A method for preparing perfluorohexanone by isomerization

Abstract

The present invention provides a method for preparing perfluorohexanone by isomerization, which belongs to the technical field of fluorine chemical industry. Specifically, the oligomerization reaction of hexafluoropropylene is carried out in a non-protonic polar solvent, using metal fluoride as a catalyst and a co-catalyst, and the reaction is carried out for several hours to obtain D1; the dimer D1 is used as a raw material, and the reaction is stirred for several hours in a non-protonic polar solvent and KF to obtain D2; D2 undergoes an epoxidation reaction under the oxidation of sodium hypochlorite (NaClO), and a high-yield epoxidation product D3 is obtained in a relatively short time; in an acetonitrile solvent, D3 undergoes an isomerization reaction, and a high-yield perfluorohexanone is obtained in a relatively short time. The perfluorohexanone prepared by this method has a high raw material conversion rate and a high selectivity of the reaction product, and the process is simple, which reduces pollution to the environment.

Description

Technical Field

[0001] The present invention relates to the technical field of fluorine chemical industry, and in particular to a method for preparing perfluorohexanone. Background Art

[0002] Perfluorohexanone, also known as hexafluorohexanone, is an organic compound with the chemical formula C6F120. Perfluorohexanone is an important halon fire extinguishing agent alternative. It is a fluorinated ketone compound. It is a clear, colorless, and odorless liquid that is superpressurized with nitrogen and stored in high-pressure cylinders as part of fire suppression systems. Its chemical structure is identical to 3M's NOVEC 1230 firefighting fluid. Perfluorohexanone possesses many excellent properties, such as extremely low surface tension, a very high dielectric constant, and high chemical stability. Therefore, it is widely used in electronics, semiconductors, coatings, plastics, and pharmaceuticals. In the electronics field, perfluorohexanone is used as a cleaning agent, solvent, and raw material for photoresist manufacturing. In the semiconductor field, it is used as a raw material for photoresist, etchants, and cleaning agents. In the coatings and plastics fields, perfluorohexanone is used as a raw material for plasticizers, lubricants, and water repellents. In the pharmaceutical field, it is used as a raw material for pharmaceuticals. Perfluorohexanone can be prepared by various methods, the most common of which is through fluorination. First, hexanone is reacted with hydrogen fluoride to generate fluorohexanone, which is then converted into perfluorohexanone through a fluorination reaction.

[0003] CN116947613A relates to an environmentally friendly and efficient method for synthesizing perfluorohexanone. The invention utilizes supercritical carbon dioxide preparation technology and a specific hypohalite as a reaction aid to design a reaction route for preparing perfluorohexanone using hexafluoropropylene as a raw material.

[0004] CN116854575A provides a production process for perfluorohexanone, which uses hexafluoropropylene and hexafluoropropylene oxide as raw materials, uses alkali metal fluoride with fluoride as carrier as catalyst, and uses perfluoro solvent as reaction solvent to construct a perfluoro environment reaction system.

[0005] CN116514642A discloses a method for preparing perfluorohexanone, comprising the following steps: 1) subjecting perfluoro-4-methyl-2-pentene to an in-situ rearrangement and epoxidation reaction to obtain perfluoro-2-methyl-2,3-epoxypentane; and 2) subjecting the perfluoro-2-methyl-2,3-epoxypentane to an isomerization reaction to produce perfluorohexanone. The technical solution provided by the present invention utilizes a rational selection of solvent, catalyst, co-catalyst, oxide, organic base, and their contents to produce perfluorohexanone through in-situ rearrangement, epoxidation, and catalytic isomerization of perfluoro-4-methyl-2-pentene.

[0006] CN112374977A discloses a method for preparing perfluorohexanone, comprising the following steps: (1) uniformly mixing a polar aprotic solvent, a catalyst and a reaction aid, adding the mixture to a high-throughput continuous flow reactor, introducing hexafluoropropylene and hexafluoropropylene oxide into the high-throughput continuous flow reactor, controlling the reactor temperature at 20°C to 40°C for reaction, and after the reaction is completed, allowing the mixture to stand for stratification and collecting the lower layer liquid; (2) rectifying the lower layer liquid collected in step (1), collecting the fractions, and obtaining perfluorohexanone.

[0007] CN112299973A discloses a method for preparing perfluorohexanone using hexafluoropropylene, comprising: a. preparation prior to production; b. assembly of a microchannel reactor; c. preparation of hexafluoropropylene oxide; and d. preparation of perfluorohexanone. The method uses hexafluoropropylene as a raw material, introduces sulfur dioxide, nitrogen monoxide, and oxygen into a microreaction channel for reaction, and after sulfur trioxide and nitrogen dioxide are generated in the microreaction channel, introduces the raw material hexafluoropropylene gas into the microreaction channel to generate hexafluoropropylene oxide gas.

[0008] There are many methods for synthesizing perfluorohexanone. In the early days, the main method was to react hexafluoropropylene with epoxy compounds or isomerize epoxy compounds under the action of a catalyst. Later, the synthesis methods of reacting hexafluoropropylene with acyl halides and perfluorocarboxylic acid compounds were invented.

[0009] Existing synthesis technologies have poor reaction selectivity, many side reactions, and low yield of target products in crude products, so the actual production cost is too high and product quality is difficult to guarantee. Summary of the Invention

[0010] In order to solve the above technical problems, the present invention adopts the following technical solutions.

[0011] A method for preparing perfluorohexanone by isomerization comprises the following steps:

[0012] Step 1: Polymerization reaction.

[0013] 80-120 parts of aprotic polar solvent, 1-3 parts of metal fluoride, and 3-5 parts of co-catalyst are added to a reactor 1 by mass. After the reactor lid is sealed, the air in the reactor 1 is replaced with nitrogen until the pressure in the reactor remains unchanged for 30 minutes. After the ventilation operation is completed, the autoclave is heated to 35-45° C., the stirrer is turned on at a speed of 200-400 rpm and the pressure is maintained at 0.1-0.48 MPa. After activation at this temperature for 50-120 minutes, the temperature is raised to 30-75° C., and 80-120 parts of hexafluoropropylene are introduced into the liquid in the reactor 1 in batches. After all the hexafluoropropylene is introduced, the reaction time is 2-5 hours, and then the stirring is stopped, the temperature is lowered to 5-10° C., and static separation is performed. The lower layer product with the largest specific gravity is collected and marked as D1.

[0014] Step 2: Isomerization reaction

[0015] 120-180 parts by weight of D1, 90-120 parts by weight of aprotic polar solvent, and 1-4 parts by weight of metal fluoride are stirred and reacted in reactor 2 at a speed of 200-400 rpm, a reaction temperature of 60-100° C., and a reaction time of 8-12 h. After the reaction, the reaction product with the largest specific gravity is collected and marked as D2.

[0016] Step 3: Epoxidation reaction

[0017] 250-350 parts by weight of D2 and 40-60 parts of aprotic polar solvent are added to reactor 3, stirred and cooled, and the reaction temperature is controlled to be maintained within -25-30°C. Then, 500-700 parts by weight of oxidant are added. The oxidant is introduced for 6-9 hours. After the addition is completed, the reaction is continued for 30-90 minutes. After cooling to -5-3°C, the upper layer product with the largest specific gravity is collected and marked as D3.

[0018] Step 4: Ketone reaction

[0019] 80-120 parts of D3, 45-55 parts of aprotic polar solvent, and 1-3 parts of metal fluoride are added to reactor 4, stirred and reacted at 60-100°C for 10-14 hours, then refluxed and cooled to 0-5°C, allowed to stand and separate, the lower layer after separation is collected and distilled, and then the boiling point of 48-50°C is collected to obtain perfluorohexanone.

[0020] Furthermore, the polar aprotic solvent is one of acetonitrile, dichloromethane, tetrahydrofuran, and tert-butyl methyl ether.

[0021] Furthermore, the metal fluoride is one of cesium fluoride, potassium fluoride and sodium fluoride.

[0022] Furthermore, the preparation method of the co-catalyst is:

[0023] 0.05-0.5 parts of 4-vinylbenzo-18-crown ether, 30-60 parts of 1,1'-bis(dimethylsilyl)iron, 500-700 parts of ethanol, and 0.003-0.02 parts of Custer catalyst (CAS No. 68478-92-2) are added to a reaction kettle in parts by mass, nitrogen is filled into the reaction bottle, and the mixture is stirred and reacted at 60-70° C. for 30-60 minutes. Then, 22-44 parts of methacryloylpropyltrimethylammonium chloride are added, and the mixture is stirred and reacted at 60-70° C. for 100-160 minutes. After the reaction is completed, the mixture is filtered and dried to obtain a co-catalyst.

[0024] Furthermore, the oxidant is one of hydrogen peroxide, sodium hypochlorite or trimethylamine oxide.

[0025] Reaction mechanism

[0026] 1) Oligomerization reaction: The oligomerization reaction of hexafluoropropylene is carried out in an aprotic polar solvent using a metal fluoride as a catalyst and a co-catalyst for several hours to obtain D1. The equation is:

[0027]

[0028] 2) Isomerization reaction, using dimer D1 as raw material, under the action of aprotic polar solvent and KF,

[0029] Stir the reaction at 60-100°C for several hours to finally obtain D2. The formula is:

[0030]

[0031] 3) Epoxidation reaction: D2 undergoes epoxidation reaction under the oxidation of sodium hypochlorite (NaClO), and a high yield of epoxidation product D3 is obtained in a relatively short time. The equation is:

[0032]

[0033] 4) Ketone reaction: In acetonitrile solvent, D3 undergoes isomerization reaction to obtain high yield perfluorohexanone in a relatively short time. The equation is:

[0034]

[0035] The Custer catalyst reaction mechanism is:

[0036] The reaction mechanism is as follows: 4-vinylbenzo-18-crown ether and 1,1'-bis(dimethylsilyl)iron first undergo a hydrosilylation reaction, and then methacryloylpropyltrimethylammonium chloride and 1,1'-bis(dimethylsilyl)iron undergo a hydrosilylation reaction to obtain a co-catalyst with functional groups such as crown ether, ferrocene, and ammonium chloride; this can improve the yield of perfluorohexanone prepared by isomerization.

[0037] Technical Effects

[0038] 1. Cocatalysts with functional groups such as crown ethers, ferrocene, and ammonium chloride: Crown ethers act as Lewis acids, interacting with other metal catalysts to enhance catalytic activity. The oxygen atoms of crown ethers are partially electronegative and can form stable complexes with metal ions, thereby aiding the catalytic reaction. Ferrocene may act as an electron transfer promoter, increasing the electron cloud density of the catalyst and enhancing its activity. The iron atom of ferrocene can accept or donate electrons, thereby aiding the catalytic reaction. The nitrogen atom of ammonium chloride is partially electronegative and can accept protons to form ammonium ions, thereby aiding the catalytic reaction.

[0039] 2. The perfluorohexanone prepared by the above process has high raw material conversion rate and reaction product selectivity, and the process is simple, which reduces pollution to the environment, reduces the cost of raw materials, avoids the introduction of new impurities, and has a high reuse rate of catalysts and solvents. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Diagram of the oligomerization reaction device.

[0041] Figure 2 Diagram of the isomerization reaction apparatus.

[0042] Figure 3 This is a diagram of the epoxidation reaction apparatus.

[0043] Figure 4 This is a diagram of the ketonization reaction device.

[0044] Figure 5 This is the perfluorohexanone chromatogram of Example 2. DETAILED DESCRIPTION

[0045] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0046] Detection method

[0047] The collected fractions were analyzed by gas chromatography to determine the purity of perfluorohexanone in the fractions. The gas chromatography detection conditions were as follows: Shimadzu GC2030 gas chromatograph was used for detection, area normalization method was used for data processing, FID detector was used, and the chromatographic column was a DB 1 non-polar chromatographic column; the test conditions were: injection volume was 1 μL; injector temperature was 200°C, detector temperature was 250°C, programmed temperature was used, starting temperature was 50°C, and heating rate was 10°C / min.

[0048] Example 1

[0049] Step 1: Polymerization reaction.

[0050] 80 kg of aprotic polar solvent, 1 kg of metal fluoride, and 3 kg of co-catalyst were added to reactor 1. After the reactor lid was sealed, the air in reactor 1 was replaced with nitrogen until the pressure in the reactor remained unchanged for 30 minutes. After the ventilation operation was completed, the autoclave was heated to 35°C, the stirrer was turned on at a speed of 200 rpm, and the pressure was maintained at 0.1 MPa. After activation at this temperature for 50 minutes, the temperature was raised to 30°C, and 80 kg of hexafluoropropylene was introduced into the liquid in reactor 1 in batches. After all the hexafluoropropylene was introduced, the reaction time was 2 hours, and then stirring was stopped, the temperature was lowered to 5°C, and static separation was performed. The lower layer product with the largest specific gravity was collected and marked as D1.

[0051] Step 2: Isomerization reaction

[0052] 120 kg of D1, 90 kg of aprotic polar solvent and 1 kg of metal fluoride were stirred in reactor 2 at a speed of 200 rpm, a reaction temperature of 60°C and a reaction time of 8 h. After the reaction, the reaction product with the largest specific gravity was collected and marked as D2.

[0053] Step 3: Epoxidation reaction

[0054] 250 kg of D2 and 40 kg of aprotic polar solvent were added to reactor 3, stirred and cooled, and the reaction temperature was controlled to be maintained within -25°C. Then 500 kg of oxidant was added, and the oxidant was introduced for 6 hours. After the addition was completed, the reaction was continued for 30 minutes. After cooling to -5°C, the upper layer product with the largest specific gravity was collected and marked as D3.

[0055] Step 4: Ketone reaction

[0056] 80 kg of D3, 45 kg of aprotic polar solvent and 1 kg of metal fluoride were added to the reactor 4. After stirring and reacting at 60 ° C for 10 hours, the mixture was refluxed and cooled to 0 ° C. The mixture was allowed to stand and separate. The lower layer after separation was collected and distilled, and then the boiling point was 48 ° C to obtain perfluorohexanone.

[0057] Furthermore, the polar aprotic solvent is acetonitrile.

[0058] Furthermore, the metal fluoride is cesium fluoride.

[0059] Furthermore, the preparation method of the co-catalyst is:

[0060] 0.05 kg of 4-vinylbenzo-18-crown ether, 30 kg of 1,1'-bis(dimethylsilyl)iron, 500 kg of ethanol, and 0.003 kg of Custer catalyst (CAS No. 68478-92-2) were added to the reactor, nitrogen was filled into the reaction bottle, and the mixture was stirred at 60° C. for 30 minutes. Then, 22 kg of methacryloylpropyltrimethylammonium chloride was added and the mixture was stirred at 60° C. for 100 minutes. After the reaction was completed, the mixture was filtered and dried to obtain a co-catalyst.

[0061] Furthermore, the oxidant is hydrogen peroxide.

[0062] Example 2

[0063] Step 1: Polymerization reaction.

[0064] 100 kg of aprotic polar solvent, 2 kg of metal fluoride, and 4 kg of co-catalyst were added to reactor 1. After the reactor lid was sealed, the air in reactor 1 was replaced with nitrogen until the pressure in the reactor remained unchanged for 30 minutes. After the ventilation operation was completed, the autoclave was heated to 35°C, the stirrer was turned on at a speed of 300 rpm, and the pressure was maintained at 0.24 MPa. After activation at this temperature for 90 minutes, the temperature was raised to 55°C, and 100 kg of hexafluoropropylene was introduced into the liquid in reactor 1 in batches. After all the hexafluoropropylene was introduced, the reaction time was 3.5 hours, and then stirring was stopped, the temperature was lowered to 8°C, and static separation was performed. The lower layer product with the largest specific gravity was collected and marked as D1.

[0065] Step 2: Isomerization reaction

[0066] 150 kg of D1, 105 kg of aprotic polar solvent and 2.5 kg of metal fluoride were stirred in reactor 2 at a speed of 300 rpm, a reaction temperature of 80°C and a reaction time of 10 h. After the reaction, the reaction product with the largest specific gravity was collected and marked as D2.

[0067] Step 3: Epoxidation reaction

[0068] 300 kg of D2 and 50 kg of aprotic polar solvent were added to reactor 3, stirred and cooled, and the reaction temperature was controlled to be maintained within 0°C. Then 600 kg of oxidant was added, and the oxidant was introduced for 7.5 hours. After the addition was completed, the reaction was continued for 60 minutes. After cooling to 0°C, the upper layer product with the largest specific gravity was collected and marked as D3.

[0069] Step 4: Ketone reaction

[0070] 100 kg of D3, 50 kg of aprotic polar solvent, and 2 kg of metal fluoride were added to the reactor 4. After stirring and reacting at 80 ° C for 12 hours, the mixture was refluxed and cooled to 3 ° C. The mixture was allowed to stand and separate. The lower layer after separation was collected and distilled, and then the boiling point was 49 ° C to obtain perfluorohexanone.

[0071] Furthermore, the polar aprotic solvent is dichloromethane.

[0072] Furthermore, the metal fluoride is potassium fluoride.

[0073] Furthermore, the preparation method of the Custer catalyst is as follows:

[0074] 0.25 kg of 4-vinylbenzo-18-crown ether, 45 kg of 1,1'-bis(dimethylsilyl)iron, 600 kg of ethanol, and 0.01 kg of Custer catalyst (CAS No. 68478-92-2) were added to a reactor, nitrogen was filled into the reaction bottle, and the mixture was stirred at 65° C. for 45 minutes. Then, 33 kg of methacryloylpropyltrimethylammonium chloride was added and the mixture was stirred at 65° C. for 130 minutes. After the reaction was completed, the mixture was filtered and dried to obtain a co-catalyst.

[0075] Furthermore, the oxidant is sodium hypochlorite.

[0076] Example 3

[0077] Step 1: Polymerization reaction.

[0078] 120 kg of aprotic polar solvent, 3 kg of metal fluoride, and 5 kg of co-catalyst were added to reactor 1. After the reactor lid was sealed, the air in reactor 1 was replaced with nitrogen until the pressure in the reactor remained unchanged for 30 minutes. After the ventilation operation was completed, the autoclave was heated to 45°C, the stirrer was turned on at a speed of 400 rpm, and the pressure was maintained at 0.48 MPa. After activation at this temperature for 120 minutes, the temperature was raised to 75°C, and 120 kg of hexafluoropropylene was introduced into the liquid in reactor 1 in batches. After all the hexafluoropropylene was introduced, the reaction time was 5 hours, and then stirring was stopped, the temperature was lowered to 10°C, and static separation was performed. The lower layer product with the largest specific gravity was collected and marked as D1.

[0079] Step 2: Isomerization reaction

[0080] 180 kg of D1, 120 kg of aprotic polar solvent and 4 kg of metal fluoride were stirred in reactor 2 at a speed of 400 rpm, a reaction temperature of 100°C and a reaction time of 12 h. After the reaction, the reaction product with the largest specific gravity was collected and marked as D2.

[0081] Step 3: Epoxidation reaction

[0082] 350 kg of D2 and 60 kg of aprotic polar solvent were added to reactor 3, stirred and cooled, and the reaction temperature was controlled to be maintained within 30°C. Then 700 kg of oxidant was added. The oxidant was introduced for 9 hours. After the addition was completed, the reaction was continued for 90 minutes. After cooling to 3°C, the upper layer product with the largest specific gravity was collected and marked as D3.

[0083] Step 4: Ketone reaction

[0084] 120 kg of D3, 55 kg of aprotic polar solvent, and 3 kg of metal fluoride were added to the reactor 4. After stirring and reacting at 100 ° C for 14 hours, the mixture was refluxed and cooled to 5 ° C. The mixture was allowed to stand for stratification. The lower layer after stratification was collected for distillation, and then the boiling point was 50 ° C to obtain perfluorohexanone.

[0085] Furthermore, the polar aprotic solvent is tetrahydrofuran.

[0086] Furthermore, the metal fluoride is sodium fluoride.

[0087] Furthermore, the preparation method of the Custer catalyst is as follows:

[0088] 0.5 kg of 4-vinylbenzo-18-crown ether, 360 kg of 1,1'-bis(dimethylsilyl)iron, 700 kg of ethanol, and 0.02 kg of Custer catalyst (CAS No. 68478-92-2) were added to a reactor, nitrogen was filled into the reaction bottle, and the mixture was stirred and reacted at 70°C for 60 minutes. Then, 44 kg of methacryloylpropyltrimethylammonium chloride was added and the mixture was stirred and reacted at 70°C for 160 minutes. After the reaction was completed, the mixture was filtered and dried to obtain a co-catalyst.

[0089] Furthermore, the oxidant is trimethylamine oxide.

[0090] Comparative Example 1

[0091] No co-catalyst is added, and the rest of the technical scheme is the same as in Example 1.

[0092] Comparative Example 2

[0093] No 4-vinylbenzo-18-crown ether was added to the co-catalyst, and the rest of the technical scheme was the same as in Example 1.

[0094] Comparative Example 3

[0095] No 1,1'-bis(dimethylsilyl)iron is added to the co-catalyst, and the rest of the technical scheme is the same as that of Example 1.

[0096] Comparative Example 4

[0097] No acryloylpropyltrimethylammonium chloride is added to the co-catalyst, and the rest of the technical scheme is the same as that of Example 1.

[0098] Test results:

[0099] Table 1 shows the conversion rates and selectivities of effective products in the reactions of Examples 1-3 and Comparative Examples 1-4.

[0100]

[0101] As can be seen from the table above, co-catalysts with functional groups such as crown ethers, ferrocene, and ammonium chloride: Crown ethers act as Lewis acids, interacting with other metal catalysts to enhance catalytic activity. The oxygen atoms of crown ethers are partially electronegative, forming stable complexes with metal ions, thereby aiding the catalytic reaction. Ferrocene may act as an electron transfer promoter, increasing the electron cloud density of the catalyst and enhancing its activity. The iron atom of ferrocene can accept or donate electrons, thereby aiding the catalytic reaction. The nitrogen atom of ammonium chloride is partially electronegative and can accept protons to form ammonium ions, thereby aiding the catalytic reaction.

[0102] The above are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or any direct or indirect application in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing perfluorohexanone by isomerization, characterized in that: The steps include: Step 1: Polymerization reaction: 80-120 parts of aprotic polar solvent, 1-3 parts of metal fluoride, and 3-5 parts of co-catalyst are added to the reactor 1 by mass. After the reactor cover is sealed, the air in the reactor 1 is replaced with nitrogen until the pressure in the reactor remains unchanged for 30 minutes. After the ventilation operation is completed, the autoclave is heated to 35-45°C, the stirrer is turned on at a speed of 200-400 rpm, and the pressure is maintained at 0.1-0.48 MPa. After activation at this temperature for 50-120 minutes, the temperature is raised to 30-75°C, and 80-120 parts of hexafluoropropylene are introduced into the liquid in the reactor 1 in batches. After all the hexafluoropropylene is introduced, the reaction time is 2-5 hours, and then the stirring is stopped and the temperature is lowered to 5-10°C for static separation. The lower layer product with the largest specific gravity is collected and marked as D1; Step 2: Isomerization reaction: 120-180 parts by weight of D1, 90-120 parts by weight of aprotic polar solvent, and 1-4 parts by weight of metal fluoride are stirred in reactor 2 at a speed of 200-400, a reaction temperature of 60-100° C., and a reaction time of 8-12 h. After the reaction, the reaction product with the largest specific gravity is collected and marked as D2. Step 3: Epoxidation reaction: 250-350 parts by weight of D2 and 40-60 parts of aprotic polar solvent are added to the reactor 3, stirred and cooled, and the reaction temperature is controlled to be maintained within -25-30°C. Then, 500-700 parts by weight of an oxidant are added. The oxidant is introduced for 6-9 hours. After the addition is complete, the reaction is continued for 30-90 minutes. After cooling to -5-3°C, the upper layer product with the largest specific gravity is collected and marked as D3; Step 4: Ketone reaction: 80-120 parts of D3, 45-55 parts of aprotic polar solvent, and 1-3 parts of metal fluoride are added to the reaction kettle 4, stirred and reacted at 60-100 ° C for 10-14 hours, then refluxed and cooled to 0-5 ° C, allowed to stand and separate, and the lower layer after separation is collected and distilled, and then the boiling point of 48-50 ° C is collected to obtain perfluorohexanone; 4-vinylbenzo-18-crown ether and 1,1'-bis(dimethylsilyl)iron are first subjected to a hydrosilylation reaction, and then methacryloylpropyltrimethylammonium chloride and 1,1'-bis(dimethylsilyl)iron are subjected to a hydrosilylation reaction to obtain a co-catalyst with crown ether, ferrocene, and ammonium chloride functional groups.

2. The method for preparing perfluorohexanone by isomerization according to claim 1, characterized in that: The polar aprotic solvent is at least one of acetonitrile, dichloromethane, tetrahydrofuran and tert-butyl methyl ether.

3. The method for preparing perfluorohexanone by isomerization according to claim 1, characterized in that: The metal fluoride is at least one of cesium fluoride, potassium fluoride and sodium fluoride.

4. The method for preparing perfluorohexanone by isomerization according to claim 1, characterized in that: The preparation method of the co-catalyst is: 0.05-0.5 parts of 4-vinylbenzo-18-crown ether, 30-60 parts of 1,1'-bis(dimethylsilyl)iron, 500-700 parts of ethanol, and 0.003-0.02 parts of Custer catalyst (CAS No. 68478-92-2) are added to a reaction kettle in parts by mass, nitrogen is filled into the reaction bottle, and the mixture is stirred and reacted at 60-70° C. for 30-60 minutes. Then, 22-44 parts of methacryloylpropyltrimethylammonium chloride are added, and the mixture is stirred and reacted at 60-70° C. for 100-160 minutes. After the reaction is completed, the mixture is filtered and dried to obtain a co-catalyst.

5. The method for preparing perfluorohexanone by isomerization according to claim 1, characterized in that: The oxidant is one of hydrogen peroxide, sodium hypochlorite or trimethylamine oxide.

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