Preparation method and application of perfluorosulfonate
By using hydrofluoroether solvent as the reaction solvent in the preparation of perfluorosulfonate, the problem of low yield caused by the large amount of by-products is solved, and the preparation of perfluorosulfonate with high yield and high purity is achieved.
Patent Information
- Application Number
- CN202311783509.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2025-06-24
AI Technical Summary
In the prior art, there are many by-products in the preparation process of perfluorosulfonate, which leads to the problem of low yields.
A hydrofluoroether solvent is used as the reaction solvent to heat the reaction solution to produce CF2=CFOCF2CF2SO3M. The difference in solubility of the hydrofluoroether solvent is used to precipitate CF2=CFOCF2CF2SO3Na to reduce the generation of by-products.
The yield of perfluorosulfonate is improved, the generation of by-products is reduced, and the selectivity of the reaction and the purity of the product is improved.
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Figure CN120192250A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of fluororesin synthesis, and particularly relates to a preparation method and application of perfluorosulfonates. Background Art
[0002] Fuel cells are a kind of high-efficiency clean energy, and their key material is the perfluorosulfonic acid ion exchange membrane, such as the Nafion membrane of DuPont and the short-side-chain fluorosulfonic acid ion exchange membrane of Dow. Due to its chemical stability and proton conductivity, it has been used in fuel cells. CF2=CFOCF2CF(CF3)OCF2CF2SO2F is the key monomer for synthesizing the Nafion membrane, and it is prepared by the decarboxylation reaction of acyl fluoride CF3CF(COF)OCF2CF(CF3)OCF2CF2SO2F with Na2CO3; CF2=CFOCF2CF2SO2F is the key monomer for synthesizing the short-side-chain fluorosulfonic acid ion exchange membrane.
[0003] Regarding the preparation method of perfluoroethylene ethers with sulfonyl fluoride groups at the short-chain end groups, US3560568 discloses the preparation of an alkyl vinyl ether monomer with a short-chain structure containing sulfonyl fluoride groups. By using the known FCOCF(CF3)OCF2CF2SO2F as the starting material, a five-membered ring intermediate is inevitably formed under the action of an alkali metal carbonate, and then it is ring-opened with sodium methoxide to generate CF2=CFOCF2CF2SO3Na, and then the terminal sodium sulfonate is chlorinated and fluorinated to obtain the final product; this method cannot generate an ether double bond in one step and can only obtain the final product through multiple steps, and the final monomer yield is very low. CF2=CFOCF2CF2SO3Na, as the key intermediate in the DuPont route, is mainly obtained by ring-opening elimination of cyclic sulfone. However, during the ring-opening process, due to the complexity of the reaction mechanism, the diversity of reaction products is caused, and the proportion of by-products is relatively large, seriously affecting the selectivity of subsequent reactions and the purity of products. Summary of the Invention
[0004] Aiming at the problem of low yield caused by many by-products in the preparation process of perfluorosulfonates in the prior art, the present invention provides a preparation method and application of perfluorosulfonates.
[0005] The technical solutions adopted by the present invention to solve the above technical problems are as follows:
[0006] The present invention provides a preparation method of perfluorosulfonates. The structural formula of perfluoroether sulfonate is CF2=CFOCF2CF2SO3M, where M = Li, Na, K or Ca; the preparation steps are as follows:
[0007]
[0008] An alcoholate and a hydrofluoroether solvent are added to the cyclic compound shown in Formula I to obtain a reaction solution, and the reaction solution is heated to obtain CF2=CFOCF2CF2SO3M.
[0009] Optionally, the hydrofluoroether solvent includes one or more of perfluorobutyl methyl ether, perfluoropropyl methyl ether, perfluorobutyl ethyl ether, perfluoropentyl methyl ether, perfluoropentyl ethyl ether, perfluorohexyl methyl ether, perfluorohexyl ethyl ether, perfluoroheptyl methyl ether, and perfluoroheptyl ethyl ether.
[0010] Optionally, the water content in the hydrofluoroether solvent is <50 ppm, the hydrogen fluoride content is <10 ppm, and the methanol and ethanol contents are both less than 1 ppm.
[0011] Optionally, the alcoholate includes one or more of sodium salt, potassium salt, calcium salt, and lithium salt, and the alcohol in the alcoholate includes one or more of methanol, ethanol, and tert-butanol.
[0012] Optionally, the mass ratio of the cyclic compound to the hydrofluoroether solvent is 1:(1-5); the molar ratio of the cyclic compound to the alcoholate is 1:(0.8-1.2).
[0013] Optionally, the heating temperature of the reaction solution is 10-60 °C.
[0014] Optionally, the reaction time of the reaction solution is 20-100 h.
[0015] Optionally, after the reaction of the reaction solution, the hydrofluoroether solvent is separated by distillation to obtain the crude product of the perfluoroether sulfonate.
[0016] Optionally, the distillation temperature is 90-100 °C and the pressure is -0.08 to -0.09 mpa.
[0017] On the other hand, the present invention also provides an application of the preparation method of the perfluorosulfonate as described in any one of the above in the preparation of a fluorosulfonic acid ion exchange membrane.
[0018] According to the preparation method of the perfluorosulfonate provided by the present invention, a hydrofluoroether solvent is used as the reaction solvent, and the solubility of the generated CF2=CFOCF2CF2SO3Na in the hydrofluoroether solvent is poor, so it precipitates in the hydrofluoroether solvent, further hindering the reaction of CF2=CFOCF2CF2SO3Na with the alcoholate or protons, reducing the generation of by-products, increasing the selectivity of the reaction of the alcoholate with the cyclic compound, and significantly increasing the yield of CF2=CFOCF2CF2SO3Na. Description of the Drawings
[0019] Figure 1 19F NMR spectrum of the perfluorosulfonate in Example 1 measured using deuterated water as the solvent;
[0020] Figure 2 is Figure 1 the enlarged partial view in
[0021] Figure 3 is the fluorine spectrum of perfluorosulfonate in Comparative Example 1 tested with deuterated water as the solvent;
[0022] Figure 4 is Figure 3 the enlarged partial view in Specific Embodiments
[0023] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0024] The embodiments of the present invention provide a method for preparing perfluorosulfonate. The structural formula of perfluoroether sulfonate is CF2=CFOCF2CF2SO3M, where M = Li, Na, K or Ca; the preparation steps are as follows:
[0025]
[0026] Add an alcoholate and a hydrofluoroether solvent to the cyclic compound shown in Formula I to obtain a reaction solution, and heat the reaction solution to obtain CF2=CFOCF2CF2SO3M.
[0027] The inventors found that when using diethyl ether as the solvent of the reaction solution, diethyl ether would dissolve CF2=CFOCF2CF2SO3Na, making the reaction solution always in a clear solution state during the reaction process and no product precipitated. In the state where CF2=CFOCF2CF2SO3Na was dissolved by diethyl ether, CF2=CFOCF2CF2SO3Na further reacted with the alcoholate to form by-products. In this embodiment, a hydrofluoroether solvent is used as the solvent of the reaction. The solubility of the generated CF2=CFOCF2CF2SO3Na in the hydrofluoroether solvent is poor, so it precipitates in the hydrofluoroether solvent, further hindering the reaction of CF2=CFOCF2CF2SO3Na with the alcoholate or protons, reducing the generation of by-products, increasing the selectivity of the reaction of the alcoholate with the cyclic compound, and significantly increasing the yield of CF2=CFOCF2CF2SO3Na.
[0028] In some embodiments, the hydrofluoroether solvent includes one or more of perfluorobutyl methyl ether, perfluoropropyl methyl ether, perfluorobutyl ethyl ether, perfluoropentyl methyl ether, perfluoropentyl ethyl ether, perfluorohexyl methyl ether, perfluorohexyl ethyl ether, perfluoroheptyl methyl ether and perfluoroheptyl ethyl ether.
[0029] In some embodiments, the moisture content in the hydrofluoroether solvent is <50 ppm, the hydrogen fluoride is <10 ppm, and the methanol and ethanol contents are both less than 1 ppm.
[0030] In some embodiments, the alcoholate includes one or more of sodium salts, potassium salts, calcium salts, and lithium salts, and the alcohol in the alcoholate includes one or more of methanol, ethanol, and tert-butanol. That is, the alcoholate can be one or more of sodium methoxide, sodium ethoxide, sodium tert-butoxide, potassium methoxide, potassium ethoxide, potassium tert-butoxide, lithium methoxide, lithium ethoxide, lithium tert-butoxide, calcium methoxide, calcium ethoxide, and calcium tert-butoxide.
[0031] In some embodiments, the mass ratio of the cyclic compound to the hydrofluoroether solvent is 1:(1 - 5); the molar ratio of the cyclic compound to the alcoholate is 1:(0.8 - 1.2).
[0032] In some embodiments, the heating temperature of the reaction solution is 10 - 60 °C.
[0033] In some embodiments, the reaction time of the reaction solution is 20 - 100 h.
[0034] In some embodiments, after the reaction of the reaction solution, the hydrofluoroether solvent is separated by distillation to obtain the crude product of the perfluoroether sulfonate.
[0035] In some embodiments, the distillation temperature is 90 - 100 °C, and the pressure is -0.08 to -0.09 mpa.
[0036] On the other hand, an embodiment of the present invention also provides an application of the preparation method of the perfluorosulfonate as described in any one of the above in the preparation of a fluorosulfonic acid ion exchange membrane.
[0037] The present invention is further illustrated by the following examples.
[0038] Example 1 Synthesis of CF2=CFOCF2CF2SO3Na
[0039] Put 56 g (0.200 mol) of the cyclic compound and 150 g of perfluoroisobutyl methyl ether into a glass bottle, slowly add 10.5 g (0.194 mol) of sodium methoxide at 50 °C, keep warm and stir for 48 h, then distill under reduced pressure to 90 - 100 °C, with a pressure of -0.08 to -0.09 mpa, and keep for 3 h. The remaining product in the glass bottle is a dry solid. 54 g of solid is obtained. NMR test shows that the molar ratio of CF2=CFOCF2CF2SO3Na: CH3OCF2CFH- and CF3CFH- structure by-products: other unknown impurities = 90.2%: 6.2%: 3.6%. The product yield spectrum is as Figure 1 and Figure 2As shown, CF2=CFOCF2CF2SO3Na: CH3OCF2CFH- and CF3CFH- structural by-products: other unknown impurities molar ratio = 3.04:0.21:0.12 = 90.2%:6.2%:3.6%.
[0040] Example 2
[0041] This example is basically the same as Example 1, except that the reaction temperature is 40 °C, and 54 g of solid is obtained. NMR test shows that the molar ratio of CF2=CFOCF2CF2SO3Na: CH3OCF2CFH- and CF3CFH- structural by-products: other unknown impurities = 89.1%:6.7%:4.2%.
[0042] Example 3
[0043] This example is basically the same as Example 1, except that 9.7 g (0.180 mol) of sodium methoxide is added, and 50.0 g of solid is obtained. NMR test shows that the molar ratio of CF2=CFOCF2CF2SO3Na: CH3OCF2CFH- and CF3CFH- structural by-products: other unknown impurities = 89.2%:6.9%:3.9%.
[0044] Example 4
[0045] This example is basically the same as Example 1, except that the alcoholate is 13.2 g (0.194 mol) of sodium ethoxide, and 48 g of solid is obtained. NMR test shows that the molar ratio of CF2=CFOCF2CF2SO3Na: CH3CH2OCF2CFH- and CF3CFH- structural by-products: other unknown impurities = 85.4%:8.7%:5.9%.
[0046] Synthesis of CF2=CFOCF2CF2SO3K in Example 5
[0047] This example is basically the same as Example 1, except that the alcoholate is 21.7 g (0.194 mol) of potassium tert-butoxide, and 49 g of solid is obtained. NMR test shows that the molar ratio of CF2=CFOCF2CF2SO3K: (CH3)3COCF2CFH- and CF3CFH- structural by-products: other unknown impurities = 88.6%:6.6%:4.8%.
[0048] Example 6
[0049] This example is basically the same as Example 1, except that the hydrofluoroether solvent is perfluoropropyl methyl ether, and 51 g of solid is obtained. NMR test shows that the molar ratio of CF2=CFOCF2CF2SO3Na: CH3OCF2CFH- and CF3CFH- structural by-products: other unknown impurities = 89.4%:6.5%:4.1%.
[0050] Comparative Example 1
[0051] This example is basically the same as Example 1, except that perfluoroisobutyl methyl ether is replaced with anhydrous ether solvent to obtain 52 g of solid. The molar ratio of CF2=CFOCF2CF2SO3Na: CH3OCF2CFH- and CF3CFH- structural by-products: other unknown impurities in the NMR test is 46.1%: 32.1%: 21.8%. The product yield spectrum is as Figure 3 and Figure 4 shown. The molar ratio of CF2=CFOCF2CF2SO3Na: CH3OCF2CFH- and CF3CFH- structural by-products: other unknown impurities C = 2.93: 2.04: 1.39 = 46.1%: 32.1%: 21.8%.
[0052] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.
Claims
1. A method for preparing perfluorosulfonate, characterized in that, The structural formula of the perfluoroether sulfonate is CF2=CFOCF2CF2SO3M, where M = Li, Na, K or Ca; the preparation steps are as follows: Add an alcohol salt and a hydrofluoroether solvent to the cyclic compound shown in Formula I to obtain a reaction solution, and heat the reaction solution to obtain CF2=CFOCF2CF2SO3M.
2. The preparation method of the perfluorosulfonate according to claim 1, wherein The hydrofluoroether solvent includes one or more of perfluorobutyl methyl ether, perfluoropropyl methyl ether, perfluorobutyl ethyl ether, perfluoropentyl methyl ether, perfluoropentyl ethyl ether, perfluorohexyl methyl ether, perfluorohexyl ethyl ether, perfluoroheptyl methyl ether and perfluoroheptyl ethyl ether.
3. The preparation method of the perfluorosulfonate according to claim 1, characterized in that, The water content in the hydrofluoroether solvent is <50 ppm, the hydrogen fluoride is <10 ppm, and the methanol and ethanol contents are both less than 1 ppm.
4. The preparation method of the perfluorosulfonate according to claim 1, wherein The alcohol salt includes one or more of sodium salt, potassium salt, calcium salt and lithium salt, and the alcohol in the alcohol salt includes one or more of methanol, ethanol and tert-butanol.
5. The preparation method of the perfluorosulfonate according to claim 1, wherein, The mass ratio of the cyclic compound to the hydrofluoroether solvent is 1:(1 - 5); the molar ratio of the cyclic compound to the alcohol salt is 1:(0.8 - 1.2).
6. The preparation method of the perfluorosulfonate according to claim 1, wherein The heating temperature of the reaction solution is 10 - 60 °C.
7. The preparation method of the perfluorosulfonate according to claim 1, wherein The reaction time of the reaction solution is 20 - 100 h.
8. The preparation method of the perfluorosulfonate according to claim 1, wherein After the reaction of the reaction solution, the hydrofluoroether solvent is separated by distillation to obtain the crude product of the perfluoroether sulfonate.
9. The preparation method of the perfluorosulfonate according to claim 8, characterized in that, The distillation temperature is 90 - 100 °C, and the pressure is -0.08 to -0.09 mpa.
10. The preparation method of the perfluorosulfonate according to any one of claims 1 - 9 is applied in the preparation of a fluorosulfonic acid ion exchange membrane.