Metalloporphyrin catalyst, graphene-immobilized metalloporphyrin catalyst, and preparation methods and applications of metalloporphyrin catalyst and graphene-immobilized metalloporphyrin catalyst

Abstract

The invention discloses a metalloporphyrin catalyst, a graphene immobilized metalloporphyrin catalyst and a preparation method and application thereof, and belongs to the technical field of applied chemistry and biomimetic catalysis. The invention aims to solve the problems of low efficiency, need of additional ligands, easiness in dimerization, difficulty in recovery and the like of existing metalloporphyrin catalytic oxidation of amino into nitro. The invention provides an imidazole modified metalloporphyrin structure, which is immobilized by using graphene and is applied to oxidation of 4-bromo-2, 6-difluoroaniline. A green and efficient 5-bromine-1, 3-difluoro-2-nitrobenzene synthesis system with a recyclable catalyst is established, 4-bromine-2, 6-difluoroaniline is taken as a raw material, hydrogen peroxide or tert-butyl hydroperoxide is taken as an oxidizing agent, newly synthesized metalloporphyrin is taken as the catalyst, and the 24-hour yield at the room temperature is 69.12% and is increased by 2.3 times compared with the yield of a porphyrin catalyst before modification; wherein the amino-substituted porphyrin still retains considerable activity after being immobilized by graphene, and the activity is retained by 90% or more after the amino-substituted porphyrin is repeatedly used for three times.

Description

Technical Field

[0001] The present invention belongs to the field of applied chemistry and biomimetic catalysis technology; specifically relates to a metalloporphyrin catalyst and a graphene-supported metalloporphyrinating agent; a method for preparing the catalyst; and application of the catalyst in catalyzing the oxidation of amino groups to nitro groups. Background Art

[0002] The nitro group in nitro compounds possesses strong electron-withdrawing properties, creating localized electron-deficient sites within the molecule. Therefore, nitro compounds have a wide range of applications, not only as energetic materials but also as pharmaceutical and chemical intermediates. For heterocyclic substrates and aliphatic amines containing unstable groups, nitro compounds can only be synthesized using the amino oxidation method. Currently, amino oxidation methods primarily include acid-catalyzed oxidation, metal-organic complex catalysis, bioenzyme catalysis, and enzyme-mimicking catalysis. However, acid-catalyzed oxidation methods suffer from the high cost of organic acids and the heavy pollution of inorganic acids, while metal-organic complex catalysis methods are associated with complex catalyst preparation processes and high costs.

[0003] Oxidase, as a green, highly selective catalyst, can catalyze the oxidation of various amino groups to nitro groups. Korboukh et al. (Proceedings of the National Academy of Sciences, 2010, 107 (36): 15722-15727) reported that the AurF enzyme can catalyze the conversion of p-aminobenzoic acid to p-nitrobenzoic acid and speculated on its possible catalytic mechanism. In order to improve the efficiency of biological enzymes, Cong et al. (Angew. Chem. Int. Ed. 2023, 62, e202217678) performed anchor modification of cytochrome P450BM3 with alkaline imidazole small molecules to promote electron transfer in the catalytic process of active center metalloporphyrin. Although directional modification or structural modification of biological enzymes can improve enzyme activity, its catalytic amino oxidation efficiency is still low, and only the target product can be detected, which makes it difficult to achieve application promotion. Therefore, by simulating the active center of oxidase, preparing enzyme-like catalysts with higher stability and better efficiency for catalytic amino oxidation has important potential.

[0004] Metalloporphyrin is as the active center of oxidases such as P450 enzyme and horseradish peroxidase, and its catalytic mechanism is more mature, therefore is as a class catalyst that imitates enzyme research more.People such as Stefano (J.Chem.Soc.Chem.Commun, 1993:442-444) reported with metalloporphyrin as catalyst, with tert-butyl hydroperoxide as oxidant, with additional imidazole nitrogen heterocycle as axial ligand, catalysis arylamine is oxidized to nitrobenzene, shows that metalloporphyrin has the activity of catalytic amino oxidation.But metalloporphyrin is that nitro still has the problems such as catalytic efficiency is low, metalloporphyrin easy dimerization deactivation, need additional imidazole ligand to be difficult for separation and purification, cannot reclaim as catalyst oxidation amino.Therefore design a kind of imidazole ligand modified metalloporphyrin and carry out immobilization, have the potentiality that improves its catalytic activity and realizes recycling. Summary of the Invention

[0005] The present invention aims to overcome the technical deficiencies of existing metalloporphyrin-catalyzed amino oxidation by providing a metalloporphyrin catalyst and a graphene-supported metalloporphyrinizing agent, as well as a method for preparing the catalyst and the use of the catalyst in catalyzing amino oxidation to nitro groups (i.e., catalytic synthesis of 5-bromo-1,3-difluoro-2-nitrobenzene). The present invention addresses the problems of existing metalloporphyrin-catalyzed amino oxidation to nitro groups, such as low efficiency, the need for an external ligand, easy dimerization, and difficulty in recovery.

[0006] The present invention establishes a green, efficient, and catalyst-recyclable synthesis system for 5-bromo-1,3-difluoro-2-nitrobenzene. Using 4-bromo-2,6-difluoroaniline as the raw material, hydrogen peroxide or tert-butyl hydroperoxide as the oxidant, and a newly synthesized metalloporphyrin as the catalyst, the yield is 69.12% in 24 hours at room temperature, a 2.3-fold increase over the yield of the original porphyrin catalyst. The amino-substituted porphyrin retains considerable activity after being immobilized on graphene, enabling reuse. This system features mild reaction conditions, high efficiency, no need for high temperature or high pressure, a safe, green process, and ease of industrial production, making it of great significance for the industrial production of 5-bromo-1,3-difluoro-2-nitrobenzene.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The object of the present invention is to provide a metalloporphyrin catalyst, the general formula of which is as follows:

[0009]

[0010] In the general formula, R is an alkyl group, an ester group, an alkoxy group, a nitro group, -NH2 or a halogen; and M is Fe, Ni, Mn, Zn or Co.

[0011] Another object of the present invention is to provide a graphene-supported metalloporphyrin catalyst; the structure of the metalloporphyrin catalyst is shown in the general formula above.

[0012] Another object of the present invention is to provide a method for preparing a metalloporphyrin catalyst in which R is an alkyl group, an ester group, an alkoxy group or a halogen, which specifically comprises the following steps:

[0013] Step 1, Synthesis of A1-A5: o-Hydroxybenzaldehyde (0.02 mol) was dissolved in 300 mL of propionic acid, followed by the addition of para-substituted benzaldehyde (0.06 mol), and stirred to completely dissolve. After heating to 141° C., freshly distilled pyrrole (0.08 mol) was slowly added dropwise. After the addition was completed within about 20 minutes, the color of the solution gradually changed to brown-black with the addition of pyrrole. The reaction temperature was maintained at 131° C. for 0.5 h, and the reaction was allowed to cool and allowed to stand until a solid was completely precipitated. The solid was collected by filtration, washed with anhydrous ethanol until it turned light purple, and then air-dried to obtain a crude product, which was purified by column chromatography to obtain the target product, Compound A1-A5.

[0014] Step 2. Synthesis of B1-B5: Compounds A1-A6 (0.075 mmol) were dissolved in 5 mL of N,N-dimethylformamide (DMF) and refluxed to dissolve. 1,2-Dibromoethane (1.12 mmol) and calcined anhydrous potassium carbonate (1.12 mmol) were added and stirred at room temperature until the reaction was complete. The reaction product was poured into ice water containing 10% methanol to precipitate a flocculent purple precipitate. The precipitate was filtered and washed with methanol to remove the remaining bromoalkanes and DM to obtain a crude product, which was then purified by column chromatography to obtain compounds B1-B5.

[0015] Step 3. Synthesis of C1-C5: Compounds B1-B6 (0.063 mmol) and imidazole (2.51 mmol) were dissolved in 10 mL of DMF, and potassium carbonate (2.51 mmol) was added. The mixture was stirred at room temperature in the dark until no raw material remained. After filtering out anhydrous potassium carbonate, the DMF was spin-dried to obtain a crude product, which was then purified by column chromatography to obtain compounds C1-C5.

[0016] Step 4, Synthesis of D1-D9: Compound C1-C5 (0.063 mmol) and a metal salt (2.51 mmol) were dissolved in 50 mL of DMF, reacted at 120° C. for 2 h, and then the reaction solution was cooled to room temperature. The metal salt was filtered to remove the DMF, and the mixture was extracted with a mixed solvent of DCM and HO. The DCM phase was collected and dried to obtain a crude product, which was then purified by column chromatography to obtain a graphene-supported metal porphyrin catalyst (D1-D9) wherein R is an alkyl group, an ester group, an alkoxy group, a nitro group, or a halogen group.

[0017] The substituent of the para-substituted benzaldehyde is an alkyl group, an ester group, an alkoxy group or a halogen group.

[0018]

[0019] Another object of the present invention is to provide a method for preparing a metalloporphyrin catalyst wherein R is -NH2, which specifically comprises the following steps:

[0020] Step 1: Add o-hydroxybenzaldehyde (0.02 mol) and p-nitrobenzaldehyde (0.06 mol) to refluxing propionic acid (300 mL). After the aldehyde is completely dissolved, freshly distilled pyrrole (0.08 mol) is slowly added dropwise within 20 minutes and refluxed for 1 hour. After the reaction mixture is cooled, it is left overnight. It is then diluted with distilled water (1 L) and the pH value is adjusted to 6-7 using a 6 mol / L sodium hydroxide solution. It is filtered and washed with hot water five times. The resulting black purple powder mixture is dried in a vacuum oven at 80 ° C overnight to obtain a crude product, which is then purified by column chromatography to obtain the product 2-(10,15,20-tri-p-nitrophenylporphyrin-5-yl)phenol (A).

[0021] Step 2: Compound A (0.075 mmol) was dissolved in 5 mL of N,N-dimethylformamide (DMF) and refluxed to dissolve it. 1,2-Dibromoethane (1.12 mmol) and calcined anhydrous potassium carbonate (1.12 mmol) were added and stirred at room temperature until the reaction was complete. The reaction product was poured into ice water containing 10% methanol to precipitate a flocculent purple precipitate. The precipitate was filtered and washed with methanol to remove the remaining brominated alkane and DM, and then purified by column chromatography to obtain compound 5-(2-(2-bromoethoxy)phenyl)-10,15,20-tri-p-nitrophenylporphyrin (B).

[0022] Step 3. Dissolve compound B (0.063 mmol) and imidazole (2.51 mmol) in 10 mL of DMF, then add potassium carbonate (2.51 mmol), stir at room temperature in the dark until no raw material remains, filter out anhydrous potassium carbonate, spin-dry DMF, and then obtain 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-nitrophenylporphyrin (C) by column chromatography.

[0023] Step 4, synthesis of TAC2IPP: C (0.027 mmol) was then dissolved in concentrated hydrochloric acid (20 mL) at room temperature, and an excess of SnCl2·2H2O (0.44 mmol) was added. The resulting green mixture was rapidly heated to 65-70°C for 30 min, then neutralized with concentrated ammonia in an ice bath and filtered. The filter cake was extracted multiple times with DCM, and the extracted solution was rotary evaporated and purified by column chromatography to obtain 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-aminophenylporphyrin TAC2IPP (D);

[0024] Step 5. Synthesis of MTAC2IPP (E1-E5): Compound TAC2IPP (0.063 mmol) and metal salt (2.51 mmol) were dissolved in an appropriate amount of DMF, reacted at 120°C for 2 h, and then the reaction solution was cooled to room temperature. The metal salt was removed by filtration, and the DMF was dried and extracted with a mixed solvent of DCM and H2O. The DCM phase was collected, dried, and then purified by column chromatography to obtain the catalyst (E1-E5).

[0025] It is further defined that the above-mentioned metal salt is FeCl2·4H2O, NiCl2·6H2O, MnCl2·4H2O, ZnCl2 or CoCl2·6H2O.

[0026]

[0027] Another object of the present invention is to provide a method for preparing a graphene-supported metalloporphyrin catalyst, comprising the following steps: adding 125 mL of DMF solvent to the above-mentioned metalloporphyrin catalyst or the metalloporphyrin catalyst prepared by the above-mentioned method (0.087 mmol), 0.35 g of GO and dicyclohexylcarbodiimide (0.97 mmol), and 1-hydroxy-benzotriazole (2.22 mmol), ultrasonicating for 30 minutes, adding a rotor for stirring, heating to 80° C., reacting for 4 days, filtering, washing with deionized water, dichloromethane and ethanol in sequence, each washing 3-5 times, and drying to obtain a graphene-supported metalloporphyrin catalyst (GO-MTAC2IPP) with a solid loading of 0.10 g / g.

[0028] The reaction process of a graphene-supported metalloporphyrin catalyst is as follows:

[0029]

[0030] Another object of the present invention is to provide a method for preparing 5-bromo-1,3-difluoro-2-nitrobenzene (using a catalyst to catalyze the oxidation of amino groups to nitro groups), wherein 4-bromo-2,6-difluoroaniline is dissolved in a solvent, a metalloporphyrin catalyst or a graphene-supported metalloporphyrin catalyst and an oxidant are added, and the mixture is reacted at a certain temperature for a period of time, followed by extraction, reduced pressure distillation, and chromatographic separation to obtain 5-bromo-1,3-difluoro-2-nitrobenzene.

[0031] It is further defined that the solvent is one of water, dichloromethane, 1,2-dichloromethane, chloroform, dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, 1,4-dioxane, acetonitrile and acetone; and the concentration of 4-bromo-2,6-difluoroaniline is (0.1-10) g / L.

[0032] It is further defined that the amount of metalloporphyrin catalyst is 2.5×10 --7~5×10 -6 Molar equivalent.

[0033] It is further defined that the oxidant is one of hydrogen peroxide, tert-butyl hydroperoxide, m-chloroperbenzoic acid, isopropylbenzene hydroperoxide, di-tert-butyl peroxide and potassium persulfate; the amount of the oxidant is 0.1 to 10 molar equivalents of the substrate 4-bromo-2,6-difluoroaniline.

[0034] It is further defined that the reaction is carried out at -10°C to 120°C for 0.2h to 48h.

[0035] Further defined, the synthesis of the above-mentioned graphene oxide (GO) is achieved by the following steps: adding 400mL of concentrated sulfuric acid to a 2L reaction flask, stirring in an ice-water bath for 5min, then slowly adding 8g of graphite powder and 4g of sodium nitrate, reacting for 30min, then slowly adding 28g of potassium permanganate, and reacting for 45min. After that, the reaction flask is moved from the ice-water bath to a 35°C constant temperature water bath, stirred for 45min, 360mL of deionized water is slowly added, and reacted for 2h, then 800mL of deionized water is added, and then 5% hydrogen peroxide is added dropwise until the solution is free of bubbles, allowed to stand and separate, the supernatant is poured off, the lower layer is washed with 5% HCl solution until the filtrate is free of sulfate ions, and then dried in vacuo at 60°C for 24h to obtain black graphene oxide.

[0036] Beneficial effects obtained by the present invention:

[0037] The present invention prepares an imidazole-modified metalloporphyrin catalyst, which catalyzes the synthesis of 5-bromo-1,3-difluoro-2-nitrobenzene with a yield increased by up to 2.3 times compared with the unmodified metalloporphyrin. After the amino-substituted metalloporphyrin is immobilized, it still retains considerable catalytic activity and has high catalytic efficiency.

[0038] The amount of the metalloporphyrin synthesized by the method of the present invention is only one percent of the amount of the substrate, which is more economical and efficient.

[0039] The novel graphene-immobilized metalloporphyrin catalyst provided by the present invention can still achieve a product yield of more than 85% of that of the first cycle after being recycled for 5 times, has good recyclability, and can further reduce costs.

[0040] In order to further understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the accompanying drawings. However, the accompanying drawings are provided for reference and illustration only and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1This is the liquid phase cation mass spectrum of 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-aminophenylporphyrin. The molecular weight of the compound is 769.91. The liquid phase cation mass spectrum at m / z 770.3207 is (M+H) + Molecular ion peak; m / z 385.6633 is (M / 2+H) + molecular ion peak.

[0042] Figure 2 It is 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-aminophenylporphyrin 1 HNMR spectrum, 600Mz, CDCl3; δ8.91 (d, J=11.9Hz) and δ8.69 (d, J=4.7Hz, 2H) are hydrogen atoms on the pyrrole ring; δ8.11–7.88 (m, 8H) and δ7.75–7.69 (m, 1H), δ7.42–7.34 (m, 1H), δ7.22–7.11 (m, 1H) and δ7.06 (d, 7H) are hydrogen atoms on the benzene ring; δ3.99 (t, 2H) and δ3.30 (t, 2H) are two methylene hydrogen atoms.

[0043] Figure 3 This is the liquid phase negative ion mass spectrum of 5-bromo-1,3-difluoro-2-nitrobenzene. The molecular weight of the compound is 237.99, of which m / z 235.9518 is (MH) - molecular ion peak.

[0044] Figure 4 It is 5-bromo-1,3-difluoro-2-nitrobenzene 1 H NMR spectrum, 600 Mz, MeOD; δ 7.62 (q, J = 1.7 Hz, 1H) and 7.61 (t, J = 1.9 Hz, 1H) indicate two hydrogen atoms on the benzene ring. DETAILED DESCRIPTION

[0045] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art further understand the present invention and are not intended to limit the present invention in any way. It should be noted that those skilled in the art may make various modifications and improvements without departing from the scope of the present invention. These modifications and improvements are all within the scope of protection of the present invention.

[0046] Unless otherwise specified, the materials, reagents, instruments and methods used in the following examples are conventional materials, reagents, instruments and methods in the art and can be obtained through commercial channels or prepared by general methods by those skilled in the art.

[0047] Example 1

[0048] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-tolylporphyrin iron (1.3×10 - 6 mol, 1.10 mg), tert-butyl hydroperoxide (0.75 mmol, 103 uL), after reaction at room temperature for 4 h, methanol was added to dilute the sample to a concentration of 1000 ppm, and liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 68.55%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 44.30%.

[0049] Example 2

[0050] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-methylphenylporphyrin manganese (1.3×10 -6 mol, 1.10 mg), tert-butyl hydroperoxide (0.75 mmol, 103 uL), after reaction at room temperature for 4 h, methanol was added to dilute the sample to a concentration of 1000 ppm, and then liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 99.08%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 45.02%.

[0051] Example 3

[0052] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-tolylporphyrin iron (1.3×10 - 6 mol, 1.10 mg), hydrogen peroxide (0.75 mmol, 76 uL), reacted at room temperature for 4 h, and then diluted with methanol to a sample concentration of 1000 ppm. Liquid phase quantification was performed, and the conversion of 4-bromo-2,6-difluoroaniline was 27.27%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 5.59%.

[0053] Example 4

[0054] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-tolylporphyrin iron (1.3×10 - 6 mol, 1.10 mg), m-chloroperbenzoic acid (0.75 mmol, 0.15 g), and reacted at room temperature for 4 h. Methanol was added to dilute the sample to a concentration of 1000 ppm, and then liquid phase quantification was performed. The conversion of 4-bromo-2,6-difluoroaniline was 100%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 7.47%.

[0055] Example 5

[0056] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-tolylporphyrin iron (1.3×10 - 6 mol, 1.10 mg), cumene hydroperoxide (0.75 mmol, 139 uL), after reacting at room temperature for 4 h, methanol was added to dilute the sample to a concentration of 1000 ppm, and then liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 65.23%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 25.86%.

[0057] Example 6

[0058] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of water, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-tolylporphyrin iron (1.3×10 -6 mol, 1.10 mg, 1.10 mg), tert-butyl hydroperoxide (0.75 mmol, 103 uL), after reaction at room temperature for 4 h, methanol was added to dilute the sample to a concentration of 1000 ppm and then liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 51.13%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 18.68%.

[0059] Example 7

[0060] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dimethylformamide, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-tolylporphyrin iron (1.3×10 -6 mol, 1.10 mg, 1.10 mg), tert-butyl hydroperoxide (0.75 mmol, 103 uL), after reaction at room temperature for 4 h, methanol was added to dilute the sample to a concentration of 1000 ppm and then liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 18.46%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 5.91%.

[0061] Example 8

[0062] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of acetone, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-tolylporphyrin iron (1.3×10 -6 mol, 1.10 mg, 1.10 mg), tert-butyl hydroperoxide (0.75 mmol, 103 uL), after reaction at room temperature for 4 h, methanol was added to dilute the sample to a concentration of 1000 ppm and then liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 88.29%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 41.18%.

[0063] Example 9

[0064] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-tolylporphyrin iron (1.3×10 - 6 mol, 1.10 mg, 1.10 mg), tert-butyl hydroperoxide (1.50 mmol, 206 uL), after reaction at room temperature for 4 h, methanol was added to dilute the sample to a concentration of 1000 ppm and liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 98.57%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 61.28%.

[0065] Example 10

[0066] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-tolylporphyrin iron (1.3×10 - 6 mol, 1.10 mg, 1.10 mg), tert-butyl hydroperoxide (1.50 mmol, 206 uL), reacted at 60°C for 4 h, and then diluted with methanol to a sample concentration of 1000 ppm. After liquid phase quantification, the conversion of 4-bromo-2,6-difluoroaniline was 99.42%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 45.78%.

[0067] Example 11

[0068] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-methoxyphenylporphyrin iron (1.3×10 -6 mol, 1.10 mg, 1.10 mg), tert-butyl hydroperoxide (1.50 mmol, 206 uL), after reaction at room temperature for 4 h, methanol was added to dilute the sample to a concentration of 1000 ppm and then liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 96.88%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 56.22%.

[0069] Example 12

[0070] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tris(p-trifluoromethoxyphenyl)porphyrin iron (1.3×10 -6 mol, 1.10 mg, 1.10 mg), tert-butyl hydroperoxide (1.50 mmol, 206 uL), after reaction at room temperature for 4 h, methanol was added to dilute the sample to a concentration of 1000 ppm and then liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 90.67%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 20.52%.

[0071] Example 13

[0072] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-nitrophenylporphyrin iron (1.3×10 -6 mol, 1.10 mg, 1.10 mg), tert-butyl hydroperoxide (1.50 mmol, 206 uL), after reaction at room temperature for 4 h, methanol was added to dilute the sample to a concentration of 1000 ppm and liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 94.90%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 51.09%.

[0073] Example 14

[0074] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-aminophenylporphyrin iron (1.3×10 -6 mol, 1.10 mg, 1.10 mg), tert-butyl hydroperoxide (1.50 mmol, 206 uL), after reaction at room temperature for 24 h, methanol was added to dilute the sample to a concentration of 1000 ppm and then liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 66.74%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 44.33%.

[0075] Example 15

[0076] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-aminophenylporphyrin iron (1.3×10 -6 mol, 1.10 mg, 2.20 mg), tert-butyl hydroperoxide (1.50 mmol, 206 uL), after reaction at room temperature for 24 h, methanol was added to dilute the sample to a concentration of 1000 ppm, and liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 99.79%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 68.97%.

[0077] Example 16

[0078] 4-Bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane in a 50 mL single-necked bottle, and then GO-FeTAC2IPP (1.3×10 -6mol,,11 mg), tert-butyl hydroperoxide (1.50 mmol, 206 uL), after reaction at room temperature for 24 h, methanol was added to dilute the sample to a concentration of 1000 ppm and then liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 85.53%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 60.95%.

[0079] Example 17

[0080] 4-Bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was added to a 50 mL single-necked bottle and dissolved in 10 mL of dichloromethane. Then GO-FeTAC2IPP (2.5×10 -6 mol,,22 mg), tert-butyl hydroperoxide (1.50 mmol, 206 uL), after reaction at room temperature for 24 h, methanol was added to dilute the sample to a concentration of 1000 ppm and then liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 99.58%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 69.12%.

[0081] Example 18

[0082] 4-Bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane in a 50 mL single-necked bottle, and then GO-MnTAC2IPP (2.5 × 10 -6 mol, 22 mg), tert-butyl hydroperoxide (1.50 mmol, 206 uL), after reaction at room temperature for 24 h, methanol was added to dilute the sample to a concentration of 1000 ppm, and liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 99.06%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 68.60%.

[0083] Comparative Example 1

[0084] In a 50 mL single-necked flask, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was added and dissolved in 10 mL of dichloromethane. Then, tert-butyl hydroperoxide (1.50 mmol, 206 uL) was added. After reacting at room temperature for 4 h, methanol was added to dilute the sample to a concentration of 1000 ppm. After liquid phase quantification, the conversion of 4-bromo-2,6-difluoroaniline was 0.01%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 0.00%.

[0085] Comparative Example 2

[0086] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then iron (III)-tetrakis(4-aminophenyl)porphyrin chloride (1.3 × 10 -6mol, 1.00 mg), tert-butyl hydroperoxide (1.50 mmol, 206 uL), reacted at room temperature for 24 h, and then diluted with methanol to a sample concentration of 1000 ppm. Liquid phase quantification was performed, and the conversion of 4-bromo-2,6-difluoroaniline was 54.48%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 28.10%.

[0087] Comparative Example 3

[0088] In a 50 mL single-necked bottle, 4-bromo-2,6-difluoroaniline (0.25 mmol, 50 mg) was dissolved in 10 mL of dichloromethane, and then iron (III)-tetrakis(4-aminophenyl)porphyrin chloride (2.5 × 10 -6 mol, 2.20 mg), tert-butyl hydroperoxide (1.50 mmol, 206 uL), after reaction at room temperature for 24 h, methanol was added to dilute the sample to a concentration of 1000 ppm, and then liquid phase quantification was performed. The conversion rate of 4-bromo-2,6-difluoroaniline was 83.78%, and the yield of 5-bromo-1,3-difluoro-2-nitrobenzene was 43.59%.

[0089] The above describes the specific embodiments of the present invention. It should be noted that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A metalloporphyrin catalyst, characterized in that The general formula of the metalloporphyrin catalyst is as follows: In the general formula, R is an alkyl group, an ester group, an alkoxy group, a nitro group, -NH2 or a halogen; and M is Fe, Ni, Mn, Zn or Co.

2. The method for preparing a metalloporphyrin catalyst wherein R is an alkyl group, an ester group, an alkoxy group, a nitro group or a halogen group as claimed in claim 1, wherein: The following steps are involved: Step 1: o-Hydroxybenzaldehyde (0.02 mol) was dissolved in 300 mL of propionic acid, followed by the addition of para-substituted benzaldehyde (0.06 mol), stirred to completely dissolve, heated to 141 ° C, and then slowly added with freshly distilled pyrrole (0.08 mol). After the addition was complete, the reaction temperature was maintained at 131 ° C. The reaction was continued for 0.5 h, cooled, and allowed to stand until the solid was completely precipitated. The solid was collected by filtration, washed with anhydrous ethanol until the solid was light purple, air-dried, and purified by column chromatography to obtain compound A; Step 2: Dissolve compound A (0.075 mmol) in 5 mL of N,N-dimethylformamide (DMF) and reflux to dissolve it. Add 1,2-dibromoethane (1.12 mmol) and calcined anhydrous potassium carbonate (1.12 mmol) and stir at room temperature until the reaction is complete. Pour the reaction product into ice water containing 10% methanol to precipitate a flocculent purple precipitate. Filter it, wash it with methanol to remove the remaining bromoalkane and DM, and then perform column chromatography to obtain compound B. Step 3: Dissolve compound B (0.063 mmol) and imidazole (2.51 mmol) in 10 mL of DMF, then add potassium carbonate (2.51 mmol), stir at room temperature in the dark until no raw material remains, filter out anhydrous potassium carbonate, spin-dry DMF, and then obtain compound C by column chromatography. Step 4: Compound C (0.063 mmol) and a metal salt (2.51 mmol) were dissolved in 50 mL of DMF, reacted at 120° C. for 2 h, and then the reaction solution was cooled to room temperature. The metal salt was removed by filtration, and the DMF was dried and extracted with a mixed solvent of DCM and HO. The DCM phase was collected, dried, and purified by column chromatography to obtain a metalloporphyrin catalyst wherein R is an alkyl group, an ester group, an alkoxy group, a nitro group, or a halogen group. The substituent of the para-substituted benzaldehyde is an alkyl group, an ester group, an alkoxy group, a nitro group or a halogen.

3. The method for preparing a metalloporphyrin catalyst wherein R is -NH2 as claimed in claim 1, wherein The following steps are involved: 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-nitrophenylporphyrin was prepared according to steps 1 to 3 of claim 2, 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-nitrophenylporphyrin (0.027 mmol) was dissolved in concentrated hydrochloric acid (20 mL) at room temperature, an excess of SnCl2·2H2O (0.44 mmol) was added, and the resulting green mixture was rapidly heated to 65-70°C for 30 min, then neutralized with concentrated ammonia in an ice bath and filtered, the filter cake was extracted multiple times with DCM, the extracted solution was rotary evaporated and then subjected to column chromatography to obtain 5-(2-(2-(1H-imidazol-1-yl)ethoxy)phenyl)-10,15,20-tri-p-aminophenylporphyrin TAC2IPP; Then, the compound TAC2IPP (0.063 mmol) and the metal salt (2.51 mmol) were dissolved in an appropriate amount of DMF, reacted at 120°C for 2 h, and then the reaction solution was cooled to room temperature. The metal salt was filtered to remove the DMF, and the DMF was dried. The mixture was extracted with a mixed solvent of DCM and H2O, and the DCM phase was collected, dried, and then subjected to column chromatography to obtain the catalyst.

4. The method according to claim 2 or 3, characterized in that The metal salt is FeCl2·4H2O, NiCl2·6H2O, MnCl2·4H2O, ZnCl2 or CoCl2·6H2O.

5. A method for preparing a graphene-supported metalloporphyrin catalyst, characterized in that: The method comprises the following steps: adding 125 mL of DMF solvent to the metalloporphyrin catalyst according to claim 1 or the amino-substituted metalloporphyrin catalyst prepared by the method according to claim 3 (0.087 mmol), 0.35 g of GO and dicyclohexylcarbodiimide (0.97 mmol), and 1-hydroxy-benzotriazole (2.22 mmol), performing ultrasonic treatment for 30 minutes, adding a rotor for stirring, heating to 80° C., reacting for 4 days, filtering, washing with deionized water, dichloromethane, and ethanol in sequence, washing each for 3-5 times, and drying to obtain a graphene-supported metalloporphyrin catalyst GO-MTAC2IPP with a solid loading amount of 0.10 g / g.

6. A method for preparing 5-bromo-1,3-difluoro-2-nitrobenzene, characterized in that: 4-Bromo-2,6-difluoroaniline is dissolved in a solvent, a metalloporphyrin catalyst or a graphene-supported metalloporphyrin catalyst and an oxidant are added, and the mixture is reacted at a certain temperature for a period of time. 5-Bromo-1,3-difluoro-2-nitrobenzene is obtained through extraction, reduced pressure distillation, and chromatographic separation.

7. The method according to claim 6, characterized in that The solvent is one of water, dichloromethane, 1,2-dichloromethane, chloroform, dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, 1,4-dioxane, acetonitrile and acetone; and the concentration of 4-bromo-2,6-difluorobenzene is (0.1-10) g / L.

8. The method according to claim 6, characterized in that The amount of metalloporphyrin catalyst was 2.5×10 of the substrate 4-bromo-2,6-difluoroaniline. -7 ~5×10 -6 Molar equivalent.

9. The method according to claim 6, characterized in that The oxidant is one of hydrogen peroxide, tert-butyl hydroperoxide, m-chloroperbenzoic acid, isopropylbenzene hydroperoxide, di-tert-butyl peroxide and potassium persulfate; the amount of the oxidant is 0.1 to 10 molar equivalents of the substrate 4-bromo-2,6-difluoroaniline.

10. The method according to claim 6, characterized in that React at -10℃~120℃ for 0.2h-48h.

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