Preparation method and preparation device of perfluoromethyl vinyl ether

Abstract

The invention belongs to the technical field of fluorine-containing modified monomer preparation, and particularly relates to a preparation method and a preparation device of perfluoromethyl vinyl ether. The preparation method comprises the following steps: (1) adding a catalyst and a solvent into a reaction kettle, and uniformly stirring to obtain a catalyst solution; introducing carbonyl fluoride gas into the catalyst solution, and then dropwise adding hexafluoropropylene oxide liquid into the catalyst solution in a liquid phase to carry out an addition reaction, so as to obtain an intermediate product perfluoro-2-methoxypropionyl fluoride; wherein the catalyst comprises potassium fluoride and cesium fluoride, and the mass ratio of the potassium fluoride to the cesium fluoride is (10-20): 1; (2) dropwise adding a liquid phase of the intermediate product perfluoro-2-methoxypropionyl fluoride into a mixed solution of carbonate and a solvent, and carrying out a salt-forming cracking reaction to obtain a crude product of perfluoromethyl vinyl ether; according to the preparation method and the preparation device, the yield of the perfluoromethyl vinyl ether can reach 90% or above, and the preparation method and the preparation device are suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of fluorine-containing modified monomers, and particularly relates to a preparation method and a preparation device for perfluoromethyl vinyl ether. Background Art

[0002] Perfluoromethyl vinyl ether (hereinafter referred to as PMVE) is a widely used fluorine-containing comonomer, which can usually be used in the production of fluoroplastics, fluororubbers and fluorine-containing polymers with fluorine-containing functional groups that can be thermoplastically processed, and is an excellent raw material for polymer modification. For example, perfluoromethyl vinyl ether and tetrafluoroethylene are copolymerized to form fluororubber. This kind of fluororubber not only has a wide temperature range, excellent chemical corrosion resistance and aging resistance, etc. like traditional polytetrafluoroethylene, but also exhibits excellent processing performance, and at the same time improves the low-temperature resistance and corrosion resistance of the product.

[0003] US Patent US3114778 reported a method for preparing perfluoromethyl vinyl ether by a three-step method. First, in the presence of CsF and diethylene glycol dimethyl ether, carbonyl fluoride and hexafluoropropylene oxide react to obtain perfluoro-2-methoxypropionyl fluoride, and then decarboxylation is carried out at 300 °C to obtain perfluoromethyl vinyl ether. The yield after two steps of this method is about 58%, the yield of this method is low, the required decarboxylation temperature is high, and the required cost is high.

[0004] Chinese Patent CN102211983B reported a method for preparing perfluoromethyl vinyl ether by using carbonyl fluoride and potassium fluoride as raw materials, acetonitrile as a solvent to form a salt without the action of a catalyst, and then adding a small amount of water, and reacting the formed salt with tetrafluoroethylene. The second step of this method is extremely dangerous, tetrafluoroethylene has the risk of explosion, and the purity is only 70%, and the yield is also low.

[0005] US Patent US3321532 discloses that using metal oxide as a catalyst, acyl fluoride ether is pyrolyzed at a high temperature of 300 °C to remove the acyl fluoride group to obtain fluorine-containing vinyl ether. The PMVE prepared by this method will have some tetrafluoroethyl ether as by-products, which are difficult to remove.

[0006] Chinese Patent CN103724167B provides a preparation method for carbonyl fluoride to react with hexafluoropropylene oxide and then crack into perfluoromethyl vinyl ether. This method lacks a purification step, and the impurities contained will corrode the equipment, and high-purity perfluoromethyl vinyl ether gas cannot be obtained, and the yield is also low.

[0007] In the above patents, high-yield perfluoromethyl vinyl ether cannot be obtained, and we still need to explore better methods to improve its yield. Summary of the Invention

[0008] In order to solve the above problems, the present invention provides a preparation method and a preparation device for perfluoromethyl vinyl ether.

[0009] In a first aspect, the present invention provides a method for preparing perfluoromethyl vinyl ether, comprising the following preparation steps:

[0010] (1) Add a catalyst and a solvent to a reaction kettle, stir evenly to obtain a catalyst solution; introduce carbonyl fluoride gas into the catalyst solution, and then dropwise add hexafluoropropylene oxide liquid to the catalyst solution in a liquid phase for an addition reaction to obtain an intermediate product, perfluoro-2-methoxypropionyl fluoride; wherein, the catalyst comprises potassium fluoride and cesium fluoride, and the mass ratio of potassium fluoride to cesium fluoride is 10-20:1;

[0011] (2) Dropwise add the intermediate product, perfluoro-2-methoxypropionyl fluoride, to a mixed solution of a carbonate and a solvent in a liquid phase for a salt-forming cracking reaction to obtain a crude product of perfluoromethyl vinyl ether.

[0012] In some preferred embodiments, the mass ratio of potassium fluoride to cesium fluoride is 10-15:1.

[0013] In some embodiments, the mass ratio of the catalyst, the solvent to hexafluoropropylene oxide is 1:30-80:100-200. In some preferred embodiments, the mass ratio of the catalyst, the solvent to hexafluoropropylene oxide is 1:30-50:120-160.

[0014] Specifically, the water content in the solvent is less than 200 ppm; more specifically, the solvent is selected from one or more of acetonitrile, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, perfluoroisobutyl ethyl ether, acetone, tetraethylene glycol dimethyl ether; in some preferred embodiments, the solvent is a mixed solvent of diethylene glycol dimethyl ether and ethylene glycol dimethyl ether.

[0015] In some embodiments, in step (1), the molar ratio of carbonyl fluoride to hexafluoropropylene oxide is 1-1.2.

[0016] In some embodiments, in step (1), the dropping rate of the hexafluoropropylene oxide in the liquid phase is 0.5 kg / h-1.5 kg / h. In some preferred embodiments, in step (1), the dropping rate of the hexafluoropropylene oxide in the liquid phase is 0.6 kg / h-1.0 kg / h.

[0017] In some embodiments, in step (1), the temperature of the addition reaction is 0°C-30°C, the pressure is 0.5 MPa-1.2 MPa, and after the dropping of the hexafluoropropylene oxide is completed, it is kept warm for 0.5 h-3 h. In some preferred embodiments, the temperature of the addition reaction is 0°C-20°C.

[0018] In some of these embodiments, in step (2), the rate of liquid-phase dropping of perfluoro-2-methoxypropionyl fluoride is 1 kg / h to 2 kg / h. In some preferred embodiments, the rate of liquid-phase dropping of perfluoro-2-methoxypropionyl fluoride is 1.2 kg / h to 1.7 kg / h.

[0019] In some of these embodiments, in step (2), the temperature of the salt-forming cracking reaction is 80°C to 170°C, and the pressure is 0.1 MPa - 0.6 MPa. After the dropping of perfluoro-2-methoxypropionyl fluoride is completed, reflux and heat preservation are carried out for 1 h to 3 h. In some preferred embodiments, the temperature of the salt-forming cracking reaction is 120°C to 160°C.

[0020] Specifically, the mixed solution of carbonate and solvent in step (2) is prepared from sodium carbonate and an organic solvent. The molar ratio of sodium carbonate to perfluoro-2-methoxypropionyl fluoride is 1 to 2:1; the organic solvent is preferably a mixed solvent of tetraethylene glycol dimethyl ether and diethylene glycol dimethyl ether, and the mass ratio of the two is 1:5 to 20; preferably, the mass ratio of the two is 1:8 to 15.

[0021] In some of these embodiments, after step (2), an operation of purifying the crude perfluoromethyl vinyl ether is further included. The purification operation is to stir for 3 h - 10 h at a temperature of -12°C to 20°C and a pressure of 0.8 MPa - 1.5 MPa, and evacuate the impurity gas to obtain the purified perfluoromethyl vinyl ether.

[0022] In a second aspect, the present invention also provides a perfluoromethyl vinyl ether preparation device. The preparation device includes an acyl fluoride tank, a hexafluoropropylene oxide tank, a reaction kettle, an intermediate receiving tank, and a salt-forming decarboxylation kettle. The acyl fluoride tank and the hexafluoropropylene oxide tank are connected to the bottom of the reaction kettle through a diaphragm compressor. A first condenser, a purification kettle, and a crude product receiving tank are sequentially connected outside the salt-forming decarboxylation kettle. A second condenser is also connected outside the purification kettle, and the purification kettle and the second condenser form a reflux.

[0023] Specifically, the hexafluoropropylene oxide tank is connected to the liquid-phase pipe orifice at the bottom of the reaction kettle through the diaphragm compressor. The pressure in the hexafluoropropylene oxide tank is greater than 0.8 MPa, and the hexafluoropropylene oxide in the hexafluoropropylene oxide tank is a compressed liquid.

[0024] In some of these embodiments, a distillation kettle is further connected outside the salt-forming decarboxylation kettle, and a distillation column is provided at the top of the distillation kettle; an internal coil is provided in the reaction kettle, and chilled brine is passed through the internal coil; both the salt-forming decarboxylation kettle and the distillation kettle are provided with heating components.

[0025] Specifically, the first condenser and the second condenser are tubular condensers, and the heat exchange area is 10 m 2~30 m 2 。

[0026] In some embodiments, the feed pipe at the bottom of the reactor is in an "n" shape.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] (1) The present invention provides a method for preparing perfluoromethyl vinyl ether, using carbonyl fluoride and hexafluoropropylene oxide as raw materials, and a mixture of potassium fluoride and cesium fluoride as a catalyst. The perfluoromethyl vinyl ether is prepared by a stepwise method. The present invention specifically selects a mixture of potassium fluoride and cesium fluoride as the catalyst. The activity of cesium fluoride is higher than that of other fluorides. Adding a part of cesium fluoride can improve the catalytic effect, so there is no need to additionally add a phase transfer catalyst. At the same time, the inventor further studies and finds that only when potassium fluoride and cesium fluoride are mixed in a specific ratio, the yield of perfluoromethyl vinyl ether is relatively high, up to 90%.

[0029] (2) In the preparation method of the present invention, the liquid-phase dropping technology is adopted in the intermediate synthesis and salt-forming cracking reaction processes, which increases the contact area of the raw materials, makes the reaction more sufficient, and thus improves the yield of the crude product. By controlling the dropping rate of the liquid-phase dropping process, impurities can be prevented from being generated while ensuring a high synthesis efficiency, and the purity of the crude product is guaranteed.

[0030] (3) The preparation method of perfluoromethyl vinyl ether of the present invention is green and environmentally friendly. The used solvent can be completely recycled, without polluting the environment, and the cost can be greatly reduced. The reaction temperature in the high-temperature decarboxylation process only needs to be 80°C - 170°C, which requires less heat than other processes and can obtain a higher yield. In the preparation method of the present invention, the yield of perfluoromethyl vinyl ether can reach more than 90%, which is suitable for industrial production.

[0031] (4) The present invention provides a preparation device for perfluoromethyl vinyl ether with a high yield, including a reactor, a salt-forming decarboxylation kettle, a purification kettle, and a distillation kettle. Using this preparation device, the preparation, purification, and solvent recovery of perfluoromethyl vinyl ether can be completed simultaneously, and the production efficiency is greatly improved. At the same time, in this preparation device, a hexafluoropropylene oxide tank is provided to contain compressed hexafluoropropylene oxide liquid, so as to realize and control the liquid-phase dropping of hexafluoropropylene oxide, make the reaction proceed fully, and the yield of the target product is significantly improved. At the same time, a reflux is formed by setting the purification kettle and the condenser, improving the purification efficiency. The preparation method and preparation device of the present invention have simple equipment and low cost, and can be used for continuous production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0033] Figure 1 It is a schematic diagram of the preparation device for perfluoromethyl vinyl ether of the present invention.

[0034] Reference numerals: 1 - acyl fluoride tank, 2 - hexafluoropropylene oxide tank, 3 - reaction kettle, 4 - intermediate receiving tank, 5 - salification and decarboxylation kettle, 6 - diaphragm compressor, 7 - first condenser, 8 - purification kettle, 9 - crude product receiving tank, 10 - second condenser, 11 - distillation kettle, 12 - distillation column. Specific embodiments

[0035] The following will clearly and completely describe the technical solutions of the present invention in combination with specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0036] As Figure 1 shown is the perfluoromethyl vinyl ether preparation device of the present invention. The preparation device includes an acyl fluoride tank 1, a hexafluoropropylene oxide tank 2, a reaction kettle 3, an intermediate receiving tank 4, and a salification and decarboxylation kettle 5. The acyl fluoride tank 1 and the hexafluoropropylene oxide tank 2 are connected to the bottom of the reaction kettle 3 through a diaphragm compressor 6. The outside of the salification and decarboxylation kettle 5 is sequentially connected with a first condenser 7, a purification kettle 8, and a crude product receiving tank 9. The outside of the purification kettle 8 is also connected with a second condenser 10. The purification kettle 8 and the second condenser 10 form a reflux. The outside of the salification and decarboxylation kettle 5 is also connected with a distillation kettle 11. A distillation column 12 is arranged at the top of the distillation kettle 11. An internal coil (not shown in the figure) is arranged in the reaction kettle 3, and chilled brine is passed through the internal coil. Heating components (not shown in the figure) are arranged in both the salification and decarboxylation kettle 5 and the distillation kettle 11. The feed pipe at the bottom of the reaction kettle 3 is in an "n" shape.

[0037] In the present invention, the preparation process of perfluoromethyl vinyl ether in the following embodiments relies on the preparation device of the present invention. Among them, all batches of hexafluoropropylene oxide are the same, with a content of 95%; all batches of carbonyl fluoride are the same, with a content of 96%. The calculation method of the PMVE yield in the present invention is as follows:

[0038] PMVE yield = (PMVE content × PMVE mass / 166) / (hexafluoropropylene oxide content × hexafluoropropylene oxide mass / 166) × 100%.

[0039] Example 1

[0040] Using the preparation device of the present invention, 18.2 g of potassium fluoride and 1.8 g of cesium fluoride were put into a 10 L reaction kettle containing 700 g of diethylene glycol dimethyl ether and stirred evenly. The temperature was lowered to 0 °C to obtain a catalyst solution. 1.3 kg of carbonyl fluoride gas was introduced into the reaction kettle from the acyl fluoride tank through a diaphragm compressor, and then 3 kg of hexafluoropropylene oxide liquid was added dropwise to the reaction kettle in liquid phase from the hexafluoropropylene oxide tank through a diaphragm compressor for an addition reaction. The dropping rate of the hexafluoropropylene oxide in liquid phase was 0.6 kg / h. After the dropping was completed, the reaction continued for 2 h. During the addition reaction, the temperature in the kettle was maintained at 0 °C to 30 °C, and the reaction pressure was below 1.2 MPa. After the reaction ended, the reaction product was collected into an intermediate receiving tank. After purification, 3.900 kg of the intermediate perfluoro-2-methoxypropionyl fluoride was obtained, and the purity was above 99.5%.

[0041] 2.70 kg of anhydrous sodium carbonate, 500 g of diethylene glycol dimethyl ether and 40 g of tetraethylene glycol dimethyl ether were added to a decarboxylation and salification kettle and stirred evenly to obtain a mixed solution of carbonate and solvent. 3.900 kg of the intermediate perfluoro-2-methoxypropionyl fluoride obtained from the addition reaction was added dropwise to the decarboxylation and salification kettle in liquid phase from the intermediate receiving tank for a salification and cracking reaction. The dropping rate of the perfluoro-2-methoxypropionyl fluoride was 1.2 kg / h. After the dropping was completed, stirring and heat preservation were continued for 2 h. The cracking temperature was 160 °C, and the pressure was below 0.6 MPa. After the reaction ended, the distillation kettle was started to recover the solvent. Finally, 3.105 kg of PMVE crude product was obtained. The content of PMVE detected by gas chromatography was 86.6%.

[0042] The PMVE crude product was pressed into a purification kettle, stirring was started and the second condenser was started for reflux purification. The temperature during the purification process was controlled at -12 °C to 20 °C, and the kettle pressure was controlled at 0.8 MPa - 1.5 MPa. The purified PMVE was pressed into the crude product tank. Finally, 2.758 kg of purified PMVE was obtained. The purity of PMVE detected by gas chromatography was 97.4%, and the yield was 94.26%.

[0043] Example 2

[0044] Using the preparation apparatus of the present invention, 18.5 g of potassium fluoride and 1.5 g of cesium fluoride were put into a 10 L reaction kettle containing 700 g of diethylene glycol dimethyl ether and stirred evenly. Then the temperature was lowered to 5 °C to obtain a catalyst solution. 1.3 kg of carbonyl fluoride gas was introduced into the reaction kettle from the acyl fluoride tank through a diaphragm compressor. Then, 3 kg of hexafluoropropylene oxide liquid was added dropwise to the reaction kettle in liquid phase from the hexafluoropropylene oxide tank through a diaphragm compressor for an addition reaction. The dropping rate of the hexafluoropropylene oxide in liquid phase was 1.0 kg / h. After the dropping was completed, the reaction continued for 2 h. During the addition reaction, the temperature in the kettle was maintained at 0 °C to 30 °C, and the reaction pressure was below 1.2 MPa. After the reaction ended, the reaction product was collected into an intermediate receiving tank. After purification, 3.872 kg of the intermediate product perfluoro-2-methoxypropionyl fluoride was obtained, and its purity was above 99.5%.

[0045] 2.7 kg of anhydrous sodium carbonate, 500 g of diethylene glycol dimethyl ether and 40 g of tetraethylene glycol dimethyl ether were added to a decarboxylation and salification kettle and stirred evenly to obtain a mixed solution of carbonate and solvent. 3.872 kg of the intermediate product perfluoro-2-methoxypropionyl fluoride obtained from the addition reaction was added dropwise to the decarboxylation and salification kettle in liquid phase from the intermediate receiving tank for a salification and cracking reaction. The dropping rate of the perfluoro-2-methoxypropionyl fluoride was 1.5 kg / h. After the dropping was completed, stirring and heat preservation were continued for 2 h. The cracking temperature was 150 °C, and the pressure was below 0.6 MPa. After the reaction ended, the distillation kettle was started to recover the solvent. Finally, 3.059 kg of PMVE crude product was obtained, and the content of PMVE detected by gas chromatography was 86.7%.

[0046] The PMVE crude product was pressed into a purification kettle, stirring was started and the second condenser was started for reflux purification. The temperature during the purification process was controlled at -12 °C to 20 °C, and the kettle pressure was controlled at 0.8 MPa - 1.5 MPa. The purified PMVE was pressed into the crude product tank. Finally, 2.734 kg of purified PMVE was obtained, and the content of PMVE detected by gas chromatography was 96.9%, and the yield was 92.96%.

[0047] Example 3

[0048] Using the preparation device of the present invention, 19 g of potassium fluoride and 1 g of cesium fluoride are put into a 10 L reaction kettle containing 700 g of diethylene glycol dimethyl ether and stirred evenly. Then the temperature is lowered to 10 °C to obtain a catalyst solution. 1.3 kg of carbonyl fluoride gas is introduced into the reaction kettle from the acyl fluoride tank through a diaphragm compressor. Then, 3 kg of hexafluoropropylene oxide liquid is added dropwise to the reaction kettle in liquid phase from the hexafluoropropylene oxide tank through a diaphragm compressor for an addition reaction. The dropping rate of the hexafluoropropylene oxide in liquid phase is 1.5 kg / h. After the dropping is completed, the reaction continues for 2 h. During the addition reaction, the temperature in the kettle is maintained at 0 °C to 30 °C, and the reaction pressure is below 1.2 MPa. After the reaction ends, the reaction product is collected into an intermediate receiving tank. After purification, 3.851 kg of the intermediate product perfluoro-2-methoxypropionyl fluoride is obtained, and the purity is above 99.5%.

[0049] 2.7 kg of anhydrous sodium carbonate, 500 g of diethylene glycol dimethyl ether and 40 g of tetraethylene glycol dimethyl ether are added to a decarboxylation and salification kettle and stirred evenly to obtain a mixed solution of carbonate and solvent. 3.851 kg of the intermediate product perfluoro-2-methoxypropionyl fluoride obtained from the addition reaction is added dropwise to the decarboxylation and salification kettle in liquid phase from the intermediate receiving tank for a salification and cracking reaction. The dropping rate of the perfluoro-2-methoxypropionyl fluoride is 1.8 kg / h. After the dropping is completed, stirring and heat preservation continue for 2 h. The cracking temperature is 120 °C, and the pressure is below 0.6 MPa. After the reaction ends, the distillation kettle is started to recover the solvent. Finally, 3.000 kg of PMVE crude product is obtained, and the content of PMVE detected by gas chromatography is 87.1%.

[0050] The PMVE crude product is pressed into a purification kettle, stirring is started and the second condenser is started for reflux purification. The temperature during the purification process is controlled at -12 °C to 20 °C, and the kettle pressure is controlled at 0.8 MPa - 1.5 MPa. The purified PMVE is pressed into the crude product tank. Finally, 2.700 kg of purified PMVE is obtained, the content of PMVE detected by gas chromatography is 96.7%, and the yield is 91.61%.

[0051] Example 4

[0052] Using the preparation device of the present invention, 18.2 g of potassium fluoride and 1.8 g of cesium fluoride were put into a 10 L reaction kettle containing 700 g of diethylene glycol dimethyl ether and stirred evenly. Then the temperature was lowered to 0 °C to obtain a catalyst solution. 1.3 kg of carbonyl fluoride gas was introduced into the reaction kettle from the acyl fluoride tank by a diaphragm compressor. Then, 3 kg of hexafluoropropylene oxide liquid was added dropwise to the reaction kettle in liquid phase from the hexafluoropropylene oxide tank by a diaphragm compressor for an addition reaction. The dropping rate of hexafluoropropylene oxide in liquid phase was 2 kg / h. After the dropping was completed, the reaction continued for 2 h. During the addition reaction, the temperature in the kettle was maintained at 0 °C to 30 °C, and the reaction pressure was below 1.2 MPa. After the reaction ended, the reaction product was collected into an intermediate receiving tank. After purification, 3.722 kg of the intermediate perfluoro-2-methoxypropionyl fluoride was collected, and its purity was above 99.5%.

[0053] 2.55 kg of anhydrous sodium carbonate, 500 g of diethylene glycol dimethyl ether and 40 g of tetraethylene glycol dimethyl ether were added to a decarboxylation and salification kettle and stirred evenly to obtain a mixed solution of carbonate and solvent. 3.722 kg of the intermediate perfluoro-2-methoxypropionyl fluoride obtained from the addition reaction was added dropwise to the decarboxylation and salification kettle in liquid phase from the intermediate receiving tank for a salification and cracking reaction. The dropping rate of perfluoro-2-methoxypropionyl fluoride was 1.2 kg / h. After the dropping was completed, stirring and heat preservation were continued for 2 h. The cracking temperature was 160 °C, and the pressure was below 0.6 MPa. After the reaction ended, the distillation kettle was started to recover the solvent. Finally, 2.875 kg of PMVE crude product was obtained, and the content of PMVE detected by gas chromatography was 87.4%.

[0054] The PMVE crude product was pressed into a purification kettle, stirring was started and the second condenser was started for reflux purification. The temperature during the purification process was controlled at -12 °C to 20 °C, and the kettle pressure was controlled at 0.8 MPa - 1.5 MPa. The purified PMVE was pressed into the crude product tank. Finally, 2.588 kg of purified PMVE was obtained, and the content of PMVE detected by gas chromatography was 97.0%, and the yield was 88.08%.

[0055] Comparative Example 1

[0056] The difference between this comparative example and Example 1 is that the catalyst only contains potassium fluoride. The specific preparation steps are as follows:

[0057] Using the preparation device of the present invention, 20 g of potassium fluoride was put into a 10 L reaction kettle containing 700 g of diethylene glycol dimethyl ether and stirred evenly. The temperature was lowered to 0 °C to obtain a catalyst solution. 1.3 kg of carbonyl fluoride gas was introduced into the reaction kettle from the acyl fluoride tank by a diaphragm compressor, and then 3 kg of hexafluoropropylene oxide liquid was added dropwise to the reaction kettle in liquid phase from the hexafluoropropylene oxide tank by a diaphragm compressor for an addition reaction. The dropping rate of the hexafluoropropylene oxide in liquid phase was 0.6 kg / h. After the dropping was completed, the reaction continued for 2 h. During the addition reaction, the temperature in the kettle was maintained at 0 °C to 30 °C, and the reaction pressure was below 1.2 MPa; after the reaction ended, the reaction product was collected into an intermediate receiving tank; through purification and collection, 3.690 kg of the intermediate perfluoro-2-methoxypropionyl fluoride was obtained, and the purity was above 99.5%.

[0058] 2.53 kg of anhydrous sodium carbonate, 500 g of diethylene glycol dimethyl ether and 40 g of tetraethylene glycol dimethyl ether were added to a decarboxylation and salification kettle and stirred evenly to obtain a mixed solution of carbonate and solvent; 3.690 kg of the intermediate perfluoro-2-methoxypropionyl fluoride obtained from the addition reaction was added dropwise to the decarboxylation and salification kettle in liquid phase from the intermediate receiving tank for a salification and cracking reaction. The dropping rate of the perfluoro-2-methoxypropionyl fluoride was 1.2 kg / h. After the dropping was completed, stirring and heat preservation continued for 2 h. The cracking temperature was 160 °C, and the pressure was below 0.6 MPa; after the reaction ended, the distillation kettle was started to recover the solvent; finally, 2.830 kg of PMVE crude product was obtained, and the content of PMVE detected by gas chromatography was 87.0%.

[0059] The PMVE crude product was pressed into a purification kettle, stirring was started and the second condenser was started for reflux purification. The temperature during the purification process was controlled at -12 °C to 20 °C, and the kettle pressure was controlled at 0.8 MPa - 1.5 MPa. The purified PMVE was pressed into the crude product tank; finally, 2.541 kg of purified PMVE was obtained, and the content of PMVE detected by gas chromatography was 96.8%, and the yield was 86.30%.

[0060] Comparative Example 2

[0061] The difference between this comparative example and Example 1 is that the catalyst only contains cesium fluoride, and the specific preparation steps are as follows:

[0062] Using the preparation device of the present invention, 20 g of cesium fluoride was put into a 10 L reaction kettle containing 700 g of diethylene glycol dimethyl ether and stirred evenly. Then the temperature was lowered to 0 °C to obtain a catalyst solution. 1.3 kg of carbonyl fluoride gas was introduced into the reaction kettle from the acyl fluoride tank by a diaphragm compressor. Then, 3 kg of hexafluoropropylene oxide liquid was added dropwise to the reaction kettle in liquid phase from the hexafluoropropylene oxide tank by a diaphragm compressor for an addition reaction. The dropping rate of the hexafluoropropylene oxide in liquid phase was 0.6 kg / h. After the dropping was completed, the reaction continued for 2 h. During the addition reaction, the temperature in the kettle was maintained at 0 °C to 30 °C, and the reaction pressure was below 1.2 MPa. After the reaction ended, the reaction product was collected into an intermediate receiving tank. After purification, 3.910 kg of the intermediate product perfluoro-2-methoxypropionyl fluoride was obtained, and the purity was above 99.5%.

[0063] 2.7 kg of anhydrous sodium carbonate, 500 g of diethylene glycol dimethyl ether and 40 g of tetraethylene glycol dimethyl ether were added to a decarboxylation and salification kettle and stirred evenly to obtain a mixed solution of carbonate and solvent. 3.910 kg of the intermediate product perfluoro-2-methoxypropionyl fluoride obtained from the addition reaction was added dropwise to the decarboxylation and salification kettle in liquid phase from the intermediate receiving tank for a salification and cracking reaction. The dropping rate of the perfluoro-2-methoxypropionyl fluoride was 1.2 kg / h. After the dropping was completed, stirring and heat preservation were continued for 2 h. The cracking temperature was 160 °C, and the pressure was below 0.6 MPa. After the reaction ended, the distillation kettle was started to recover the solvent. Finally, 3.101 kg of PMVE crude product was obtained, and the content of PMVE detected by gas chromatography was 87.2%.

[0064] The PMVE crude product was pressed into a purification kettle, stirring was started and the second condenser was started for reflux purification. The temperature during the purification process was controlled at -12 °C to 20 °C, and the kettle pressure was controlled at 0.8 MPa - 1.5 MPa. The purified PMVE was pressed into the crude product tank. Finally, 2.770 kg of purified PMVE was obtained. The content of PMVE detected by gas chromatography was 97.5%, and the yield was 94.76%.

[0065] Comparative Example 3

[0066] The difference between this comparative example and Example 1 is that the catalyst consists of potassium fluoride and tetrabutylammonium bromide. The specific preparation steps are as follows:

[0067] Using the preparation device of the present invention, 18.2 g of potassium fluoride and 1.8 g of tetrabutylammonium bromide were put into a 10 L reaction kettle containing 700 g of diethylene glycol dimethyl ether and stirred evenly. Then the temperature was lowered to 0 °C to obtain a catalyst solution. 1.3 kg of carbonyl fluoride gas was introduced into the reaction kettle from the acyl fluoride tank by a diaphragm compressor. Then, 3 kg of hexafluoropropylene oxide liquid was added dropwise to the reaction kettle in liquid phase from the hexafluoropropylene oxide tank by a diaphragm compressor for an addition reaction. The dropping rate of hexafluoropropylene oxide in liquid phase was 0.6 kg / h. After the dropping was completed, the reaction continued for 2 h. During the addition reaction, the temperature in the kettle was maintained at 0 °C to 30 °C, and the reaction pressure was below 1.2 MPa. After the reaction ended, the reaction product was collected into an intermediate receiving tank. After purification, 3.710 kg of the intermediate perfluoro-2-methoxypropionyl fluoride was obtained, and its purity was above 99.5%.

[0068] 2.55 kg of anhydrous sodium carbonate, 500 g of diethylene glycol dimethyl ether and 40 g of tetraethylene glycol dimethyl ether were added to a decarboxylation and salification kettle and stirred evenly to obtain a mixed solution of carbonate and solvent. 3.710 kg of the intermediate perfluoro-2-methoxypropionyl fluoride obtained from the addition reaction was added dropwise to the decarboxylation and salification kettle in liquid phase from the intermediate receiving tank for a salification and cracking reaction. The dropping rate of perfluoro-2-methoxypropionyl fluoride was 1.2 kg / h. After the dropping was completed, stirring and heat preservation were continued for 2 h. The cracking temperature was 160 °C, and the pressure was below 0.6 MPa. After the reaction ended, the distillation kettle was started to recover the solvent. Finally, 2.881 kg of PMVE crude product was obtained, and the content of PMVE detected by gas chromatography was 87.0%.

[0069] The PMVE crude product was pressed into a purification kettle, stirring was started and the second condenser was started for reflux purification. During the purification process, the temperature was controlled at -12 °C to 20 °C, and the kettle pressure was controlled at 0.8 MPa - 1.5 MPa. The purified PMVE was pressed into the crude product tank. Finally, 2.571 kg of purified PMVE was obtained, the content of PMVE detected by gas chromatography was 97.4%, and the yield was 87.87%.

[0070] Comparative Example 4

[0071] The difference between this comparative example and Example 1 is that the catalyst consists of potassium fluoride and lithium fluoride. The specific preparation steps are as follows:

[0072] Using the preparation device of the present invention, 18.2 g of potassium fluoride and 1.8 g of lithium fluoride were put into a 10 L reaction kettle containing 700 g of diethylene glycol dimethyl ether and stirred evenly. Then the temperature was lowered to 0 °C to obtain a catalyst solution. 1.3 kg of carbonyl fluoride gas was introduced into the reaction kettle from the acyl fluoride tank by a diaphragm compressor. Then, 3 kg of hexafluoropropylene oxide liquid was added dropwise to the reaction kettle in liquid phase from the hexafluoropropylene oxide tank by a diaphragm compressor for an addition reaction. The dropping rate of the hexafluoropropylene oxide in liquid phase was 0.6 kg / h. After the dropping was completed, the reaction continued for 2 h. During the addition reaction, the temperature in the kettle was maintained at 0 °C to 30 °C, and the reaction pressure was below 1.2 MPa. After the reaction ended, the reaction product was collected into an intermediate receiving tank. Through purification, 3.682 kg of the intermediate product perfluoro-2-methoxypropionyl fluoride was obtained, and its purity was above 99.5%.

[0073] 2.52 kg of anhydrous sodium carbonate, 500 g of diethylene glycol dimethyl ether and 40 g of tetraethylene glycol dimethyl ether were added to a decarboxylation and salification kettle and stirred evenly to obtain a mixed solution of carbonate and solvent. 3.682 kg of the intermediate product perfluoro-2-methoxypropionyl fluoride obtained from the addition reaction was added dropwise to the decarboxylation and salification kettle in liquid phase from the intermediate receiving tank for a salification and cracking reaction. The dropping rate of the perfluoro-2-methoxypropionyl fluoride was 1.2 kg / h. After the dropping was completed, stirring and heat preservation were continued for 2 h. The cracking temperature was 160 °C, and the pressure was below 0.6 MPa. After the reaction ended, the distillation kettle was started to recover the solvent. Finally, 2.794 kg of PMVE crude product was obtained, and the content of PMVE detected by gas chromatography was 87.2%.

[0074] The PMVE crude product was pressed into a purification kettle, stirring was started and the second condenser was started for reflux purification. The temperature during the purification process was controlled at -12 °C to 20 °C, and the kettle pressure was controlled at 0.8 MPa - 1.5 MPa. The purified PMVE was pressed into the crude product tank. Finally, 2.501 kg of purified PMVE was obtained, and the content of PMVE detected by gas chromatography was 97.3%, and the yield was 85.39%.

[0075] Comparative Example 5

[0076] The difference between this comparative example and Example 1 lies in the different ratio of potassium fluoride to cesium fluoride. The specific preparation steps are as follows:

[0077] Using the preparation apparatus of the present invention, 17 g of potassium fluoride and 3 g of cesium fluoride are put into a 10 L reaction kettle containing 700 g of diethylene glycol dimethyl ether and stirred evenly. Then the temperature is reduced to 0 °C to obtain a catalyst solution. 1.3 kg of carbonyl fluoride gas is introduced into the reaction kettle from the acyl fluoride tank by a diaphragm compressor. Then, 3 kg of hexafluoropropylene oxide liquid is added dropwise to the reaction kettle in liquid phase from the hexafluoropropylene oxide tank by a diaphragm compressor for an addition reaction. The dropping rate of the hexafluoropropylene oxide in liquid phase is 0.6 kg / h. After the dropping is completed, the reaction continues for 2 h. During the addition reaction, the temperature in the kettle is maintained at 0 °C to 30 °C, and the reaction pressure is below 1.2 MPa. After the reaction is completed, the reaction product is collected into an intermediate receiving tank. Through purification and collection, 3.905 kg of the intermediate product perfluoro-2-methoxypropionyl fluoride is obtained, and the purity is above 99.5%.

[0078] 2.7 kg of anhydrous sodium carbonate, 500 g of diethylene glycol dimethyl ether and 40 g of tetraethylene glycol dimethyl ether are added to a decarboxylation and salification kettle and stirred evenly to obtain a mixed solution of carbonate and solvent. 3.905 kg of the intermediate product perfluoro-2-methoxypropionyl fluoride obtained from the addition reaction is added dropwise to the decarboxylation and salification kettle in liquid phase from the intermediate receiving tank for a salification and cracking reaction. The dropping rate of the perfluoro-2-methoxypropionyl fluoride is 1.2 kg / h. After the dropping is completed, stirring and heat preservation continue for 2 h. The cracking temperature is 120 °C, and the pressure is below 0.6 MPa. After the reaction is completed, the distillation kettle is started to recover the solvent. Finally, 3.085 kg of PMVE crude product is obtained, and the content of PMVE detected by gas chromatography is 87.2%.

[0079] The PMVE crude product is pressed into a purification kettle, stirring is started and the second condenser is started for reflux purification. The temperature during the purification process is controlled at -12 °C to 20 °C, and the kettle pressure is controlled at 0.8 MPa - 1.5 MPa. The purified PMVE is pressed into the crude product tank. Finally, 2.764 kg of purified PMVE is obtained. The content of PMVE detected by gas chromatography is 97.2%, and the yield is 94.27%.

[0080] Comparative Example 6

[0081] The difference between this comparative example and Example 1 lies in the different ratio of potassium fluoride to cesium fluoride. The specific preparation steps are as follows:

[0082] By using the preparation device of the present invention, 19.5g of potassium fluoride and 0.5g of cesium fluoride are put into a 10L reactor containing 700g of diethylene glycol dimethyl ether and stirred evenly, and the temperature is lowered to 0°C to obtain a catalyst solution. 1.3kg of carbonyl fluoride gas 3 is introduced into the reactor from the acyl fluoride tank through a diaphragm compressor, and then 3kg of hexafluoropropylene oxide liquid is dripped from the hexafluoropropylene oxide tank to the liquid phase in the reactor through a diaphragm compressor for addition reaction, the rate of dripping the hexafluoropropylene oxide liquid phase is 0.6kg / h, and the reaction is continued for 2h after the dripping is completed. During the addition reaction, the temperature in the reactor is kept at 0°C to 30°C, and the reaction pressure is below 1.2MPa; after the reaction is completed, the reaction product is collected to an intermediate receiving tank; after purification and collection, 3.705kg of the intermediate product perfluoro-2-methoxypropionyl fluoride is obtained, and the purity is above 99.5%.

[0083] 2.54 kg of anhydrous sodium carbonate, 500 g of diethylene glycol dimethyl ether and 40 g of tetraethylene glycol dimethyl ether are added to the decarboxylation salt-forming kettle and stirred evenly to obtain a mixed solution of carbonate and solvent; 3.705 kg of the intermediate product perfluoro-2-methoxypropionyl fluoride obtained by the addition reaction is added dropwise from the liquid phase in the intermediate receiving tank to the decarboxylation salt-forming kettle for salt-forming cracking reaction, the dropping rate of perfluoro-2-methoxypropionyl fluoride is 1.2 kg / h, and after the dropwise addition is completed, stirring and heat preservation are continued for 2 hours, the cracking temperature is 120°C, and the pressure is below 0.6 MPa; after the reaction is completed, the distillation kettle is started to recover the solvent; finally 2.858 kg of PMVE crude product is obtained, and the PMVE content detected by gas chromatography is 87.0%.

[0084] The crude PMVE was pressed into a purification kettle, stirring was turned on and the second condenser was started for reflux purification. The temperature of the purification process was controlled at -12°C ~ 20°C, the kettle pressure was controlled at 0.8MPa-1.5MPa, and the purified PMVE was pressed into a crude product tank; finally, 2.552kg of purified PMVE was obtained, and the PMVE content was 97.3% as determined by gas chromatography, with a yield of 87.13%.

[0085] Comparative Example 7

[0086] The difference between this comparative example and Example 1 is that hexafluoropropylene oxide is added in one go through the gas phase. The specific preparation steps are as follows:

[0087] 18.2 g of potassium fluoride and 1.8 g of cesium fluoride were put into a 10 L reactor containing 700 g of diglyme and stirred evenly. The temperature was lowered to 0 °C to obtain a catalyst solution. 1.3 kg of carbonyl fluoride gas and 3 kg of hexafluoropropylene oxide gas were introduced into the reactor from the acyl fluoride tank and the hexafluoropropylene oxide tank respectively by a diaphragm compressor for an addition reaction. During the addition reaction, the temperature in the reactor was maintained at 0 °C to 30 °C, the reaction time was 2 h, and the reaction pressure was below 1.2 MPa. After the reaction ended, the reaction product was collected into an intermediate receiving tank. After purification, 3.708 kg of perfluoro-2-methoxypropionyl fluoride, the intermediate product, was obtained with a purity of over 99.5%.

[0088] 2.54 kg of anhydrous sodium carbonate, 500 g of diglyme and 40 g of tetraethylene glycol dimethyl ether were added to a decarboxylation and salification kettle and stirred evenly to obtain a mixed solution of carbonate and solvent. 3.708 kg of the intermediate product perfluoro-2-methoxypropionyl fluoride obtained from the addition reaction was added dropwise in liquid phase from the intermediate receiving tank to the decarboxylation and salification kettle for a salification and cracking reaction. The dropping rate of perfluoro-2-methoxypropionyl fluoride was 1.2 kg / h. After the dropping was completed, stirring was continued for heat preservation for 2 h. The cracking temperature was 160 °C and the pressure was below 0.6 MPa. After the reaction ended, the distillation kettle was started to recover the solvent. Finally, 2.873 kg of PMVE crude product was obtained. The content of PMVE detected by gas chromatography was 87.1%.

[0089] The PMVE crude product was pressed into a purification kettle, stirring was started and the second condenser was started for reflux purification. The temperature during the purification process was controlled at -12 °C to 20 °C, and the kettle pressure was controlled at 0.8 MPa - 1.5 MPa. The purified PMVE was pressed into the crude product tank. Finally, 2.564 kg of purified PMVE was obtained. The content of PMVE detected by gas chromatography was 97.5%, and the yield was 87.72%.

[0090] The above results show that by controlling the catalyst composition and the raw material addition method, the present invention successfully obtained perfluoromethyl vinyl ether with a high yield. The yield of perfluoromethyl vinyl ether after purification was 91% - 95%, and the purity was 96.5% - 98%, showing good application effects. Especially for the methods described in Examples 1 - 3, by controlling the dropping rate of the reactants in liquid phase, the yield of perfluoromethyl vinyl ether obtained was over 90%, which was suitable for industrial production.

[0091] By comparing Example 1 and Comparative Examples 1-4, it can be seen that although a higher yield can be obtained by using cesium fluoride alone as a catalyst, cesium fluoride is expensive and has poor economic efficiency, and is not suitable for industrial application; and potassium fluoride alone has poor catalytic activity, resulting in a low yield; on the basis of potassium fluoride as the main catalyst, adding a co-catalyst to synergistically improve the catalytic activity of potassium fluoride is a relatively economical and effective method. However, the selection of co-catalysts will also affect the product yield. When a conventional surfactant is selected as a co-catalyst, it is found by comparison that the reaction yield is not improved, and the addition of a phase transfer catalyst has no obvious effect; when lithium fluoride is selected as a co-catalyst, due to the relatively low activity of lithium fluoride, the reaction effect is poor, and the yield of the intermediate product is not improved. The inventors have found that only when potassium fluoride and cesium fluoride are used as catalysts at the same time, the catalytic effect is good, and the yield of the intermediate product can reach more than 90%.

[0092] By comparing Example 1 and Comparative Examples 5-6, it can be seen that on the basis of selecting potassium fluoride and cesium fluoride as catalysts, when only the two are added in a specific ratio, the yield of the intermediate product is higher, when the proportion of cesium fluoride is too high, the yield of the intermediate remains basically unchanged; when the proportion of cesium fluoride is too low, the yield will be reduced.

[0093] By comparing Example 1 and Comparative Example 7, it can be seen that the addition method of the raw materials in the intermediate synthesis process and the intermediate salt-forming cleavage process has a great influence on the product yield: when hexafluoropropylene oxide is added in the gas phase in the intermediate synthesis process, its contact area with carbonyl fluoride and the catalyst is small, and the reaction is not sufficient; when perfluoro-2-methoxypropionyl fluoride is added to the mixed solution of carbonate and solvent at one time in the intermediate salt-forming cleavage process, the salt-forming cleavage reaction is not sufficient; when hexafluoropropylene oxide and perfluoro-2-methoxypropionyl fluoride are added dropwise in the liquid phase, it is conducive to the full reaction, and the reaction yield is higher at this time.

[0094] By comparing Example 1 and Example 4, it can be seen that the first step of the reaction to generate the intermediate product perfluoro-2-methoxypropionyl fluoride is a key step, and the yield of the intermediate product greatly affects the yield of the target product PMVE. In the process of preparing the intermediate product perfluoro-2-methoxypropionyl fluoride by the addition reaction, it is also necessary to control the liquid phase dripping rate of hexafluoropropylene oxide. Too slow dripping will lead to a decrease in the synthesis efficiency, while too fast dripping will easily produce impurities, resulting in a decrease in the yield of the target product.

[0095] In summary, the present invention uses potassium fluoride and cesium fluoride as catalysts and carbonyl fluoride and hexafluoropropylene oxide as raw materials to prepare perfluoromethyl vinyl ether in two steps. The reaction can be fully carried out by controlling the ratio of potassium fluoride and cesium fluoride and the addition method of the raw materials in the two-step reaction. The preparation method and preparation device of the present invention can prepare perfluoromethyl vinyl ether with a high yield, which is suitable for industrial promotion.

[0096] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the essence and scope of the present invention. Various modifications made by those of ordinary skill in the art to the above embodiments after reading this specification all fall within the scope protected by the present invention.

Claims

1. A method for preparing perfluoromethyl vinyl ether, characterized in that, It includes the following preparation steps: (1) Add a catalyst and a solvent into a reaction kettle, stir evenly to obtain a catalyst solution; introduce carbonyl fluoride gas into the catalyst solution, and then dropwise add hexafluoropropylene oxide liquid into the catalyst solution in a liquid phase for an addition reaction to obtain an intermediate product, perfluoro-2-methoxypropionyl fluoride; wherein, the catalyst contains potassium fluoride and cesium fluoride, and the mass ratio of potassium fluoride to cesium fluoride is 10-20:1; (2) Dropwise add the intermediate product, perfluoro-2-methoxypropionyl fluoride, into a mixed solution of carbonate and solvent in a liquid phase for a salt-forming cleavage reaction to obtain a crude product of perfluoromethyl vinyl ether.

2. The method for preparing perfluoromethyl vinyl ether according to claim 1, characterized in that, In step (1), the mass ratio of the catalyst, the solvent to hexafluoropropylene oxide is 1:30-80:100-200.

3. The method for preparing perfluoromethyl vinyl ether according to claim 1, characterized in that, In step (1), the molar ratio of carbonyl fluoride to hexafluoropropylene oxide is 1-1.

2.

4. The method for preparing perfluoromethyl vinyl ether according to claim 1, characterized in that, In step (1), the dropping rate of the hexafluoropropylene oxide in the liquid phase is 0.5 kg / h-1.5 kg / h.

5. The method for preparing perfluoromethyl vinyl ether according to claim 1, characterized in that, In step (1), the temperature of the addition reaction is 0°C-30°C, the pressure is 0.5 MPa-1.2 MPa, and after the dropping of the hexafluoropropylene oxide is completed, it is kept warm for 0.5 h-3 h.

6. The method for preparing perfluoromethyl vinyl ether according to claim 1, characterized in that, In step (2), the dropping rate of the perfluoro-2-methoxypropionyl fluoride in the liquid phase is 1 kg / h-2 kg / h.

7. The method for preparing perfluoromethyl vinyl ether according to claim 1, characterized in that, In step (2), the temperature of the salt-forming cleavage reaction is 80°C-170°C, the pressure is 0.1 MPa-0.6 MPa, and after the dropping of the perfluoro-2-methoxypropionyl fluoride is completed, it is refluxed and kept warm for 1 h-3 h.

8. A perfluoromethyl vinyl ether preparation device, characterized in that, It includes an acyl fluoride tank, a hexafluoropropylene oxide tank, a reaction kettle, an intermediate receiving tank and a salt-forming decarboxylation kettle. The acyl fluoride tank and the hexafluoropropylene oxide tank are connected to the bottom of the reaction kettle through a diaphragm compressor. A first condenser, a purification kettle and a crude product receiving tank are sequentially connected outside the salt-forming decarboxylation kettle. A second condenser is also connected outside the purification kettle, and the purification kettle and the second condenser form a reflux.

9. The perfluoromethyl vinyl ether preparation device according to claim 8, characterized in that, A distillation kettle is also connected outside the salt-forming decarboxylation kettle, and a distillation column is arranged at the top of the distillation kettle; an internal coil is arranged in the reaction kettle, and chilled brine is passed through the internal coil; both the salt-forming decarboxylation kettle and the distillation kettle are provided with heating components.

10. The perfluoromethyl vinyl ether preparation device according to claim 8, characterized in that, The feed pipe at the bottom of the reaction kettle is in an "n" shape.

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