Production method for improving yield of trifluoromethanesulfonic acid

Abstract

The invention discloses a production method for improving the yield of trifluoromethanesulfonic acid, and relates to the technical field of chemical engineering, trifluoromethanesulfonic acid is obtained by reacting trifluoromethanesulfonyl fluoride with trifluoromethanesulfonate under the action of a catalyst to generate trifluoromethanesulfonic anhydride and then hydrolyzing the trifluoromethanesulfonic anhydride. The catalyst is a product containing tertiary amine, pyridine and nanoparticles, wherein the pyridine is obtained through reaction of hydroxyl-containing pyridine, cyano-containing halogenated hydrocarbon, a silane coupling agent, the nanoparticles and the like, the fifth and third sites of the pyridine are substituted by methoxy and alkenyl-containing alkoxy respectively, and the product is obtained through reaction of the pyridine, the cyano-containing halogenated hydrocarbon, the silane coupling agent, the nanoparticles and the like. The catalyst has relatively strong nucleophilicity and high separability with a product, the production yield and purity of trifluoromethanesulfonic acid are improved, and the production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and specifically to a production method for improving the yield of trifluoromethanesulfonic acid. Background Technology

[0002] Trifluoromethanesulfonic acid, as a superacid, possesses not only the basic functions of a typical superacid but also exceptional oxidation and reduction resistance. Furthermore, it does not release fluoride ions in the presence of strong nucleophiles, thus functioning as a halogen-free liquid superacid. In recent years, the application range of trifluoromethanesulfonic acid has gradually expanded, playing a vital role in various related fields, particularly in the chemical industry, where its importance is increasingly prominent, leading to a continuous increase in demand.

[0003] Currently, the main methods for synthesizing trifluoromethanesulfonic acid include electrolytic fluorination, CF3SSCF3 synthesis, and CHF3 oxidation. Among these, electrolytic fluorination is the mainstream process, but it consumes a lot of electricity and has high costs. Both the CF3SSCF3 synthesis and CHF3 oxidation methods have the drawback of low product yields. The CF3SSCF3 synthesis method also has the disadvantage of highly toxic bis(trifluoromethyl)disulfide, making it unsuitable for production.

[0004] The hydrolysis of trifluoromethanesulfonic anhydride to trifluoromethanesulfonic acid is typically carried out at room temperature and pressure under mild conditions. Water or ethanol are commonly used solvents, resulting in few byproducts and high yields and purity, making it a low-cost route for preparing trifluoromethanesulfonic acid. Among the many methods for preparing trifluoromethanesulfonic anhydride, the method involving the reaction of trifluoromethanesulfonyl fluoride with trifluoromethanesulfonate under 4-dialkylaminopyridine catalysis offers advantages such as easy byproduct handling and high purity. However, commonly used 4-dialkylaminopyridines, such as 4-dimethylaminopyridine, are readily soluble in the reaction system and difficult to separate from the product using conventional methods, leading to high purification costs. Furthermore, the limited nucleophilicity of 4-dialkylaminopyridine limits its catalytic efficiency, resulting in insufficient ability to improve the yield of trifluoromethanesulfonic anhydride, which in turn hinders the improvement of trifluoromethanesulfonic acid yield.

[0005] Therefore, there is an urgent need for suitable modification methods to enhance the nucleophilicity of pyridine catalysts and improve their separability from the product, thereby obtaining a production method for trifluoromethanesulfonic acid with high yield and purity. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a production method for improving the yield of trifluoromethanesulfonic acid.

[0007] The objective of this invention can be achieved through the following technical solutions: A method for improving the yield of trifluoromethanesulfonic acid includes the following steps: Step S1: Trifluoromethanesulfonyl fluoride and trifluoromethanesulfonate are reacted with a catalyst to generate trifluoromethanesulfonic anhydride; Step S2: Hydrolyze trifluoromethanesulfonic anhydride to obtain trifluoromethanesulfonic acid; The production method for improving the yield of trifluoromethanesulfonic anhydride includes the following specific steps: Step S1: In a protective gas atmosphere, trifluoromethanesulfonate and solvent are mixed and stirred for 20-25 min. Catalyst is added, and stirring is continued for 1-1.5 h to obtain a mixed system. Trifluoromethanesulfonyl fluoride is added dropwise to the mixed system under ice-water bath conditions. The dropping rate is controlled to ensure that the temperature in the mixed system is within the range of 40-50℃. After the dropping is completed, the temperature is controlled at 25-30℃, and the reaction is carried out at a constant temperature for 3.5-4 h to obtain trifluoromethanesulfonic anhydride. Furthermore, the ratio of trifluoromethanesulfonate, solvent, catalyst, and trifluoromethanesulfonyl fluoride is 1-1.5 mol: 1000-1200 mL: 6.5-7.5 g: 5-7 mol; the trifluoromethanesulfonate is selected from lithium trifluoromethanesulfonate, sodium trifluoromethanesulfonate, and potassium trifluoromethanesulfonate; the solvent is selected from anhydrous acetonitrile, anhydrous DMF, and anhydrous DMAC. Step S2: Trifluoromethanesulfonic anhydride is added dropwise to the mixed solvent at 0-10℃, the dropping rate is controlled and the temperature is kept within the range of 40-45℃. After the addition is completed, the temperature is controlled at 23-27℃, the auxiliary agent is added, and the reaction is stirred for 2.5-3 hours to obtain trifluoromethanesulfonic acid. Furthermore, the ratio of trifluoromethanesulfonic anhydride, mixed solvent, and auxiliary agent is 33-35g: 110-120mL: 0.22-0.30g; the mixed solvent is obtained by mixing ethanol and water in a volume ratio of 1-1.5:1; the volume fraction of ethanol is 95%; the auxiliary agent is one of sodium carbonate and potassium carbonate. The catalyst is prepared by the following steps: Step (1): In a protective gas atmosphere, hydroxypyridine and anhydrous DMF are mixed and stirred. Potassium carbonate and tetrabutylammonium bromide are added and stirred under ice-water bath conditions. Then, cyano-halogenated hydrocarbons are added. The mixture is first heated and refluxed and stirred, and then heated and refluxed and stirred again to obtain product 1. Step (2): Mix product 1, methanol and DMF, introduce protective gas, stir and then add ammonia water, stir and then add Pd / C, stir and then introduce hydrogen gas, heat and stir to obtain product 2. Step (3): Add nanoparticles to anhydrous ethanol, disperse by ultrasonication, and then heat and vacuum dry to obtain pretreated nanoparticles; then mix the pretreated nanoparticles and anhydrous ethanol, add silane hydrolysate under stirring, and heat and stir to obtain product 3; mix product 3, product 2, anhydrous THF and anhydrous DMF, add alkali, and heat and stir to obtain catalyst; The preparation of the catalyst includes the following specific steps: Step (1): In a protective gas atmosphere, hydroxypyridine and anhydrous DMF are mixed and stirred for 30-35 min. Potassium carbonate and tetrabutylammonium bromide are added under ice-water bath conditions and stirred for 35-40 min. Cyano-containing haloalkanes are added. The temperature is first raised to 40-45℃, and the mixture is refluxed and stirred for 1-1.2 h. Then the temperature is raised to 60-65℃ and the mixture is refluxed and stirred for 1.5-2 h to obtain product 1. Furthermore, the ratio of hydroxypyridine, anhydrous DMF, potassium carbonate, tetrabutylammonium bromide, and cyanohalogenated hydrocarbon is 14-16g: 85-95mL: 19-21g: 0.3-0.5g: 21-23g; the hydroxypyridine is 3-hydroxy-5-methoxypyridine; and the cyanohalogenated hydrocarbon is 2-chloro-4-(2-cyanophenyl)-1-butene. In step (1) of the reaction, the hydroxyl group of the hydroxypyridine reacts with the halogen atom of the cyano-halogenated hydrocarbon to form an ether, yielding product 1 containing pyridine and cyano groups substituted at the 5 and 3 positions, respectively, by methoxy and alkenylalkoxy groups. Step (2): Mix product 1, methanol and DMF, introduce protective gas, stir for 20-25 min, add ammonia water, stir for 5-10 min, add Pd / C, stir for 30-35 min, then introduce hydrogen gas, heat to 50-55℃, stir and react for 6-6.5 h to obtain product 2. Furthermore, the ratio of product 1, methanol, DMF, ammonia, and Pd / C is 38-40g: 25-35mL: 55-65mL: 4.5-5.5mL: 0.6-0.8g; the mass fraction of ammonia is 25-28%; and the pressure of hydrogen is controlled at 0.3-0.5MPa. In step (2) of the reaction, under low hydrogen pressure conditions, the cyano group of product 1 is selectively reduced to amino group, while retaining the carbon-carbon double bond, to obtain product 2. Step (3): Add nanoparticles to anhydrous ethanol, ultrasonically disperse for 30-35 min, and vacuum dry at 75-80℃ for 4-4.5 h to obtain pretreated nanoparticles; then mix the pretreated nanoparticles and anhydrous ethanol, add silane hydrolysis solution while stirring, and stir and react at 55-60℃ for 5.5-6 h to obtain product 3; mix product 3, product 2, anhydrous THF and anhydrous DMF and stir for 1-1.5 h, add alkali, heat to 50-60℃, and stir and react for 9-9.5 h to obtain the catalyst; Further, the ratio of nanoparticles to anhydrous ethanol is 10-12g:110-120mL; the nanoparticles are either nano-alumina or nano-silica; the ratio of pretreated nanoparticles, anhydrous ethanol, and silane hydrolysate is 15-20g:160-170mL:11-13mL; the silane hydrolysate is obtained by mixing silane coupling agent, methanol, and water, and stirring at pH 4-5 and temperature 25-30℃ for 4-4.5h; silicon The ratio of silane coupling agent, methanol, and water in the alkyl hydrolysate is 26-28 g: 40-45 mL: 15-20 mL; the silane coupling agent is selected from bromobutyltrimethoxysilane and 3-bromopropyltrimethoxysilane; the ratio of product 3, product 2, anhydrous THF, anhydrous DMF, and alkali is 32-34 g: 42-44 g: 80-85 mL: 425-435 mL: 14-18 g; the alkali is selected from potassium carbonate and sodium carbonate. In step (3) of the reaction, the silane coupling agent is hydrolyzed and modified to obtain product 3; the alkyl bromide of product 3 reacts with the amino group of product 2 to generate a tertiary amine, and a product containing a tertiary amine, pyridine substituted at the 5 and 3 positions respectively with methoxy and alkenyl alkoxy groups, and nanoparticles, i.e., the catalyst. The beneficial effects of this invention are as follows: This invention discloses a production method for improving the yield of trifluoromethanesulfonic acid. The trifluoromethanesulfonic acid is obtained by reacting trifluoromethanesulfonyl fluoride with trifluoromethanesulfonate under the action of a catalyst to produce trifluoromethanesulfonic anhydride, followed by hydrolysis of the trifluoromethanesulfonic anhydride. The catalyst is a product containing tertiary amines, pyridines with methoxy and alkenylalkoxy substitutions at positions 5 and 3, respectively, obtained by reacting hydroxypyridines, cyanohalogenated hydrocarbons, silane coupling agents, and nanoparticles. In the obtained catalyst, the combined use of hydroxypyridine and cyanohalo hydrocarbons allows the 5- and 3-positions of pyridine to be substituted with methoxy and alkenylalkoxy groups, respectively, enhancing the nucleophilicity of pyridine catalysts. The use of a silane coupling agent further enhances the nucleophilicity of the catalyst, thereby increasing the yield of trifluoromethanesulfonic anhydride and consequently the yield of trifluoromethanesulfonic acid. Grafting the tertiary amine, the pyridine substituted with methoxy and alkenylalkoxy groups at the 5- and 3-positions, respectively, onto nanoparticles enhances the easy separation of the catalyst from the product. Furthermore, the nanoparticles can adsorb fluoride ions introduced by trifluoromethanesulfonyl fluoride in the reaction, which is beneficial for improving the purity of trifluoromethanesulfonic anhydride and reducing production costs. Detailed Implementation

[0008] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0009] Example 1 A catalyst, the preparation of which includes the following steps: Step (1): Under a nitrogen atmosphere, 3-hydroxy-5-methoxypyridine and anhydrous DMF were mixed and stirred for 30 min. Potassium carbonate and tetrabutylammonium bromide were added under ice-water bath conditions and stirred for 35 min. 2-chloro-4-(2-cyanophenyl)-1-butene was added. The temperature was first raised to 40℃, and the mixture was refluxed and stirred for 1 h. Then the temperature was raised to 60℃ and refluxed and stirred for 1.5 h to obtain product 1. The ratio of 3-hydroxy-5-methoxypyridine, anhydrous DMF, potassium carbonate, tetrabutylammonium bromide and 2-chloro-4-(2-cyanophenyl)-1-butene was 14 g: 85 mL: 19 g: 0.3 g: 21 g. Step (2): Mix product 1, methanol, and DMF, purge with nitrogen, stir for 20 min, add ammonia, stir for 5 min, add Pd / C, stir for 30 min, purge with hydrogen, heat to 50℃, stir and react for 6 h to obtain product 2; the ratio of product 1, methanol, DMF, ammonia, and Pd / C is 38 g: 25 mL: 55 mL: 4.5 mL: 0.6 g; the mass fraction of ammonia is 25%; the pressure of hydrogen is controlled at 0.3 MPa; Step (3): Add nano-alumina to anhydrous ethanol, ultrasonically disperse for 30 min, and vacuum dry at 75℃ for 4 h to obtain pretreated nano-alumina; then mix the pretreated nano-alumina and anhydrous ethanol, add silane hydrolysis solution under stirring, and stir at 55℃ for 5.5 h to obtain product 3; mix product 3, product 2, anhydrous THF and anhydrous DMF and stir for 1 h, add potassium carbonate, heat to 50℃, and stir for 9 h to obtain catalyst; the ratio of nano-alumina to anhydrous ethanol is 10 g: 110 mL; The ratio of pretreated nano-alumina, anhydrous ethanol, and silane hydrolysate was 15g:160mL:11mL; the silane hydrolysate was obtained by mixing 3-bromopropyltrimethoxysilane, methanol, and water, and stirring at pH 4.2 and 25℃ for 4h; the ratio of 3-bromopropyltrimethoxysilane, methanol, and water in the silane hydrolysate was 26g:40mL:15mL; the ratio of product 3, product 2, anhydrous THF, anhydrous DMF, and potassium carbonate was 32g:42g:80mL:425mL:17g.

[0010] Example 2 A catalyst, the preparation of which includes the following steps: Step (1): Under a nitrogen atmosphere, 3-hydroxy-5-methoxypyridine and anhydrous DMF were mixed and stirred for 33 min. Potassium carbonate and tetrabutylammonium bromide were added under ice-water bath conditions and stirred for 37 min. 2-chloro-4-(2-cyanophenyl)-1-butene was added. The temperature was first raised to 43℃, and the mixture was refluxed and stirred for 1.1 h. Then the temperature was raised to 63℃ and refluxed and stirred for 1.8 h to obtain product 1. The ratio of 3-hydroxy-5-methoxypyridine, anhydrous DMF, potassium carbonate, tetrabutylammonium bromide and 2-chloro-4-(2-cyanophenyl)-1-butene was 15 g: 90 mL: 20 g: 0.4 g: 22 g. Step (2): Mix product 1, methanol, and DMF, purge with nitrogen, stir for 23 min, add ammonia, stir for 8 min, add Pd / C, stir for 33 min, purge with hydrogen, heat to 53℃, stir and react for 6.3 h to obtain product 2; the ratio of product 1, methanol, DMF, ammonia, and Pd / C is 39 g: 30 mL: 60 mL: 5.0 mL: 0.7 g; the mass fraction of ammonia is 27%; the pressure of hydrogen is controlled at 0.4 MPa; Step (3): Add nano-silica to anhydrous ethanol, ultrasonically disperse for 33 min, and vacuum dry at 78℃ for 4.3 h to obtain pretreated nano-silica; then mix the pretreated nano-silica and anhydrous ethanol, add silane hydrolysis solution while stirring, and stir and react at 58℃ for 5.8 h to obtain product 3; mix product 3, product 2, anhydrous THF, and anhydrous DMF and stir for 1.2 h, add potassium carbonate, heat to 55℃, and stir and react for 9.3 h to obtain the catalyst; the ratio of nano-silica to anhydrous ethanol is 11 g: 115 mL; the ratio of pretreated nano-silica, anhydrous ethanol, and silane hydrolysate was 17 g: 165 mL: 12 mL; the silane hydrolysate was obtained by mixing bromobutyltrimethoxysilane, methanol, and water, and stirring at pH 4.3 and temperature 27 °C for 4.2 h; the ratio of bromobutyltrimethoxysilane, methanol, and water in the silane hydrolysate was 27 g: 43 mL: 18 mL; the ratio of product 3, product 2, anhydrous THF, anhydrous DMF, and potassium carbonate was 33 g: 43 g: 83 mL: 430 mL: 18 g.

[0011] Example 3 A catalyst, the preparation of which includes the following steps: Step (1): Under a nitrogen atmosphere, 3-hydroxy-5-methoxypyridine and anhydrous DMF were mixed and stirred for 35 min. Potassium carbonate and tetrabutylammonium bromide were added under ice-water bath conditions and stirred for 40 min. 2-chloro-4-(2-cyanophenyl)-1-butene was added. The temperature was first raised to 45℃, and the mixture was refluxed and stirred for 1.2 h. Then the temperature was raised to 65℃ and refluxed and stirred for 2 h to obtain product 1. The ratio of 3-hydroxy-5-methoxypyridine, anhydrous DMF, potassium carbonate, tetrabutylammonium bromide and 2-chloro-4-(2-cyanophenyl)-1-butene was 16 g: 95 mL: 21 g: 0.5 g: 23 g. Step (2): Mix product 1, methanol, and DMF, purge with nitrogen, stir for 25 min, add ammonia, stir for 10 min, add Pd / C, stir for 35 min, purge with hydrogen, heat to 55℃, stir and react for 6.5 h to obtain product 2; the ratio of product 1, methanol, DMF, ammonia, and Pd / C is 40 g: 35 mL: 65 mL: 5.5 mL: 0.8 g; the mass fraction of ammonia is 28%; the pressure of hydrogen is controlled at 0.5 MPa. Step (3): Add nano-alumina to anhydrous ethanol, ultrasonically disperse for 35 min, and vacuum dry at 80℃ for 4.5 h to obtain pretreated nano-alumina; then mix the pretreated nano-alumina and anhydrous ethanol, add silane hydrolysis solution while stirring, and stir at 60℃ for 6 h to obtain product 3; mix product 3, product 2, anhydrous THF, and anhydrous DMF and stir for 1.5 h, add potassium carbonate, heat to 60℃, and stir for 9.5 h to obtain the catalyst; the ratio of nano-alumina to anhydrous ethanol is 12 g: 120 g. mL; the ratio of pretreated nano-alumina, anhydrous ethanol, and silane hydrolysate is 20g:170mL:13mL; the silane hydrolysate is obtained by mixing bromobutyltrimethoxysilane, methanol, and water, and stirring at pH 4.7 and temperature 30℃ for 4.5h; the ratio of bromobutyltrimethoxysilane, methanol, and water in the silane hydrolysate is 28g:45mL:20mL; the ratio of product 3, product 2, anhydrous THF, anhydrous DMF, and potassium carbonate is 34g:44g:85mL:435mL:17g.

[0012] Example 4 A method for improving the yield of trifluoromethanesulfonic acid includes the following steps: Step S1: Under a nitrogen atmosphere, lithium trifluoromethanesulfonate and anhydrous acetonitrile were mixed and stirred for 20 min. The catalyst obtained in Example 1 was added, and stirring was continued for 1 h to obtain a mixed system. Trifluoromethanesulfonyl fluoride was added dropwise to the mixed system under ice-water bath conditions. The dropping rate was controlled to ensure that the temperature of the mixed system was 44°C. After the dropping was completed, the temperature was controlled at 25°C, and the reaction was carried out at a constant temperature for 3.5 h to obtain trifluoromethanesulfonic anhydride. The ratio of lithium trifluoromethanesulfonate, anhydrous acetonitrile, the catalyst obtained in Example 1, and trifluoromethanesulfonyl fluoride was 1 mol: 1000 mL: 6.5 g: 5 mol. Step S2: Trifluoromethanesulfonic anhydride was added dropwise to the mixed solvent at 0°C, controlling the dropping rate and maintaining the temperature at 42°C. After the addition was complete, the temperature was controlled at 23°C, sodium carbonate was added, and the mixture was stirred for 2.5 hours to obtain trifluoromethanesulfonic acid. The ratio of trifluoromethanesulfonic anhydride, mixed solvent, and auxiliary agent was 33g:110mL:0.22g. The mixed solvent was obtained by mixing ethanol and water in a 1:1 volume ratio. The volume fraction of ethanol was 95%. The yield of the obtained trifluoromethanesulfonic acid was 89.5%, and the purity was 99.95%.

[0013] Example 5 A method for improving the yield of trifluoromethanesulfonic acid includes the following steps: Step S1: In a nitrogen atmosphere, sodium trifluoromethanesulfonate and anhydrous DMF were mixed and stirred for 23 min. The catalyst obtained in Example 2 was added, and stirring was continued for 1.3 h to obtain a mixed system. Trifluoromethanesulfonyl fluoride was added dropwise to the mixed system under ice-water bath conditions. The dropping rate was controlled to ensure that the temperature in the mixed system was within the range of 45°C. After the dropping was completed, the temperature was controlled at 28°C, and the reaction was carried out at a constant temperature for 3.7 h to obtain trifluoromethanesulfonic anhydride. The ratio of sodium trifluoromethanesulfonate, anhydrous DMF, catalyst obtained in Example 2, and trifluoromethanesulfonyl fluoride was 1.3 mol: 1100 mL: 7.0 g: 6 mol. Step S2: Trifluoromethanesulfonic anhydride was added dropwise to the mixed solvent at 5°C, controlling the dropping rate and maintaining the temperature at 43°C. After the addition was complete, the temperature was controlled at 25°C, potassium carbonate was added, and the mixture was stirred for 2.8 hours to obtain trifluoromethanesulfonic acid. The ratio of trifluoromethanesulfonic anhydride, mixed solvent, and potassium carbonate was 34g:115mL:0.26g. The mixed solvent was obtained by mixing ethanol and water in a volume ratio of 1.3:1, with an ethanol volume fraction of 95%. The yield of the obtained trifluoromethanesulfonic acid was 89.6%, and the purity was 99.94%.

[0014] Example 6 A method for improving the yield of trifluoromethanesulfonic acid includes the following steps: Step S1: Under a nitrogen atmosphere, potassium trifluoromethanesulfonate and anhydrous DMAC were mixed and stirred for 25 min. The catalyst obtained in Example 3 was added, and stirring was continued for 1.5 h to obtain a mixed system. Trifluoromethanesulfonyl fluoride was added dropwise to the mixed system under ice-water bath conditions. The dropping rate was controlled to ensure that the temperature of the mixed system was 47°C. After the dropping was completed, the temperature was controlled at 30°C, and the reaction was carried out at a constant temperature for 4 h to obtain trifluoromethanesulfonic anhydride. The ratio of potassium trifluoromethanesulfonate, anhydrous DMAC, the catalyst obtained in Example 3, and trifluoromethanesulfonyl fluoride was 1.5 mol: 1200 mL: 7.5 g: 7 mol. Step S2: Trifluoromethanesulfonic anhydride was added dropwise to the mixed solvent at 10°C, controlling the dropping rate and maintaining the temperature at 44°C. After the addition was complete, the temperature was controlled at 27°C, potassium carbonate was added, and the mixture was stirred for 3 hours to obtain trifluoromethanesulfonic acid. The ratio of trifluoromethanesulfonic anhydride, mixed solvent, and potassium carbonate was 35g:120mL:0.30g. The mixed solvent was obtained by mixing ethanol and water in a volume ratio of 1.5:1. The volume fraction of ethanol was 95%. The yield of the obtained trifluoromethanesulfonic acid was 90.4%, and the purity was 99.97%.

[0015] Comparative Example 1 Compared with Example 6, the 3-hydroxy-5-methoxypyridine used in the catalyst preparation process of trifluoromethanesulfonic acid production was replaced with 3-hydroxy-4-methoxypyridine, and the rest was exactly the same as in Example 6, to obtain trifluoromethanesulfonic acid; the yield of the obtained trifluoromethanesulfonic acid was 83.3%, and the purity was 99.90%.

[0016] Comparative Example 2 Compared with Example 6, the 3-hydroxy-5-methoxypyridine used in the catalyst preparation process of trifluoromethanesulfonic acid production was replaced with 2-ethoxy-3-hydroxypyridine, and the rest was exactly the same as in Example 6, to obtain trifluoromethanesulfonic acid; the yield of the obtained trifluoromethanesulfonic acid was 83.4%, and the purity was 99.91%.

[0017] Comparative Example 3 Compared with Example 6, product 3 in the catalyst preparation process used in the production of trifluoromethanesulfonic acid was replaced with bromobutane to obtain catalyst-1. At the same time, nano-alumina was added in proportion (mass ratio of catalyst-1 to nano-alumina was 2:1.5). The rest was exactly the same as in Example 6 to obtain trifluoromethanesulfonic acid. The yield of the obtained trifluoromethanesulfonic acid was 85.9% and the purity was 94.98%.

[0018] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for improving the yield of trifluoromethanesulfonic acid, characterized in that: Includes the following steps: Step S1: Trifluoromethanesulfonyl fluoride and trifluoromethanesulfonate are reacted with a catalyst to generate trifluoromethanesulfonic anhydride; Step S2: Hydrolyze trifluoromethanesulfonic anhydride to obtain trifluoromethanesulfonic acid.

2. The production method for improving the yield of trifluoromethanesulfonic acid according to claim 1, characterized in that: The specific steps include the following: Step S1: In a protective gas atmosphere, trifluoromethanesulfonate and solvent are mixed and stirred for 20-25 min. Catalyst is added, and stirring is continued for 1-1.5 h to obtain a mixed system. Trifluoromethanesulfonyl fluoride is added dropwise to the mixed system under ice-water bath conditions. The dropping rate is controlled to ensure that the temperature in the mixed system is within the range of 40-50℃. After the dropping is completed, the temperature is controlled at 25-30℃, and the reaction is carried out at a constant temperature for 3.5-4 h to obtain trifluoromethanesulfonic anhydride. Step S2: Trifluoromethanesulfonic anhydride is added dropwise to the mixed solvent at 0-10℃, the dropping rate is controlled and the temperature is kept within the range of 40-45℃. After the addition is completed, the temperature is controlled at 23-27℃, the auxiliary agent is added, and the reaction is stirred for 2.5-3 hours to obtain trifluoromethanesulfonic acid.

3. The production method for improving the yield of trifluoromethanesulfonic acid according to claim 1, characterized in that: The trifluoromethanesulfonate in step S1 is selected from lithium trifluoromethanesulfonate, sodium trifluoromethanesulfonate, and potassium trifluoromethanesulfonate.

4. The production method for improving the yield of trifluoromethanesulfonic acid according to claim 1, characterized in that: The catalyst in step S1 is prepared by the following steps: Step (1): In a protective gas atmosphere, hydroxypyridine and anhydrous DMF are mixed and stirred. Potassium carbonate and tetrabutylammonium bromide are added and stirred under ice-water bath conditions. Then, cyano-halogenated hydrocarbons are added. The mixture is first heated and refluxed and stirred, and then heated and refluxed and stirred again to obtain product 1. Step (2): Mix product 1, methanol and DMF, introduce protective gas, stir and then add ammonia water, stir and then add Pd / C, stir and then introduce hydrogen gas, heat and stir to obtain product 2. Step (3): Add nanoparticles to anhydrous ethanol, disperse them by ultrasonication, and then heat and vacuum dry them to obtain pretreated nanoparticles; then mix the pretreated nanoparticles and anhydrous ethanol, add silane hydrolysate while stirring, and heat and stir to obtain product 3; mix product 3, product 2, anhydrous THF and anhydrous DMF, add alkali, and heat and stir to obtain catalyst.

5. The production method for improving the yield of trifluoromethanesulfonic acid according to claim 4, characterized in that: In step (1), the hydroxypyridine is 3-hydroxy-5-methoxypyridine.

6. The production method for improving the yield of trifluoromethanesulfonic acid according to claim 4, characterized in that: In step (1), the cyano-containing haloalkane is 2-chloro-4-(2-cyanophenyl)-1-butene.

7. The production method for improving the yield of trifluoromethanesulfonic acid according to claim 4, characterized in that: In step (3), the silane hydrolysate is obtained by mixing silane coupling agent, methanol and water, and stirring at pH 4-5 and temperature 25-30℃ for 4-4.5h.

8. The production method for improving the yield of trifluoromethanesulfonic acid according to claim 4, characterized in that: In step (3), the alkali is selected from potassium carbonate and sodium carbonate.

9. The method for improving the yield of trifluoromethanesulfonic acid according to claim 7, characterized in that: The silane coupling agent is selected from one of bromobutyltrimethoxysilane and 3-bromopropyltrimethoxysilane.