Preparation method of perfluoropropylidene divinyl ether

Abstract

The invention relates to a preparation method of perfluoropropylidene divinyl ether, which comprises the following steps: carrying out regulation polymerization reaction on perfluoromalonyl fluoride and hexafluoropropylene oxide under the action of a catalyst to generate an acyl fluoride intermediate; rectifying and separating the acyl fluoride intermediate to obtain a refined acyl fluoride intermediate; under the condition of high temperature, the two ends of the refined acyl fluoride intermediate are subjected to decarbonylation elimination reaction under the catalysis of anhydrous sodium carbonate, crude perfluoropropylidene divinyl ether is generated through the reaction, and then refined perfluoropropylidene divinyl ether is obtained through rectification and purification. The high-temperature reaction furnace is utilized to realize decarbonylation elimination reaction, nitrogen protection is carried out in the reaction process, the contact time of liquid-solid reaction raw materials and the diffusion area of the gasified liquid raw materials are adjusted, the reaction rate and the reaction conversion rate are improved, and directional generation of perfluoropropylidene divinyl ether is ensured; the purity of the obtained product is up to 99% or above, the highest yield of the product can reach 95%, the reaction can be continuously carried out, and the method is suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the field of fine fluorine chemical industry, and in particular to a method for preparing perfluoropropylene divinyl ether. Background Art

[0002] Perfluoropropylene divinyl ether is a chemical synthesis intermediate that can be used as a modified monomer of polytetrafluoroethylene. It can be copolymerized with tetrafluoroethylene to synthesize fusible polytetrafluoroethylene with excellent thermoplastic processing properties. In recent years, a series of high-performance fluorine-containing elastomers, fluorine plastics, high-purity fluorine polymer materials, fluorine-containing medicines and pesticides have developed rapidly and applied to various industries. Perfluoropropylene divinyl ether is a key compound in the preparation process of such fluorine-containing materials, and its demand and quality requirements are getting higher and higher.

[0003] Most of the existing preparation methods of perfluoropropyl vinyl ether disclosed are solvent methods to prepare perfluoropropyl vinyl ether. Patent CN118515554A provides a preparation method of perfluoro n-propyl vinyl ether, which includes the following steps: in the presence of catalyst a, fluorine-containing quaternary ammonium salt and aprotic solvent, hexafluoropropylene oxide is introduced into the reaction, after the reaction is completed, the reaction is allowed to stand for stratification, the lower clear liquid is released and distilled to obtain hexafluoropropylene oxide dimer; fluorine-containing solvent, salt-forming agent and catalyst b are added to the reaction container, the temperature is increased, hexafluoropropylene oxide dimer is added dropwise, the temperature is continuously increased, and the temperature is increased again and maintained after the titration is completed; the fluorine-containing solvent is removed by reduced pressure distillation. , heating and cracking, collecting the crude product of perfluoro-n-propyl vinyl ether, and rectifying to obtain the finished product of perfluoro-n-propyl vinyl ether; Patent CN115043711B provides a method for preparing perfluoro-n-propyl vinyl ether, comprising the following steps: using hexafluoropropylene oxide to undergo addition reaction in a catalytic reaction system, the catalytic reaction system comprising aromatic compounds, solvents and catalysts, to obtain hexafluoropropylene oxide dimers; hexafluoropropylene oxide dimers and alkali metal carbonates undergo salt formation and decarboxylation reactions to generate perfluoro-n-propyl vinyl ether. However, in the above preparation methods, the solvent method is adopted, and the reaction device is mostly a reactor, that is, the solvent diethylene glycol dimethyl ether and the raw materials are added into the reactor, and the reaction is carried out at high temperature under reflux conditions. This method has low yield, many side reactions, low product purity, and large development restrictions. Summary of the invention

[0004] The invention aims to overcome the shortcomings of low yield, many side reactions and low product purity of perfluoropropylene divinyl ether prepared by a solvent method, and to provide a new method for synthesizing perfluoropropylene divinyl ether.

[0005] To achieve the purpose of the present invention, the specific technical solutions provided by the present invention are as follows:

[0006] A preparation method of perfluoropropylene divinyl ether comprises the following steps: perfluoromalonyl fluoride and hexafluoropropylene oxide undergo a regulated polymerization reaction under the action of a catalyst to generate an acyl fluoride intermediate; the acyl fluoride intermediate undergoes rectification and separation to obtain a fine acyl fluoride intermediate; under high temperature conditions, the fine acyl fluoride intermediate undergoes a decarbonylation elimination reaction at both ends under the catalysis of anhydrous sodium carbonate to generate a crude perfluoropropylene divinyl ether, which is then subjected to rectification and purification to obtain a fine perfluoropropylene divinyl ether.

[0007] Preferably, the method comprises the following steps:

[0008] S1. Preparation of crude acyl fluoride intermediate: adding a solvent and a catalyst to a reactor previously placed in a low temperature environment, and introducing perfluoromalonyl fluoride into the reactor, stirring and mixing sufficiently, and then introducing hexafluoropropylene oxide to regulate the polymerization reaction to generate a crude acyl fluoride intermediate;

[0009] S2. Purification of crude acyl fluoride intermediate: separating the fluorine phase crude acyl fluoride intermediate from the organic solvent, and after the fluorine phase is separated, heating and rectification are performed to take the middle fraction to obtain the refined acyl fluoride intermediate;

[0010] S3, preparing crude perfluoropropylene divinyl ether: adding sodium carbonate to a high temperature reaction vessel, heating the reactor under nitrogen protection, then dropping the acyl fluoride intermediate, causing a decarboxylation elimination reaction to generate crude perfluoropropylene divinyl ether, and condensing and collecting the product;

[0011] S4. Purification of crude perfluoropropylene divinyl ether: The crude perfluoropropylene divinyl ether is taken out, washed with an aqueous sodium carbonate solution, and then dried with anhydrous sodium sulfate to remove water. After removal of water, the mixture is filtered, and the filtrate is heated and distilled, and the middle fractions are collected to obtain fine perfluoropropylene divinyl ether.

[0012] Preferably, in step S1, the temperature of the reactor for preparing the crude acyl fluoride intermediate is set to -50°C to 50°C, preferably -20°C.

[0013] Preferably, in step S1, the solvent for preparing the crude acyl fluoride intermediate is any one of diethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether or ethylene glycol dimethyl ether, and the amount of the solvent added is 1 / 2 of the reactor volume; the catalyst for preparing the crude acyl fluoride intermediate is KF, NaF or CsF, and the amount of the catalyst is 0.1% to 10% of the amount of perfluoromalonyl fluoride substance.

[0014] Preferably, in step S1, the solvent for preparing the crude acyl fluoride intermediate is diethylene glycol dimethyl ether, the catalyst is CsF, and the amount of the catalyst is 5% of the amount of the perfluoromalonyl fluoride substance.

[0015] Preferably, in step S3, the molar ratio of the amount of the acyl fluoride intermediate added to the amount of the sodium carbonate added is 1:1-20, and the reaction temperature is controlled at 50°C-350°C.

[0016] Preferably, the molar ratio of the amount of the acyl fluoride intermediate added to the amount of sodium carbonate added is 1:4, and the reaction temperature is controlled at 220°C.

[0017] Preferably, in step S3, a vertical high-temperature reactor is used to prepare crude perfluoropropylene divinyl ether, and the preparation process includes:

[0018] Sodium carbonate is filled into a vertical high-temperature reactor, the vertical high-temperature reactor is heated, nitrogen is introduced, and in a nitrogen atmosphere, an acyl fluoride intermediate is dripped in using an automatic sampler. After the reaction is completed, the product is collected in a cold trap immersed in a -40°C low-temperature refrigerant.

[0019] Preferably, the gas outlet of the cold trap is connected to the gas inlet of the tail gas treatment bottle, and the gas outlet of the tail gas treatment bottle is connected to the oil bubbler.

[0020] Preferably, in step S3, when nitrogen is used as the protective gas, the nitrogen gas flow rate is controlled to be about 40 mL / min to 100 mL / min, and 2 to 5 bubbles are generated in the oil bubbler per second.

[0021] The reaction principle for preparing perfluoropropylene divinyl ether is as follows:

[0022]

[0023] The preparation method of perfluoropropylene divinyl ether of the present invention has the following beneficial effects:

[0024] 1. In the traditional solvent preparation process, there are often a lot of side reactions, resulting in low product yield and difficult to ensure purity. The present invention uses a high-temperature reactor to gasify the raw materials to achieve decarbonylation elimination reaction. The reaction process is accompanied by nitrogen, which increases the reaction rate and reaction conversion rate, effectively avoids the occurrence of adverse reactions such as cyclization, and ensures the directional generation of perfluoropropylene divinyl ether; after precise distillation and purification steps, the purity of the obtained product is as high as 99% or more, and can even reach 99.9%, far exceeding the existing technical level.

[0025] 2. The preparation method adopted by the present invention not only has simple and easy-to-obtain reagents, but also has clear preparation steps, and is easy and safe to operate. By optimizing the reaction conditions and equipment configuration, such as the use of a vertical high-temperature reactor and the uniform dripping technology under nitrogen protection, the reaction time is significantly shortened and the production efficiency is improved. This makes the method of the present invention more suitable for large-scale industrial production and has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The schematic diagram of the device for preparing perfluoropropylene divinyl ether of the present invention is shown;

[0027] Explanation of the markings in the figure: 1. Automatic sample injector; 2. Vertical high-temperature reactor; 3. Cold trap; 4. Low-temperature refrigerant; 5. Exhaust gas treatment bottle; 6. Oil bubbler. DETAILED DESCRIPTION

[0028] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0029] Example 1

[0030] The present invention provides a method for preparing perfluoropropylene divinyl ether, and the specific steps are as follows:

[0031] S1. Preparation of crude acyl fluoride intermediate: fix a glass reactor with a condenser in a low-temperature refrigerant at a temperature of -20°C, add 200 mL of solvent diethylene glycol dimethyl ether and 1.5 g of cesium fluoride catalyst, stir to dissolve, then introduce 29 g of perfluoromalonyl fluoride into the reactor, stir and mix thoroughly, then introduce 66 g of hexafluoropropylene oxide, stir and react for about 10 hours, and a regulated polymerization reaction occurs, and one hexafluoropropylene oxide is polymerized at each end of the perfluoromalonyl fluoride to generate a crude acyl fluoride intermediate.

[0032] S2. Purification of crude acyl fluoride intermediate: Separate the fluorine phase from the reaction solution, the fluorine phase is the crude acyl fluoride intermediate, separate the fluorine phase crude acyl fluoride intermediate from the organic solvent, add the fluorine phase into a single-mouth bottle with a distillation column after separation, and perform heating distillation. The boiling point of the acyl fluoride intermediate is about 112°C. Collect the fractions at 110-115°C to obtain 90g of fine acyl fluoride intermediate. The purity tested by gas chromatography is 99.50%, and the yield is 94.50%.

[0033] S3, preparation of crude perfluoropropylene divinyl ether: Figure 1As shown, 42g of sodium carbonate is filled into a vertical high-temperature reactor 2, and nitrogen is introduced, and the nitrogen gas flow rate is controlled to be about 50mL / min. In a nitrogen atmosphere, the vertical high-temperature reactor 2 is heated to 220°C, and 48g of acyl fluoride intermediate is uniformly dripped into the vertical high-temperature reactor 2 at a speed of 5mL / min using an automatic sampler 1. A decarboxylation elimination reaction occurs in the vertical high-temperature reactor 2 to generate a crude product of perfluoropropylene divinyl ether. After the reaction is completed, the product is collected in a cold trap 3, and the cold trap 3 is immersed in a -40°C low-temperature refrigerant 4. The gas outlet of the cold trap 3 is connected to the gas inlet of the tail gas treatment bottle 5, and the acidic gas generated by the reaction is treated in the tail gas treatment bottle 5. The gas outlet of the tail gas treatment bottle 5 is connected to the oil bubbler 6, and the treated tail gas is discharged into the oil bubbler 6, and 2 to 5 bubbles are generated per second in the oil bubbler 6. The purpose of nitrogen in the reaction process is to adjust the contact time between liquid and solid reaction raw materials and the diffusion area after the liquid raw materials are vaporized, so as to increase the reaction rate and reaction conversion rate; the outlet end of the tail gas treatment bottle 5 is connected to an oil bubbler 6, which plays a role of liquid sealing and can prevent external gas from entering the reaction system.

[0034] S4. Purification of crude perfluoropropylene divinyl ether: The crude perfluoropropylene divinyl ether was taken out from the cold trap 3, first washed with a 10% mass concentration sodium carbonate aqueous solution to remove acidic impurities, then dried with anhydrous sodium sulfate to remove water, filtered after removal of water, and the filtrate was rectified with a 1L distillation kettle with an adjustable reflux ratio distillation head and a 1m effective length distillation tower, and the middle fraction at about 82°C was collected to obtain 33g of fine perfluoropropylene divinyl ether with a yield of 95.93%. The purity of perfluoropropylene divinyl ether tested by gas chromatography (model Agilent 7820A) was 99.84%.

[0035] Example 2

[0036] The present invention provides a method for preparing perfluoropropylene divinyl ether, and the specific steps are as follows:

[0037] S1. Preparation of crude acyl fluoride intermediate: fix a glass reactor with a condenser in a low-temperature refrigerant at a temperature of -20°C, add 200 mL of solvent diethylene glycol dimethyl ether and 1 g of potassium fluoride catalyst, stir to dissolve, then introduce 29 g of perfluoromalonyl fluoride into the reactor, stir and mix thoroughly, then introduce 66 g of hexafluoropropylene oxide, stir and react for about 10 hours, a regulated polymerization reaction occurs, and one hexafluoropropylene oxide is polymerized at each end of the perfluoromalonyl fluoride to generate a crude acyl fluoride intermediate.

[0038] S2. Purification of crude acyl fluoride intermediate: Separate the fluorine phase from the reaction solution, the fluorine phase is the crude acyl fluoride intermediate, separate the fluorine phase crude acyl fluoride intermediate from the organic solvent, add the fluorine phase into a single-necked bottle with a distillation column after separation, and perform heating distillation. The boiling point of the acyl fluoride intermediate is about 112°C. Collect the fractions at 110-115°C to obtain 80g of fine acyl fluoride intermediate. The purity tested by gas chromatography is 99.48%, and the yield is 84.03%.

[0039] S3. Preparation of crude perfluoropropylene divinyl ether: 106 g of sodium carbonate was filled into a vertical high-temperature reactor 2, and nitrogen was introduced, and the nitrogen gas flow rate was controlled to be about 50 mL / min. In a nitrogen atmosphere, the vertical high-temperature reactor 2 was heated to 220° C., and 48 g of acyl fluoride intermediate was dripped at a rate of 5 mL / min using an automatic sampler 1. Decarboxylation elimination reaction occurred in the vertical high-temperature reactor 2 to generate crude perfluoropropylene divinyl ether. After the reaction was completed, the product was collected in a cold trap 3 at -40° C.

[0040] S4. Purification of crude perfluoropropylene divinyl ether: The crude perfluoropropylene divinyl ether is taken out from the cold trap 3, first washed with a 10% mass concentration sodium carbonate aqueous solution to remove acidic impurities, then dried with anhydrous sodium sulfate to remove water, filtered after removal of water, and the filtrate is rectified with a 1L distillation kettle with an adjustable reflux ratio distillation head and a 1m effective length distillation tower, and the middle fraction at about 82°C is collected to obtain 28g of fine perfluoropropylene divinyl ether with a yield of 81.39%. The purity of perfluoropropylene divinyl ether tested by gas chromatography is 99.70%.

[0041] Example 3

[0042] The present invention provides a method for preparing perfluoropropylene divinyl ether, and the specific steps are as follows:

[0043] S1. Preparation of crude acyl fluoride intermediate: fix a glass reactor with a condenser in a low-temperature refrigerant at a temperature of -20°C, add 200 mL of solvent diethylene glycol dimethyl ether and 3.0 g of cesium fluoride catalyst, stir to dissolve, then introduce 57.6 g of perfluoromalonyl fluoride into the reactor, stir and mix thoroughly, then introduce 133 g of hexafluoropropylene oxide, stir and react for about 10 hours, and a regulated polymerization reaction occurs, and one hexafluoropropylene oxide is polymerized at each end of the perfluoromalonyl fluoride to generate a crude acyl fluoride intermediate.

[0044] S2. Purification of crude acyl fluoride intermediate: Separate the fluorine phase from the reaction solution, the fluorine phase is the crude acyl fluoride intermediate, separate the fluorine phase crude acyl fluoride intermediate from the organic solvent, add the fluorine phase into a single-necked bottle with a distillation column after separation, and perform heating distillation. The boiling point of the acyl fluoride intermediate is about 112°C. Collect the fractions at 110-115°C to obtain 170g of fine acyl fluoride intermediate. The purity tested by gas chromatography is 99.53%, and the yield is 89.28%.

[0045] S3. Preparation of crude perfluoropropylene divinyl ether: 85 g of sodium carbonate was filled into a vertical high-temperature reactor 2, and nitrogen was introduced, and the nitrogen gas flow rate was controlled to be about 50 mL / min. In a nitrogen atmosphere, the vertical high-temperature reactor 2 was heated to 100° C., and 95 g of the acyl fluoride intermediate was dripped at a rate of 5 mL / min using an automatic sampler 1. A decarboxylation elimination reaction occurred in the vertical high-temperature reactor 2 to generate crude perfluoropropylene divinyl ether. After the reaction was completed, the product was collected in a cold trap 3 at -40° C.

[0046] S4. Purification of crude perfluoropropylene divinyl ether: The crude perfluoropropylene divinyl ether was taken out from the cold trap 3, first washed with a 10% mass concentration sodium carbonate aqueous solution to remove acidic impurities, then dried with anhydrous sodium sulfate to remove water, filtered after removal of water, and the filtrate was rectified with a 1L distillation kettle with an adjustable reflux ratio distillation head and a 1m effective length distillation tower, and the middle fraction at about 82°C was collected to obtain 51g of fine perfluoropropylene divinyl ether with a yield of 74.13%. The purity of perfluoropropylene divinyl ether tested by gas chromatography was 99.78%.

[0047] Comparative Example 1

[0048] Compared with Example 1, in step S3, this comparative example uses a high-temperature and high-pressure reactor as a reactor, and the remaining steps and material parameters are consistent with Example 1, to obtain crude perfluoropropylene divinyl ether, and after distillation, 48 g of fine perfluoropropylene divinyl ether is obtained, with a yield of 50.42%.

[0049] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing perfluoropropylene divinyl ether, characterized in that: The method comprises the following steps: perfluoromalonyl fluoride and hexafluoropropylene oxide undergo a regulated polymerization reaction under the action of a catalyst to generate an acyl fluoride intermediate; the acyl fluoride intermediate is subjected to distillation separation to obtain a fine acyl fluoride intermediate; under high temperature conditions, the fine acyl fluoride intermediate undergoes a decarbonylation elimination reaction at both ends under the catalysis of anhydrous sodium carbonate to generate a crude product of perfluoropropylene divinyl ether, which is then subjected to distillation purification to obtain a fine product of perfluoropropylene divinyl ether.

2. The method for preparing perfluoropropylene divinyl ether according to claim 1, characterized in that: The following steps are involved: S1. Preparation of crude acyl fluoride intermediate: adding a solvent and a catalyst to a reactor previously placed in a low temperature environment, and introducing perfluoromalonyl fluoride into the reactor, after sufficient mixing, and then introducing hexafluoropropylene oxide to regulate the polymerization reaction to generate a crude acyl fluoride intermediate; S2. Purification of crude acyl fluoride intermediate: separating the fluorine phase crude acyl fluoride intermediate from the organic solvent, and after the fluorine phase is separated, heating and rectification are performed to take the middle fraction to obtain the refined acyl fluoride intermediate; S3, preparing crude perfluoropropylene divinyl ether: adding sodium carbonate to a high temperature reaction vessel, heating the reactor under nitrogen protection, then dropping the acyl fluoride intermediate, causing a decarboxylation elimination reaction to generate crude perfluoropropylene divinyl ether, and condensing and collecting the product; S4. Purification of crude perfluoropropylene divinyl ether: The crude perfluoropropylene divinyl ether is taken out, washed with an aqueous sodium carbonate solution, and then dried with anhydrous sodium sulfate to remove water. After removal of water, the mixture is filtered, and the filtrate is heated and distilled, and the middle fractions are collected to obtain fine perfluoropropylene divinyl ether.

3. The method for preparing perfluoropropylene divinyl ether according to claim 2, characterized in that: In step S1, the temperature of the reactor for preparing the crude acyl fluoride intermediate is set to -50°C to 50°C.

4. The method for preparing perfluoropropylene divinyl ether according to claim 2, characterized in that: In step S1, the solvent for preparing the crude acyl fluoride intermediate is any one of diethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether or ethylene glycol dimethyl ether, and the amount of the solvent added is 1 / 2 of the reactor volume; the catalyst for preparing the crude acyl fluoride intermediate is KF, NaF or CsF, and the amount of the catalyst is 0.1% to 10% of the amount of the perfluoromalonyl fluoride substance.

5. The method for preparing perfluoropropylene divinyl ether according to claim 4, characterized in that: In step S1, the solvent for preparing the crude acyl fluoride intermediate is diethylene glycol dimethyl ether, the catalyst is CsF, and the amount of the catalyst is 5% of the amount of the perfluoromalonyl fluoride substance.

6. The method for preparing perfluoropropylene divinyl ether according to claim 2, characterized in that: In step S3, the molar ratio of the amount of the acyl fluoride intermediate added to the amount of the sodium carbonate added is 1:1-20, and the reaction temperature is controlled at 50°C-350°C.

7. The method for preparing perfluoropropylene divinyl ether according to claim 6, characterized in that: The molar ratio of the amount of the acyl fluoride intermediate added to the amount of the sodium carbonate added was 1:4, and the reaction temperature was controlled at 220°C.

8. A method for preparing perfluoropropylene divinyl ether according to any one of claims 2, 6 or 7, characterized in that: In step S3, a vertical high temperature reactor (2) is used to prepare crude perfluoropropylene divinyl ether, and the preparation process includes: Sodium carbonate is filled into a vertical high-temperature reaction furnace (2), the vertical high-temperature reaction furnace (2) is heated, nitrogen is introduced, and an acyl fluoride intermediate is dripped into the reaction furnace using an automatic sampler (1) under a nitrogen atmosphere. After the reaction is completed, the product is collected in a cold trap (3), and the cold trap (3) is immersed in a -40°C low-temperature refrigerant (4).

9. The method for preparing perfluoropropylene divinyl ether according to claim 9, characterized in that: The gas outlet of the cold trap (3) is connected to the gas inlet of the tail gas treatment bottle (5), and the gas outlet of the tail gas treatment bottle (5) is connected to the oil bubbler (6).

10. The method for preparing perfluoropropylene divinyl ether according to claim 9, characterized in that: In step S3, when nitrogen is used as the protective gas, the nitrogen gas flow rate is controlled to be 40 mL / min to 100 mL / min, and 2 to 5 bubbles are generated in the oil bubbler (6) per second.

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