A method for synthesizing octafluorocyclopentene

Abstract

The present application relates to a method for synthesizing octafluorocyclopentene, belonging to the field of organic chemical synthesis. The method for synthesizing octafluorocyclopentene is characterized in that cyclopentene, bromine and anhydrous hydrogen fluoride are reacted in a certain temperature and under the action of a fluorination catalyst to generate octafluorocyclopentene in a gas phase. The raw material is cheap and convenient to obtain; the product is easy to separate and purify; the industrial production is easy; and the industrial waste is less.

Description

Technical Field

[0001] This invention relates to an efficient and safe method for synthesizing octafluorocyclopentene, specifically an industrially feasible method for synthesizing octafluorocyclopentene. Background Technology

[0002] Octafluorocyclopentene (CAS No.: 559-40-0) is an important perfluorocycloolefin compound. At room temperature and pressure, it is a colorless and transparent liquid with high chemical stability, low dielectric constant, and good thermal stability. Its main applications are in high-end electronics, serving as an environmentally friendly gaseous solvent or working medium in the cleaning and etching processes of precision electronic components, used in precision cleaning and plasma etching processes. Simultaneously, it is a key fluorinated building block in the synthesis of fluorinated polymers, specialty surfactants, and pharmaceutical intermediates, used in the preparation of specialty fluororubbers, fluororesins, and functional fluorinated surfactants. Furthermore, due to its ability to generate CF2 groups through thermal decomposition, this substance possesses excellent fire-extinguishing properties.

[0003] There are few reports on the synthesis methods of octafluorocyclopentene. Patent (WO9855429 A1) reports a reaction route for the production of octafluorocyclopentene from octachlorocyclopentene. Under 18-crown ether-6 and potassium fluoride catalysis, the chlorine in octachlorocyclopentene is replaced with fluorine. The reported yield is close to 100%. However, the reaction conditions are quite demanding, making industrial application difficult. Patent (WO2018235566A1) reports a liquid-phase production route for octafluorocyclopentene. 1-Chloroheptafluorocyclopentene is added to a reactor and heated to above 40°C, then mixed with an alkali metal suspension at 85°C for fluorination to obtain octafluorocyclopentene. The overall reaction yield is relatively high. This reaction route consumes a large amount of organic solvent, causing serious environmental pollution and limiting its industrial application. Patent (CN107188778B) reports a gas-phase synthesis route for octafluorocyclopentene. Octafluorocyclopentene is synthesized from 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride via a substitution reaction catalyzed by Zn, Co, Ni, Ge, and In at 280–400 °C. This reaction process suffers from low yield and involves high-temperature operation, making product purification difficult and hindering industrialization. Patent (CN202510476050.5) reports a catalytic synthesis method for octafluorocyclopentene, which involves a gas-phase catalytic fluorination reaction of 1-chloroheptafluorocyclopentene and anhydrous hydrogen fluoride at 80–120 °C under the action of a fluorinated chlorine catalyst. The fluorinated chlorine catalyst used in this method is prepared in multiple steps: first, a metal chloride is dissolved in water, a precipitant is added, and a slurry is formed; after filtration and washing until neutral, an aluminum nitrate solution is added, followed by stirring and drying to obtain a precursor; finally, the precursor is pressed, calcined, and activated to obtain the desired fluorinated chlorine catalyst. Patent (CN119569531A) reports a method for preparing octafluorocyclopentene, using 4-cyclopenten-1,3-dione as the starting material. The reaction is first carried out under reflux with a selective fluorine reagent in a solvent. After quenching, extraction with ethyl acetate, washing with saturated sodium chloride, and drying, a crude intermediate is obtained by vacuum distillation. This crude product is further purified by column chromatography and the solvent is removed to obtain a pure intermediate. Finally, it is reacted with diethylaminosulfur trifluoride in another solvent to convert it into the target product, octafluorocyclopentene. This reaction process also involves a large amount of organic solvent, which will cause significant environmental pollution.

[0004] In summary, there are currently few reports on routes for the synthesis of octafluorocyclopentene, and the related technical challenges have not yet been overcome. The reported route, which involves the reaction of 1-chloroheptafluorocyclopentene with anhydrous hydrogen fluoride, suffers from drawbacks such as long route length, demanding conditions, and expensive raw materials, thus limiting the industrial production of octafluorocyclopentene. Summary of the Invention

[0005] The purpose of this invention is to prepare octafluorocyclopentene in high yield using a simple reaction system and suitable reaction conditions. The raw materials are inexpensive and readily available; the product separation and purification are simple; and the synthesis process is safe and suitable for industrial production.

[0006] A method for synthesizing octafluorocyclopentene, characterized in that: cyclopentene, bromine (molecular formula Br2), and anhydrous hydrogen fluoride react in the gas phase under certain temperature and the action of a fluorination catalyst to generate octafluorocyclopentene; the active component of the fluorination catalyst is one or more of Cr, Zn, Mg, Co, Al, Sn, Cu, Bi, and In, and Cr must be present; the gas phase reaction temperature is 200-650 °C.

[0007] The active component of the fluorination catalyst is Cr-Al with a metal molar ratio of 60:40; or Cr-Zn with a metal molar ratio of 90:10; or Cr-Co-Al-Bi with a metal molar ratio of 90:4:4:2.

[0008] The fluorinated catalyst is prepared by co-precipitation. Soluble salts of various metal elements are mixed into a solution, the pH of the solution is adjusted to alkaline, the precipitate is filtered, the filter material is washed, and dried to obtain the catalyst precursor. The catalyst is then obtained by sequentially drying and hydrogen fluoride activation processes.

[0009] The soluble salts of each metal element are chloride salts or nitrate salts, and the pH of the solution is adjusted to alkaline by using ammonia water to adjust the pH to 9-12.

[0010] The drying process involves loading the catalyst precursor into a fixed-bed reactor and drying it for 10 hours at a temperature of 400°C at a rate of 1°C / min under nitrogen protection. Then, the temperature is lowered to 200°C to complete the drying process.

[0011] The activation process involves heating the reactor to 300°C, first activating the catalyst with 100 ml / min nitrogen and 20 ml / min hydrogen fluoride for 10 hours; then activating the catalyst with 100 ml / min nitrogen and 50 ml / min hydrogen fluoride for 10 hours; then activating the catalyst with 50 ml / min nitrogen and 100 ml / min hydrogen fluoride for 10 hours; then activating the catalyst with 100 ml / min pure hydrogen fluoride for 10 hours; raising the temperature to 400°C, and finally activating the catalyst with 100 ml / min pure hydrogen fluoride for 10 hours.

[0012] The contact time for the gas-phase reaction is 0.1-40 s.

[0013] The gas-phase reaction temperature is 400-500 ℃.

[0014] The molar ratio of cyclopentene, bromine, and anhydrous hydrogen fluoride is 1:5-30:8-30.

[0015] Preferably, the molar ratio of cyclopentene, bromine, and anhydrous hydrogen fluoride is 1:5-10:8-20.

[0016] This invention discloses a method for synthesizing octafluorocyclopentene, wherein cyclopentene (molecular formula Cyclo-CH=CH-CH2-CH2-CH2-), bromine (molecular formula Br2), and anhydrous hydrogen fluoride (molecular formula HF) are reacted in the gas phase under certain temperature and the action of a fluorination catalyst to generate octafluorocyclopentene (molecular formula Cyclo-CF=CF-CF2-CF2-CF2-).

[0017]

[0018] The beneficial effects of this invention are as follows:

[0019] 1. The raw material cyclopentene used in this invention is readily available and inexpensive.

[0020] 2. This invention uses a gas-phase fluorination method, which produces less industrial waste and has a high product yield. Due to the reduced byproducts and waste, production costs are significantly lowered.

[0021] 3. This invention uses an atmospheric pressure gas-phase fluorination method, which reduces the risk of industrial safety production and is fully suitable for industrial production.

[0022] 4. The process route of this invention belongs to a green process that is safe to produce, has a wide range of raw material sources, high product yield, and low industrial waste.

[0023] Specific implementation methods

[0024] The present invention will be further described below through specific embodiments, but this is not a limitation of the present invention. Those skilled in the art can make various modifications or improvements based on the basic idea of ​​the present invention, but as long as they do not depart from the basic idea of ​​the present invention, they are all within the scope of the present invention.

[0025] Example 1

[0026] (1) The fluorinated catalyst was prepared by co-precipitation method, and the steps are as follows:

[0027] A CrCl3 and Zn(NO3)2 solution with a molar ratio of 90:10 was mixed, and 30wt% ammonia solution was added dropwise to the mixed solution to adjust the pH to 10.0. The precipitate was filtered, washed with deionized water, dried, and pressed into shape to obtain the Cr-Zn precursor of the cyclofluorination catalyst.

[0028] 50 ml of the cyclofluorination catalyst Cr-Zn precursor was introduced into a fixed-bed reactor, which was heated using an open-tube furnace. Under nitrogen protection at a rate of 100 ml / min, the catalyst was first dried at 400 °C for 20 hours at a rate of 1 °C / min, and then the temperature was lowered to 200 °C. This completed the drying process of the fluorination catalyst.

[0029] The reactor was heated to 200℃, and the catalyst was activated with nitrogen at a rate of 100 ml / min and hydrogen fluoride at a rate of 20 ml / min for 10 hours; then activated with nitrogen at a rate of 100 ml / min and hydrogen fluoride at a rate of 50 ml / min for 10 hours; then activated with nitrogen at a rate of 50 ml / min and hydrogen fluoride at a rate of 100 ml / min for 10 hours; finally activated with pure hydrogen fluoride at a rate of 100 ml / min for 10 hours; and then the temperature was increased to 400℃, and the catalyst was activated with pure hydrogen fluoride at a rate of 100 ml / min for 10 hours. This completed the catalyst activation process. The specific surface area, determined by the BET method, was 198.25 m². 2 / g, pyridine adsorption infrared spectroscopy (Py-FTIR) shows that it is a strong acid.

[0030] The reactor was heated to 400 °C. Cyclopentene (25 ml / min), bromine (125 ml / min), and anhydrous hydrogen fluoride (200 ml / min) were introduced into the mixing chamber and mixed thoroughly. The mixture was then passed through the reactor to a buffer bottle, a washing bottle, a concentrated alkali absorber, and a cooling collector. After the experiment, the product was mainly distributed in the cooling collector. GC analysis of the collected product showed that it contained 62% octafluorocyclopentene (Cyclo-CF=CF-CF2-CF2-CF2-), 18% monobromoheptafluorocyclopentene (Cyclo-CBr=CF-CF2-CF2-CF2-), and 5% dibromohexafluorocyclopentene (Cyclo-CF=CF-CF2-CBr2-CF2-).

[0031] Example 2

[0032] (1) The fluorinated catalyst was prepared by co-precipitation method, and the steps are as follows:

[0033] A CrCl3 and Al(NO3)2 solution with a molar ratio of 60:40 was mixed, and 30wt% ammonia solution was added dropwise to the mixed solution to adjust the pH to 10.0. The precipitate was filtered, washed with deionized water, dried, and pressed into shape to obtain the Cr-Al cyclofluorination catalyst precursor.

[0034] 50 ml of the fluorination catalyst Cr-Al precursor was added to a fixed-bed reactor, which was heated using an open-tube furnace. Under nitrogen protection at a rate of 100 ml / min, the catalyst was first dried at 400°C for 20 hours at a rate of 1°C / min, and then the temperature was lowered to 200°C. This completed the drying process of the fluorination catalyst.

[0035] The reactor was heated to 200℃, and the catalyst was activated with nitrogen at a rate of 100 ml / min and hydrogen fluoride at a rate of 20 ml / min for 10 hours; then activated with nitrogen at a rate of 100 ml / min and hydrogen fluoride at a rate of 50 ml / min for 10 hours; then activated with nitrogen at a rate of 50 ml / min and hydrogen fluoride at a rate of 100 ml / min for 10 hours; finally activated with pure hydrogen fluoride at a rate of 100 ml / min for 10 hours; and then the temperature was increased to 400℃, and the catalyst was activated with pure hydrogen fluoride at a rate of 100 ml / min for 10 hours. This completed the catalyst activation process. The specific surface area determined by the BET method was 165.23 m². 2 / g, pyridine adsorption infrared spectroscopy (Py-FTIR) shows that it is a strong acid.

[0036] The reactor was heated to 450 °C, and cyclopentene (12 ml / min), bromine (96 ml / min), and anhydrous hydrogen fluoride (96 ml / min) were introduced into the mixing chamber and mixed thoroughly. The mixture was then passed through the reactor to a buffer bottle, a washing bottle, a concentrated alkali absorber, and a cooling collector. After the experiment, the product was mainly distributed in the cooling collector. GC analysis of the collected product showed that it contained 84% octafluorocyclopentene (Cyclo-CF=CF-CF2-CF2-CF2-), 11% monobromoheptafluorocyclopentene (Cyclo-CBr=CF-CF2-CF2-CF2-), and 3% dibromohexafluorocyclopentene (Cyclo-CF=CF-CF2-CBr2-CF2-).

[0037] Example 3

[0038] (1) The fluorinated catalyst was prepared by co-precipitation method, and the steps are as follows:

[0039] A solution of CrCl3, Co(NO3)2, Al(NO3)2, and Bi(NO3)2 in a molar ratio of 90:4:4:2 was mixed. 30 wt% ammonia solution was added dropwise to the mixture to adjust the pH to 11.0. The precipitate was filtered, washed with deionized water, dried, and pressed into shape to obtain the cyclofluorination catalyst precursor Cr-Co-Al-Bi.

[0040] 50 ml of the fluorination catalyst Cr-Co-Al-Bi precursor was introduced into a fixed-bed reactor, which was heated using an open-tube furnace. Under nitrogen protection at a rate of 100 ml / min, the catalyst was first dried at 400°C for 20 hours at a rate of 1°C / min, and then the temperature was lowered to 200°C. This completed the drying process of the fluorination catalyst.

[0041] The reactor was heated to 200℃, and the catalyst was activated with nitrogen at a rate of 100 ml / min and hydrogen fluoride at a rate of 20 ml / min for 10 hours; then activated with nitrogen at a rate of 100 ml / min and hydrogen fluoride at a rate of 50 ml / min for 10 hours; then activated with nitrogen at a rate of 50 ml / min and hydrogen fluoride at a rate of 100 ml / min for 10 hours; finally activated with pure hydrogen fluoride at a rate of 100 ml / min for 10 hours; and then the temperature was increased to 400℃, and the catalyst was activated with pure hydrogen fluoride at a rate of 100 ml / min for 10 hours. This completed the catalyst activation process. The specific surface area, determined by the BET method, was 135.78 m². 2 / g, pyridine adsorption infrared spectroscopy (Py-FTIR) shows that it is a strong acid.

[0042] The reactor was heated to 500 °C. Cyclopentene (12 ml / min), bromine (120 ml / min), and anhydrous hydrogen fluoride (240 ml / min) were introduced into the mixing chamber and mixed thoroughly. The mixture was then passed through the reactor to a buffer bottle, a washing bottle, a concentrated alkali absorber, and a cooling collector. After the experiment, the product was mainly distributed in the cooling collector. GC analysis of the collected product showed that it contained 88% octafluorocyclopentene (Cyclo-CF=CF-CF2-CF2-CF2-), 6% monobromoheptafluorocyclopentene (Cyclo-CBr=CF-CF2-CF2-CF2-), and 2% dibromohexafluorocyclopentene (Cyclo-CF=CF-CF2-CBr2-CF2-).

Claims

1. A method for synthesizing octafluorocyclopentene, characterized in that: Cyclopentene, bromine (molecular formula Br2), and anhydrous hydrogen fluoride react in the gas phase under certain temperature and the action of a fluorination catalyst to produce octafluorocyclopentene; the active component of the fluorination catalyst is one or more of Cr, Zn, Mg, Co, Al, Sn, Cu, Bi, and In, and Cr must be present; the gas phase reaction temperature is 200-650℃.

2. The method according to claim 1, wherein the active component of the fluorination catalyst is Cr-Al with a metal molar ratio of 60:40; or Cr-Zn with a metal molar ratio of 90:10; or Cr-Co-Al-Bi with a metal molar ratio of 90:4:4:

2.

3. According to the method of claim 2, the fluorination catalyst is prepared by co-precipitation, wherein soluble salts of each metal element are mixed into a solution, the pH of the solution is adjusted to alkaline, the precipitate is filtered, the filter is washed, and the precipitate is dried to obtain the catalyst precursor, which is then subjected to drying and hydrogen fluoride activation processes to obtain the catalyst.

4. The method according to claim 3, wherein the soluble salts of each metal element are chloride salts or nitrate salts, and the pH of the solution is adjusted to alkaline by using ammonia water to adjust the pH to 9-12.

5. The method according to claim 3, wherein the drying process involves loading the catalyst precursor into a fixed-bed reactor, drying it for 10 hours at a temperature increased to 400°C at a rate of 1°C / min under nitrogen protection (100 ml / min), and then lowering the temperature to 200°C to complete the drying process.

6. The method according to claim 3, wherein the activation process comprises heating the reactor to 300°C, first activating the catalyst with 100 ml / min nitrogen and 20 ml / min hydrogen fluoride for 10 hours; then activating the catalyst with 100 ml / min nitrogen and 50 ml / min hydrogen fluoride for 10 hours; then activating the catalyst with 50 ml / min nitrogen and 100 ml / min hydrogen fluoride for 10 hours; then activating the catalyst with 100 ml / min pure hydrogen fluoride for 10 hours; raising the temperature to 400°C, and finally activating the catalyst with 100 ml / min pure hydrogen fluoride for 10 hours.

7. The method according to claim 1, wherein the contact time of the gas-phase reaction is 0.1-40 s.

8. The method according to claim 1, wherein the gas-phase reaction temperature is 400-500 °C.

9. The method according to claim 1, wherein the molar ratio of cyclopentene, bromine, and anhydrous hydrogen fluoride is 1:5-30:8-30.

10. The method according to claim 9, wherein the molar ratio of cyclopentene, bromine, and anhydrous hydrogen fluoride is 1:5-10:8-20.

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