A method for synthesizing perfluoropentanone

Abstract

This invention relates to "an efficient and safe method for synthesizing perfluoropentanone," belonging to the field of organic chemical synthesis. The method for synthesizing perfluoropentanone is characterized by the following steps: under the action of hexafluoropropylene CF2=CF-CF3, fluorophosgene CF2O, and trifluorobromomethane CF3Br, perfluoropentanone (C5F) is generated in the gas phase. 10 O. The raw materials of this invention are inexpensive and readily available; the product separation and purification are simple; it is easy to industrialize; and it produces less industrial waste.

Description

Technical Field

[0001] This invention relates to a gas-phase catalytic synthesis method for perfluoropentanone, specifically an industrially feasible method for synthesizing perfluoropentanone. Background Technology

[0002] Perfluoropentanone (CAS No.: 756-12-7) is a highly symmetrical liquid perfluoroketone compound. At room temperature and pressure, it is a colorless and transparent liquid with excellent chemical and thermal stability. Fluorine atoms replace all hydrogen sites in its molecule, giving it a series of unique properties: non-flammable and non-explosive, extremely low surface tension, no residue after evaporation, and excellent electrical insulation properties. Its chemical structure is stable, with extremely low ozone depletion potential (ODP) and low global warming potential (GWP). Its most prominent application is as a new generation of clean gas fire extinguishing agent, effectively extinguishing electrical fires without leaving residue. Its volatility and residue-free characteristics make it highly promising for fire protection of high-value targets, especially in the field of fire prevention for ancient buildings. Furthermore, it is also used as an environmentally friendly working medium in precision cleaning and etching processes in semiconductor and electronics manufacturing.

[0003] Currently, there are few reports in the literature regarding the synthesis of perfluoropentanone. One report (Bulletin of the Academy of Sciences of the USSR. 1988, 37, 2389–2389.) describes a reaction route for preparing perfluoropentanone from the pyrolysis of perfluoro4-methyl-2,3-butanedione. In this reaction, cesium fluoride is used as a catalyst to catalyze the pyrolysis of perfluoro4-methyl-2,3-butanedione under heating conditions for one hour, yielding the target product. The yield of this reaction is approximately 76%, but its main drawback is the high cost of the raw materials, making industrial application difficult. Another report (J. Fluor. Chem. 1985, 29, 4.) describes a photochemical reaction route for the production of perfluoropentanone. Perfluoro2,3-dimethyl-2-butene forms free radicals under light irradiation, ultimately yielding the target product with a yield of 48%. This reaction process has a lower yield and produces more photochemical byproducts, making it unsuitable for industrial application. Patent (CN108440261 A) reports a process for preparing perfluoropentanone. The raw material trifluoroacetyl fluoride, hexafluoropropylene, and the catalyst cesium carbonate are added to a high-pressure reactor, followed by the addition of solvent acetonitrile and 18-crown ether-6. The reaction system is heated to 80°C and reacted for 10 hours to obtain the target product, with a yield of approximately 98%. This reaction route consumes a large amount of organic solvent, causing serious environmental pollution and limiting its industrial application. Patent (CN201811458206.3) reports a method for preparing perfluoropentanone by pyrolysis of hexafluoropropylene dimer. This method uses hexafluoropropylene dimer and oxygen as raw materials, and carries out a gas-phase oxidative cracking reaction (contact time 0.1-200 seconds) at 150-600°C and 0-1 MPa using a supported catalyst containing Ag, Cu, or alkali metal fluorides to generate perfluoroacetyl fluoride. After the reaction, a mixture containing perfluoroisobutyryl fluoride and unreacted dimers is first collected in a -2℃ cold trap. The dimers recovered by distillation can be returned to the cracking furnace for reuse. Finally, high-purity perfluoroacetyl fluoride is collected in a -70℃ cold trap. The conversion rate of this reaction is approximately 60%. Subsequently, perfluoroacetyl fluoride and hexafluoropropylene gas are passed into a reaction tube containing a catalyst and reacted at 200℃ for 1-2 hours to obtain perfluoropentanone. The yield of the second step reaction is 85%. This reaction route is relatively long, difficult to industrialize, and costly. Patent (CN108440261 A) reports a one-pot synthesis process for perfluoropentanone. This method uses trifluoroacetyl chloride and perfluoropropylene as raw materials, and reacts them in a potassium fluoride catalyst and acetonitrile solvent at 60℃ in a high-pressure reactor for 8 hours to synthesize perfluoro(3-methyl-2-butanone). After the reaction was completed, the system was cooled in an ice bath to release unreacted raw materials and volatile intermediates. The remaining liquid was then subjected to simple distillation, and the fraction collected at 26–28 °C yielded 35.86 g of product, with a yield of 67.4%. This reaction involves a significant amount of organic solvent, and the conversion rate remains low, which limits further industrial applications.

[0004] In summary, there are currently few reports on routes for the synthesis of perfluoropentanone, and the related technical challenges have not yet been overcome. The reported routes using trifluoroacetyl chloride and perfluoropropylene as raw materials suffer from drawbacks such as long routes, demanding conditions, and expensive raw materials, which limit the industrial production of perfluoropentanone. Summary of the Invention

[0005] The purpose of this invention is to prepare perfluoropentanone in high yield using a simple reaction system and suitable reaction conditions. The raw materials used in this invention 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 perfluoropentanone, characterized in that: hexafluoropropylene CF2=CF-CF3, fluorophosgene CF2O, and trifluorobromomethane CF3Br react in the gas phase under certain temperature and the action of a polymerization catalyst to generate perfluoropentanone C5F. 10 O, the active metal component of the polymerization catalyst is one or more of Cr, Fe, Cu, Zn, Ni, Co, and In, of which Cr must be present; the gas phase reaction temperature is 50-600℃.

[0007] The active metal component of the polymerization catalyst is Cr-Fe with a metal element molar ratio of 90:10, or Cr-Cu-Ni with a metal element molar ratio of 80:15:5; or Cr-Zn-Ni-Co with a metal element molar ratio of 90:4:4:2.

[0008] The polymerization 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 0.1-30 s.

[0013] The preferred gas-phase reaction temperature is 100-400℃.

[0014] The molar ratio of hexafluoropropylene, fluorophosgene, and trifluorobromomethane is 1:1-10:1-10.

[0015] The preferred molar ratio of hexafluoropropylene, fluorophosgene, and trifluorobromomethane is 1:1-3:1-4.

[0016] The method for synthesizing perfluoropentanone of the present invention involves reacting hexafluoropropylene (molecular formula CF2=CF-CF3), fluorophosgene (molecular formula CF2O), and trifluorobromomethane (molecular formula CF3Br) in the gas phase under certain temperature and with the aid of an addition catalyst to generate perfluoropentanone (molecular formula C5F). 10 O).

[0017]

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

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

[0020] 2. This invention uses a gas-phase addition 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] The cyclofluorination catalyst was prepared by co-precipitation method, and the steps are as follows:

[0027] A CrCl3 and Fe(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-Fe cyclofluorination catalyst precursor.

[0028] 50 ml of the cyclofluorination catalyst Cr-Fe 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 10 hours, with the temperature increased at 1 °C / min. Then, the temperature was lowered to 200 °C. This completed the drying process of the cyclofluorination catalyst.

[0029] The reactor was heated to 300℃, 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 158.2 m². 2 / g, pyridine adsorption infrared spectroscopy (Py-FTIR) shows that it is a strong acid.

[0030] The reactor was heated to 130°C, and hexafluoropropylene (24 ml / min), fluorophosgene (30 ml / min), and trifluorobromomethane (34 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 65% perfluoropentanone (molecular formula C5F). 10 O).

[0031] Example 2

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

[0033] A solution of CrCl3, Cu(NO3)2, and Ni(NO3)2 in a molar ratio of 80:15:5 was mixed, and 30wt% ammonia solution was added dropwise to the mixed solution 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-Cu-Ni.

[0034] 50 ml of the cyclofluorination catalyst Cr-Cu-Ni 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 10 hours at a rate of 1 °C / min, and then the temperature was lowered to 200 °C. This completed the drying process of the cyclofluorination catalyst.

[0035] The reactor was heated to 300℃, 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 145.0 m². 2 / g, pyridine adsorption infrared spectroscopy (Py-FTIR) shows that it is a strong acid.

[0036] The reactor was heated to 280°C, and hexafluoropropylene (24 ml / min), fluorophosgene (48 ml / min), and trifluorobromomethane (40 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 73% perfluoropentanone (molecular formula C5F). 10 O).

[0037] Example 3

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

[0039] A solution of CrCl3, Zn(NO3)2, Ni(NO3)2, and Co(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 10.0. The precipitate was filtered, washed with deionized water, dried, and pressed into shape to obtain the cyclofluorination catalyst precursor Cr-Zn-Ni-Co.

[0040] 50 ml of the cyclofluorination catalyst Cr-Zn-Ni-Co 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 10 hours at a rate of 1 °C / min, and then the temperature was lowered to 200 °C. This completed the drying process of the cyclofluorination catalyst.

[0041] The reactor was heated to 300℃, 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 135.0 m². 2 / g, pyridine adsorption infrared spectroscopy (Py-FTIR) shows that it is a strong acid.

[0042] The reactor was heated to 400 °C, and hexafluoropropylene (12 ml / min), fluorophosgene (36 ml / min), and trifluorobromomethane (48 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 81% perfluoropentanone (molecular formula C5F). 10 O).

Claims

1. A method for synthesizing perfluoropentanone, characterized in that: Hexafluoropropylene (CF2=CF-CF3), fluorophosgene (CF2O), and trifluorobromomethane (CF3Br) react in the gas phase under certain temperature and with a polymerization catalyst to produce perfluoropentanone (C5F). 10 O, the active metal component of the polymerization catalyst is one or more of Cr, Fe, Cu, Zn, Ni, Co, and In, of which Cr must be present; the gas phase reaction temperature is 50-600℃.

2. According to claim 1, the active metal component of the polymerization catalyst is Cr-Fe with a metal element molar ratio of 90:10, or Cr-Cu-Ni with a metal element molar ratio of 80:15:5; or Cr-Zn-Ni-Co with a metal element molar ratio of 90:4:4:

2.

3. According to the method of claim 2, the polymerization 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 material is washed, and 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 0.1-30 s.

8. The method according to claim 1, wherein the gas-phase reaction temperature is 100-400℃.

9. The method according to claim 1, wherein the molar ratio of hexafluoropropylene, fluorophosgene, and trifluorobromomethane is 1:1-10:1-10.

10. The method according to claim 9, wherein the molar ratio of hexafluoropropylene, fluorophosgene, and trifluorobromomethane is 1:1-3:1-4.

Images