Preparation method of special monomer perfluoro (3-oxapent-4-ene) sulfonyl fluoride (PFSAF) for perfluorinated sulfonic acid resin

Abstract

The invention discloses a preparation method of a special monomer perfluoro (3-oxapent-4-ene) sulfonyl fluoride (PFSAF) for perfluorosulfonic acid resin, belongs to the technical field of special fluorine material synthesis, and is characterized in that a specific preparation system is utilized, fluorosulfonyl ethyl oxatetrafluoroiodoethane (II) is used as a raw material, and different organic metal reagents are used for preparing the special monomer perfluoro (3-oxapent-4-ene) sulfonyl fluoride (PFSAF) for the perfluorosulfonic acid resin, so that the special monomer perfluoro (3-oxapent-4-ene) sulfonyl fluoride (PFSAF) is obtained. The one-step removal of iodine and fluorine is realized to construct a perfluoroalkenyl functional group, and the synthesis of the special monomer (PFSAF, I) of the perfluorosulfonic acid resin exchange membrane is completed. Compared with the existing synthesis method, the method has the advantages of short steps, cheap and easily available reagents and high yield, has the potential of large-scale engineering preparation, and provides a solid foundation for low-cost development of the perfluorosulfonic acid proton exchange membrane.

Description

Technical Field

[0001] The present invention belongs to the technical field of special fluorine material synthesis, and particularly relates to a preparation method of a special monomer of short-side-chain perfluorosulfonic acid resin. Background Art

[0002] A proton exchange membrane (PEM) is a solid electrolyte membrane, which not only plays a key role in PEM electrolyzed water technology, but is also one of the core components of a proton exchange membrane fuel cell (PEMFC). The proton exchange membrane is mainly used to isolate the two electrodes and transfer protons (H+). Its basic principle is that hydrogen ions combine with the sulfonic acid groups on the proton exchange membrane, and then move from one sulfonic acid group to another, and finally reach the other end of the membrane. Electrons and anions cannot pass through.

[0003] As a key component of fuel cells and electrolyzers, the proton exchange membrane needs to have good proton conductivity and physical and chemical stability. The current mainstream proton exchange membrane solution is the perfluorosulfonic acid proton exchange membrane, which is composed of a carbon-fluorine main chain and an ether side chain with a sulfonic acid group. The raw material of the perfluorosulfonic acid proton membrane, perfluorosulfonic acid resin (PFAR), is copolymerized from perfluoro vinyl ether (PSVE) monomers and tetrafluoroethylene (TFE). Its typical structure is as follows:

[0004] Among them, in the above commercial perfluorinated proton membranes, a special monomer perfluoro(3-oxapent-4-ene)sulfonyl fluoride (PFSAF) is required for a type of perfluorosulfonic acid resin (x = 0, y = 2), which plays an important role in the synthesis of perfluorosulfonic acid resin. At present, there are mainly the following two methods for the synthesis of this monomer with practical value. The specific routes are shown in the following formula.

[0005] Synthesis Method 1

[0006] Synthesis Method 2

[0007] Method 1: Refer to Patent EP3766866A1. Using hexafluorocyclopropane (HFPO) and 2-(fluorosulfonyl)difluoroacetyl fluoride (COFCF2SO2F) as raw materials for telomerization reaction, the separated monofluoroacyl fluoride product is pyrolyzed at high temperature under alkaline conditions to obtain a five-membered cyclic product (2,4,4,5,5-pentafluoro-2-(trifluoromethyl)-1,3-oxathiolane 3,3-dioxide). Then, sodium methoxide is used to open the ring to construct a perfluoro vinyl ether structure. After the obtained sodium sulfonate group is converted to sulfonyl chloride with phosphorus pentachloride (PCl5), a fluorine-chlorine exchange reaction is carried out with sodium fluoride (NaF) to obtain the target product perfluoro(3-oxa-4-pentenyl)sulfonyl fluoride (CF2 = CFOCF2CF2SO2F, abbreviated as PFSAF).

[0008] Method 2: Refer to the literature (J. Fluor. Chem, 2006, 127, 1595). Using 2-(chlorodifluoromethyl)-2,3,3-trifluoroepoxyethane as a substitute for HFPO to carry out telomerization with 2-(fluorosulfonyl)difluoroacetyl fluoride (COFCF2SO2F). The separated monofluoroacyl fluoride product is pyrolyzed at high temperature under alkaline action to directly obtain the target product perfluoro(3-oxa-4-pentenyl)sulfonyl fluoride (PFSAF).

[0009] The steps of Method 1 are cumbersome and there are many by-products, requiring very strict control of reaction and separation conditions. It should be noted that some hydrogenated by-products will be generated during the high-temperature pyrolysis process, and their boiling points are close to those of the target product, making it difficult to separate, resulting in a very high synthesis cost. Method 2 requires the use of the carefully designed and synthesized raw material 2-(chlorodifluoromethyl)-2,3,3-trifluoroepoxyethane, which can avoid the problems in Method 1 to a certain extent. However, the preparation of its raw materials is difficult, and it is already a very rare and expensive material, resulting in a high production cost of the final PFSAF monomer as well.

[0010] Due to the defects in the prior art such as large synthesis difficulty, long synthesis route, expensive raw materials, and difficulty in repeating reaction results; in the current prior art: a preparation method of a resin monomer for an ion exchange membrane with the publication number CN111072526A uses 5-iodooctafluoro-3-oxapentanesulfonyl fluoride as a raw material to complete the synthesis of the monomer through a metal dehalogenating reagent. However, the target product cannot be obtained by repeating the experiment under the optimal conditions disclosed in the patent. Summary of the Invention

[0011] 1. Technical problems to be solved: Based on the above background, the main technical problem to be solved by the present invention is, based on the structural characteristics of PFSAF (I), by using 5-iodooctafluoro-3-oxapentanesulfonyl fluoride (ICF 2 CF 2 OCF2 CF 2 SO 2 F) as a raw material, through a metal organic reagent for deiodofluorination, to construct the target monomer in one step.

[0012] 2. Technical solution: To solve the above problems, the present invention adopts the following technical solutions.

[0013] A preparation method for perfluoro(3-oxapent-4-ene)sulfonyl fluoride (PFSAF), a special monomer for perfluorosulfonic acid resin, which includes the following steps: in the presence of an organometallic reagent, in an aprotic solvent, the compound of formula II undergoes a deiodofluorination reaction to obtain the compound of formula I; .

[0014] In a certain embodiment of the present invention, the organometallic reagent is an organoaluminum reagent, an organomagnesium reagent or an organolithium reagent; preferably an organolithium reagent or an organomagnesium reagent; The organoaluminum reagent is preferably (R 1 ) 3 Al, R 1 independently is C 1-6 alkyl, such as methyl or ethyl; the organoaluminum reagent is more preferably triethylaluminum; The organomagnesium reagent is preferably R 2 MgX, R 2 is C 1-6 alkyl or C 6-12 aryl, such as methyl, ethyl or phenyl; X is a halogen, such as Br; The organomagnesium reagent is more preferably methylmagnesium bromide, ethylmagnesium bromide or phenylmagnesium bromide; The organolithium reagent is preferably R 3 Li, R 3 is C 1-6 alkyl or C 6-12 aryl, such as methyl, ethyl, n-butyl or phenyl; The organolithium reagent is more preferably methyllithium, n-butyllithium; In a certain embodiment of the present invention, the organometallic reagent is introduced into the reaction system in the form of an organometallic reagent solution, and the solvent of the organometallic reagent solution is an alkane solvent, an aromatic hydrocarbon solvent, a chain ether solvent or a cyclic ether solvent; The alkane solvent is preferably a C 3-10 linear or branched alkane solvent, such as n-hexane or n-pentane; The aromatic hydrocarbon solvent is preferably benzene substituted by one or more C 1-6 alkyl, such as toluene; The chain ether solvent is preferably R 4 -O-R5 , wherein R 4 and R 5 are independently C 1-6 linear or branched alkyl; the chain ether solvent is more preferably diethyl ether; The cyclic ether solvent is preferably a heterocycloalkane containing 4-10 ring atoms and having at least 1 ring atom as O, such as tetrahydrofuran; Preferably, the organometallic reagent solution is an organoaluminum reagent solution, an organomagnesium reagent solution, an organolithium reagent solution or an organozinc reagent solution; The solvent of the organoaluminum reagent solution is preferably C 3-10 linear or branched alkane solvent, such as n-hexane; the concentration of the organoaluminum reagent solution is preferably 1-1.5 mol / L, such as 1.3 mol / L; The solvent of the organomagnesium reagent solution is preferably a chain ether solvent or a cyclic ether solvent, such as diethyl ether or tetrahydrofuran; The concentration of the organomagnesium reagent solution is preferably 1-3 mol / L, such as 1 mol / L or 2 mol / L; The solvent of the organolithium reagent solution is preferably C 3-10 linear or branched alkane solvent, chain ether solvent or cyclic ether solvent, such as n-hexane, n-pentane, diethyl ether or tetrahydrofuran; The concentration of the organolithium reagent solution is preferably 1-5 mol / L, such as 1 mol / L, 2 mol / L, 3.1 mol / L; In a certain embodiment of the present invention, the organometallic reagent solution is any of the following:

[0015] In the above table, each row represents an organometallic reagent solution. For example, organometallic reagent solution 1 means that the organometallic reagent solution is a n-hexane solution of triethylaluminum; Preferably, the organometallic reagent solution is any of the following:

[0016] In the above table, each row represents an organometallic reagent solution. For example, organometallic reagent solution 1-1 means that the organometallic reagent solution is a n-hexane solution of triethylaluminum, wherein the concentration of triethylaluminum is 1.3 mol / L.

[0017] In a certain embodiment of the present invention, the organometallic reagent solution is added dropwise to the reaction system through a constant pressure dropping funnel; The dropping rate is preferably 1-10 ml / min, such as 1.96 ml / min, 5 ml / min, 5.6 ml / min or 8.3 ml / min; The dropping is preferably carried out under the liquid surface of the reaction system.

[0018] In a certain embodiment of the present invention, in the reaction system, the molar ratio of the organometallic reagent to the compound of formula II is (1 - 3):1, preferably (1.5 - 2.5):1, such as 1.5:1, 2:1 or 2.5:1.

[0019] In a certain embodiment of the present invention, the aprotic solvent is one or more of cyclic ether solvents, chain ether solvents, R 5 -O-R 6 , ketone solvents, nitrile solvents, amide solvents or ester solvents; R 5 is C 4-8 cycloalkyl or -C 1-6 alkylene - O - C 1-6 alkyl, and R 6 is C 1-6 alkyl; The cyclic ether solvent is preferably a heterocycloalkane containing 4 - 10 ring atoms and having at least 1 or 2 ring atoms as O, such as tetrahydrofuran or 1,4 - dioxane; The chain ether solvent is preferably R 7 -O-R 8 , where R 7 and R 8 are independently C 1-6 linear or branched alkyl; the chain ether solvent is more preferably diethyl ether, methyl tert - butyl ether or isopropyl ether; In the R 5 -O-R 6 , R 5 is preferably C 4-8 cycloalkyl (such as cyclopentyl) or -C 1-3 alkylene - O - C 1-3 alkyl; R 6 is preferably C 1-3 alkyl, such as methyl; The R 5 O-R 6 is preferably cyclopentyl methyl ether or ethylene glycol dimethyl ether.

[0020] In a certain embodiment of the present invention, the aprotic solvent is one or more of diethyl ether, tetrahydrofuran, 1,4 - dioxane, ethylene glycol dimethyl ether, isopropyl ether, cyclopentyl methyl ether or methyl tert - butyl ether.

[0021] In a certain embodiment of the present invention, the molar volume ratio of the compound of formula II to the aprotic solvent is 0.1 - 2.0 mol / L, such as 0.33 mol / L, 0.5 mol / L or 1 mol / L.

[0022] In one embodiment of the present invention, the temperature of the deiodofluorination reaction is 50 - 180°C, preferably 50 - 150°C, such as 60°C, 80°C, 90°C or 160°C.

[0023] In one embodiment of the present invention, the progress of the deiodofluorination reaction is monitored by conventional detection methods in the art (such as TLC, HPLC or GC), and generally the disappearance or no longer reaction of the compound of formula II in the reaction solution is taken as the end point of the reaction. In the deiodofluorination reaction, the reaction time of the deiodofluorination reaction is preferably 1 - 15 h, more preferably 2 - 8 h, such as 3 h, 4 h, 5 h, 6 h, 7 h or 8 h.

[0024] In one embodiment of the present invention, the deiodofluorination reaction is carried out under the protection of an inert gas; the inert gas is preferably nitrogen or argon.

[0025] In one embodiment of the present invention, the deiodofluorination reaction is carried out under anhydrous and anaerobic conditions.

[0026] In one embodiment of the present invention, the materials used in the deiodofluorination reaction only involve the organometallic reagent, the aprotic solvent and the compound of formula II.

[0027] In one embodiment of the present invention, in the preparation method of the compound of formula I, the deiodofluorination reaction preferably includes one or more of the following post-treatment steps: Cooling to obtain a crude product, distilling the crude product and collecting the distillate; The cooling is preferably carried out using an ice-water bath for cooling; The distillation is preferably carried out using a Vigreux column for distillation, such as distillation using a 10 cm Vigreux column, distillation using a 20 cm Vigreux column or distillation using a 30 cm Vigreux column; The distillation is preferably carried out under the positive pressure protection of an inert gas (such as nitrogen); The collection of the distillate is preferably carried out using water circulation or low-temperature ethanol circulation condensation; The distillate needs to be further rectified to obtain a high-purity monomer.

[0028] In one embodiment of the present invention, the preparation method of the compound of formula I is carried out through the following steps: Dropwise add the organometallic reagent solution to the aprotic solvent solution of the compound of formula II, and then raise the temperature to the reflux temperature of the reaction system, and react until the compound of formula II disappears or no longer reacts; The dropping rate is preferably 1 - 10 ml / min; the dropping is preferably carried out under the liquid surface of the reaction system; Preferably, the preparation method of the compound of formula I further includes the following post-treatment steps: Cool the reaction solution to obtain the crude product, and distill the crude product using a vertical spike distillation column under the protection of positive nitrogen pressure. Use a low-temperature dry ice-ethanol bath cold trap to collect the distillate to obtain the compound of formula II.

[0029] In one embodiment of the present invention, the deiodofluorination reaction is any of the following cases: (1) The organometallic reagent is (R 1 ) 3 Al (such as triethylaluminum), the aprotic solvent is tetrahydrofuran, and the deiodofluorination reaction is carried out at 50-70 °C (such as 60 °C); (2) The organometallic reagent is R 2 MgX (such as methylmagnesium bromide), the aprotic solvent is 1,4-dioxane, and the deiodofluorination reaction is carried out at 70-90 °C (such as 80 °C); (3) The organometallic reagent is R 3 Li (such as methyllithium), the aprotic solvent is diethyl ether, and the deiodofluorination reaction is carried out at 40-60 °C (such as 50 °C); (4) The organometallic reagent is R 3 Li (such as ethyllithium), the aprotic solvent is methyl tert-butyl ether, and the deiodofluorination reaction is carried out at 100-120 °C (such as 110 °C); (5) The organometallic reagent is R 2 MgX (such as phenylmagnesium bromide), the aprotic solvent is 1,4-dioxane, and the deiodofluorination reaction is carried out at 100-120 °C (such as 110 °C); (6) The organometallic reagent is R 2 MgX (such as ethylmagnesium bromide), the aprotic solvent is tetrahydrofuran, and the deiodofluorination reaction is carried out at 80-100 °C (such as 90 °C); (7) The organometallic reagent is R 3 Li (such as phenyllithium), the aprotic solvent is ethylene glycol dimethyl ether, and the deiodofluorination reaction is carried out at 140-180 °C (such as 160 °C); (8) The organometallic reagent is R 3 Li (such as n-butyllithium), the aprotic solvent is diethyl ether, and the deiodofluorination reaction is carried out at 50-70 °C (such as 60 °C).

[0030] Term Explanation: The term "alkyl" refers to a straight-chain or branched-chain alkyl group having a specified number of carbon atoms (such as C 1 -C 6 ). Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, sec-butyl, etc.

[0031] The term "alkylene" refers to a straight-chain or branched-chain divalent hydrocarbon group having a specified number of carbon atoms (e.g., C 1 -C 6 ). Examples of alkylene include, but are not limited to, methylene, ethylene, propylene, 1-methylpropylene, butylene, etc.

[0032] The term "cycloalkyl" refers to a saturated cyclic group having a specified number of ring carbon atoms (e.g., C 3- C 6 ), and the ring atoms are composed only of carbon atoms. Examples of cycloalkyl include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.

[0033] The term "heterocycloalkane" refers to a saturated cyclic alkane having a specified number of ring atoms (e.g., 3-6 membered), a specified number of heteroatoms (e.g., 1 or 2), and a specified type of heteroatoms (1, 2, or 3 of N, O, and S).

[0034] Based on the common knowledge in the art, the above preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

[0035] 3. Beneficial effects: Adopting the technical solution provided by the present invention, compared with the prior art, it has the following beneficial effects: (1) The process is simple, the required equipment is simple, the mass transfer and heat transfer methods are simple and direct, and it is easy to industrialize; (2) The raw material process of the present invention is mature, cheap and easy to obtain, and has the value of industrialization; (3) The conversion rate is high, the yield is high, the yield is above 90%, and the highest can reach 96%; (4) It can conveniently and quickly synthesize short-side-chain perfluorosulfonic acid resin special monomers.

[0036] It should be noted that the structures not described in the present invention are the same as the prior art or can be implemented by the prior art because they do not involve the design key points and improvement directions of the present invention, and will not be elaborated here. Brief description of the drawings

[0037] Figure 1 It is a result diagram of repeated experiments under the optimal conditions disclosed in the patent (CN111072526A). Detailed implementation manners

[0038] The present invention will be further described below by way of examples, but the present invention is not limited to the scope of the examples described herein. The experimental methods without specific conditions in the following examples are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0039] The structure of the compound was determined by nuclear magnetic resonance ( 19 F NMR) technology. An Agilent AM-400 nuclear magnetic resonance spectrometer was used, and the solvent for measurement was the solvent used in the reaction. The purity was determined by gas chromatography (GC) technology using an Agilent 7890A GC instrument. The infrared spectrum test was completed by a Thermo Fisher Fourier transform infrared spectrometer. The FI-MS test was completed by a JEOL-AccuTOF-GCT MS. The HRMS-ESI test was completed by a Thermo Scientific Q Exactive HF Orbitrap-FTMS.

[0040] In the following examples, the full Chinese names corresponding to the English abbreviations are as follows:

[0041] Example 1

[0042] Under a nitrogen atmosphere, 42.6 g of II (0.1 mol) and 300 mL of the solvent 1,4-Dioxane were added to a 1 L glass reaction kettle with stirring. Under a nitrogen atmosphere, 100 mL of triethylaluminum solution (1.3 M in hexane) was added using a constant pressure dropping funnel over a period of 1 h. Note that the addition should be below the liquid level and the rate should not be too fast, otherwise local reagent excess will occur, causing the substrate to decompose and the yield to decrease. The temperature was raised to 80 °C, and the reaction continued under reflux for 6 h. After the substrate was completely converted as detected by 19 F NMR, the reaction was stopped. The reaction solution was directly distilled using a 20 cm vertical spike distillation column, and the crude product was collected using circulating water. Then, the crude product was rectified using a 60 cm rectification column, and the fraction at 102 - 103 °C was collected to obtain 25.5 g of the target monomer I (CF 2 =CFOCF 2 CF 2 SO 2 F), with a yield of 91.1% and a purity of 99.5%.

[0043] Example 2

[0044] Under a nitrogen atmosphere, 426 g of II (1 mol) and 1 L of the solvent CPME were added to a 3 L glass reaction kettle with stirring. Methylmagnesium bromide (500 mL, 3 M in Et 2O), The dropping time is 2 h. Note that the dropping should be carried out below the liquid surface and the rate should not be too fast, otherwise it will cause local reagent excess, resulting in substrate decomposition and reduced yield. After the dropping is completed, the temperature is raised to 110 °C, and the reaction is continued for 5 h under reflux. After the substrate conversion is detected to be complete by 19 F NMR, stop the reaction. The reaction solution is directly distilled using a 20 cm vertical spike distillation column, and the crude product is collected by circulating water cooling. Under nitrogen protection, the crude product is rectified using a 90 cm rectification column, and the fraction at 102 - 103 °C is collected to obtain the target monomer I (CF 2 =CFOCF 2 CF 2 SO 2 F) totaling 567.8 g, with a yield of 95.8% and a purity of 99.7%.

[0045] Example 3

[0046] Under a nitrogen atmosphere, 426 g of II (1 mol) and 1 L of the solvent tetrahydrofuran (THF) are added to a 5 L glass reaction kettle with stirring. 1 L of ethylmagnesium bromide solution (2 M in THF) is added using a constant pressure dropping funnel. The dropping time is 4 h. Note that the dropping should be carried out below the liquid surface and the rate should not be too fast, otherwise it will cause local reagent excess, resulting in substrate decomposition and reduced yield. After the dropping is completed, the temperature is raised to 70 °C, and the reaction is continued for 8 h under reflux. After the substrate conversion is detected to be complete by 19 F NMR, stop the reaction. The reaction solution is directly distilled using a 30 cm vertical spike distillation column, and the crude product is collected by circulating water cooling. Under nitrogen protection, the crude product is rectified using a 90 cm rectification column, and the fraction at 102 - 103 °C is collected to obtain the target monomer I (CF 2 =CFOCF 2 CF 2 SO 2 F) totaling 257.6 g, with a yield of 92% and a purity of 99.6%.

[0047] Example 4

[0048] Under a nitrogen atmosphere, 213 g of II (0.5 mol) and 1 L of the solvent ether (Et2O) are added to a 2 L glass reaction kettle with stirring. 280 mL of phenylmagnesium bromide (2 M in THF) is added using a constant pressure dropping funnel. The dropping time is 2 h. Note that the dropping should be carried out below the liquid surface and the rate should not be too fast, otherwise it will cause local reagent excess, resulting in substrate decomposition and reduced yield. After the dropping is completed, the temperature is raised to 60 °C, and the reaction is continued for 7 h under reflux. After the substrate conversion is detected to be complete by19 After the substrate conversion was detected to be complete by \(^{19}\)F NMR, the reaction was stopped. The reaction solution was directly distilled using a 10-cm vertical spike distillation column, and the crude product was collected by cooling with circulating water. Under nitrogen protection, the crude product was rectified using a 60-cm rectification column, and the fraction at 102 - 103 °C was collected to obtain the target monomer I (CF 2 =CFOCF 2 CF 2 SO 2 F), with a total of 131.6 g, a yield of 94%, and a purity of 99.5%.

[0049] Example 5

[0050] Under a nitrogen atmosphere, 426 g of II (1 mol) and 1 L of the solvent n-pentane were added to a 3-L glass reaction kettle with stirring. Vigorous stirring was required to avoid stratification. 430 mL of methyllithium (3.1 M in Et2O) was added using a constant-pressure dropping funnel over a period of 5 h. Note that the addition should be below the liquid level and the rate should not be too fast, otherwise local reagent excess would occur, causing the substrate to decompose and the yield to decrease. After the addition was completed, the temperature was raised to 50 °C, and the reaction continued for 9 h under reflux. After the substrate conversion was detected to be complete by \(^{19}\)F NMR, the reaction was stopped. The reaction solution was directly distilled using a 20-cm vertical spike distillation column, and the crude product was collected by cooling with circulating water. Under nitrogen protection, the crude product was rectified using a 90-cm rectification column, and the fraction at 102 - 103 °C was collected to obtain the target monomer I (CF 19 After the substrate conversion was detected to be complete by \(^{19}\)F NMR, the reaction was stopped. The reaction solution was directly distilled using a 20-cm vertical spike distillation column, and the crude product was collected by cooling with circulating water. Under nitrogen protection, the crude product was rectified using a 90-cm rectification column, and the fraction at 102 - 103 °C was collected to obtain the target monomer I (CF 2 =CFOCF 2 CF 2 SO 2 F), with a total of 260.4 g, a yield of 93%, and a purity of 99.7%.

[0051] Example 6

[0052] Under a nitrogen atmosphere, 852 g of II (2 mol) and 1 L of the solvent ethylene glycol dimethyl ether (EGDME) were added to a 5-L glass reaction kettle with stirring. 2.6 L of ethyllithium solution (1 M in Et2O) was added using a constant-pressure dropping funnel over a period of 8 h. Note that the addition should be below the liquid level and the rate should not be too fast, otherwise local reagent excess would occur, causing the substrate to decompose and the yield to decrease. After the addition was completed, the temperature was raised to 80 °C, and the reaction continued for 5 h under reflux. After the substrate conversion was detected to be complete by \(^{19}\)F NMR, 19After the substrate conversion was completely detected by \(^{19}\)F NMR, the reaction was stopped. The reaction solution was directly distilled using a 30-cm vertical spike distillation column, and the crude product was collected by cooling with circulating water. Under nitrogen protection, the crude product was rectified using a 90-cm rectification column, and the fraction at 102 - 103 °C was collected to obtain 526.4 g of the target monomer I (CF 2 =CFOCF 2 CF 2 SO 2 F), with a yield of 94% and a purity of 99.6%.

[0053] Example 7

[0054] Under a nitrogen atmosphere, 213 g of II (0.5 mol) and 1 L of the solvent tetrahydrofuran (THF) were added to a 2-L glass reaction kettle with stirring. 330 mL of n-butyllithium (2 M in hexane) was added using a constant-pressure dropping funnel, and the dropping time was 3 h. Note that the dropping should be below the liquid level and the rate should not be too fast, otherwise local reagent excess will occur, causing the substrate to decompose and the yield to decrease. After the dropping was completed, the temperature was raised to 50 °C, and the reaction was continued for 6 h under reflux. After the substrate conversion was completely detected by \(^{19}\)F NMR, the reaction was stopped. The reaction solution was directly distilled using a 10-cm vertical spike distillation column, and the crude product was collected by cooling with circulating water. Under nitrogen protection, the crude product was rectified using a 60-cm rectification column, and the fraction at 102 - 103 °C was collected to obtain 134.4 g of the target monomer I (CF 19 =CFOCF 2 =CFOCF 2 CF 2 SO 2 F), with a yield of 96% and a purity of 99.7%.

[0055] Example 8

[0056] Under a nitrogen atmosphere, 426 g of II (1 mol) and 1 L of the solvent methyl tert-butyl ether (MTBE) were added to a 3-L glass reaction kettle with stirring. 1.1 L of phenyllithium (1.5 M in Et2O) was added using a constant-pressure dropping funnel, and the dropping time was 6 h. Note that the dropping should be below the liquid level and the rate should not be too fast, otherwise local reagent excess will occur, causing the substrate to decompose and the yield to decrease. After the dropping was completed, the temperature was raised to 110 °C, and the reaction was continued for 9 h under reflux. After the \(^{19}\)F NMR 19After the substrate conversion was detected to be complete by \(^{19}\)F NMR, the reaction was stopped. The reaction solution was directly distilled using a 30 cm vertical spike distillation column, and the crude product was collected under cooling with circulating water. Under nitrogen protection, the crude product was rectified using a 90 cm rectification column, and the fraction at 102 - 103 °C was collected to obtain the target monomer I (CF 2 =CFOCF 2 CF 2 SO 2 F) with a total of 263.2 g, a yield of 94%, and a purity of 99.4%.

[0057] Summary of the spectral information of product I: \(^{19}\)F NMR (376 MHz, CDCl\(_3\)) δ ppm 45.35 (p, J = 5.9 Hz, 1F), -83.91 (dp, J = 9.0, 3.0 Hz, 2F), -112.03 (dt, J = 5.9, 3.3 Hz, 2F), -112.34 (dd, J = 81.7, 67.1 Hz, 1F), -120.53 (ddt, J = 113.0, 81.7, 5.6 Hz, 1F), -135.67 (ddt, J = 112.9, 67.1, 5.7 Hz, 1F). \(^{13}\)C NMR (126 MHz, CDCl\(_3\)) δ ppm 146.95, 129.40, 115.34, 115.32, 112.73, 112.45. IR (KBr): νmax 1473, 1344, 1289, 1249, 1212, 1177, 1150, 996, 831, 800 cm\(^{-1}\). MS (FI): m / z 280 M\(^+\). HRMS (FI Positive Ion mode): m / z M\(^+\) Calculated for C\(_4\)O\(_3\)F\(_8\)S: 279.9435; Found: 279.9431. The above-described embodiments merely represent certain implementation manners of the present invention, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the present invention patent; it should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention; therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for preparing perfluoro(3-oxapent-4-ene)sulfonyl fluoride (PFSAF), a special monomer for perfluorosulfonic acid resin, characterized in that: The following steps are involved: Under inert gas protection and anhydrous and oxygen-free conditions, the compound of formula II, 5-iodooctafluoro-3-oxopentanesulfonyl fluoride (ICF2CF2OCF2CF2SO2F), is dissolved in an aprotic solvent, and then an organic metal reagent solution is added dropwise to perform a deiodination and fluorination reaction to obtain a compound of formula I; The organometallic reagent is selected from an organoaluminum reagent, an organomagnesium reagent or an organolithium reagent; The temperature of the deiodination and defluorination reaction is 50-180° C., and the reaction time is 1-15 hours; The ratio of the amount of the organometallic reagent to the amount of the compound of formula II is (1-3):

1.

2. The method for preparing perfluoro(3-oxapent-4-ene)sulfonyl fluoride (PFSAF), a special monomer for perfluorosulfonic acid resin according to claim 1, characterized in that: The organometallic reagent is any one of the following: The organoaluminum reagent has the structural formula (R 1 )3Al, where R 1 Independently selected from C 1-6 alkyl; An organomagnesium reagent having the structural formula R²MgX, wherein R² is selected from C 1-6 Alkyl or C 6-12 Aryl, X is halogen; An organolithium reagent having the structural formula R 3 Li, where R 3 Selected from C 1-6 Alkyl or C 6-12 Aryl.

3. The method for preparing perfluoro(3-oxapent-4-ene)sulfonyl fluoride (PFSAF), a special monomer for perfluorosulfonic acid resin according to claim 1, characterized in that: The organoaluminum reagent is triethylaluminum, the organomagnesium reagent is methylmagnesium bromide, ethylmagnesium bromide or phenylmagnesium bromide, and the organolithium reagent is methyllithium, ethyllithium, n-butyllithium or phenyllithium.

4. The method for preparing perfluoro(3-oxapent-4-ene)sulfonyl fluoride (PFSAF), a special monomer for perfluorosulfonic acid resin according to claim 1, characterized in that: The aprotic solvent is selected from one or more of diethyl ether, tetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, isopropyl ether, cyclopentyl methyl ether, and methyl tert-butyl ether.

5. The method for preparing perfluoro(3-oxapent-4-ene)sulfonyl fluoride (PFSAF), a special monomer for perfluorosulfonic acid resin according to claim 1, characterized in that: The solvent of the organic metal reagent solution is selected from n-hexane, n-pentane, ether or tetrahydrofuran; the concentration of the organic metal reagent solution is 1-5 mol / L.

6. The method for preparing perfluoro(3-oxapent-4-ene)sulfonyl fluoride (PFSAF), a special monomer for perfluorosulfonic acid resin according to claim 1, characterized in that: The dropping speed is 1-10 ml / min, and the dropping process is carried out below the liquid surface of the reaction system.

7. The method for preparing perfluoro(3-oxapent-4-ene)sulfonyl fluoride (PFSAF), a special monomer for perfluorosulfonic acid resin according to claim 1, characterized in that: The temperature of the deiodination and defluorination reaction is 50-150° C., and the reaction time is 2-8 hours.

8. The method for preparing perfluoro(3-oxapent-4-ene)sulfonyl fluoride (PFSAF), a special monomer for perfluorosulfonic acid resin according to claim 1, characterized in that: After the deiodination and fluorination reaction is completed, the following post-processing steps are included: The reaction solution was cooled to room temperature to obtain a crude product; Under the protection of inert gas, the crude product is distilled through a vertical stab distillation column, and the fraction at 102-103° C. is collected to obtain a high-purity compound of formula I.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The molar ratio of the organometallic reagent to the compound of formula II is (1.5-2.5):

1.

10. The method for preparing perfluoro(3-oxapent-4-ene)sulfonyl fluoride (PFSAF), a special monomer for perfluorosulfonic acid resin according to claim 1, characterized in that: The specific conditions of the deiodination and defluorination reaction are any combination of the following: (1) The organometallic reagent is triethylaluminum, the aprotic solvent is tetrahydrofuran, and the reaction temperature is 50-70°C; (2) The organometallic reagent is methylmagnesium bromide, the aprotic solvent is 1,4-dioxane, and the reaction temperature is 70-90°C; (3) The organometallic reagent is methyl lithium, the aprotic solvent is ether, and the reaction temperature is 40-60°C; (4) The organometallic reagent is phenylmagnesium bromide, the aprotic solvent is 1,4-dioxane, and the reaction temperature is 100-120°C; (5) The organometallic reagent is n-butyl lithium, the aprotic solvent is ether, and the reaction temperature is 50-70°C; (6) The organometallic reagent is ethylmagnesium bromide, the aprotic solvent is tetrahydrofuran, and the reaction temperature is 70-90°C; (7) The organometallic reagent is ethyl lithium, the aprotic solvent is ethylene glycol dimethyl ether, and the reaction temperature is 80-100°C; (8) The organometallic reagent is phenyllithium, the aprotic solvent is methyl tert-butyl ether, and the reaction temperature is 100-120°C.

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