Preparation process of 1, 4-bis (4-fluorobenzoyl) benzene

Abstract

The invention provides a preparation process of 1, 4-bis (4-fluorobenzoyl) benzene, which is obtained by Friedel-Crafts acylation of fluorobenzene and terephthaloyl chloride under the catalysis of an iron-based covalent organic framework derivative material, after the reaction is finished, filtering to obtain a solid, namely the iron-based covalent organic framework derivative material, and recycling and drying for cyclic utilization; washing the obtained solution with a sodium hydroxide aqueous solution, standing, collecting the upper organic layer as fluorobenzene and 1, 4-bis (4-fluorobenzoyl) benzene, evaporating and condensing the organic layer to recover fluorobenzene, and drying the obtained white solid to obtain 1, 4-bis (4-fluorobenzoyl) benzene; the iron-based covalent organic framework derivative material is obtained by coordinating an iron group and a diimine structure in a covalent organic framework and then carbonizing, and the iron group is uniformly dispersed and wrapped in the framework, so that the iron-based covalent organic framework derivative material has the advantages of high catalytic activity, high cycling stability and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of compound synthesis, and specifically relates to a preparation process of 1,4-bis(4-fluorobenzoyl)benzene. Background Art

[0002] 1,4-bis(4-fluorobenzoyl)benzene, as a monomer required for poly(aryletherketone), plays an important role in the synthesis field. At present, the method for synthesizing 1,4-bis(4-fluorobenzoyl)benzene is mainly to obtain it by Friedel-Crafts-acylation of fluorobenzene and terephthaloyl chloride.

[0003] Aluminum chloride is the most commonly used catalyst for Friedel-Crafts acylation. When synthesizing 1,4-bis(4-fluorobenzoyl)benzene, aluminum chloride will coordinate with the carbonyl group. It is more used as a catalyst for acylation than alkylation, resulting in the need for a large amount of aluminum chloride to synthesize 1,4-bis(4-fluorobenzoyl)benzene. However, it has the following disadvantages: it is highly corrosive and can easily damage the reactor and other equipment, thus affecting the service life of the equipment; using AlCl 3 A large amount of wastewater will be generated during the production of the catalyst. If it cannot be treated in time, it will seriously pollute the environment. It is difficult to recycle after the reaction and needs to be post-treated, otherwise a large amount of corrosive waste will be generated. 1,4-bis(4-fluorobenzoyl)benzene can also be obtained by reacting iodobenzene and 1,4-phenylenediboronic acid in a carbon monoxide atmosphere. The reaction yield is high and the environmental pollution is small. Only a small amount of palladium catalyst is needed. However, palladium catalysts are expensive and easily deactivated, and the reuse rate is low. In order to meet the needs of green chemistry, people have been committed to designing environmentally friendly heterogeneous Friedel-Crafts-acylation catalysts in recent years, including various proton zeolites, supported heteropoly acids and other solid acid catalysts. Patent (CN109772406A) reports a method for preparing nitrogen-doped graphite carbon-coated iron carbide catalyst by high-temperature pyrolysis using a class of iron-based metal organic framework materials modified with nitrogen-containing ligands as precursors. The obtained catalyst can efficiently catalyze the Friedel-Crafts acylation reaction of various types of aromatic compounds and acyl chlorides under relatively mild reaction conditions, and the catalyst after the reaction can be recycled and reused many times after simple filtration, and the performance is significantly better than other types of solid acid catalysts. However, the iron-based metal is not evenly dispersed in the metal organic framework, and the loading capacity for iron is low, and some iron nanoparticles are easily deactivated, resulting in low catalytic activity and reaction yield. Patent (CN111604075) reports a nitrogen-free carbon-loaded iron carbide catalyst, which has no group that can coordinate with iron in its precursor structure, and the carbon layer is not uniformly wrapped around iron, so the catalytic activity is low and the catalyst addition amount is high. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an iron-based covalent organic framework derivative material for catalyzing the Friedel-Crafts-acylation reaction of fluorobenzene and terephthaloyl chloride to obtain 1,4-bis(4-fluorobenzoyl)benzene. The iron-based covalent organic framework derivative material is obtained by carbonizing the iron group after coordination with the diimine structure in the covalent organic framework. Since the iron group is dispersed and wrapped uniformly in the framework, it has the advantages of high catalytic activity and high cyclic stability.

[0005] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0006] The invention provides a preparation process of 1,4-bis(4-fluorobenzoyl)benzene. 1,4-bis(4-fluorobenzoyl)benzene is obtained by Friedel-Crafts-acylation of fluorobenzene and terephthaloyl chloride under the catalysis of an iron-based covalent organic framework derivative material; after the reaction is completed, the solid is filtered, and the solid is the iron-based covalent organic framework derivative material, which is recycled after being recovered and dried; the solution is washed with an alkaline aqueous solution and then allowed to stand, and the upper organic layer is collected to be fluorobenzene and 1,4-bis(4-fluorobenzoyl)benzene, and the organic layer is evaporated and condensed to recover fluorobenzene, and the white solid is dried to obtain 1,4-bis(4-fluorobenzoyl)benzene; the preparation method of the iron-based covalent organic framework derivative material is as follows:

[0007] S1. In a nitrogen atmosphere, 1 eq of benzene triformaldehyde compound and 1.45-1.55 eq of ethylenediamine are dispersed in a mixed solution of 1,4-dioxane, ethanol and acetic acid in a reaction kettle, reacted at a temperature of 110-120°C for 2-3 days, and the solid is separated. After washing with acetone and tetrahydrofuran in turn, it is dispersed in a methanol solution and 0.6-0.8 eq of an iron-based compound is added. The solid is stirred at room temperature for 46-50 hours, and the solid is separated. It is extracted with methanol Soxhlet for 22-24 hours, washed with water, and vacuum dried at 70-80°C for 4-24 hours to obtain an iron-based covalent organic framework;

[0008] S2. The iron-based covalent organic framework obtained in S1 is subjected to pyrolysis and carbonization treatment at a temperature of 400 to 800° C. under an inert atmosphere to obtain an iron-based covalent organic framework derivative material.

[0009] Preferably, the molar ratio of fluorobenzene to terephthaloyl chloride is (5-10):1; the mass molar ratio of the iron-based covalent organic framework derivative material to terephthaloyl chloride is 2-3 g / mol;

[0010] Preferably, the alkaline aqueous solution is one or more of a sodium hydroxide aqueous solution, a saturated sodium carbonate aqueous solution and a saturated sodium bicarbonate aqueous solution; the concentration of the sodium hydroxide aqueous solution is 1 to 2 mol / L.

[0011] More preferably, the alkaline aqueous solution is a sodium hydroxide aqueous solution with a concentration of 1 to 2 mol / L.

[0012] Preferably, the reaction conditions of the Friedel-Crafts acylation are: adding fluorobenzene, terephthaloyl chloride and an iron-based covalent organic framework derivative material at 0-10°C in a nitrogen-protected anhydrous environment, stirring for 20-30 minutes, and then heating to 85-100°C for reflux reaction for 5-6 hours; the drying conditions of the iron-based covalent organic framework derivative material and 1,4-bis(4-fluorobenzoyl)benzene are vacuum drying at 70-80°C for 60-90 minutes; and the fluorobenzene is recovered by a rotary evaporator.

[0013] Preferably, the benzene triformaldehyde compound is at least one of trimesicaldehyde, tris(4-formylphenyl)amine, tris(3-formylphenyl)amine, 1,3,5-tris(4-formylphenyl)benzene, 1,3,5-tris(3-formylphenyl)benzene, 2,4,6-tris(4-formylphenyl)-1,3,5-triazine, 2,4,6-tris(3-formylphenyl)-1,3,5-triazine and 4,4',4"-[benzene-1,3,5-triyltris(acetylene-2,1-diyl)]tribenzaldehyde; the iron-based compound is ferrous chloride; the volume ratio of 1,4-dioxane, ethanol and acetic acid is 4:1:1; the concentration of acetic acid is 3-4 mol / L; the heating rate of the pyrolysis carbonization is 5-10°C / min, and the carbonization time is 3-5h.

[0014] More preferably, the benzene tricarboxaldehyde compound is 2,4,6-tris(3-formylphenyl)-1,3,5-triazine.

[0015] Specifically, the preparation method of the 2,4,6-tris(3-formylphenyl)-1,3,5-triazine is as follows:

[0016] 1) In a nitrogen atmosphere, at a temperature of 0 to 5°C, add 1 eq of m-bromobenzonitrile into a three-necked flask, add 2 to 3 eq of trifluoromethanesulfonic acid dropwise through a constant pressure funnel, stir for 25 to 35 min, warm to room temperature and continue stirring for 12 to 16 h, then add sodium hydroxide aqueous solution for neutralization, extract with a mixed solvent of chloroform and acetone, collect the organic phase, dry with anhydrous magnesium sulfate, and remove the solvent to obtain 2,4,6-tris(3-bromophenyl)-1,3,5-triazine;

[0017] 2) 1 eq of 2,4,6-tris(3-bromophenyl)-1,3,5-triazine obtained in step 1) was dissolved in anhydrous tetrahydrofuran solvent and placed in a two-necked flask. Under an argon atmosphere, at a temperature of -78°C, 5 eq of 1.6 M n-butyl lithium was slowly added dropwise using a syringe. After 25 to 35 minutes, 8 to 10 eq of anhydrous N,N-dimethylamide was added. After warming to room temperature, 0.1 mol / L aqueous hydrochloric acid solution was added until the solution was clear. Tetrahydrofuran was removed by rotary evaporation, and the precipitate was filtered out. It was recrystallized from acetone and dried in vacuo to obtain 2,4,6-tris(3-formylphenyl)-1,3,5-triazine.

[0018] The benzene triformaldehyde compounds used in the present invention can be sourced from commercial products or can be homemade, and the raw materials and preparation methods thereof are conventional techniques.

[0019] Beneficial Effects

[0020] Compared with the prior art, the present invention has the following beneficial effects: providing an iron-based covalent organic framework derivative material for catalyzing the Friedel-Crafts-acylation reaction of fluorobenzene and terephthaloyl chloride to obtain 1,4-bis(4-fluorobenzoyl)benzene, the preparation process is simple to operate, the target product yield is high, the catalyst used is highly efficient and the environmental pollution is small, and the catalyst used can be simply dried and recycled. Among them: the outer carbon layer of the iron-based covalent organic framework derivative material provides protection for the Fe nanoparticles in the shell, effectively avoiding the loss of the Fe nanoparticles, so that the catalyst exhibits high structural stability and recyclability; by pre-synthesizing the covalent organic framework, the Fe 2+ Complexation with bidentate ligand structure effectively increases Fe 2+ The dispersion and stability of the carbon coating layer are uniform in thickness, which avoids the problem that the thick carbon layer in some parts will cause the internal Fe 3+ The charge is difficult to transfer to the outside of the carbon layer to catalyze the acylation, or the thin carbon layer causes the loss of Fe nanoparticles, resulting in a decrease in catalyst activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The preparation route and structural schematic diagram of the iron-based covalent organic framework 1 of the present invention;

[0022] Figure 2 The preparation route of 2,4,6-tris(3-formylphenyl)-1,3,5-triazine of the present invention;

[0023] Figure 3 The infrared spectra of the covalent organic framework of the present invention and after coordination with ferrous chloride of different masses;

[0024] Figure 4 The X-ray powder diffraction patterns of the iron-based covalent organic framework derivative materials obtained by carbonization at different temperatures of the present invention are shown.

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0027] In the examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0028] The raw materials and equipment used in the embodiments and comparative examples are described as follows:

[0029] Fluorobenzene: Liaoning Xingfu New Materials;

[0030] Ethylenediamine: purchased from Nanjing Reagent;

[0031] p-Phenylenediamine: product number P816015, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0032] Terephthaloyl chloride: Liaoning Xingfu New Materials;

[0033] Ferrous chloride: product number 5222, purchased from Shandong West Asia Chemical Co., Ltd.;

[0034] m-Bromobenzonitrile: product number 535976, purchased from Beijing Bailingwei Technology Co., Ltd.;

[0035] Trifluoromethanesulfonic acid: product number T818884, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0036] n-Butyl lithium: product number B803316, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0037] 2,4,6-tris(3-formylphenyl)-1,3,5-triazine (commercially available or homemade, the present invention is homemade):

[0038] 1) In a nitrogen atmosphere, at a temperature of 0 to 5°C, 1 eq of m-bromobenzonitrile was added to a three-necked flask, and 3 eq of trifluoromethanesulfonic acid was added dropwise through a constant pressure funnel, and stirred for 30 min. After warming to room temperature and continuing stirring for 13 h, an aqueous sodium hydroxide solution (1 mol / L) was added for neutralization, and extracted with a mixed solvent of chloroform and acetone (volume ratio of 1:1), the organic phase was collected, dried over anhydrous magnesium sulfate, and the solvent was removed to obtain 2,4,6-tris(3-bromophenyl)-1,3,5-triazine;

[0039] 2) 1 eq of 2,4,6-tris(3-bromophenyl)-1,3,5-triazine obtained in step 1) was dissolved in anhydrous tetrahydrofuran solvent and placed in a two-necked flask. Under an argon atmosphere, at a temperature of -78°C, 5 eq of 1.6 M n-butyl lithium was slowly added dropwise with a syringe. After 30 min, 10 eq of anhydrous N,N-dimethylamide was added. After warming to room temperature, 0.1 mol / L aqueous hydrochloric acid solution was added until the solution was clear. Tetrahydrofuran was removed by rotary evaporation, and the precipitate was filtered out. It was recrystallized from acetone and dried in vacuo to obtain 2,4,6-tris(3-formylphenyl)-1,3,5-triazine.

[0040] Iron-based covalent organic framework derived materials 1:

[0041] S1. Under nitrogen atmosphere, 1 eq of 2,4,6-tris(3-formylphenyl)-1,3,5-triazine and 1.5 eq of ethylenediamine were dispersed in a mixed solution of 1,4-dioxane, ethanol and 3-4 mol / L acetic acid in a reaction kettle (volume ratio of 4:1:1), reacted at 120°C for 3 days, separated the solid, washed with acetone and tetrahydrofuran in turn, dispersed in a methanol solution, added with 0.6 eq of ferrous chloride, stirred at room temperature for 50 hours, separated the solid, extracted with methanol Soxhlet for 24 hours, washed with water, and dried in vacuum at 70°C for 12 hours to obtain the iron-based covalent organic framework 1;

[0042] S2. The iron-based covalent organic framework 1 obtained in S1 is pyrolyzed and carbonized at 400°C for 4 hours under an inert atmosphere to obtain an iron-based covalent organic framework derivative material 1.

[0043] Iron-based covalent organic framework derived materials 2:

[0044] Compared with the preparation method of the iron-based covalent organic framework derivative material 1, the difference is that 0.6 eq of ferrous chloride is replaced by 0.7 eq of ferrous chloride.

[0045] Iron-based covalent organic framework derived materials 3:

[0046] Compared with the preparation method of the iron-based covalent organic framework derivative material 1, the difference is that 0.6 eq of ferrous chloride is replaced by 0.8 eq of ferrous chloride.

[0047] Iron-based covalent organic framework derived materials 4:

[0048] Compared with the preparation method of the iron-based covalent organic framework derivative material 1, the difference is that the pyrolysis carbonization at a temperature of 400°C for 4 hours is replaced by the pyrolysis carbonization at a temperature of 600°C for 4 hours.

[0049] Iron-based covalent organic framework-derived materials 5:

[0050] Compared with the preparation method of the iron-based covalent organic framework derivative material 1, the difference is that the pyrolysis carbonization at a temperature of 400°C for 4 hours is replaced by the pyrolysis carbonization at a temperature of 800°C for 4 hours.

[0051] Iron-based covalent organic framework-derived materials 6:

[0052] Compared with the preparation method of the iron-based covalent organic framework derivative material 1, the difference is that the carbonization treatment in step S2 is not performed.

[0053] Iron-based covalent organic framework-derived materials 7:

[0054] Compared with the preparation method of the iron-based covalent organic framework derivative material 1, the difference is that 1.5 eq of ethylenediamine is replaced by 1.5 eq of p-phenylenediamine.

[0055] Iron-based covalent organic framework-derived materials 8:

[0056] Compared with the preparation method of the iron-based covalent organic framework derivative material 1, the difference is that no iron-based compound is added in step S1.

[0057] Iron-based covalent organic framework-derived materials 9:

[0058] Compared with the preparation method of the iron-based covalent organic framework derivative material 1, the difference is that 0.6 eq of ferrous chloride is replaced by 1.0 eq of ferrous chloride.

[0059] The following is the test method of the performance parameters involved in the present invention:

[0060] X-ray powder diffraction (XRD): Empyrean X-ray diffractometer was used to analyze the catalytic material. The specific test conditions were: using a Cu Kα ray source The output power is 4kW, the operating voltage is 40kV, and the working tube current is 60mA;

[0061] Fourier transform infrared spectroscopy (FT-IR): The catalytic material was analyzed by FT-IR using a Thermo Nicolet IS10 Fourier transform infrared spectrometer. The specific process is as follows: First, a certain mass of sample and potassium bromide were weighed and mechanically ground in a mortar. A small amount of white powder was taken out and placed in a tablet pressing mold. The sample was pressed into a thin sheet at 15 MPa and then heated at 500 to 4000 cm -1 Conduct infrared testing on samples within the test range;

[0062] Reaction conversion rate: The reaction liquid components were analyzed by gas chromatography and the conversion rate of benzoyl chloride was calculated.

[0063] Depend on Figure 3 It can be seen that with the increase of ferrous chloride content, 1630cm -1 The stretching vibration of the imine bond -C=N- gradually decreases, while the 1600cm -1 A new broad peak appeared, indicating that the imine bond and Fe 2+ A coordination bond is formed.

[0064] Depend on Figure 4 It can be obtained that the iron-based covalent organic framework derived material obtained by carbonization at 400 °C mainly contains Fe 2 O 3 The iron-based covalent organic framework derived materials obtained by carbonization at 600-800℃ mainly include Fe 3 C; Fe obtained by carbonization at 600℃ 3 The C nanoparticles are slightly agglomerated, so the catalytic activity is low; when carbonized at 800℃, they have a higher degree of graphitization and more effectively encapsulate Fe 3 C nanoparticles.

[0065] Preparation process of 1,4-bis(4-fluorobenzoyl)benzene

[0066] Example 1

[0067] Under nitrogen protection, 8 mol of fluorobenzene, 1 mol of terephthaloyl chloride and 2 g of iron-based covalent organic framework derivative material 1 are added to a reactor at a temperature of 0 to 5°C, stirred for 30 minutes, and then heated to 95°C for reflux reaction for 6 hours; after the reaction, the solid is filtered to recover the iron-based covalent organic framework derivative material, which is vacuum dried at 80°C for 60 minutes for recycling, and the obtained organic layer is washed with sodium hydroxide aqueous solution and then allowed to stand, and the upper organic layer is collected to be fluorobenzene and 1,4-bis(4-fluorobenzoyl)benzene. The organic layer is evaporated and condensed to recover fluorobenzene, and the obtained white solid is vacuum dried at 80°C for 90 minutes to obtain 1,4-bis(4-fluorobenzoyl)benzene.

[0068] Example 2

[0069] Compared with the preparation process of Example 1, the difference is that the iron-based covalent organic framework derivative material 1 is replaced by the iron-based covalent organic framework derivative material 2.

[0070] Example 3

[0071] Compared with the preparation process of Example 1, the difference is that the iron-based covalent organic framework derivative material 1 is replaced by the iron-based covalent organic framework derivative material 3.

[0072] Example 4

[0073] Compared with the preparation process of Example 1, the difference is that the iron-based covalent organic framework derivative material 1 is replaced by the iron-based covalent organic framework derivative material 4.

[0074] Example 5

[0075] Compared with the preparation process of Example 1, the difference is that the iron-based covalent organic framework derivative material 1 is replaced by the iron-based covalent organic framework derivative material 5.

[0076] Comparative Example 1

[0077] Compared with the preparation process of Example 1, the difference is that the iron-based covalent organic framework derivative material 1 is replaced by the iron-based covalent organic framework derivative material 6.

[0078] Comparative Example 2

[0079] Compared with the preparation process of Example 1, the difference is that the iron-based covalent organic framework derivative material 1 is replaced by the iron-based covalent organic framework derivative material 7.

[0080] Comparative Example 3

[0081] Compared with the preparation process of Example 1, the difference is that the iron-based covalent organic framework derivative material 1 is replaced by the iron-based covalent organic framework derivative material 8.

[0082] Comparative Example 4

[0083] Compared with the preparation process of Example 1, the difference is that the iron-based covalent organic framework derivative material 1 is replaced by the iron-based covalent organic framework derivative material 9.

[0084] Table 1 Reaction conversion rate

[0085]

[0086] As can be seen from the data in Table 1, the conversion rates of benzoyl chloride in Examples 1 to 5 are all above 94%, and the conversion rates in Examples 2 to 3 are all above 99%.

[0087] From the data of Examples 1 to 3 in Table 1, it can be seen that with the increase of the iron content in the iron-based covalent organic framework derivative material, the conversion first increases and then tends to be stable, and with the increase of the number of repeated uses, the conversion rate of Example 1 decreases slightly; with the increase of the number of repeated uses, the conversion rates of Examples 2 to 3 change slightly, and all remain above 99%. From the data of Examples 1, 4, and 5, it can be seen that the catalytic effect obtained by carbonization at 400°C and 800°C is better, and 400°C is mainly Fe 2 O 3 Nanoparticle catalysis, 800℃ mainly Fe 3 C 3 Nanoparticle catalysis; at 600℃, due to the low degree of graphitization, some Fe 3 The agglomeration of C nanoparticles caused a slight decrease in conversion rate. From the data of Comparative Example 1, it can be seen that the catalytic effect of the iron-based covalent organic framework derivative material 6 obtained without carbonization is poor, and the cycle stability is poor. From the data of Comparative Example 2, it can be seen that the iron-based covalent organic framework derivative material 7 obtained by replacing ethylenediamine with p-phenylenediamine has no bidentate ligand structure and Fe 2+ Complexation is carried out, so the dispersibility is poor, resulting in a low conversion rate of the reaction; from Comparative Example 3, it can be seen that without the addition of ferrous chloride, the iron-based covalent organic framework derivative material 8 has no catalytic activity; from Comparative Example 4, it can be seen that excessive addition of ferrous chloride will cause the obtained iron nanoparticles to agglomerate, thereby resulting in a decrease in the conversion rate.

[0088] The applicant declares that the preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all details in detail, nor do they limit the invention to only the specific embodiments described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and use the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A process for preparing 1,4-bis(4-fluorobenzoyl)benzene, characterized in that: The 1,4-bis(4-fluorobenzoyl)benzene is obtained by Friedel-Crafts-acylation of fluorobenzene and terephthaloyl chloride under the catalysis of an iron-based covalent organic framework derivative material; after the reaction is completed, the solid is filtered, and the obtained solid is an iron-based covalent organic framework derivative material; the obtained solution is washed with an alkaline aqueous solution and then allowed to stand, and the upper organic layer is collected to be fluorobenzene and 1,4-bis(4-fluorobenzoyl)benzene, and the organic layer is evaporated and condensed to recover fluorobenzene, and the obtained white solid is dried to obtain 1,4-bis(4-fluorobenzoyl)benzene; the preparation method of the iron-based covalent organic framework derivative material is as follows: S1. In a nitrogen atmosphere, 1 eq of benzene triformaldehyde compound and 1.45-1.55 eq of ethylenediamine are dispersed in a mixed solution of 1,4-dioxane, ethanol and acetic acid in a reaction kettle, and reacted at a temperature of 110-120°C for 2-3 days. The solid is separated, washed with acetone and tetrahydrofuran in turn, dispersed in a methanol solution, and 0.6-0.8 eq of an iron-based compound is added. The solid is stirred at room temperature for 46-50 hours, and the solid is separated. The solid is extracted with methanol Soxhlet, washed with water, and vacuum dried to obtain an iron-based covalent organic framework; S2. The iron-based covalent organic framework obtained in S1 is subjected to pyrolysis and carbonization treatment at a temperature of 400 to 800° C. under an inert atmosphere to obtain an iron-based covalent organic framework derivative material.

2. The process for preparing 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The molar ratio of fluorobenzene to terephthaloyl chloride is (5-10):1; the mass molar ratio of the iron-based covalent organic framework derivative material to terephthaloyl chloride is 2-3 g / mol.

3. The process for preparing 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The alkaline aqueous solution is one or more of a sodium hydroxide aqueous solution, a saturated sodium carbonate aqueous solution and a saturated sodium bicarbonate aqueous solution; the concentration of the sodium hydroxide aqueous solution is 1-2 mol / L.

4. The process for preparing 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The reaction conditions of the Friedel-Crafts acylation are nitrogen protection, in an anhydrous environment, adding fluorobenzene, terephthaloyl chloride and an iron-based covalent organic framework derivative material at 0-10° C. and stirring for 20-30 minutes, then heating to 85-100° C. and reflux reaction for 5-6 hours; the drying conditions of the iron-based covalent organic framework derivative material and 1,4-bis(4-fluorobenzoyl)benzene are vacuum drying at 70-80° C. for 60-90 minutes; the fluorobenzene is recovered by a rotary evaporator.

5. The process for preparing 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The benzene triformaldehyde compound in step S1 is at least one of trimesic acid, tris(4-formylphenyl)amine, tris(3-formylphenyl)amine, 1,3,5-tris(4-formylphenyl)benzene, 1,3,5-tris(3-formylphenyl)benzene, 2,4,6-tris(4-formylphenyl)-1,3,5-triazine, 2,4,6-tris(3-formylphenyl)-1,3,5-triazine and 4,4',4"-[benzene-1,3,5-triyltris(acetylene-2,1-diyl)]tribenzaldehyde; and the iron-based compound is ferrous chloride.

6. The process for preparing 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that: In step S1, the volume ratio of 1,4-dioxane, ethanol and acetic acid is 4:1:1; the concentration of acetic acid is 3-4 mol / L.

7. The process for preparing 1,4-bis(4-fluorobenzoyl)benzene according to claim 1, characterized in that: The heating rate of the pyrolysis carbonization in step S2 is 5-10°C / min, and the carbonization time is 3-5h.

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