Method for efficiently synthesizing perfluoroalkyl ether

Abstract

The invention provides a method for efficiently synthesizing perfluoroalkyl ether, and belongs to the technical field of fluorine-containing fine chemical engineering. The method comprises the following two steps: firstly, taking butyryl chloride and anhydrous hydrogen fluoride as raw materials, and preparing perfluorobutyryl fluoride through an electrolytic fluorination process; and then synthesizing the perfluoroalkyl ether through chemical reaction of perfluorobutyryl fluoride and an alkylating reagent. The method is simple and convenient in process and mild in reaction condition, and the prepared target product has high purity and high yield and is suitable for industrial large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of fluorine-containing fine chemicals, in particular to a method for efficiently synthesizing perfluoroalkyl ether. Background Art

[0002] As an important class of fluorinated compounds, perfluoroalkyl ethers have unique physical and chemical properties, such as high thermal stability, high chemical stability, low surface energy, and excellent lubrication and dielectric properties. These properties make them have extensive and important application value in the fields of high-performance lubricants, pharmaceutical intermediates, electronic chemicals, high-end coatings and anti-corrosion materials. For example, in high-temperature environments or extreme working conditions, traditional organic materials are usually unable to maintain their performance, while perfluoroalkyl ethers can operate stably for a long time at temperatures as high as 300°C or even higher. In addition, as pharmaceutical intermediates, perfluoroalkyl ethers are widely used in the synthesis of special drugs and bioactive molecules due to their low toxicity and excellent chemical inertness.

[0003] Chinese patent application number CN201710481807.5 discloses a method for preparing a linear perfluorovinyl ether with a sulfonyl fluoride group as the terminal group. Using chloroalkyl vinyl ether as the raw material, the product obtained by sulfonation reaction and chlorination reaction is added with chlorine to obtain a chloroalkyl ether with a sulfonyl chloride terminal group; the chloroalkyl ether with a sulfonyl chloride terminal group is fluorinated to obtain a perfluoroalkyl ether; the perfluoroalkyl ether is subjected to a reduction reaction to obtain a linear perfluorovinyl ether with a sulfonyl fluoride terminal group CF2=CFOCF2(CF2)nSO2F, n=1-6.

[0004] At present, the industrial preparation methods of perfluoroalkyl ethers mainly include gas phase fluorination, electrolytic fluorination and direct chemical synthesis. However, these methods still have the following significant shortcomings: Gas-phase fluorination method: This method uses fluorine gas to directly react with alkyl compounds to produce perfluorinated products. However, fluorine gas is highly reactive and can easily cause violent side reactions during the reaction, resulting in low yields and low product selectivity. In addition, the toxicity and high corrosiveness of fluorine gas increase safety risks and equipment costs during the production process.

[0005] Electrolytic fluorination: Electrolytic fluorination is a relatively mature technology for preparing perfluorinated compounds. It achieves perfluorination by electrolyzing fluorinated compounds (such as hydrogen fluoride or organic fluorides). However, in existing electrolysis technologies, the current efficiency is low, some by-products are difficult to separate, and the corrosion resistance of electrolysis equipment is extremely high, resulting in high costs during the industrialization process.

[0006] Direct chemical synthesis: Direct chemical synthesis usually involves complex multi-step reactions and harsh reaction conditions, such as high pressure or high temperature operation. These limitations make it difficult to apply on an industrial scale, and it is difficult to achieve environmental friendliness and green chemistry requirements.

[0007] In recent years, with the popularization of green chemistry concepts and the increase in industrialization needs, the development of efficient, environmentally friendly and economical perfluoroalkyl ether preparation technology has become a research hotspot in academia and industry. In this context, optimizing process flow, reducing energy consumption and raw material consumption, and improving target product selectivity and purity are the core directions of technological progress. In addition, it has become an important development trend to further improve the safety, economy and environmental protection of the production process by adopting recyclable raw material systems and new catalysts. Summary of the invention

[0008] Based on the above problems, the present invention proposes a new process for the efficient synthesis of perfluoroalkyl ethers, which is centered on electrolytic fluorination and optimized alkylation reactions, overcomes the limitations of traditional technologies, significantly improves production efficiency and product purity, and has high industrial application value.

[0009] To achieve this object, the present invention adopts the following technical solutions: A method for efficiently synthesizing perfluoroalkyl ether comprises the following steps: Step 1: mixing butyryl chloride and anhydrous hydrogen fluoride in an electrolytic cell at a mass ratio of 1:6-1:10, adding 0.05wt%-0.15wt% of a fluoride salt, applying current to carry out an electrolytic fluorination reaction, the reaction time is 1-5 hours, recovering the generated mixed gaseous product, and obtaining perfluorobutyryl fluoride by condensation purification, and at the same time washing the residual liquid in the electrolytic cell with water for purification and recovery; Step 2: 0.1-1 parts by weight of perfluorobutyryl fluoride, 0.2-2 parts by weight of an alkylating agent and 0.1wt%-5wt% of a supported catalyst are placed in a reaction kettle, reacted for 5-12 hours under set conditions, cooled to room temperature after the reaction is completed, and subjected to separation, water washing, drying and rectification steps to obtain a perfluoroalkyl ether; The preparation method of the supported catalyst in step 2 is: F1: Add 100-150 parts of ZSM-5 molecular sieve, 5-10 parts of γ-mercaptopropyltrimethoxysilane and 3-7 parts of palladium nitrate to 1000-1500 parts of water by weight, and then stir at 40-50° C. for 10-20 hours, filter and dry to obtain a mercapto precursor; F2: Add 0.5-2 parts of methallyl nickel chloride dimer (CAS: 12145-60-7), 0.003-0.03 parts of bis-(2-methylallyl)cyclooct-1,5-dieneruthenium (CAS: 12289-94-0), 100-150 parts of thiol precursor, 1000-1500 parts of toluene, and 1-3 parts of sodium ethoxide into a stirred tank, stir at 70-80°C for 50-100 minutes, filter, and dry to obtain a supported catalyst.

[0010] In some embodiments, the fluoride salt in step 1 is selected from at least one of potassium fluoride, lithium fluoride or sodium fluoride.

[0011] In some of the embodiments, the current density in the electrolytic fluorination reaction in step 1 is 0.1-0.3 A / cm² and the electrolysis voltage is 5-15 V.

[0012] In some embodiments, the electrolytic fluorination reaction temperature in step 1 is -10°C to 10°C.

[0013] In some of the embodiments, the condensation in step 1 adopts multi-stage condensation, and the temperature of the cooling medium is controlled at -30°C to 0°C.

[0014] In some embodiments, the alkylating agent in step 2 is selected from at least one of dimethyl carbonate and diethyl carbonate.

[0015] In some embodiments, the setting conditions in step 2 are: after the mixture is stirred uniformly under -0.08 to -0.1 MPa conditions, it is heated to 80°C to 150°C for reaction.

[0016] In some of the embodiments, the distillation process in step 2 adopts atmospheric pressure or reduced pressure distillation, and the top temperature of the tower is controlled at 60°C to 90°C.

[0017] Catalyst synthesis reaction mechanism of this application: 1) Introduction of palladium nitrate and generation of thiol precursor: Palladium nitrate enters the micropores of the ZSM-5 molecular sieve and then reacts with γ-mercaptopropyltrimethoxysilane to obtain a palladium-loaded mercapto precursor. The palladium ions are stably fixed in the micropores of the molecular sieve to form a mercapto-functionalized palladium catalyst.

[0018] 2) Reaction of thiol precursor with methallyl nickel chloride dimer: The mercapto precursor reacts with methallyl nickel chloride dimer to undergo a mercapto-allyl addition reaction, where the mercapto group reacts with the allyl group to form a new carbon-sulfur bond.

[0019] 3) Reaction with bis-(2-methylallyl)cyclooct-1,5-dieneruthenium: Next, the thiol precursor undergoes a thiol-allyl addition reaction with bis-(2-methylallyl)cyclooct-1,5-dieneruthenium. Similar to the previous step, the thiol here also undergoes an addition reaction with the allyl group, further expanding the molecular structure and adding more functional groups.

[0020] Through the above reaction, a grafted nickel complex is obtained, and a cyclooctane-1,5-dieneruthenium structure is formed at the same time. This structure not only provides multiple active sites, but also enhances the stability and activity of the catalyst.

[0021] This application improves the catalytic effect: 1) The number of active sites of the catalyst is significantly increased by introducing a variety of functional groups (such as thiol, allyl, nickel complex, etc.). The synergistic effect between these functional groups improves the overall activity of the catalyst, making it more efficient in catalyzing the preparation of perfluoroalkyl ethers by perfluorobutyryl fluoride and alkylating agents.

[0022] 2) The spatial structure of the catalyst is carefully designed to ensure that each active site can effectively contact the reactants. This structure is conducive to the adsorption and activation of reactant molecules on the catalyst surface, thereby improving the reaction rate and product selectivity.

[0023] Compared with the prior art, the method of the present invention has the following advantages: 1) Mild reaction conditions and low energy consumption; 2) The process is simple and the equipment requirements are low; 3) The product has high purity and the yield is significantly improved; 4) The electrolytic fluorination process avoids the large amount of by-products that may be produced in traditional methods and is green and environmentally friendly. DETAILED DESCRIPTION

[0024] The technical scheme of the present invention is further described below by specific embodiments. Those skilled in the art should understand that the specific embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention. Unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art, and the raw materials used are all commercially available conventional commodities.

[0025] Example 1 In the electrolytic cell, butyryl chloride and anhydrous hydrogen fluoride are mixed in a mass ratio of 1:6, and 0.1wt% potassium fluoride is added as an additive. At a temperature of -5°C, a current density of 0.2 A / cm² and an electrolysis voltage of 10 V are applied for electrolytic fluorination reaction for 3 hours. After the reaction is completed, perfluorobutyryl fluoride is collected and purified by multi-stage condensation (cooling medium temperature is -15°C). Subsequently, 0.5kg of perfluorobutyryl fluoride, 1kg of dimethyl carbonate and 1wt% of the supported catalyst are placed in a reactor and reacted for 8 hours at -0.09 MPa and 120°C. After the reaction is completed, perfluoroalkyl ether is obtained by liquid separation, water washing, drying and reduced pressure distillation (tower top temperature 75°C).

[0026] The preparation method of the supported catalyst is: F1: 100 g of ZSM-5 molecular sieve, 5 g of γ-mercaptopropyltrimethoxysilane and 3 g of palladium nitrate were added to 1000 g of water, and then stirred at 40° C. for 10 hours, filtered and dried to obtain a mercapto precursor; F2: Add 0.5 g methallyl nickel chloride dimer (CAS: 12145-60-7), 0.003 g bis-(2-methylallyl)cyclooct-1,5-dieneruthenium (CAS: 12289-94-0), 100 g thiol precursor, 1000 g toluene and 1 g sodium ethoxide into a stirring kettle, stir at 70°C for 50 minutes, filter and dry to obtain a supported catalyst.

[0027] Example 2 In the electrolytic cell, butyryl chloride and anhydrous hydrogen fluoride were mixed in a mass ratio of 1:7, and 0.05wt% of lithium fluoride was added. In the electrolytic fluorination reaction, a current density of 0.1 A / cm², an electrolysis voltage of 5 V and a reaction temperature of 0°C were applied for 1 hour. After condensation and purification, 0.1kg of perfluorobutyryl fluoride, 0.2kg of diethyl carbonate and 2.5wt% of the supported catalyst were taken for alkylation reaction, and the reaction conditions were -0.1 MPa and 80°C, and the reaction time was 12 hours. Finally, the perfluoroalkyl ether was obtained by atmospheric distillation (tower top temperature 60°C).

[0028] The preparation method of the supported catalyst is: F1: 115 g of ZSM-5 molecular sieve, 7 g of γ-mercaptopropyltrimethoxysilane, and 5 g of palladium nitrate were added to 1250 g of water, and then stirred at 45° C. for 15 hours, filtered, and dried to obtain a mercapto precursor; F2: Add 1 g of methallyl nickel chloride dimer (CAS: 12145-60-7), 0.015 g of bis-(2-methylallyl)cyclooct-1,5-dieneruthenium (CAS: 12289-94-0), 125 g of thiol precursor, 1250 g of toluene, and 2 g of sodium ethoxide into a stirring kettle, stir at 75°C for 75 minutes, filter, and dry to obtain a supported catalyst.

[0029] Example 3 In the electrolytic cell, butyryl chloride and anhydrous hydrogen fluoride were mixed in a mass ratio of 1:8, and 0.15wt% of sodium fluoride was added. The electrolytic fluorination reaction was carried out at -10°C, a current density of 0.3 A / cm² and an electrolysis voltage of 15 V for 5 hours. After condensation and purification, 0.3kg of perfluorobutyryl fluoride, 0.5kg of dimethyl carbonate and 4wt% of a supported catalyst were used to react at -0.08MPa and 150°C for 5 hours. After the reaction, the product was separated, washed with water, dried and distilled under reduced pressure (tower top temperature 90°C) to obtain a perfluoroalkyl ether.

[0030] The preparation method of the supported catalyst is: F1: 125 g of ZSM-5 molecular sieve, 8 g of γ-mercaptopropyltrimethoxysilane, and 5 g of palladium nitrate were added to 1250 g of water, and then stirred at 45° C. for 15 hours, filtered, and dried to obtain a mercapto precursor; F2: Add 1.5 g methallyl nickel chloride dimer (CAS: 12145-60-7), 0.025 g bis-(2-methylallyl)cyclooct-1,5-dieneruthenium (CAS: 12289-94-0), 125 g thiol precursor, 1250 g toluene and 2 g sodium ethoxide into a stirring kettle, stir at 75°C for 75 minutes, filter and dry to obtain a supported catalyst.

[0031] Example 4 In the electrolytic cell, butyryl chloride and anhydrous hydrogen fluoride were mixed in a mass ratio of 1:10, and 0.1wt% potassium fluoride was added. The electrolytic fluorination reaction conditions were set to -5°C, a current density of 0.2 A / cm², and an electrolysis voltage of 7.5 V, and the reaction was carried out for 4 hours. After condensation and purification, 0.7kg of perfluorobutyryl fluoride, 1.5kg of diethyl carbonate, and 5wt% of a supported catalyst were taken and reacted for 10 hours at -0.09MPa and 100°C. Finally, perfluoroalkyl ether was obtained by atmospheric distillation (tower top temperature 80°C).

[0032] The preparation method of the supported catalyst is: F1: 150 g of ZSM-5 molecular sieve, 10 g of γ-mercaptopropyltrimethoxysilane and 7 g of palladium nitrate were added to 1500 g of water, and then stirred at 50° C. for 20 hours, filtered and dried to obtain a mercapto precursor; F2: Add 2 g of methallyl nickel chloride dimer (CAS: 12145-60-7), 0.03 g of bis-(2-methylallyl)cyclooct-1,5-dieneruthenium (CAS: 12289-94-0), 150 g of thiol precursor, 1500 g of toluene, and 3 g of sodium ethoxide into a stirring kettle, stir at 80°C for 100 minutes, filter, and dry to obtain a supported catalyst.

[0033] Comparative Example 1 The difference between this example and Example 1 is that methallyl nickel chloride dimer is not added during the preparation of the supported catalyst.

[0034] Comparative Example 2 The difference between this example and Example 1 is that bis-(2-methylallyl)cyclooct-1,5-dieneruthenium is not added during the preparation of the supported catalyst.

[0035] Test methods and results: 1) Purity test: Use gas chromatography-mass spectrometry (GC-MS) to analyze the purity of perfluoroalkyl ether. The purity is calculated by the ratio of the main peak area of ​​the target product to the total peak area; 2) Yield test: The yield of perfluoroalkyl ether is calculated by accurately weighing the mass of the target product obtained after distillation and comparing it with the mass ratio of the theoretical conversion product of perfluorobutyryl fluoride.

[0036]

[0037] The test results show that the embodiments of the present invention are significantly better than the comparative examples in terms of purity and yield of the target product, which confirms the effectiveness of the present method.

[0038] Although specific forms of the invention have been selected in the foregoing disclosure describing specific terms for the purpose of fully and comprehensively describing those forms of the invention for those skilled in the relevant art, it should be understood that various alternatives and modifications resulting in substantially equivalent or better results and / or performance are deemed to be within the scope of the following claims.

Claims

1. A method for efficiently synthesizing perfluoroalkyl ether, characterized in that: The steps include: Step 1: mixing butyryl chloride and anhydrous hydrogen fluoride in an electrolytic cell at a mass ratio of 1:6-1:10, adding 0.05wt%-0.15wt% of a fluoride salt, applying current to carry out an electrolytic fluorination reaction, the reaction time is 1-5 hours, recovering the generated mixed gaseous product, and obtaining perfluorobutyryl fluoride by condensation purification, and at the same time washing the residual liquid in the electrolytic cell with water for purification and recovery; Step 2: 0.1-1 parts by weight of perfluorobutyryl fluoride, 0.2-2 parts by weight of an alkylating agent and 0.1wt%-5wt% of a supported catalyst are placed in a reaction kettle, reacted for 5-12 hours under set conditions, cooled to room temperature after the reaction is completed, and subjected to separation, water washing, drying and rectification steps to obtain a perfluoroalkyl ether; The supported catalyst is prepared by the reaction of a mercapto precursor with methallyl nickel chloride dimer, and the mercapto precursor and bis-(2-methylallyl)cyclooctane-1,5-dieneruthenium undergo a mercapto-allyl addition reaction; The preparation method of the supported catalyst in step 2 is: F1: Add 100-150 parts of ZSM-5 molecular sieve, 5-10 parts of γ-mercaptopropyltrimethoxysilane and 3-7 parts of palladium nitrate to 1000-1500 parts of water by weight, and then stir at 40-50° C. for 10-20 hours, filter and dry to obtain a mercapto precursor; F2: Add 0.5-2 parts of methallyl nickel chloride dimer, 0.003-0.03 parts of bis-(2-methylallyl)cyclooct-1,5-dieneruthenium, 100-150 parts of thiol precursor, 1000-1500 parts of toluene, and 1-3 parts of sodium ethoxide into a stirred tank, stir at 70-80°C for 50-100 minutes, filter, and dry to obtain a supported catalyst.

2. A method for efficiently synthesizing perfluoroalkyl ether according to claim 1, characterized in that: The fluoride salt in step 1 is selected from at least one of potassium fluoride, lithium fluoride or sodium fluoride.

3. A method for efficiently synthesizing perfluoroalkyl ether according to claim 1, characterized in that: In the electrolytic fluorination reaction in step 1, the current density is 0.1-0.3 A / cm² and the electrolysis voltage is 5-15 V.

4. A method for efficiently synthesizing perfluoroalkyl ether according to claim 1, characterized in that: The electrolytic fluorination reaction temperature in step 1 is -10°C to 10°C.

5. A method for efficiently synthesizing perfluoroalkyl ether according to claim 1, characterized in that: The condensation in step 1 adopts multi-stage condensation, and the temperature of the cooling medium is controlled at -30°C to 0°C.

6. A method for efficiently synthesizing perfluoroalkyl ether according to claim 1, characterized in that: In step 2, the alkylating agent is selected from at least one of dimethyl carbonate and diethyl carbonate.

7. A method for efficiently synthesizing perfluoroalkyl ether according to claim 1, characterized in that: The setting conditions in step 2 are: after the mixture is stirred evenly under -0.08 to -0.1 MPa conditions, it is heated to 80° C. to 150° C. for reaction.

8. A method for efficiently synthesizing perfluoroalkyl ether according to claim 1, characterized in that: The distillation step in step 2 adopts atmospheric pressure or reduced pressure distillation, and the tower top temperature is controlled at 60°C to 90°C.

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