Method for preparing trifluoromethyl sulfonate

Abstract

The invention provides a method for preparing trifluoromethyl sulfonate, which comprises the following steps: dissolving methylsulfonyl halide in an inert solvent, cooling, introducing fluorine-nitrogen mixed gas, stirring for reaction, and introducing nitrogen to purge residual fluorine gas; carrying out reduced pressure distillation on the reaction liquid, collecting a fraction at a certain temperature, namely trifluoromethylsulfonyl fluoride, drying by using a molecular sieve, and sealing and storing under the protection of nitrogen; the preparation method comprises the following steps: mixing and stirring alkali metal hydroxide and a proper amount of deionized water until the alkali metal hydroxide and the deionized water are completely dissolved, cooling in an ice-water bath, dropwise adding trifluoromethylsulfonyl fluoride, maintaining the temperature to be less than or equal to 30 DEG C, and stirring and reacting at room temperature after dropwise adding; and after the reaction is finished, filtering, collecting filtrate, carrying out reduced pressure distillation on the filtrate, and carrying out vacuum drying. The main content of the trifluoromethanesulfonate prepared by the method reaches 99.9% or above, the trifluoromethanesulfonate can completely meet the requirements of the trifluoromethanesulfonate in the fields of lithium battery electrolyte or sodium ion battery electrolyte, organic synthesis catalysts and the like, and the trifluoromethanesulfonate has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical synthesis, and particularly relates to a method for preparing trifluoromethanesulfonate. Background Art

[0002] Lithium trifluoromethanesulfonate (LTF) is a lithium salt with excellent performance. Due to its high ionic conductivity, excellent thermal stability, and chemical inertness, it is widely used in lithium-ion battery electrolytes, electrochemical catalysts, organic synthesis reagents, and special functional materials. In particular, in the field of high-performance lithium batteries, LTF as an electrolyte additive or main salt can significantly improve the battery's high and low temperature performance, cycle life, and safety. With the rapid development of the new energy industry, the market demand for high-purity, low-cost LTFF is growing, and the optimization of its preparation process has become an increasingly research hotspot.

[0003] Traditionally, sulfur trioxide or fuming sulfuric acid reacts with anhydrous hydrogen fluoride at low temperatures to produce trifluoromethanesulfonyl fluoride, which is then acidified and lithiated to produce lithium trifluoromethanesulfonate. This method uses highly toxic hydrogen fluoride, posing significant risks to operators and the environment. Special protective equipment is required, and the reaction conditions require low temperatures (below -78°C) and high pressure, placing high demands on equipment materials and incurring significant investment costs. Furthermore, this process struggles to consistently produce lithium trifluoromethanesulfonate with a purity exceeding 99.9%, limiting its application in high-end batteries.

[0004] Therefore, developing a low-cost, high-efficiency, high-purity trifluoromethanesulfonate preparation process is of great significance for promoting technological upgrades in related industries, reducing production costs, and improving product competitiveness. Based on this, this application was developed. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the prior art and provide a method for preparing trifluoromethanesulfonate. By optimizing the reaction pathway and process conditions, the present invention addresses key shortcomings of the prior art and provides an innovative solution for the industrial production of trifluoromethanesulfonate. This method has the advantages of low cost, mild reaction conditions, and high product purity.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A method for preparing trifluoromethanesulfonate comprises the following steps: 1) Low-temperature fluorination of methylsulfonyl halides: Dissolve the methylsulfonyl halide in an inert solvent, cool it, slowly introduce a fluorine-nitrogen mixture into it, stir the reaction, and then introduce nitrogen to purge the residual fluorine gas; transfer the reaction solution to a distillation flask for vacuum distillation, collect the fraction at a certain temperature, which is trifluoromethylsulfonyl fluoride, and after confirming the absence of other fluorinated by-products based on the results of nuclear magnetic resonance detection, dry it with molecular sieves and store it in a sealed container under nitrogen protection; 2) One-pot preparation of trifluoromethanesulfonate: An excess amount of alkali metal hydroxide and an appropriate amount of deionized water are mixed and stirred until completely dissolved, and then cooled in an ice-water bath. Trifluoromethylsulfonyl fluoride is slowly added dropwise through a constant pressure tube, while controlling the addition rate and maintaining the temperature ≤ 30°C. After the addition is complete, the mixture is stirred and reacted at room temperature. After the reaction is completed, insoluble impurities are removed by filtration, and the filtrate is collected. The filtrate is subjected to reduced pressure distillation to remove water, and then dried in vacuo to obtain the final product, a white solid trifluoromethylsulfonate product.

[0007] Specifically, trifluoromethanesulfonate includes lithium trifluoromethanesulfonate and sodium trifluoromethanesulfonate, etc. In step 1), the methylsulfonyl halide is CX m H n SO2Y, X, Y are independently selected from Cl, Br, or I, m = 0, 1, 2, 3 and m + n = 3. For example, the methylsulfonyl halide can be methylsulfonyl chloride (CH3SO2Cl, m = 0, n = 3, Y = Cl), methylsulfonyl iodide (CH3SO2I, m = 0, n = 3, Y = 1), chloromethylsulfonyl chloride (CClH2SO2Cl, m = 1, n = 2, X = Y = Cl), etc.

[0008] Furthermore, in step 1), the inert solvent may be a perfluorocarbon, such as perfluorohexane, perfluorocyclohexane, perfluorooctane, etc.; and the molar ratio of the methylsulfonyl halide to the inert solvent may be 1:(1-1.2).

[0009] Specifically, in step 1), the cooling temperature is below -40°C; the volume concentration of fluorine in the fluorine-nitrogen mixture is 10% to 20%; and the flow rate of the fluorine-nitrogen mixture is 90 to 110 mL / min. Furthermore, in step 1), the stirring reaction time is 4 to 7 hours. In step 1), the vacuum distillation pressure is reduced to below 30 mmHg, the cooling rate is 1 to 2°C / min, and the temperature range of the collected fractions is -50°C to -45°C; NMR analysis is performed. 9 F should be a single peak (δ≈-76 ppm) and the molecular sieve should be 4A molecular sieve.

[0010] Specifically, in step 2), the alkali metal hydroxide is lithium hydroxide or sodium hydroxide, and the mixture is cooled in an ice-water bath to a temperature of 0-5°C. Furthermore, in step 2), the molar ratio of the alkali metal hydroxide to deionized water and trifluoromethylsulfonyl fluoride is (2.5-3):(12-15):1.

[0011] Specifically, in step 2), the trifluoromethylsulfonyl fluoride is added at a rate of (1-2) drops / second, and the reaction time is 2-4 hours under stirring at room temperature. Furthermore, in step 2), the vacuum drying temperature is 60-100°C, and the drying time is 4-12 hours.

[0012] Compared with the prior art, the advantages and beneficial effects of the method of the present invention are as follows: The present invention provides a method for preparing trifluoromethanesulfonate. In this method, an alkali metal hydroxide can serve as a base to neutralize HF generated by the hydrolysis of trifluoromethanesulfonyl fluoride and also serve as a lithium or sodium source to provide the corresponding metal ions for reaction with trifluoromethanesulfonic acid to produce the target product, trifluoromethanesulfonate. Excess alkali metal hydroxide can also ensure complete neutralization of HF while reducing residual byproducts. The trifluoromethanesulfonate prepared by this method has a main content of over 99.9%, fully meeting the requirements for trifluoromethanesulfonate use in lithium battery electrolytes, organic synthesis catalysts, and other fields, and has broad application prospects. DETAILED DESCRIPTION

[0013] The technical solution of the present invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited thereto.

[0014] In the following examples, the raw materials used are all common commercial products that can be purchased directly, or are prepared using conventional techniques in the art.

[0015] Room temperature refers to 25±5°C.

[0016] Example 1 A method for preparing lithium trifluoromethanesulfonate comprises the following steps: 1) Low-temperature fluorination of methanesulfonyl chloride: Dissolve 115g of methanesulfonyl chloride in 370g of perfluorohexane and cool to -40°C. Slowly introduce a 10% fluorine-nitrogen mixture (flow rate 100 mL / min). After stirring for 4 hours, introduce nitrogen to purge any remaining fluorine. Transfer the reaction mixture to a distillation flask and perform vacuum distillation. After slowly reducing the pressure to 30 mmHg, cool at a rate of 1-2°C / min and collect fractions between -50°C and -45°C. NMR analysis results show¹ 9 F is a single peak (δ≈-76 ppm), without other fluorinated by-products. It was dried over 4A molecular sieves and stored in a sealed container under nitrogen protection.

[0017] 2) One-pot preparation of lithium trifluoromethanesulfonate: Add 12.6 g of lithium hydroxide and 45 g of deionized water to a reaction flask and stir until completely dissolved. Place the flask in an ice-water bath and cool to 0–5°C. Slowly add 32 g of trifluoromethylsulfonyl fluoride dropwise via a constant pressure tube, controlling the addition rate at 1–2 drops / second to maintain the reaction temperature ≤ 30°C. After the addition is complete, continue stirring at room temperature for 3 hours. After the reaction is complete, filter to remove insoluble impurities, collect the filtrate, and concentrate it by vacuum distillation to obtain a white solid. Dry under vacuum at 60°C for 12 hours to obtain the final product, lithium trifluoromethylsulfonate.

[0018] The component test results of the lithium trifluoromethanesulfonate product prepared in this embodiment are shown in Table 1. The results in Table 1 show that the purity of the lithium trifluoromethanesulfonate product prepared in this embodiment is 99.94%, F - Content 92ppm, SO4 2- The content is 153ppm and the H2O content is 210ppm, which can fully meet the requirements of lithium trifluoromethanesulfonate for lithium battery electrolytes, organic synthesis catalysts and other fields. Table 1 Component content of lithium trifluoromethanesulfonate product in Example 1 Example 2 A method for preparing lithium trifluoromethanesulfonate comprises the following steps: 1) Low-temperature fluorination of methanesulfonyl chloride: Dissolve 247g of methylsulfonyl iodide in 450g of perfluorohexane and cool to -40°C. Slowly introduce a 15% fluorine-nitrogen mixture (at a flow rate of 90 mL / min). After stirring for 4.5 hours, introduce nitrogen to purge any remaining fluorine. Transfer the reaction mixture to a distillation flask and perform vacuum distillation. Slowly reduce the pressure to 30 mmHg. Once stabilized, cool at a rate of 1-2°C / min. Collect fractions between -50°C and -45°C. NMR analysis results show¹ 9 F is a single peak (δ≈-76 ppm), without other fluorinated by-products. It was dried over 4A molecular sieves and stored in a sealed container under nitrogen protection.

[0019] 2) One-pot preparation of lithium trifluoromethanesulfonate: Add 33g of lithium hydroxide and 109g of deionized water to a reaction flask and stir until completely dissolved. Place the flask in an ice-water bath and cool to 0-5°C. Slowly add 71g of trifluoromethylsulfonyl fluoride dropwise via a constant pressure tube, controlling the addition rate at 1-2 drops / second to maintain the reaction temperature ≤30°C. After the addition is complete, continue stirring at room temperature for 3 hours. After the reaction is complete, filter to remove insoluble impurities, collect the filtrate, and concentrate it by vacuum distillation to obtain a white solid. Dry it in vacuo at 70°C for 10 hours to obtain the final product, lithium trifluoromethylsulfonate.

[0020] The component test results of the lithium trifluoromethanesulfonate product prepared in this embodiment are shown in Table 2. The results in Table 2 show that the purity of the lithium trifluoromethanesulfonate product prepared in this embodiment is 99.91%, F - Content 87ppm, SO4 2- The content is 177ppm and the H2O content is 194ppm, which can fully meet the requirements of lithium trifluoromethanesulfonate for lithium battery electrolytes, organic synthesis catalysts and other fields. Table 2 Component content of lithium trifluoromethanesulfonate product in Example 2 Example 3 A method for preparing sodium trifluoromethanesulfonate comprises the following steps: 1) Low-temperature fluorination of methanesulfonyl chloride: Dissolve 224g of chloromethylsulfonyl chloride in 550g of perfluorohexane and cool to -40°C. Slowly introduce a 20% fluorine-nitrogen mixture (at a flow rate of 110 mL / min). After stirring for 5 hours, introduce nitrogen to purge any remaining fluorine. Transfer the reaction mixture to a distillation flask and perform vacuum distillation. Slowly reduce the pressure to 30 mmHg. Once stabilized, cool at a rate of 1-2°C / min and collect the fractions between -50°C and -45°C. NMR analysis results show¹ 9 F is a single peak (δ≈-76 ppm), without other fluorinated by-products. It was dried over 4A molecular sieves and stored in a sealed container under nitrogen protection.

[0021] 2) One-pot preparation of sodium trifluoromethanesulfonate: Add 42 g of sodium hydroxide and 160 g of deionized water to a reaction flask and stir until completely dissolved. Place the flask in an ice-water bath and cool to 0–5°C. Slowly add 90 g of trifluoromethylsulfonyl fluoride dropwise via a constant pressure tube, controlling the addition rate at 1–2 drops / second to maintain the reaction temperature ≤ 30°C. After the addition is complete, continue stirring at room temperature for 3 hours. After the reaction is complete, filter to remove insoluble impurities, collect the filtrate, and concentrate it by vacuum distillation to obtain a white solid. Dry it in vacuo at 100°C for 5 hours to obtain the final product, sodium trifluoromethylsulfonate.

[0022] The component test results of the sodium trifluoromethanesulfonate product prepared in this embodiment are shown in Table 3. The results in Table 3 show that the purity of the sodium trifluoromethanesulfonate product prepared in this embodiment is 99.95%, F - Content 95ppm, SO4 2- The content is 136ppm and the H2O content is 236ppm, which can fully meet the requirements of sodium trifluoromethanesulfonate for use in sodium ion battery electrolytes, organic synthesis catalysts and other fields. Table 3 Component content of sodium trifluoromethanesulfonate product in Example 3 In the method for preparing trifluoromethanesulfonate described herein, lithium hydroxide or sodium hydroxide serves as a base to neutralize HF generated by the hydrolysis of trifluoromethanesulfonyl fluoride and also as a lithium source or sodium salt to provide the corresponding metal ions for reaction with trifluoromethanesulfonic acid to produce the target product, trifluoromethanesulfonate. Excess alkali metal hydroxide also ensures complete neutralization of HF while reducing residual byproducts. This method has the advantages of low cost, mild reaction conditions, and high product purity. The prepared trifluoromethanesulfonate has a main content of over 99.9%, fully meeting the requirements for trifluoromethanesulfonate use in lithium battery electrolytes, sodium ion battery electrolytes, organic synthesis catalysts, and other fields, and has broad application prospects.

Claims

1. A method for preparing trifluoromethanesulfonate, characterized in that: The steps include: 1) Dissolve the methylsulfonyl halide in an inert solvent, cool it, introduce a fluorine-nitrogen mixture, stir it for reaction, and then introduce nitrogen to purge the residual fluorine gas; subject the reaction solution to vacuum distillation, collect the fraction at a certain temperature, which is trifluoromethylsulfonyl fluoride, dry it with molecular sieves, and store it in a sealed container under nitrogen protection; 2) Mix an alkali metal hydroxide and an appropriate amount of deionized water and stir until completely dissolved. Cool in an ice-water bath, add trifluoromethylsulfonyl fluoride dropwise while maintaining the temperature ≤30°C, and stir at room temperature after the addition is complete. After the reaction is complete, filter, collect the filtrate, distill the filtrate under reduced pressure, and dry in vacuo to obtain the product.

2. The method for preparing trifluoromethanesulfonate according to claim 1, wherein In step 1), the methylsulfonyl halide is CX m H n SO2Y, X, Y are independently selected from Cl, Br, or I, m=0, 1, 2, 3 and m+n=3.

3. The method for preparing trifluoromethanesulfonate according to claim 1, wherein In step 1), the inert solvent is a perfluorocarbon, and the molar ratio of methylsulfonyl halide to the inert solvent is 1:(1-1.2).

4. The method for preparing trifluoromethanesulfonate according to claim 1, wherein In step 1), the cooling temperature is below -40°C; and the fluorine concentration in the fluorine-nitrogen mixed gas is 10% to 20%.

5. The method for preparing trifluoromethanesulfonate according to claim 1, wherein In step 1), the stirring reaction time is 4 to 7 hours.

6. The method for preparing trifluoromethanesulfonate according to claim 1, wherein: In step 1), the vacuum distillation pressure is reduced to below 30 mmHg, and the temperature range corresponding to the collected fraction is -50°C to -45°C.

7. The method for preparing trifluoromethanesulfonate according to claim 1, wherein: In step 2), the mixture is cooled in an ice-water bath to a temperature of 0-5°C.

8. The method for preparing trifluoromethanesulfonate according to claim 1, wherein In step 2), the molar ratio of alkali metal hydroxide to deionized water and trifluoromethylsulfonyl fluoride is (2.5-3): (12-15):

1.

9. The method for preparing trifluoromethanesulfonate according to claim 1, wherein In step 2), the reaction time is 2 to 4 hours under stirring at room temperature.

10. The method for preparing trifluoromethanesulfonate according to claim 1, wherein In step 2), the vacuum drying temperature is 60-100°C and the drying time is 4-12 hours.

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