Synthesis method of perfluoroalkoxy methylene vinyl ether

Abstract

The invention discloses a synthetic method of perfluoroalkoxy methylene vinyl ether, which comprises the following steps of: 1, reacting alkyl fluoroformate with halogenated olefin under the action of an auxiliary agent to generate halogenated alkyl ether, and performing dehalogenation reaction to generate perfluoroalkoxy methylene vinyl ether; the method II comprises the following steps: reacting alkyl fluoroformate with hexafluoropropylene oxide under the action of an auxiliary agent to generate alkoxy propionyl fluoride, and carrying out salification and decarboxylation reaction to generate perfluoroalkoxy methylene vinyl ether (RfOCF2OCF = CF2); the auxiliary agent is metal fluoride or fluoro quaternary ammonium salt. In the first method and the second method, the alkyl fluoroformate and the halogenated olefin or the hexafluoropropylene oxide need to react under the action of the aid (metal fluoride or fluoro quaternary ammonium salt), so that the safety problem caused by direct use of fluorine gas is avoided, and the conversion rate of the trifluoromethyl fluoroformate and the yield and selectivity of the product can be improved.

Description

Technical Field

[0001] This invention relates to the field of fluorinated chemical technology, specifically to a method for synthesizing perfluoroalkoxymethylene vinyl ether. Background Technology

[0002] Perfluoroalkoxymethylene vinyl ethers, with the general formula R f OCF2OCF=CF2, where R f It can have a C1-C6 perfluorinated straight-chain, branched, or cyclic structure, with carbon atoms possibly linked by ether bonds, double bonds, etc. Perfluoroalkoxymethylene vinyl ether, R f OCF2OCF=CF2, such as CF3OCF2OCF=CF2, CF3CF2OCF2OCF=CF2, etc., are important monomers for preparing low-temperature resistant fluororubber. Because these compounds contain multiple oxygen atoms in their molecular structure, their molecular flexibility is greater than that of perfluoroalkyl vinyl ethers containing only one oxygen atom. f OCF=CF2(R) f Fluororubbers (C1-C6 perfluorinated linear, branched, or cyclic structures, such as CF3OCF=CF2) exhibit better low-temperature resistance. The lowest low-temperature resistance of synthesized fluororubbers is only -30 ℃, while the low-temperature resistance of fluororubbers synthesized from perfluoroalkoxymethylene vinyl ethers can reach -40 or even -50 ℃. Therefore, they have important applications in high-tech fields such as petrochemicals, automobiles, aerospace, and military industries.

[0003] The currently reported methods for synthesizing perfluoroalkoxymethylene vinyl ethers are as follows: Patent document US20060025635A discloses a process where carbonyl fluoride reacts with fluorine gas to produce trifluoromethyl hypofluoroester (CF3OF). Trifluoromethyl hypofluoroester then reacts with carbon monoxide to produce trifluoromethyl fluoroformate. Trifluoromethyl fluoroformate further reacts with fluorine gas and 1,2-difluorodichloroethylene to produce haloalkoxymethylene vinyl ether. The haloalkoxymethylene vinyl ether is then dehalogenated in the presence of zinc and other reagents to produce perfluoroalkoxymethylene vinyl ether. The conversion rate of trifluoromethyl fluoroformate is only 54%, with a selectivity of 93%. This process uses highly hazardous, highly toxic, and highly corrosive carbonyl fluoride and fluorine gas, posing a high safety risk.

[0004] Patent document WO2001046107A1 discloses a process where methyl 2-hydroxypropionate reacts with diethoxymethane to produce methyl 2-ethoxymethoxypropionate, which is then directly fluorinated with fluorine gas to form CF3CF2OCF2OCF(CF3)COOMe, with a yield of 30%. Subsequently, the ester is deesterified to form a salt in the presence of NaOH aqueous solution, and further decarboxylation is performed at elevated temperature to synthesize CF3CF2OCF2OCF=CF2. This process has a low yield, uses highly hazardous, toxic, and corrosive fluorine gas, and poses a high safety risk.

[0005] Patent document US4905770A discloses a process where tetrafluoroethylene reacts with oxygen to form perfluoropolyethers. These perfluoropolyethers then undergo pyrolysis under ultraviolet light to form perfluoropolyethers terminated with -OCOF groups. This substance can further react with fluorine gas to form perfluoropolyethers terminated with -OF groups. The perfluoropolyethers terminated with -OF groups can then undergo further addition reactions with olefins, such as 1,2-difluorodichloroethylene, to obtain the corresponding perfluorohalogenated ethers. Dehalogenation of the perfluorohalogenated ethers yields the corresponding perfluoroolefins. This process involves raw materials with large molecular weights and involves highly hazardous, toxic, and corrosive fluorine gas, posing a high safety risk.

[0006] Therefore, in order to solve the above problems, we continue to look for a method for synthesizing perfluoroalkoxymethylene vinyl ethers. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for synthesizing perfluoroalkoxymethylene vinyl ether, which avoids the safety issues associated with the direct use of fluorine gas and improves the conversion rate, yield, and selectivity of trifluoromethyl fluoroformate.

[0008] A method for synthesizing perfluoroalkoxymethylene vinyl ether includes the following steps: Method 1: Alkyl fluoroformate and haloolefin react with an auxiliary agent to generate haloalkyl ether, which is then dehalogenated to generate perfluoroalkoxymethylene vinyl ether. Method 2: Alkyl fluoroformate and hexafluoropropylene oxide react with an auxiliary agent to generate alkoxypropionyl fluoride. Following salt formation and decarboxylation, perfluoroalkoxymethylene vinyl ether (R) is produced. f OCF2OCF=CF2); The additives are metal fluorides or fluorinated quaternary ammonium salts.

[0009] The additives in this invention can be KF, NaF, CsF, AgF, LiF, NiF2, tetramethylammonium fluoride, tetrabutylammonium fluoride, etc.

[0010] In Method 1 and Method 2 of this invention, the alkyl fluoroformate reacts with the haloolefin or hexafluoropropylene oxide under the action of an auxiliary agent (metal fluoride or fluorinated quaternary ammonium salt), which avoids the safety problems caused by the direct use of fluorine gas and can improve the conversion rate of alkyl fluoroformate, the yield of the product and the selectivity.

[0011] Preferably, the alkyl fluoroformate is R. f OCOF, where R f Alkyl groups of C1 to C6 that are substituted with halogen atoms include trifluoromethyl, pentafluoroethyl, heptafluoropropyl, nonafluorobutyl, difluorochloromethyl, monofluorodichloromethyl, tetrafluorochloroethyl, octafluorochlorobutyl, hexafluorochloropropyl, etc.

[0012] Preferably, in method one, the molar ratio of alkyl fluoroformate, haloolefin and auxiliaries is 1:0.5~4:0.1~3.

[0013] Preferably, in method one, the solvent for the dehalogenation reaction is at least one of acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, triethylamine, N-methylpyrrolidone, and dimethyl sulfoxide.

[0014] More preferably, the mass ratio of the haloalkyl ether to the solvent for the dehalogenation reaction is 1:1 to 10.

[0015] Preferably, in method one, the dehalogenating agent for the dehalogenation reaction is zinc powder or iron powder.

[0016] Preferably, in method one, the molar ratio of the haloalkyl ether to the dehalogenating agent is 0.5 to 3:1.

[0017] Preferably, in method one, the dehalogenation reaction temperature is 0~200 ℃ and the time is 2~12 h.

[0018] Preferably, in the second method, the molar ratio of alkyl fluoroformate, hexafluoropropylene oxide and auxiliaries is 1:0.5~4:0.1~3.

[0019] Preferably, in the second method, the salt formation temperature is 0~100 ℃ and the time is 1~12 h.

[0020] Preferably, in the second method, the solvent for the decarboxylation reaction is at least one of diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol dimethyl ether, acetonitrile, and butyronitrile.

[0021] More preferably, the mass ratio of the alkoxypropionyl fluoride to the solvent in the decarboxylation reaction is 1:1 to 10.

[0022] Preferably, in the second method, a metal carbonate is added as an additive in the decarboxylation reaction, and the metal carbonate can be sodium carbonate, potassium carbonate, etc.

[0023] Preferably, the molar ratio of the alkoxypropionyl fluoride to the metal carbonate is 1 to 8:1.

[0024] Preferably, in the second method, the temperature of the decarboxylation reaction is 80~300 ℃.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: In Method 1 and Method 2 of this invention, the alkyl fluoroformate reacts with the haloolefin or hexafluoropropylene oxide under the action of an auxiliary agent (metal fluoride or fluorinated quaternary ammonium salt), which avoids the safety problems caused by the direct use of fluorine gas and can improve the conversion rate of alkyl fluoroformate, the yield of the product and the selectivity. Attached Figure Description

[0026] Figure 1 and Figure 2 The mass spectra of the perfluoroalkoxymethylene vinyl ethers prepared in Examples 1 and 4 are shown respectively. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited to the following embodiments.

[0028] All raw materials used in this invention are commercially available.

[0029] Example 1 11.5 g of cesium fluoride was added to a 50 mL four-necked flask, and the reactor was cooled to -50 °C. Then, 10 g of trifluoromethyl fluoroformate and 10.1 g of 1,2-difluorodichloroethylene were added. After purging with nitrogen 2-3 times, stirring was started, and the reaction temperature was maintained at -50 °C. The reaction was carried out at 500 rpm for 4 h. After the reaction was completed, the reactor was slowly restored to room temperature, and the filtrate was collected to obtain 20.5 g of crude product, with a yield of 89%, of which CF3OCF2OCFClCF2Cl content was 95%. The crude product was added to a 100 mL four-necked flask equipped with a -30 °C condenser, along with 40 g of N,N-dimethylacetamide and 4.2 g of zinc powder. The mixture was stirred at 80 °C for 5 h, then cooled to room temperature. The reaction solution was further distilled, and 13.9 g of CF3OCF2OCF=CF2 was collected by condensation at -30 °C, yielding a yield of 93.2% and a purity of 97%. The mass spectrum of CF3OCF2OCF=CF2 is shown below. Figure 1As shown, the vertical axis represents the relative percentage intensity of fragment ions, and the horizontal axis represents the mass-to-charge ratio (m / z) of fragment ions. Among them, m / z 232 is the peak of the CF3OCF2OCF=CF2 molecular ion; m / z 166 is the rearranged CF2OCFCF3 fragment peak; m / z 135 is the CF3OCF2 fragment peak; m / z 119 is the rearranged CF3CF2 fragment peak; m / z 81 is the CF=CF2 fragment peak; and m / z 69 is the CF3 fragment peak.

[0030] Example 2 5 g of potassium fluoride was added to a 50 mL four-necked flask, and the reactor was cooled to -40 °C. Then, 13.8 g of pentafluoroethyl fluoroformate and 10.1 g of 1,2-difluorodichloroethylene were added. After purging with nitrogen 2-3 times, stirring was started, and the reaction temperature was maintained at -40 °C. The reaction was carried out at 500 rpm for 2 h. After the reaction was completed, the reactor was slowly restored to room temperature, and the filtrate was collected to obtain 24.4 g of crude product, with a yield of 91%, of which the content of CF3CF2OCF2OCFClCF2Cl was 97%. The crude product was added to a 100 mL four-necked flask equipped with a -30 °C condenser, along with 50 g of acetonitrile and 5 g of zinc powder. After stirring at 80 °C for 5 h, the mixture was cooled to room temperature. The reaction solution was further distilled and collected by condensation at -30 °C to obtain 17.7 g of CF3CF2OCF2OCF=CF2, with a yield of 93.6% and a purity of 97%.

[0031] Example 3 12 g of potassium fluoride and 50 g of diethylene glycol dimethyl ether were added to a 50 mL four-necked flask. The reactor was then cooled to -40 °C. Subsequently, 13.5 g of pentafluoroethyl fluoroformate and 12 g of hexafluoropropylene oxide were added. After purging with nitrogen 2-3 times, stirring was started, and the reaction temperature was maintained at -40 °C. The reaction was carried out at 500 rpm for 4 h. After the reaction was completed, the reactor was slowly restored to room temperature, and the filtrate was collected to obtain 24.6 g of crude product, with a yield of 98%, of which the CF3CF2OCF2OCF(CF3)COF content was 94%. The crude product was added to a dropping funnel. Separately, 10 g of potassium carbonate and 50 g of diethylene glycol dimethyl ether were added to a 100 mL four-necked flask equipped with a -30 °C condenser. After the addition was complete, stirring was started, and the temperature was raised to 50 °C. The crude product from the dropping funnel was then added dropwise to the four-necked flask. After the addition was complete, the mixture was stirred at 50 °C for 4 h to complete the reaction. The reaction solution was slowly heated to 160 °C and distilled. The distillate was collected by condensation at -30 °C to obtain 16.8 g of CF3CF2OCF2OCF=CF2, with a yield of 90% and a purity of 98%.

[0032] Example 4 12 g of potassium fluoride and 50 g of diethylene glycol dimethyl ether were added to a 50 mL four-necked flask. The reactor was then cooled to -50 °C, followed by the addition of 10 g of trifluoromethyl fluoroformate and 12 g of hexafluoropropylene oxide. After purging with nitrogen 2-3 times, stirring was started, and the reaction temperature was maintained at -50 °C. The reaction was carried out at 500 rpm for 4 h. After the reaction was completed, the reactor was slowly restored to room temperature, and the filtrate was collected to obtain 20.7 g of crude product, with a yield of 96%, of which the CF3OCF2OCF(CF3)COF content was 97%. The crude product was added to a dropping funnel. Separately, 10 g of potassium carbonate and 50 g of diethylene glycol dimethyl ether were added to a 100 mL four-necked flask equipped with a -30 °C condenser. After the addition was complete, stirring was started, and the temperature was raised to 50 °C. The crude product from the dropping funnel was then added dropwise to the four-necked flask. After the addition was complete, stirring was continued at 50 °C for 4 h to complete the reaction. The reaction solution was slowly heated to 160 °C and distilled. The distillate was collected by condensation at -30 °C to obtain 14.3 g of CF3OCF2OCF=CF2, with a yield of 91% and a purity of 98%. The mass spectrum of CF3OCF2OCF=CF2 is shown below. Figure 2 As shown, the vertical axis represents the relative percentage intensity of fragment ions, and the horizontal axis represents the mass-to-charge ratio (m / z) of fragment ions. Among them, m / z 232 is the peak of the CF3OCF2OCF=CF2 molecular ion; m / z 166 is the rearranged CF2OCFCF3 fragment peak; m / z 135 is the CF3OCF2 fragment peak; m / z 119 is the rearranged CF3CF2 fragment peak; m / z 81 is the CF=CF2 fragment peak; and m / z 69 is the CF3 fragment peak.

[0033] Comparative Example 1 The reaction was carried out under the same conditions as in Example 1, but without the addition of cesium fluoride. During the reaction, a fluorine-nitrogen mixture with a fluorine content of 20 wt% was introduced into the reactor at a flow rate of 4 g / h. The crude product collected did not contain CF3OCF2OCFClCF2Cl.

[0034] Comparative Example 2 The reaction was carried out under the same conditions as in Example 3, but without the addition of potassium fluoride. During the reaction, a fluorine-nitrogen mixture with a content of 20 wt% was introduced into the reactor at a flow rate of 4 g / h. The pentafluoroethyl fluoroformate was decomposed to obtain CF3CF2OCF(CF3)COF. The crude product collected did not contain CF3CF2OCF2OCF(CF3)COF.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for the synthesis of a perfluoroalkoxymethylene vinyl ether, characterized in that, The method comprises the following steps: Method one: alkyl fluoroformate and haloalkene are reacted in the presence of an auxiliary to generate haloalkyl ether, which is then dehalogenated to generate perfluoroalkoxy methylene vinyl ether; Method two: alkyl fluoroformate and hexafluoropropylene oxide are reacted in the presence of an auxiliary to generate alkoxyl propionyl fluoride, which is then salified and decarboxylated to generate perfluoroalkoxy methylene vinyl ether; The auxiliary is metal fluoride or fluoro quaternary ammonium salt.

2. The method of synthesizing perfluoroalkoxymethylene vinyl ethers according to claim 1, wherein, The fluorocarbon acid alkyl ester is R f OCOF, wherein R f is a halogen atom-substituted C1-C6 alkyl group.

3. The method of synthesizing perfluoroalkoxymethylene vinyl ethers according to claim 1, wherein, In the method one, the molar ratio of alkyl fluoroformate, haloalkene and auxiliary is 1:0.5-4:0.1-3.

4. The method of synthesizing perfluoroalkoxymethylene vinyl ethers according to claim 1, wherein, In the method one, the dehalogenating agent for the dehalogenation reaction is zinc powder or iron powder; in the method one, the molar ratio of haloalkyl ether and dehalogenating agent is 0.5-3:

1.

5. The method of synthesizing perfluoroalkoxymethylene vinyl ethers according to claim 1, wherein, In the method one, the temperature for the dehalogenation reaction is 0-200 DEG C, and the time is 2-12 h.

6. The method of synthesizing perfluoroalkoxymethylene vinyl ethers according to claim 1, wherein, In the method two, the molar ratio of alkyl fluoroformate, hexafluoropropylene oxide and auxiliary is 1:0.5-4:0.1-3.

7. The method of synthesizing perfluoroalkoxymethylene vinyl ethers according to claim 1, wherein, In the method two, the temperature for the salification is 0-100 DEG C, and the time is 1-12 h.

8. The method of claim 1, wherein the perfluoroalkoxymethylene vinyl ether is represented by the following formula: ###0001### 8 In the method two, metal carbonate is added as an additive for the decarboxylation reaction, and the metal carbonate is sodium carbonate or potassium carbonate.

9. The method of claim 1, wherein the perfluoroalkoxymethylene vinyl ether is represented by the following formula: ###0001### 9 The molar ratio of alkoxyl propionyl fluoride and metal carbonate is 1-8:

1.

10. The method of claim 1, wherein the perfluoroalkoxymethylene vinyl ether is represented by the following formula: ###0001### 10 In the method two, the temperature for the decarboxylation reaction is 80-300 DEG C.

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