A method for synthesizing perfluorohexanone from hexafluoropropylene

Abstract

The present invention provides a method for synthesizing perfluorohexanone from hexafluoropropylene, belonging to the field of fluorine-containing ketone synthesis. This method synthesizes perfluorohexanone through four steps, specifically: step one, a hexafluoropropylene oligomerization reaction, in which HFPD is synthesized using a non-protonic polar solvent, a metal fluoride, and an organic cesium co-catalyst as raw materials; step two, an isomerization reaction; step three, an epoxidation reaction, in which perfluoroepoxide is synthesized under the action of an oxidant; and step four, a ketone reaction, in which perfluoroepoxide is ketoneized in a polar non-protonic solvent and a metal fluoride to obtain perfluorohexanone. The method has high perfluorohexanone raw material conversion rate and reaction product selectivity, low raw material cost, simple process, and greatly improved purity of perfluorohexanone.

Description

Technical Field

[0001] The present invention relates to the field of fluorine-containing ketone synthesis, and in particular to a preparation method of perfluorohexanone from hexafluoropropylene. Background Art

[0002] Perfluorohexanone, a fluorinated ketone compound, is an important halon fire extinguishing agent alternative. It is a clear, colorless, and odorless liquid superpressurized with nitrogen and stored in high-pressure cylinders as part of a fire suppression system. Its chemical structure is identical to 3M's NOVEC 1230 fire extinguishing fluid. Typical applications include fires in computer rooms, data centers, aviation, ships, vehicles, libraries, and oil and gas production. Perfluorohexanone fire extinguishing agents are distinguished by their excellent environmental performance.

[0003] CN116854574A discloses a method for preparing perfluorohexanone, comprising: S1. passing hexafluoropropylene into a first reaction tube filled with a first catalyst to carry out a dimerization reaction to obtain perfluoro-2-methyl-2-pentene; S2. mixing perfluoro-2-methyl-2-pentene with hydrogen and oxygen to obtain a mixed gas; the mixed molar ratio of perfluoro-2-methyl-2-pentene, hydrogen and oxygen is 1:2:2; S3. passing the mixed gas into a second reaction tube filled with a second catalyst to carry out a co-oxidation reaction to obtain an epoxide; wherein the reaction temperature of the co-oxidation reaction is 150-230°C and the reaction pressure is 1-9 MPa; S4. carrying out an isomerization catalytic reaction between the epoxide and a third catalyst to obtain perfluorohexanone.

[0004] CN112374977B 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.

[0005] CN108929212B discloses a method for preparing perfluorohexanone. The method uses hexafluoropropylene as a raw material. In the presence of an alkyl hexamethylenetetramine fluoride, a portion of the hexafluoropropylene is oxidized by oxygen to produce hexafluoropropylene oxide. The hexafluoropropylene oxide is then acylated in the presence of an aminopyridine resin solid base to produce perfluoropropionyl fluoride. The perfluoropropionyl fluoride is then condensed with unreacted hexafluoropropylene under fluoride ion catalysis to produce perfluorohexanone.

[0006] The catalysts used in the prior art are metal fluorides and organic amines as catalysts for synthesizing perfluorohexanone from hexafluoropropylene, but there are still problems of low selectivity and conversion rate. A new process is needed to solve the above problems. Summary of the Invention

[0007] The present invention aims to address the deficiencies in the prior art and to provide a process for producing perfluorohexanone using hexafluoropropylene as a raw material. The perfluorohexanone prepared by the process has high raw material conversion rate and reaction product selectivity, low raw material cost and simple process. At the same time, the purity of the perfluorohexanone is greatly improved, the introduction of new impurities is avoided, and the reuse rate of the catalyst and solvent is high.

[0008] To achieve the above object, the present invention provides the following technical solution: a method for synthesizing perfluorohexanone from hexafluoropropylene, comprising the following steps:

[0009] Step 1: Hexafluoropropylene polymerization

[0010] 80-120 parts of aprotic polar solvent are measured and placed in reactor 1, 1-3 parts of metal fluoride and 0.5-5 parts of organic cesium co-catalyst are added, the reactor lid is sealed, the reactor is evacuated and nitrogen is introduced, and then evacuated again, and the ventilation operation is repeated three times. After the ventilation operation is completed, the autoclave is heated to 30-75°C and activated for 40-100 minutes. Then, the stirrer is turned on and 100-200 parts of hexafluoropropylene gas are introduced into the liquid at this temperature. The pressure is maintained at 0.1-0.48 MPa and the speed is 200-600 rpm. After the reaction time is 2-5 hours, stirring is stopped, the temperature is lowered to 5-10°C, and static separation is performed. The lower layer product flows out from the delamination tank at the bottom of the reactor. The delamination tank is connected to the discharge tank. The lower layer product is a mixture of dimer HFPD and trimer HFPT. The mixture is distilled to obtain HFPD, which is a mixture of HFPD1 and HFPD2.

[0011] Step 2: Isomerization reaction: 120-150 parts of HFPD, 80-120 parts of polar aprotic solvent, and 0.8-1.5 parts of metal fluoride are stirred in a vacuum reactor 2 for 2-5 hours at a speed of 200-600 rpm and a temperature of 60-100°C.

[0012] Step 3: Epoxidation reaction: 20-25 parts of polar aprotic solvent are added to reactor 2, stirred and cooled, 240-300 parts of oxidant are added dropwise, and the reaction is carried out at -25-30°C for 1-9 hours. After the reaction is completed, the reaction is cooled to 0°C and allowed to stand for 28-32 minutes. The lower layer is collected and distilled to obtain perfluoroepoxide;

[0013] Step 4: Ketone reaction, add 90-110 parts by weight of perfluoroepoxide, 45-55 parts by weight of polar aprotic solvent and 1-3 parts by weight of metal fluoride into reactor 3, stir and react at 48-52°C for 8-14h, reflux and cool to 0-5°C, stand and separate, collect the lower layer after separation and perform distillation, and then collect the boiling point of 48-50°C to obtain perfluorohexanone.

[0014] Furthermore, the polar aprotic solvent in step 1 is one of acetonitrile, dichloromethane, tetrahydrofuran, and tert-butyl methyl ether.

[0015] Furthermore, the metal fluoride in step 1 is one of cesium fluoride, potassium fluoride and sodium fluoride.

[0016] Furthermore, the preparation method of the organic cesium co-catalyst described in step 1 is:

[0017] B1: Add 20-30 parts of cesium nitrate, 400-500 parts of acetone, and 20-30 parts of 5,6-dihydroxypyrazine-2,3-dicarboxylic acid to a reactor by weight, and stir at 30-40° C. for 20-50 minutes to obtain a cesium dihydroxypyrazine-2,3-dicarboxylate complex;

[0018] B2: Then add 15-22 parts of 2-hydroxyethyl-bistrimethylammonium chloride, 45-64 parts of 2-isocyanatoethyl methacrylate, and 2-5 parts of stannous octoate, control the temperature at 50-60°C, react for 100-140 minutes, and distill off the acetone to form an organic cesium co-catalyst.

[0019] Furthermore, the oxidant in step three is one of hydrogen peroxide, sodium hypochlorite or trimethylamine oxide.

[0020] Reaction mechanism:

[0021] 1) Oligomerization reaction: The oligomerization reaction of hexafluoropropylene is carried out in acetonitrile using KF as catalyst and organic cesium co-catalyst as co-catalyst. The equation is:

[0022] 1) Oligomerization reaction:

[0023]

[0024] 2) Isomerization reaction: Using dimer D1 as raw material, under the action of acetonitrile and KF, stirring and reacting at 60-100°C for several hours, D2 is finally obtained. The equation is:

[0025] 2) Isomerization reaction

[0026]

[0027] 3) Epoxidation reaction: D2 undergoes epoxidation reaction under the oxidation of sodium hypochlorite (NaClO), and the epoxidation product D3 with high yield is obtained in a relatively short time. The equation is:

[0028]

[0029] 4) Ketone reaction: In acetonitrile solvent, D2 undergoes epoxidation reaction under the oxidation of sodium hypochlorite (NaClO), and the epoxidation product D3 is obtained in a short time with high yield. The equation is:

[0030] 4) Ketone reaction

[0031]

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The perfluorohexanone prepared by the above process has high raw material conversion rate and reaction product selectivity, low raw material cost and simple process. At the same time, the purity of perfluorohexanone is greatly improved, the introduction of new impurities is avoided, and the reuse rate of catalysts and solvents is high.

[0034] 2. 2-Hydroxyethyl-bistrimethylammonium chloride and 2-isocyanatoethyl methacrylate undergo polycondensation, and cesium dihydroxypyrazine-2,3-dicarboxylate complexes react with 2-isocyanatoethyl methacrylate. These complexes can act as cocatalysts. The cesium complex catalyst is first activated, and the interaction between the catalyst and the reactants or intermediates reduces the energy barrier of the reaction. Trimethylammonium chloride then interacts with the reactants (e.g., olefins or alkynes), and the activated reactants coordinate with the active centers of the catalyst, connecting the reactants and the catalyst. This assists FK catalysis, thereby improving HFP conversion and product selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Diagram of the oligomerization reaction device.

[0036] Figure 2 Diagram of the isomerization reaction and epoxidation reaction equipment.

[0037] Figure 3 This is a diagram of the ketonization reaction device.

[0038] Figure 4-6 This is the chromatogram of perfluorohexanone obtained in Example 1-3. DETAILED DESCRIPTION

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0040] Detection method: After the reaction is completed, remove the lower layer of product, use a micro-injector to extract 0.2μl sample, perform gas chromatography analysis, analyze the product according to the gas chromatography spectrum, and further calculate the reaction conversion rate and the selectivity of the effective product.

[0041] Example 1

[0042] Step 1: Measure 80g of anhydrous acetonitrile and place it in reactor 1, add 1g of anhydrous potassium fluoride and 1g of organic cesium co-catalyst, seal the reactor lid, evacuate the reactor, introduce nitrogen, evacuate again, and repeat the ventilation operation three times. After the ventilation operation is completed, heat the autoclave to 30°C and activate for 40 minutes. Then turn on the agitator and introduce 100g of hexafluoropropylene gas into the liquid at this temperature. The pressure is maintained at 0.1MPa and the speed is 200 rpm. After the reaction time is 2h, stop stirring, cool to 5°C and let it stand for separation. The lower layer of light yellow transparent product reaction product flows out from the delamination tank at the bottom of the reactor. The delamination tank is connected to the discharge tank. The lower layer product is a mixture of dimer HFPD and trimer HFPT. The mixture is distilled to obtain HFPD, which is a mixture of HFPD1 and HFPD2.

[0043] Step 2: Isomerization reaction: 120 g of HFPD, 80 g of anhydrous acetonitrile and 0.8 g of anhydrous potassium fluoride were stirred in a vacuum reactor for 2 h at a rotation speed of 200 min and a temperature of 60°C.

[0044] Step 3: Epoxidation reaction: 20 g of polar aprotic solvent was added to reactor 2, stirred and cooled, and 240 g of sodium hypochlorite was added dropwise. The reaction was carried out at -25°C for 1 hour. After the reaction, the mixture was cooled to 0°C and allowed to stand for 28 minutes. The lower layer was collected and distilled to obtain perfluoroepoxide.

[0045] Step 4: Ketone Reaction: Add 90g of perfluoroepoxide, 45g of anhydrous acetonitrile, and 1g of anhydrous potassium fluoride to reactor 3. Stir and react at 48°C for 12h. After cooling to 0°C under reflux, stand and separate the layers. Collect the lower layer and perform rectification. Then, collect the boiling point at 48°C to obtain perfluorohexanone.

[0046] The preparation method of the organic cesium co-catalyst described in step 1 is:

[0047] B1: Add 20 g of cesium nitrate, 400 g of acetone, and 20 g of 5,6-dihydroxypyrazine-2,3-dicarboxylic acid to a reactor, and stir at 30° C. for 20 minutes to obtain a cesium dihydroxypyrazine-2,3-dicarboxylate complex;

[0048] B2: Then add 15g of 2-hydroxyethyl-bistrimethylammonium chloride, 45g of 2-isocyanatoethyl methacrylate, and 2g of stannous octoate, and react at 50°C for 100min. Then, distill off the acetone to form an organic cesium co-catalyst;

[0049] Example 2:

[0050] Step 1: Hexafluoropropylene polymerization reaction. Measure 100g of anhydrous dichloromethane and put it into the reactor 1, add 2g of anhydrous cesium fluoride and 3g of organic cesium co-catalyst, seal the reactor lid, evacuate the reactor and then introduce nitrogen, evacuate again, and repeat the ventilation operation three times. After the ventilation operation is completed, heat the autoclave to 50℃ and activate for 60min, then turn on the agitator and introduce 150g of hexafluoropropylene gas into the liquid at this temperature, maintain the pressure at 0.25MPa, and the speed at 400 rpm. After the reaction time is 3h, stop stirring, cool to 8℃ and let it stand for separation. The lower layer product flows out from the delamination tank at the bottom of the reactor. The delamination tank is connected to the discharge tank. The lower layer product is a mixture of dimer HFPD and trimer HFPT. The mixture is distilled to obtain HFPD, which is a mixture of HFPD1 and HFPD2.

[0051] Step 2: Isomerization reaction: 135 g of HFPD, 100 g of anhydrous dichloromethane and 1.25 g of anhydrous cesium fluoride were stirred in a vacuumed reactor 2 for 3 h at a rotation speed of 400 min and a temperature of 80°C.

[0052] Step 3: Epoxidation reaction: 22.5 g of anhydrous dichloromethane was added to reactor 2, stirred and cooled, and 270 g of hydrogen peroxide was added dropwise. The reaction was carried out at 5°C for 5 hours. After the reaction was completed, the mixture was cooled to 0°C and allowed to stand for 30 minutes. The lower layer was collected and distilled to obtain perfluoroepoxide.

[0053] Step 4: Ketone Reaction: Add 100g of perfluoroepoxide, 50g of anhydrous dichloromethane, and 2g of anhydrous cesium fluoride to reactor 3 and stir at 50°C for 12 hours. After cooling to 2°C under reflux, stand and separate the layers. Collect the lower layer and perform rectification. The boiling point is 49°C to obtain perfluorohexanone.

[0054] The preparation method of the organic cesium co-catalyst described in step 1 is:

[0055] B1: Add 23 g of cesium nitrate, 420 g of acetone, and 24 g of 5,6-dihydroxypyrazine-2,3-dicarboxylic acid to a reactor, and stir at 34° C. for 40 minutes to obtain a cesium dihydroxypyrazine-2,3-dicarboxylate complex;

[0056] B2: Then, 16 g of 2-hydroxyethyl-bistrimethylammonium chloride, 49 g of 2-isocyanatoethyl methacrylate, and 3 g of stannous octoate were added, and the reaction was controlled at 55°C for 120 min. The acetone was distilled off to form an organic cesium co-catalyst;

[0057] Example 3

[0058] Step 1: Hexafluoropropylene polymerization reaction. 120g of tetrahydrofuran was measured and placed in the reactor 1, 3g of anhydrous sodium fluoride and 5g of organic cesium co-catalyst were added, the reactor lid was sealed, the reactor was evacuated and nitrogen was introduced, and then evacuated again, and the ventilation operation was repeated three times. After the ventilation operation was completed, the autoclave was heated to 75°C for activation for 100min, and then the agitator was turned on and 200% of hexafluoropropylene gas was introduced into the liquid at this temperature. The pressure was maintained at 0.48MPa and the speed was 600 rpm. After the reaction time was 5h, stirring was stopped, and the temperature was lowered to 10°C for static separation. The reaction product of the lower layer flowed out from the delamination tank at the bottom of the reactor. The delamination tank was connected to the discharge tank. The lower layer product was a mixture of dimer HFPD and trimer HFPT. The mixture was distilled to obtain HFPD, which was a mixture of HFPD1 and HFPD2.

[0059] Step 2: Isomerization reaction: 150 g of HFPD, 120 g of tetrahydrofuran and 1.5 g of anhydrous sodium fluoride were stirred in a vacuumed reactor 2 for 5 h at a speed of 600 rpm and a temperature of 100°C.

[0060] Step 3: Epoxidation Reaction: 350 g of HFPD2 and 60 g of a polar aprotic solvent were added to Reactor 2, stirred, and cooled. 700 g of trimethylamine oxide was added dropwise. The reaction was carried out at 30°C for 9 hours. After the reaction, the mixture was cooled to 0°C and allowed to stand for 32 minutes. The lower layer was collected and distilled to obtain a perfluoroepoxide.

[0061] Step 4: Ketone Reaction: Add 110g of perfluoroepoxide, 55g of tetrahydrofuran, and 3g of anhydrous sodium fluoride to reactor 3 and stir at 52°C for 14 hours. After cooling to 5°C under reflux, allow to stand and separate. Collect the lower layer and perform rectification. Then collect the boiling point at 50°C to obtain perfluorohexanone.

[0062] The preparation method of the organic cesium co-catalyst described in step 1 is:

[0063] B1: Add 30 g of cesium nitrate, 500 g of acetone, and 30 g of 5,6-dihydroxypyrazine-2,3-dicarboxylic acid to a reactor, and stir at 40° C. for 50 minutes to obtain a cesium dihydroxypyrazine-2,3-dicarboxylate complex;

[0064] B2: Then add 22g of 2-hydroxyethyl-bistrimethylammonium chloride, 64g of 2-isocyanatoethyl methacrylate, and 5g of stannous octoate, control the temperature at 60°C to react for 140min, and distill off the acetone to form an organic cesium co-catalyst.

[0065] Comparative Example 1

[0066] No organic cesium co-catalyst was added, and the other technical solutions were the same as those in Example 1.

[0067] Comparative Example 2

[0068] The technical solution is the same as that in Example 1 except that the dihydroxypyrazine-2,3-dicarboxylate cesium complex is not added.

[0069] Comparative Example 3

[0070] Without adding 2-hydroxyethyl-bistrimethylammonium chloride, the other technical solutions were the same as those in Example 1.

[0071] Table 1 shows the conversion rates and selectivities of effective products in the reactions of Examples 1-3 and Comparative Examples 1-3.

[0072]

[0073] As shown in Table 1, 2-hydroxyethyl-bistrimethylammonium chloride undergoes a polycondensation reaction with 2-isocyanatoethyl methacrylate, and dihydroxypyrazine-2,3-dicarboxylic acid cesium complex undergoes a polycondensation reaction with 2-isocyanatoethyl methacrylate, which can serve as co-catalysts to assist FK catalysis and improve the conversion rate of HFP and the selectivity of the reaction products.

[0074] Although the present invention has been described in detail above using general explanations, specific embodiments, and experiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A method for synthesizing perfluorohexanone from hexafluoropropylene, characterized in that: The steps include: Step 1: Hexafluoropropylene polymerization 80-120 parts of aprotic polar solvent are measured by mass and placed in reactor 1, 1-3 parts of metal fluoride and 0.5-5 parts of organic cesium co-catalyst are added, the reactor lid is sealed, the reactor is evacuated and nitrogen is introduced, and then evacuated again, and the ventilation operation is repeated three times. After the ventilation operation is completed, the autoclave is heated to 30-75°C and activated for 40-100 minutes. Then, the agitator is turned on and 100-200 parts of hexafluoropropylene gas are introduced into the liquid at this temperature. The pressure is maintained at 0.1-0.48 MPa and the speed is 200-600 rpm. After the reaction time is 2-5 hours, stirring is stopped, the temperature is lowered to 5-10°C and static separation is carried out. The lower layer product flows out from the delamination tank at the bottom of the reactor. The delamination tank is connected to the discharge tank. The lower layer product is a mixture of dimer HFPD and trimer HFPT. The mixture is distilled to obtain HFPD, which is a mixture of HFPD1 and HFPD2. Step 2: Isomerization reaction: 120-150 parts of HFPD, 80-120 parts of polar aprotic solvent, and 0.8-1.5 parts of metal fluoride are stirred in a vacuum reactor 2 for 2-5 hours at a speed of 200-600 rpm and a temperature of 60-100°C. Step 3: Epoxidation reaction: 20-25 parts of polar aprotic solvent are added to reactor 2, stirred and cooled, 240-300 parts of oxidant are added dropwise, and the reaction is carried out at -25-30°C for 1-9 hours. After the reaction is completed, the reaction is cooled to 0°C and allowed to stand for 28-32 minutes. The lower layer is collected and distilled to obtain perfluoroepoxide; Step 4: Ketone reaction, 90-110 parts by weight of perfluoroepoxide, 45-55 parts by weight of polar aprotic solvent and 1-3 parts by weight of metal fluoride are added to the reaction kettle 3, stirred and reacted at 48-52°C for 8-14 hours, refluxed and cooled to 0-5°C, and then 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; The preparation method of the organic cesium co-catalyst described in step 1 is: B1: Add 20-30 parts of cesium nitrate, 400-500 parts of acetone, and 20-30 parts of 5,6-dihydroxypyrazine-2,3-dicarboxylic acid to a reactor by weight, and stir at 30-40° C. for 20-50 minutes to obtain a cesium dihydroxypyrazine-2,3-dicarboxylate complex; B2: Then add 15-22 parts of 2-hydroxyethyl-bistrimethylammonium chloride, 45-64 parts of 2-isocyanatoethyl methacrylate, and 2-5 parts of stannous octoate, control the temperature at 50-60°C, react for 100-140 minutes, and distill off the acetone to form an organic cesium co-catalyst.

2. The method for synthesizing perfluorohexanone from hexafluoropropylene according to claim 1, wherein: The polar aprotic solvent in step 1 is one of acetonitrile, dichloromethane, tetrahydrofuran, and tert-butyl methyl ether.

3. The method for synthesizing perfluorohexanone from hexafluoropropylene according to claim 1, wherein: The metal fluoride in step 1 is one of cesium fluoride, potassium fluoride and sodium fluoride.

4. The method for synthesizing perfluorohexanone from hexafluoropropylene according to claim 1, wherein: The oxidant in step 3 is one of hydrogen peroxide, sodium hypochlorite or trimethylamine oxide.

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