity of 99.23%.

[0051] Example 4

[0052] This embodiment provides a method for preparing 2-amino-5-chlorobenzophenone, comprising the following steps:

[0053] Step 1: Catalyst preparation (same as Example 1)

[0054] Step 2: Preparation of 2-amino-5-chlorobenzophenone

[0055] 200g of 5-chloro-3-phenylbenzisoxazole was weighed and dissolved in 1200mL of ethyl acetate. The solution was then transferred to a 2000mL hydrogenation reactor. 1.0g of Pt@NHG catalyst was added, and hydrogen gas was introduced to maintain a pressure of 0.5MPa. The reaction was carried out at 50℃ for 1 hour. After sampling, the product content was found to be 95.2%. The reaction was stopped, filtered, and the solvent was recovered by vacuum distillation of the filtrate, yielding crude 2-amino-5-chlorobenzophenone as a yellow solid. 1500mL of 95% ethanol was added, and the mixture was heated until dissolved. Approximately 1000mL of ethanol was then recovered by distillation. The remaining liquid was cooled to -10℃ with ice-salt water and stirred to crystallize, yielding a pale yellow solid product. The yellow solid was filtered, dried, and weighed, yielding 194.1g of product, with a yield of 96.18% and a purity of 98.82%.

[0056] Comparative Example 1

[0057] This comparative example provides a method for preparing 2-amino-5-chlorobenzophenone, which differs from Example 1 in that the NHG catalyst prepared in this invention is used instead of the Pt@NHG catalyst, and includes the following steps:

[0058] 20g of 5-chloro-3-phenylbenzisoxazole was weighed, dissolved in 150mL of ethyl acetate, and then transferred to a 500mL hydrogenation reactor. 1.0g of NHG catalyst was added, and hydrogen gas was introduced to maintain a hydrogen pressure of 0.5MPa. After reacting at 50℃ for 1h, the product content was measured to be 22.7%. The reaction was continued for 6h, and the product content was measured to be 28.9%. The reaction rate was slow, and the reaction was stopped because it could not be completed due to the extended reaction time. No further processing was carried out.

[0059] Comparing the data from Example 1 and Comparative Example 1, it can be seen that when using NHG catalyst instead of Pt@NHG catalyst, the reaction can still proceed, but the reaction rate is very slow and the reaction cannot be completed. The reason may be that although the microscopic defects on NHG can promote the hydrogenation reaction, the effect is far less than that of Pt@NHG with metal support, resulting in a very slow hydrogenation reaction rate and the reaction cannot be completed even after a long time.

[0060] Comparative Example 2

[0061] This comparative example provides a method for preparing 2-amino-5-chlorobenzophenone, which differs from Example 1 in that a 3% platinum-carbon (Pt / C) catalyst is used instead of a Pt@NHG catalyst, and includes the following steps:

[0062] 4.6 g of 5-chloro-3-phenyl-2,1-benzisoxazole and 0.46 g of platinum-carbon (Pt / C) catalyst (65% water content, 3% platinum content) were added to a three-necked flask, followed by 30 mL of ethyl acetate. The mixture was evacuated and then purged with hydrogen gas at a pressure of 0.1 MPa. The mixture was stirred at room temperature for 3 h. The reaction was stopped when the reactants disappeared as monitored by TLC. The mixture was filtered, and the solvent was recovered by vacuum distillation of the filtrate, yielding crude 2-amino-5-chlorobenzophenone as a yellow solid. 25 mL of 95% ethanol was added, and the mixture was heated until dissolved. The solution was cooled to -10 °C with ice-salt water and stirred to crystallize, yielding a pale yellow solid product. The yellow solid was filtered, dried, and weighed, yielding 2.6 g of the product, with a yield of 94.83% and a purity of 98.93%.

[0063] Comparing the data from Example 1 and Comparative Example 2, it can be seen that the yield and purity of 2-amino-5-chlorobenzophenone obtained using a 3% platinum-carbon (Pt / C) catalyst are close to those obtained using a Pt@NHG catalyst. However, when using the platinum-carbon (Pt / C) catalyst, the reaction solvent is ethyl acetate, while the product recrystallization solvent is ethanol. Therefore, the solvent needs to be replaced after the reaction, increasing the workload. When using Pt@NHG as the catalyst, the reaction solvent and recrystallization solvent are the same. After the reaction, only the catalyst needs to be recovered by filtration before direct recrystallization, simplifying the reaction operation.

[0064] Comparative Example 3

[0065] The difference from Example 1 is that a 3% palladium on carbon (Pd / C) catalyst is used instead of a Pt@NHG catalyst. This comparative example provides a method for preparing 2-amino-5-chlorobenzophenone, comprising the following steps:

[0066] 4.6 g of 5-chloro-3-phenyl-2,1-benzisoxazole and 0.23 g of palladium on carbon (Pd / C) catalyst (65% water content, 3% palladium content) were weighed and added to a three-necked flask. 30 mL of ethyl acetate was then added. The mixture was evacuated and hydrogen gas was introduced, maintaining a hydrogen pressure of 0.1 MPa. The mixture was stirred at room temperature for 3 h. The reaction was stopped when the reactants disappeared as monitored by TLC. The mixture was filtered, and the solvent was recovered by vacuum distillation of the filtrate, yielding a crude yellow solid of 2-amino-5-chlorobenzophenone. 25 mL of 95% ethanol was added, and the mixture was heated until dissolved. The solution was cooled to -10 °C with ice-salt water and stirred to crystallize, yielding a pale yellow solid. The product was filtered to obtain a yellow solid. The product was separated by column chromatography, dried, and weighed, yielding 1.2 g of product, with a yield of 47.41% and a purity of 98.51%. Another impurity was isolated and its structure was confirmed to be 2-aminobenzophenone (dechlorination product).

[0067] Comparing the data from Example 1 and Comparative Example 3, it is evident that the yield of 2-amino-5-chlorobenzophenone obtained using a 3% palladium on carbon (Pd / C) catalyst is significantly lower than that obtained using a Pt@NHG catalyst. This is primarily because using palladium on carbon as a catalyst readily generates a dechlorination byproduct (2-aminobenzophenone). Furthermore, this byproduct cannot be separated from the product by recrystallization and requires column chromatography.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing 2-amino-5-chlorobenzophenone, characterized in that, Includes the following steps: 5-Chloro-3-phenyl-2,1-benzoxazole was dissolved in ethyl acetate. Under the action of a composite catalyst, the reaction was carried out under vacuum and then hydrogen was introduced. The 2-amino-5-chlorobenzophenone content in the reaction solution was not less than 93% as determined by HPLC. The filtrate was collected by pressure filtration, and the filtrate was recrystallized and dried after vacuum distillation to obtain 2-amino-5-chlorobenzophenone. The composite catalyst is a platinum single-atom catalyst supported on nitrogen-doped porous graphene.

2. The method for preparing 2-amino-5-chlorobenzophenone according to claim 1, characterized in that, The mass ratio of the 5-chloro-3-phenyl-2,1-benzisoxazole, the ethyl acetate, and the composite catalyst is 1:4-6:0.005-0.

03.

3. The method for preparing 2-amino-5-chlorobenzophenone according to claim 1, characterized in that, The hydrogen pressure is 0.1-0.5 MPa.

4. The method for preparing 2-amino-5-chlorobenzophenone according to claim 1, characterized in that, The reaction temperature is 20-50℃, and the reaction time is 1-3h.

5. The method for preparing 2-amino-5-chlorobenzophenone according to claim 1, characterized in that, In the nitrogen-doped porous graphene-supported platinum single-atom catalyst, the loading of platinum single atoms is 0.3-0.1%, the doping amount of nitrogen atoms is 5-10%, and the average pore size of the porous graphene is 2-5 nm.

6. The method for preparing 2-amino-5-chlorobenzophenone as described in claim 5, characterized in that, The preparation of the nitrogen-doped porous graphene-supported platinum single-atom catalyst includes the following steps: S1. Hydrogen peroxide solution and ammonia were added to the aqueous solution of graphene oxide, and a hydrothermal reaction was carried out to obtain nitrogen-doped porous graphene. S2. Nitrogen-doped porous graphene was dispersed in water, potassium chloroplatinate was added, and the mixture was stirred in the dark. After filtration and drying, a platinum single-atom catalyst supported on nitrogen-doped porous graphene was obtained.

7. The method for preparing 2-amino-5-chlorobenzophenone according to claim 6, characterized in that, In step S1, the hydrogen peroxide solution has a mass fraction of 20-30%, and the ammonia solution has a mass fraction of 25-28%.

8. The method for preparing 2-amino-5-chlorobenzophenone according to claim 7, characterized in that, In step S1, the mass ratio of the graphene oxide dispersion, the hydrogen peroxide solution, and the ammonia water is 1:0.05-2:

30.

9. The method for preparing 2-amino-5-chlorobenzophenone as described in claim 8, characterized in that, In step S1, the temperature of the hydrothermal reaction is 150-250℃, and the time is 4-24h.

10. The method for preparing 2-amino-5-chlorobenzophenone according to claim 6, characterized in that, In step S2, the mass concentration of the nitrogen-doped porous graphene dispersion is 1-10 mg / mL; The mass ratio of the nitrogen-doped porous graphene to the potassium chloroplatinate is 1:0.03-0.1.

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