Method for continuously preparing hexafluoropropylene oxide dimer

Abstract

The invention relates to the field of fluorine-containing fine chemicals, and discloses a method for continuously preparing a hexafluoropropylene oxide dimer. The method comprises the following steps: mixing an organic solvent with specific moisture, a composite catalyst consisting of an organic amine catalyst and a metal salt catalyst, and a polymer inhibitor, continuously adding hexafluoropropylene oxide in a nitrogen environment, and continuously synthesizing the hexafluoropropylene oxide dimer through reaction at a certain reaction temperature and stirring rate. Compared with an existing hexafluoropropylene oxide dimer preparation technology, the preparation method has the advantages that the dosage of the composite catalyst is small, the catalytic efficiency is high, the environmental protection property is good, and the yield of the obtained hexafluoropropylene oxide dimer is high; meanwhile, the process and used equipment are simple, easy to operate, low in cost and suitable for industrial continuous production.

Description

Technical Field

[0001] The invention relates to the field of fluorine-containing fine chemicals, and in particular to a method for continuously preparing hexafluoropropylene oxide dimer. Background Art

[0002] Hexafluoropropylene oxide dimer, also known as perfluoro(2-methyl-3-oxahexyl)fluoride, is a colorless and transparent liquid at room temperature, volatile, and stored at low temperatures. Its molecular formula is C6F 12 O2, boiling point 54~56℃, molecular weight 332.044, density about 1.61g / cm 3 , refractive index is about 1.3, CAS number is 2062-98-8.

[0003] Hexafluoropropylene oxide dimer is a fluorine-containing polymer. Because of the "shielding" effect of the carbon-fluorine bond in the dimer molecule on the main chain, it has very high chemical inertness, non-flammability, oxidation resistance, corrosion resistance and radiation resistance. Stabilizing the acyl fluoride end groups of the dimer can prepare perfluoropolyether materials with properties such as heat resistance, radiation resistance, corrosion resistance, flame retardancy, chemical inertness, low freezing point, and low surface tension. It is widely used in the fields of chemical industry, electronics, electrical appliances, machinery, nuclear industry, aerospace, magnetic media, textiles, etc. Among them, as an important fluorine-containing monomer, the dimer is an important raw material for the synthesis of perfluoro n-propyl vinyl ether (PPVE). PPVE can be used to modify a variety of fluoroplastics and fluororubbers to improve product performance; at the same time, PPVE can also be copolymerized with tetrafluoroethylene or other olefins to prepare high-end fluorine-containing products such as soluble polytetrafluoroethylene (PFA), with broad application prospects.

[0004] At present, patents on the preparation method of hexafluoropropylene oxide dimer are not uncommon at home and abroad, but patents on the continuous preparation of hexafluoropropylene oxide dimer are rarely seen, and the common patents have high process requirements and complex operations. In Japanese patent JP 62195345, cesium fluoride is used as a catalyst, and different amounts of water are added to prepare hexafluoropropylene oxide oligomers. The selectivity of hexafluoropropylene oxide dimer in the product of this method is not high, and it needs to be carried out under a -20°C environment, the conditions are harsh, and the actual operation is difficult. In addition, the catalyst cesium fluoride is expensive, which is not conducive to large-scale production. In Chinese patent CN1044092A, German Herchester AG mentioned the use of a catalytic system composed of transition metal salts such as CuCl2, CoCl2, ZnCl2, etc. and tertiary diamines, and the resulting hexafluoropropylene oxide dimer has a low yield, a long reaction time, a high reaction pressure, and a complex process. Chinese patent CN 108264458 A mentions that in a polar aprotic solvent, hexafluoropropylene oxide is used as a raw material, a phase transfer agent is added, and a composite catalyst composed of tertiary amine and tertiary diamine is used to prepare hexafluoropropylene oxide dimer through reaction. The catalysts of this method all use organic amines, which have a high dosage and increase material costs; the catalytic efficiency is low, the reaction time is increased, and it is not conducive to industrial production; and the catalyst dosage is large and the environmental protection is poor. Chinese patent CN117486714A mentions that an imidazole-type ionic liquid is used as a catalyst to prepare hexafluoropropylene oxide dimer, but this method requires a long activation time for the catalyst, the catalyst is difficult to obtain, the cost is high, and it is not suitable for industrial production and application, and the selectivity of the hexafluoropropylene oxide dimer prepared by this method is not significantly improved.

[0005] Currently, there is no related method for the continuous preparation of hexafluoropropylene oxide dimer in the published patents and literature. Therefore, from the perspective of industrial production, how to achieve the continuous production of hexafluoropropylene oxide dimer while ensuring the high conversion rate and selectivity of the raw material hexafluoropropylene oxide is an urgent problem to be solved in the production process. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems in the prior art and provide a method for continuously preparing hexafluoropropylene oxide dimer which is simple to operate, low in price and can be industrially produced. The method can simultaneously ensure high selectivity of hexafluoropropylene oxide and high yield of hexafluoropropylene oxide dimer.

[0007] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0008] A method for continuously preparing hexafluoropropylene oxide dimer comprises the following steps: mixing an organic solvent with a specific water content, a composite catalyst composed of an organic amine catalyst and a metal salt catalyst, and a polymer inhibitor, and continuously adding hexafluoropropylene oxide thereto under a nitrogen environment to continuously synthesize the hexafluoropropylene oxide dimer through reaction.

[0009] Preferably, the method comprises the following steps:

[0010] S1, fully mixing an organic solvent with a specific water content, a composite catalyst, and a polymer inhibitor, and then adding the mixture into a reactor, continuously introducing hexafluoropropylene oxide into the system at a uniform speed under a nitrogen environment, and controlling the reaction to proceed at a certain stirring rate and temperature; when the volume of the material in the reactor exceeds 80% of the total volume of the reactor, opening the discharge valve at the bottom of the reactor to discharge the lower layer product, wherein the lower layer product is a crude hexafluoropropylene oxide dimer; and repeating the cycle until the reaction rate decreases significantly;

[0011] S2, after the reaction is completed, the mixed product in the reactor is separated to obtain a crude hexafluoropropylene oxide dimer, and the organic solvent and the composite catalyst are recovered; the obtained crude hexafluoropropylene oxide dimer is purified by distillation to obtain a high-purity hexafluoropropylene oxide dimer.

[0012] Preferably, the organic solvent is at least one of acetonitrile, propionitrile, butyronitrile, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, dichloromethane and tetrahydrofuran; and the water content in the organic solvent is 200 to 1200 ppm.

[0013] More preferably, the water content in the organic solvent is 300 to 800 ppm.

[0014] Preferably, the organic amine catalyst is at least one of N,N-dimethylaniline, tetramethylurea, N,N,N,N-tetramethylmethanediamine, tetramethylpropylenediamine, tetrabutylammonium fluoride, and N,N-dimethylformamide;

[0015] The metal salt catalyst is at least one of magnesium fluoride, zinc fluoride, manganese fluoride, silver nitrate, cuprous chloride, and potassium iodide;

[0016] The molar ratio of the organic amine catalyst to the metal salt catalyst is 1:(1-5).

[0017] More preferably, the molar ratio of the organic amine catalyst to the metal salt catalyst is 1:(1-2).

[0018] Preferably, the polymer inhibitor is at least one of methanol, toluene and xylene;

[0019] The mass ratio of the organic solvent to the polymer inhibitor is 1000:(1-5).

[0020] More preferably, the mass ratio of the organic solvent to the polymer inhibitor is 1000:(2-4).

[0021] The polymer inhibitor mainly inhibits the formation of hexafluoropropylene oxide trimer and higher polymers. The polymer inhibitor mainly reduces the activity of the composite catalyst to prevent the chain growth reaction, thereby reducing the formation of polymers and increasing the selectivity of dimers.

[0022] Preferably, stirring is performed during the reaction, and the stirring rate is 200 to 600 r / min.

[0023] More preferably, the stirring rate is 300-500 r / min.

[0024] Preferably, the reaction temperature during the reaction is -40 to 50°C.

[0025] More preferably, the reaction temperature is 10-40°C.

[0026] Preferably, the purity of the hexafluoropropylene oxide is not less than 99.5%; the hexafluoropropylene oxide is added by passing it into the bottom of the reaction liquid through a gas flow meter, and the addition rate of the hexafluoropropylene oxide is 2 to 10 g / min.

[0027] More preferably, the addition rate of hexafluoropropylene oxide is 4 to 8 g / min.

[0028] Preferably, the molar ratio of the organic solvent to the composite catalyst is (50-200):1.

[0029] Further preferably, the molar ratio of the organic solvent to the composite catalyst is (50-100):1.

[0030] The composite catalyst works mainly through the metal ions in the metal salt catalyst and the organic amine catalyst forming a complex through homogenization in an organic solvent. The two use the formed complex as a composite catalyst to promote the efficient progress of the reaction.

[0031] Preferably, the molar ratio of the organic solvent to hexafluoropropylene oxide is 1:(1-8).

[0032] More preferably, the molar ratio of the organic solvent to hexafluoropropylene oxide is 1:(3-6).

[0033] Specifically, the step S1 is as follows:

[0034] S1.1 The organic solvent, composite catalyst and polymer inhibitor are fully mixed and added into a vertical reactor equipped with a stirring device and a bottom discharge valve;

[0035] S1.2 Fully replace the reactor with nitrogen to completely remove the air in the reactor, then evacuate to -0.1~-0.08MPa and stir at room temperature for 5~10min;

[0036] S1.3 Control the material temperature in the reactor at 10-30°C, and continuously add hexafluoropropylene oxide into the reactor through a gas flow meter. When the volume of the material in the reactor exceeds 80% of the total volume of the reactor, open the discharge valve at the bottom of the reactor to discharge the lower layer product, and repeat this cycle until the reaction rate decreases significantly; the lower layer product is a crude hexafluoropropylene oxide dimer.

[0037] In the process of steps S1.1 and S1.2, after the addition of materials in the reactor is completed, nitrogen is fully replaced first, and then vacuum treatment is performed, but this process cannot achieve a complete vacuum state, and a certain amount of nitrogen will remain in the reactor, so it is considered that the overall environment is still in a nitrogen environment. Therefore, in step S1.3, hexafluoropropylene oxide is added to the reactor under a nitrogen environment.

[0038] Specifically, step S2 is as follows:

[0039] S2.1 After the reaction is completed, the mixed product in the reactor is further separated to obtain a crude hexafluoropropylene oxide dimer product, and the obtained crude hexafluoropropylene oxide dimer product is distilled and purified to obtain a hexafluoropropylene oxide dimer product;

[0040] S2.2 Recover the organic solvent and composite catalyst.

[0041] The continuity of the present invention means that in step S1, when the volume of the material in the reactor exceeds 80% of the total volume of the reactor, the discharge valve at the bottom of the reactor is opened, and the material is still fed normally during the process of discharging the lower layer product, and the reaction does not need to be interrupted and can maintain continuity.

[0042] The reason why the reaction rate is significantly reduced is that: a catalyst is used in the reaction of the present invention, but the amount of the catalyst used is limited, and the entire reaction system will become more and more complicated as the reaction proceeds, so the catalysis is limited; when the catalytic efficiency is significantly reduced, the reaction rate will decrease; the reactor is a closed container, and the pressure in the reactor remains unchanged during normal reaction, but when the reaction rate decreases, the pressure in the reactor will gradually increase, so when the catalyst efficiency decreases and the reaction rate decreases significantly, the reaction needs to be interrupted; then the reaction product is collected and the solvent and catalyst are recovered. The solvent and catalyst can be recycled and reused many times.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] Compared with the existing hexafluoropropylene oxide dimer preparation technology, the invention has the advantages of less composite catalyst usage, high catalytic efficiency, good environmental protection, and high hexafluoropropylene oxide dimer yield; at the same time, the process and the equipment used are simple, easy to operate, low cost, and suitable for industrial continuous production. DETAILED DESCRIPTION

[0045] In order to further explain the method of the present invention in more detail, the method for continuously preparing hexafluoropropylene oxide dimer of the present invention is described below in conjunction with preferred embodiments. Although the preferred embodiments of the present invention are described in the embodiments, it should be understood that they cannot be regarded as limiting the scope of protection of the present invention.

[0046] The reagents used in the present invention are purchased from conventional channels or prepared by existing technical methods.

[0047] Comparative Example 1

[0048] 400mL of acetonitrile (600ppm of water), 7g of N,N,N,N-tetramethylethylenediamine, and 6g of triethylamine were fully homogenized and mixed, and then added to a 2L 316L stainless steel vertical reactor with a temperature control jacket. After the reactor was fully replaced with nitrogen, it was evacuated to -0.1~-0.08MPa and stirred at room temperature for 5~10min. The temperature in the reactor was controlled by the temperature control jacket to maintain 20±0.5℃, the stirring rate was set to 300r / min, and hexafluoropropylene oxide was continuously introduced into the bottom of the reactor at a rate of 5g / min through a gas flowmeter. When the material volume reached 80% of the reactor volume, the discharge valve at the bottom of the reactor was opened, and the crude hexafluoropropylene oxide dimer of the lower layer was taken out in an appropriate amount until 3Kg of hexafluoropropylene oxide raw material was introduced, and the feeding was stopped, and the reaction was continued for 30min to terminate the reaction.

[0049] The material was taken out from the reactor for conventional liquid separation, the upper layer of solvent and catalyst were recovered, and the lower layer was the crude hexafluoropropylene oxide dimer, which was then purified by distillation to obtain the product hexafluoropropylene oxide dimer. Among them, the hexafluoropropylene oxide conversion rate was 82.6%, the hexafluoropropylene oxide dimer after distillation and purification had a GC purity of 99.3%, and a GC yield of 59.4%.

[0050] Comparative Example 2

[0051] 400mL of acetonitrile (600ppm of water), 7g of N,N,N,N-tetramethylethylenediamine, and 6g of cuprous chloride were fully homogenized and mixed, and then added to a 2L 316L stainless steel vertical reactor with a temperature control jacket. After the reactor was fully replaced with nitrogen, it was evacuated to -0.1~-0.08MPa and stirred at room temperature for 5~10min. The temperature in the reactor was controlled by the temperature control jacket to maintain 20±0.5℃, the stirring rate was set to 300r / min, and hexafluoropropylene oxide was continuously introduced into the bottom of the reactor at a rate of 5g / min through a gas flowmeter. When the material volume reached 80% of the reactor volume, the discharge valve at the bottom of the reactor was opened, and the crude hexafluoropropylene oxide dimer of the lower layer was taken out in an appropriate amount until 3Kg of hexafluoropropylene oxide raw material was introduced, and the feeding was stopped, and the reaction was continued for 30min to terminate the reaction.

[0052] The material was taken out from the reactor for conventional liquid separation, the upper layer of solvent and catalyst were recovered, and the lower layer was the crude hexafluoropropylene oxide dimer, which was then purified by distillation to obtain the product hexafluoropropylene oxide dimer. Among them, the hexafluoropropylene oxide conversion rate was 90.3%, the hexafluoropropylene oxide dimer after distillation and purification had a GC purity of 99.3%, and a GC yield of 77.8%.

[0053] Example 1

[0054] 400mL of acetonitrile (600ppm of water), 7.26g of N,N-dimethylaniline, 6g of cuprous chloride, and 1g of toluene were fully homogenized and mixed, and then added to a 2L 316L stainless steel vertical reactor with a temperature control jacket. After the reactor was fully replaced with nitrogen, it was evacuated to -0.1~-0.08MPa and stirred at room temperature for 5~10min. The temperature in the reactor was controlled by the temperature control jacket to maintain 20±0.5℃, the stirring rate was set to 300r / min, and hexafluoropropylene oxide was continuously introduced into the bottom of the reactor at a rate of 5g / min through a gas flowmeter. When the material volume reached 80% of the reactor volume, the discharge valve at the bottom of the reactor was opened, and the crude hexafluoropropylene oxide dimer of the lower layer was taken out in an appropriate amount until 3Kg of hexafluoropropylene oxide raw material was introduced, and the feeding was stopped, and the reaction was continued for 30min to terminate the reaction.

[0055] The material was taken out from the reactor for conventional liquid separation, the upper layer of solvent and catalyst were recovered, and the lower layer was crude hexafluoropropylene oxide dimer, which was then distilled and purified to obtain the product hexafluoropropylene oxide dimer. Among them, the hexafluoropropylene oxide conversion rate was 98.7%, the hexafluoropropylene oxide dimer after distillation and purification had a GC purity of 99.5%, and a GC yield of 90.4%.

[0056] Example 2

[0057] 400mL of acetonitrile (700ppm of water), 4.4g of N,N-dimethylformamide, 6.2g of zinc fluoride, and 1g of toluene were fully homogenized and mixed, and then added to a 2L 316L stainless steel vertical reactor with a temperature control jacket. After the reactor was fully replaced with nitrogen, it was evacuated to -0.1~-0.08MPa and stirred at room temperature for 5~10min. The temperature in the reactor was controlled by the temperature control jacket to maintain 20±0.5℃, the stirring rate was set to 300r / min, and hexafluoropropylene oxide was continuously introduced into the bottom of the reactor at a rate of 5g / min through a gas flowmeter. When the material volume reached 80% of the reactor volume, the discharge valve at the bottom of the reactor was opened, and the crude hexafluoropropylene oxide dimer of the lower layer was taken out in an appropriate amount until 3Kg of hexafluoropropylene oxide raw material was introduced, and the feeding was stopped, and the reaction was continued for 30min to terminate the reaction.

[0058] The material was taken out from the reactor for conventional liquid separation, the upper layer of solvent and catalyst were recovered, and the lower layer was the crude hexafluoropropylene oxide dimer, which was then distilled and purified to obtain the product hexafluoropropylene oxide dimer. Among them, the hexafluoropropylene oxide conversion rate was 97.8%, the hexafluoropropylene oxide dimer after distillation and purification had a GC purity of 99.5%, and a GC yield of 83.8%.

[0059] Example 3

[0060] 400mL of acetonitrile (water content 400ppm), 7.26g of N,N-dimethylaniline, 6g of cuprous chloride, and 1g of methanol were fully homogenized and mixed, and then added to a 2L 316L stainless steel vertical reactor with a temperature control jacket. After the reactor was fully replaced with nitrogen, it was evacuated to -0.1~-0.08MPa and stirred at room temperature for 5~10min. The temperature in the reactor was controlled by the temperature control jacket to maintain 20±0.5℃, the stirring rate was set to 300r / min, and hexafluoropropylene oxide was continuously introduced into the bottom of the reactor at a rate of 5g / min through a gas flowmeter. When the material volume reached 80% of the reactor volume, the discharge valve at the bottom of the reactor was opened, and the crude hexafluoropropylene oxide dimer of the lower layer was taken out in an appropriate amount until 3Kg of hexafluoropropylene oxide raw material was introduced, and the feeding was stopped, and the reaction was continued for 30min to terminate the reaction.

[0061] The material was taken out from the reactor for conventional liquid separation, the upper layer of solvent and catalyst were recovered, and the lower layer was the crude hexafluoropropylene oxide dimer, which was then purified by distillation to obtain the product hexafluoropropylene oxide dimer. Among them, the hexafluoropropylene oxide conversion rate was 98.3%, the hexafluoropropylene oxide dimer after distillation and purification had a GC purity of 99.6%, and a GC yield of 91.7%.

[0062] Example 4

[0063] 400mL of acetonitrile (700ppm of water), 7g of tetramethylurea, 6g of cuprous chloride, and 1g of methanol were fully homogenized and mixed, and then added to a 2L 316L stainless steel vertical reactor with a temperature control jacket. After the reactor was fully replaced with nitrogen, it was evacuated to -0.1~-0.08MPa, and stirred at room temperature for 5~10min. The temperature in the reactor was controlled by the temperature control jacket to maintain 20±0.5℃, the stirring rate was set to 300r / min, and hexafluoropropylene oxide was continuously introduced into the bottom of the reactor at a rate of 5g / min through a gas flowmeter. When the material volume reached 80% of the reactor volume, the discharge valve at the bottom of the reactor was opened, and the crude hexafluoropropylene oxide dimer of the lower layer was taken out in an appropriate amount until 3Kg of hexafluoropropylene oxide raw material was introduced, and the feeding was stopped, and the reaction was continued for 30min to terminate the reaction.

[0064] The material was taken out from the reactor for conventional liquid separation, the upper layer of solvent and catalyst were recovered, and the lower layer was the crude hexafluoropropylene oxide dimer, which was then purified by distillation to obtain the product hexafluoropropylene oxide dimer. Among them, the hexafluoropropylene oxide conversion rate was 98.3%, the hexafluoropropylene oxide dimer after distillation and purification had a GC purity of 99.5%, and a GC yield of 89.9%.

[0065] Example 5

[0066] 400mL of tetrahydrofuran (700ppm of water), 13g of tetrabutylammonium fluoride, 5g of cuprous chloride, and 1g of xylene were fully homogenized and mixed, and then added to a 2L 316L stainless steel vertical reactor with a temperature control jacket. After the reactor was fully replaced with nitrogen, it was evacuated to -0.1-0.08MPa, and stirred at room temperature for 5-10min. The temperature in the reactor was controlled by the temperature control jacket to maintain 20±0.5°C, the stirring rate was set to 300r / min, and hexafluoropropylene oxide was continuously introduced into the bottom of the reactor at a rate of 5g / min through a gas flowmeter. When the material volume reached 80% of the reactor volume, the discharge valve at the bottom of the reactor was opened, and the crude hexafluoropropylene oxide dimer of the lower layer was taken out in an appropriate amount until 3Kg of hexafluoropropylene oxide raw material was introduced, and the feeding was stopped, and the reaction was continued for 30min to terminate the reaction.

[0067] The material was taken out from the reactor for conventional liquid separation, the upper layer of solvent and catalyst were recovered, and the lower layer was the crude hexafluoropropylene oxide dimer, which was then purified by distillation to obtain the product hexafluoropropylene oxide dimer. Among them, the hexafluoropropylene oxide conversion rate was 98.1%, the hexafluoropropylene oxide dimer after distillation and purification had a GC purity of 99.4%, and a GC yield of 89.5%.

[0068] Example 6

[0069] 400mL of tetrahydrofuran (700ppm of water), 5g of N,N,N,N-tetramethylmethanediamine, 8.2g of silver nitrate, and 1g of toluene were fully homogenized and mixed, and then added to a 2L 316L stainless steel vertical reactor with a temperature control jacket. After the reactor was fully replaced with nitrogen, it was evacuated to -0.1~-0.08MPa and stirred at room temperature for 5~10min. The temperature in the reactor was controlled by the temperature control jacket to maintain 20±0.5℃, the stirring rate was set to 300r / min, and hexafluoropropylene oxide was continuously introduced into the bottom of the reactor at a rate of 5g / min through a gas flowmeter. When the material volume reached 80% of the reactor volume, the discharge valve at the bottom of the reactor was opened, and the crude hexafluoropropylene oxide dimer of the lower layer was taken out in an appropriate amount until 3Kg of hexafluoropropylene oxide raw material was introduced, and the feeding was stopped, and the reaction was continued for 30min to terminate the reaction.

[0070] The material was taken out from the reactor for conventional liquid separation, the upper layer of solvent and catalyst were recovered, and the lower layer was the crude hexafluoropropylene oxide dimer, which was then purified by distillation to obtain the product hexafluoropropylene oxide dimer. Among them, the hexafluoropropylene oxide conversion rate was 97.7%, the hexafluoropropylene oxide dimer after distillation and purification had a GC purity of 99.4%, and a GC yield of 85.9%.

[0071] Example 7

[0072] 400mL of tetrahydrofuran (400ppm of water), 13g of tetrabutylammonium fluoride, 5g of cuprous chloride, and 1g of toluene were fully homogenized and mixed, and then added to a 2L 316L stainless steel vertical reactor with a temperature control jacket. After the reactor was fully replaced with nitrogen, it was evacuated to -0.1-0.08MPa, and stirred at room temperature for 5-10min. The temperature in the reactor was controlled by the temperature control jacket to maintain 20±0.5°C, the stirring rate was set to 300r / min, and hexafluoropropylene oxide was continuously introduced into the bottom of the reactor at a rate of 5g / min through a gas flow meter. When the material volume reached 80% of the reactor volume, the discharge valve at the bottom of the reactor was opened, and the crude hexafluoropropylene oxide dimer of the lower layer was taken out in an appropriate amount until 3Kg of hexafluoropropylene oxide raw material was introduced, and the feeding was stopped, and the reaction was continued for 30min to terminate the reaction.

[0073] The material was taken out from the reactor for conventional liquid separation, the upper layer of solvent and catalyst were recovered, and the lower layer was the crude hexafluoropropylene oxide dimer, which was then purified by distillation to obtain the product hexafluoropropylene oxide dimer. Among them, the hexafluoropropylene oxide conversion rate was 98%, the hexafluoropropylene oxide dimer after distillation and purification had a GC purity of 99.5%, and a GC yield of 90.8%.

[0074] Example 8

[0075] 400mL of tetrahydrofuran (water content 400ppm), 5.8g of tetramethylurea, 8.2g of potassium iodide, and 1g of methanol were fully homogenized and mixed, and then added to a 2L 316L stainless steel vertical reactor with a temperature control jacket. After the reactor was fully replaced with nitrogen, it was evacuated to -0.1-0.08MPa, and stirred at room temperature for 5-10min. The temperature in the reactor was controlled by the temperature control jacket to maintain 20±0.5℃, the stirring rate was set to 300r / min, and hexafluoropropylene oxide was continuously introduced into the bottom of the reactor at a rate of 5g / min through a gas flowmeter. When the material volume reached 80% of the reactor volume, the discharge valve at the bottom of the reactor was opened, and the crude hexafluoropropylene oxide dimer of the lower layer was taken out in an appropriate amount until 3Kg of hexafluoropropylene oxide raw material was introduced, and the feeding was stopped, and the reaction was continued for 30min to terminate the reaction.

[0076] The material was taken out from the reactor for conventional liquid separation, the upper layer of solvent and catalyst were recovered, and the lower layer was the crude hexafluoropropylene oxide dimer, which was then distilled and purified to obtain the product hexafluoropropylene oxide dimer. Among them, the hexafluoropropylene oxide conversion rate was 96.7%, the hexafluoropropylene oxide dimer after distillation and purification had a GC purity of 99.5%, and a GC yield of 88.7%.

[0077] Example 9

[0078] 400mL of diethylene glycol dimethyl ether (600ppm of water), 7.26g of N,N-dimethylaniline, 6g of cuprous chloride, and 1g of methanol were fully homogenized and mixed, and then added to a 2L 316L stainless steel vertical reactor with a temperature control jacket. After the reactor was fully replaced with nitrogen, it was evacuated to -0.1~-0.08MPa and stirred at room temperature for 5~10min. The temperature in the reactor was controlled by the temperature control jacket to maintain 20±0.5℃, the stirring rate was set to 300r / min, and hexafluoropropylene oxide was continuously introduced into the bottom of the reactor at a rate of 5g / min through a gas flowmeter. When the material volume reached 80% of the reactor volume, the discharge valve at the bottom of the reactor was opened, and the crude hexafluoropropylene oxide dimer in the lower layer was taken out in an appropriate amount until 3Kg of hexafluoropropylene oxide raw material was introduced, and the feeding was stopped, and the reaction was continued for 30min to terminate the reaction.

[0079] The material was taken out from the reactor for conventional liquid separation, the upper layer of solvent and catalyst were recovered, and the lower layer was the crude hexafluoropropylene oxide dimer, which was then purified by distillation to obtain the product hexafluoropropylene oxide dimer. Among them, the hexafluoropropylene oxide conversion rate was 98%, the hexafluoropropylene oxide dimer after distillation and purification had a GC purity of 99.6%, and a GC yield of 90.5%.

[0080] Example 10

[0081] 400mL of propionitrile (600ppm of water), 13g of tetrabutylammonium fluoride, 5g of cuprous chloride, and 1g of xylene were fully homogenized and mixed, and then added to a 2L 316L stainless steel vertical reactor with a temperature control jacket. After the reactor was fully replaced with nitrogen, it was evacuated to -0.1-0.08MPa, and stirred at room temperature for 5-10min. The temperature in the reactor was controlled by the temperature control jacket to maintain 20±0.5°C, the stirring rate was set to 300r / min, and hexafluoropropylene oxide was continuously introduced into the bottom of the reactor at a rate of 5g / min through a gas flow meter. When the material volume reached 80% of the reactor volume, the discharge valve at the bottom of the reactor was opened, and the crude hexafluoropropylene oxide dimer of the lower layer was taken out in an appropriate amount until 3Kg of hexafluoropropylene oxide raw material was introduced, and the feeding was stopped, and the reaction was continued for 30min to terminate the reaction.

[0082] The material was taken out from the reactor for conventional liquid separation, the upper layer of solvent and catalyst were recovered, and the lower layer was the crude hexafluoropropylene oxide dimer, which was then purified by distillation to obtain the product hexafluoropropylene oxide dimer. Among them, the hexafluoropropylene oxide conversion rate was 98.5%, the hexafluoropropylene oxide dimer after distillation and purification had a GC purity of 99.5%, and a GC yield of 89%.

[0083] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. All technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for continuously preparing hexafluoropropylene oxide dimer, characterized in that: The method comprises the following steps: mixing an organic solvent with a specific water content, a composite catalyst composed of an organic amine catalyst and a metal salt catalyst, and a polymer inhibitor, and continuously adding hexafluoropropylene oxide thereto in a nitrogen environment to continuously synthesize hexafluoropropylene oxide dimer through reaction.

2. The method for continuously preparing hexafluoropropylene oxide dimer according to claim 1, characterized in that: The following steps are involved: S1, fully mixing an organic solvent with a specific water content, a composite catalyst, and a polymer inhibitor, and then adding the mixture into a reactor, continuously introducing hexafluoropropylene oxide into the system at a uniform speed under a nitrogen environment, and controlling the reaction to proceed at a certain stirring rate and temperature; when the volume of the material in the reactor exceeds 80% of the total volume of the reactor, opening the discharge valve at the bottom of the reactor to discharge the lower layer product, wherein the lower layer product is a crude hexafluoropropylene oxide dimer; and repeating the cycle until the reaction rate decreases significantly; S2, after the reaction is completed, the mixed product in the reactor is separated to obtain a crude hexafluoropropylene oxide dimer, and the organic solvent and the composite catalyst are recovered; the obtained crude hexafluoropropylene oxide dimer is purified by distillation to obtain a high-purity hexafluoropropylene oxide dimer.

3. The method for continuously preparing hexafluoropropylene oxide dimer according to claim 1, characterized in that: The organic solvent is at least one of acetonitrile, propionitrile, butyronitrile, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, dichloromethane and tetrahydrofuran; and the water content in the organic solvent is 200-1200 ppm.

4. The method for continuously preparing hexafluoropropylene oxide dimer according to claim 1, characterized in that: The organic amine catalyst is at least one of N,N-dimethylaniline, tetramethylurea, N,N,N,N-tetramethylmethanediamine, tetramethylpropylenediamine, tetrabutylammonium fluoride, and N,N-dimethylformamide; The metal salt catalyst is at least one of magnesium fluoride, zinc fluoride, manganese fluoride, silver nitrate, cuprous chloride, and potassium iodide; The molar ratio of the organic amine catalyst to the metal salt catalyst is 1:(1-5).

5. The method for continuously preparing hexafluoropropylene oxide dimer according to claim 1, characterized in that: The polymer inhibitor is at least one of methanol, toluene and xylene; The mass ratio of the organic solvent to the polymer inhibitor is 1000:(1-5).

6. The method for continuously preparing hexafluoropropylene oxide dimer according to claim 1, characterized in that: Stirring is performed during the reaction at a rate of 200 to 600 r / min.

7. The method for continuously preparing hexafluoropropylene oxide dimer according to claim 1, characterized in that: The reaction temperature during the reaction is -40 to 50°C.

8. The method for continuously preparing hexafluoropropylene oxide dimer according to claim 1, characterized in that: The purity of the hexafluoropropylene oxide is not less than 99.5%. The hexafluoropropylene oxide is added by passing it into the bottom of the reaction liquid through a gas flow meter, and the addition rate of the hexafluoropropylene oxide is 2-10 g / min.

9. The method for continuously preparing hexafluoropropylene oxide dimer according to claim 1, characterized in that: The molar ratio of the organic solvent to the composite catalyst is (50-200):

1.

10. The method for continuously preparing hexafluoropropylene oxide dimer according to claim 1, characterized in that: The molar ratio of the organic solvent to hexafluoropropylene oxide is 1:(1-8).