Preparation method of battery-grade lithium trifluoromethanesulfinate

Abstract

The invention discloses a preparation method of battery-grade lithium trifluoromethanesulfinate, which comprises the following steps: reacting sodium trifluoromethanesulfinate with benzyl halide in a solvent to prepare benzyl trifluoromethyl sulfone, and carrying out hydrogenation reduction on the benzyl trifluoromethyl sulfone under the catalysis of a catalyst to prepare trifluoromethanesulfinic acid, according to the method, all the adopted raw materials are industrial chemicals and are low in price and easy to obtain, the reaction process is mild and controllable, the product purity is high, the battery use requirement is met, and the method has the industrialization prospect.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing battery-grade lithium trifluoromethanesulfinate. Background Art

[0002] In February 2025, Peng Huisheng's research group at Fudan University reported on a lithium battery tonic—lithium trifluoromethanesulfinate (Nature volume 638, pages 676–683 (2025)). Lithium trifluoromethanesulfinate can be injected into worn or degraded lithium batteries like a drug, precisely replenishing lost lithium ions and restoring capacity, significantly extending battery life. This promising market is promising.

[0003] Currently, the most common synthesis method involves reducing lithium trifluoromethanesulfonate, lithium bistrifluoromethanesulfonyl imide, or trifluoromethanesulfonyl chloride with a strong reducing agent. However, these raw materials are expensive. Reducing lithium trifluoromethanesulfonate requires the even more expensive lithium iodide as a reducing agent, while reducing lithium bistrifluoromethanesulfonyl imide requires the extremely dangerous lithium aluminum tetrahydride. Trifluoromethanesulfonyl chloride is also expensive and has a low boiling point, making it difficult to store. This method is suitable only for laboratory synthesis and cannot be used in industrial production. Sodium trifluoromethanesulfinate is typically prepared by reacting inexpensive bromotrifluoromethane with hydrosulfite, sodium sulfite, or sodium thiosulfate. However, this method is difficult to prepare lithium trifluoromethanesulfinate. Firstly, lithium sulfite and lithium thiosulfate are difficult to obtain industrially. Furthermore, the bromide salts generated by this method are difficult to completely remove, resulting in a low product purity. Typical industrial sodium trifluoromethanesulfinate purity is only around 65-75%. Summary of the Invention

[0004] The object of the present invention is to provide a method for synthesizing battery-grade lithium trifluoromethanesulfinate to solve the problems raised in the above background technology.

[0005] A method for preparing battery-grade lithium trifluoromethylsulfinate comprises the following steps: sodium trifluoromethylsulfinate reacts with a benzyl halide in a solvent to prepare benzyl trifluoromethyl sulfone; benzyl trifluoromethyl sulfone is hydrogenated and reduced under a catalyst to prepare trifluoromethylsulfinic acid; battery-grade trifluoromethylsulfinic acid is obtained after distillation and purification; and the obtained trifluoromethylsulfinic acid is reacted with a battery-grade lithium salt to prepare lithium trifluoromethylsulfinate;

[0006] The synthetic route is as follows:

[0007]

[0008] Wherein, X is chlorine or bromine;

[0009] The solvent for the reaction of the sodium trifluoromethylsulfinate and benzyl halide includes any one of water, ethyl acetate, propyl acetate, butyl acetate, dichloromethane, 1,2-dichloroethane, chloroform, carbon tetrachloride, tetrahydrofuran, dioxane, acetone, acetonitrile, ethylene glycol dimethyl ether, toluene, xylene, N,N-dimethylformamide and N,N-dimethylacetamide or a mixed solvent of two of them.

[0010] When the ester, alkane or arene is used as the solvent, the solubility of the sodium trifluoromethylsulfinate is poor, and it is generally necessary to be mixed with water, acetonitrile, acetone, N,N-dimethylformamide and N,N-dimethylacetamide.

[0011] The catalyst is any one of palladium-carbon, platinum-carbon, palladium chloride, palladium sulfate, platinum dioxide, nickel or nickel chloride.

[0012] The battery-grade lithium salt includes any one of lithium carbonate, lithium hydroxide, lithium chloride, lithium bromide or lithium iodide, preferably lithium carbonate or lithium hydroxide.

[0013] The rectification is a reduced-pressure rectification, and the pressure for the rectification is 10-300 pa, and the temperature is 40-60 DEG C.

[0014] The molar ratio of the sodium trifluoromethylsulfinate to the benzyl halide is 3:1-1.2:1, and the excess of the sodium trifluoromethylsulfinate can ensure the complete conversion of the benzyl halide.

[0015] The pressure for the hydrogenation reduction is 0.1 Mpa-1 Mpa.

[0016] The temperature for the hydrogenation reduction is 20-120 DEG C.

[0017] The solvent for the hydrogenation reduction is any one of toluene, xylene, ethylbenzene, methanol, ethanol, isopropanol, n-butanol, tert-butanol, tetrahydrofuran or dioxane.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] The raw materials, such as the sodium trifluoromethylsulfinate, the benzyl halide, the solvent, the catalyst and the lithium salt, used in the present application are all industrial products, which are cheap and easy to obtain; the reaction process utilizes the physical property difference between the benzyl trifluoromethylsulfone and the sodium bromide and the sodium trifluoromethylsulfinate, so that the raw materials and the sodium bromide can be easily separated, the benzyl trifluoromethylsulfone is prepared with high purity, and the subsequent purification is simpler; the trifluoromethylsulfonic acid is prepared by the hydrogenation debenzyl method, the reaction is single, the product, the raw material and the by-product can be easily separated by rectification, and the acid with high purity is obtained, and finally the battery-grade lithium trifluoromethylsulfonate is prepared by the neutralization process. The method has the advantages of easy-to-obtain raw materials, simple process and convenient purification, and is very suitable for industrialization and can be widely used. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0021] A preparation method of battery-grade lithium trifluoromethanesulfinate comprises the following steps: reacting sodium trifluoromethanesulfinate with benzyl halide in a solvent to prepare benzyl trifluoromethanesulfone, hydrogenating and reducing the benzyl trifluoromethanesulfone under catalysis of a catalyst to prepare trifluoromethanesulfonic acid, obtaining battery-grade trifluoromethanesulfonic acid after rectification and purification, and preparing lithium trifluoromethanesulfinate by reacting the battery-grade trifluoromethanesulfonic acid with a battery-grade lithium salt.

[0022] The synthetic route is as follows:

[0023]

[0024] In the formula, X is chlorine or bromine, preferably bromine; the reaction rate of benzyl bromide is relatively fast, the by-product is sodium bromide, which is consistent with the impurities contained in the raw material, and thus is convenient for industrial processing.

[0025] The solvent for the reaction of the sodium trifluoromethanesulfinate and the benzyl halide comprises any one of water, ethyl acetate, propyl acetate, butyl acetate, dichloromethane, 1,2-dichloroethane, chloroform, carbon tetrachloride, tetrahydrofuran, dioxane, acetone, acetonitrile, ethylene glycol dimethyl ether, toluene, xylene, N,N-dimethylformamide and N,N-dimethylacetamide, or a mixed solvent of two of the above.

[0026] When esters, alkanes or arenes are used as the solvent, the solubility of the sodium trifluoromethanesulfinate is relatively poor, and thus it is generally necessary to be mixed with water, acetonitrile, acetone, N,N-dimethylformamide and N,N-dimethylacetamide, etc.

[0027] A more preferred selection is to use a mixed solvent of water and dichloromethane, 1,2-dichloroethane, chloroform or butyl acetate, the raw material and the impurity sodium bromide are easily soluble in water, the intermediate product benzyl trifluoromethanesulfone is soluble in an organic solvent, and thus it is convenient to separate the benzyl trifluoromethanesulfone with higher purity.

[0028] The molar ratio of the sodium trifluoromethanesulfinate to the benzyl halide is 3:1 to 1.2:1, and the excess of the sodium trifluoromethanesulfinate can ensure complete conversion of the benzyl halide.

[0029] The catalyst is any one of palladium-carbon, platinum-carbon, palladium chloride, palladium sulfate, platinum dioxide, nickel or nickel chloride. The amount of the catalyst is 0.1% to 20%, wherein the amount of the platinum-based or palladium-based catalyst is generally below 5%, and the amount of the nickel-based catalyst is above 2%.

[0030] The rectification is reduced pressure rectification, the pressure of the rectification is 10-300 pa, and the temperature is 40-60℃.

[0031] The pressure of the hydrogenation reduction is 0.1-1 Mpa, and 0.1 Mpa normal pressure reduction is generally adopted, and the increased pressure is beneficial to the improvement of the reaction speed.

[0032] The temperature of the hydrogenation reduction is 20-120℃.

[0033] The solvent of the hydrogenation reduction is any one of toluene, dimethylbenzene, ethylbenzene, methanol, ethanol, isopropyl alcohol, n-butanol, tert-butyl alcohol, tetrahydrofuran and dioxane, preferably toluene, and the byproduct after debenzyl is also toluene, and the selection of the toluene reaction system is more single, and the industrial treatment is more convenient.

[0034] The battery grade lithium salt includes any one of lithium carbonate, lithium hydroxide, lithium chloride, lithium bromide and lithium iodide, and preferably lithium carbonate and lithium hydroxide, and the reaction is carried out in an aqueous system.

[0035] Example 1

[0036] Synthesis of benzyl trifluoromethyl sulfone

[0037] In a 500 mL reaction bottle, 150 mL of water, 100 mL of 1,2-dichloroethane, 50 grams of sodium trifluoromethyl sulfinate (content 70%) were added, and after stirring and dissolving at 60℃, 16 grams of benzyl chloride was slowly added, and the stirring was continued for 4 hours after 30 minutes of dropwise addition. The reaction was stopped. The organic phase was washed with 50 mL of saturated brine twice and with 50 mL of water once. After drying with anhydrous magnesium sulfate, the solvent was removed and dried to obtain 24.92 g of white solid with a melting point of 96-98℃, and the yield was 90.0%.

[0038] Example 2

[0039] Synthesis of benzyl trifluoromethyl sulfone

[0040] In a 500 mL reaction bottle, 150 mL of water, 100 mL of 1,2-dichloroethane, 50 grams of sodium trifluoromethyl sulfinate (content 70%) were added, and after stirring and dissolving at 60℃, 16 grams of benzyl chloride was slowly added, and the stirring was continued for 4 hours after 30 minutes of dropwise addition. The reaction was stopped. The organic phase was washed with 50 mL of saturated brine twice and with 50 mL of water once. After drying with anhydrous magnesium sulfate, the solvent was removed and dried to obtain 24.92 g of white solid with a melting point of 96-98℃, and the yield was 90.0%.

[0041] Example 3

[0042] Synthesis of trifluoromethyl sulfinate

[0043] In a 500ml flask, add 200ml toluene, 30g benzyl trifluoromethyl sulfone, 0.5g 5% Pd / C, close the reactor, vacuum to -0.095Mpa, let nitrogen in to normal pressure, operate three times, vacuum to -0.095Mpa, let hydrogen in to 0.15Mpa, stir the reaction at 30°C, supplement hydrogen in time to keep the pressure in the reactor at 0.15Mpa, react for 5 hours, stop the reaction, filter to separate the catalyst, and recycle. Remove toluene from the filtrate by vacuum distillation, and distill the residue. Control the distillation pressure at 200pa, and the external temperature at 90°C, collect the fraction with boiling point of 78-80°C, and receive the white solid at 0°C. The yield is 85.87%.

[0044] Example 4

[0045] Synthesis of trifluoromethyl sulfmic acid

[0046] In a 500ml flask, add 200ml toluene, 30g benzyl trifluoromethyl sulfone, 0.5g 5% Pd / C, close the reactor, vacuum to -0.095Mpa, let nitrogen in to normal pressure, operate three times, vacuum to -0.095Mpa, let hydrogen in to 0.15Mpa, stir the reaction at 30°C, supplement hydrogen in time to keep the pressure in the reactor at 0.15Mpa, react for 5 hours, stop the reaction, filter to separate the catalyst, and recycle. Remove toluene from the filtrate by vacuum distillation, and distill the residue. Control the distillation pressure at 200pa, and the external temperature at 90°C, collect the fraction with boiling point of 78-80°C, and receive the white solid at 0°C. The yield is 85.87%.

[0047] Example 5

[0048] Synthesis of lithium trifluoromethyl sulfmate

[0049] In a 1000ml flask, add 500ml deionized water, 134g trifluoromethyl sulfmic acid, 40g battery grade lithium carbonate in batches at 0-40°C, keep the reaction temperature, continue to stir for 3 hours, stop the reaction. Filter to separate the insoluble matter, add a small amount of deionized water solution of trifluoromethyl sulfmic acid, adjust the pH of the reaction system to 6-7. Spray dry to remove most of the water, vacuum dry to less than 100ppm of moisture, and obtain white powder 13.6g, yield 97.8%. Test results are as follows

[0050] Test item SO4 2- ]] Cl - ]] Moisture Fe 2+ ]] Na + ]] Ca 2+ ]] Mg 2+ ]]> Result 5.6 ppm 7.2 ppm 59 ppm 1.1 ppm 3.9 ppm 2.8 ppm 1.6 ppm

[0051] Example 6

[0052] Synthesis of lithium trifluoromethyl sulfmate

[0053] In a 1000 mL reaction bottle, 500 mL of deionized water, 24 grams of lithium hydroxide of battery grade, 0-40 ℃, batchwise addition of trifluoromethyl sulfinic acid, adjust the PH value of the reaction system to 6-7, add 132 g of trifluoromethyl sulfinic acid, stop the reaction. Spray drying to remove most of the water, vacuum drying to less than 100 ppm of moisture, white powder 13.5 g, yield 97.8%. Test results: as follows

[0054] Test item SO4 2- ]]> Cl - ]]> Moisture <![CDATA[Fe 2+ ]]> Na + ]]> Ca 2+ ]]> Mg 2+ ]]> Result 2.7 ppm 11.4 ppm 36 ppm 0.7 ppm 4.9 ppm 2.1 ppm 1.4 ppm

[0055] While the embodiments of the application have been shown and described, it is to be understood that the embodiments can be varied, modified, substituted and changed by those skilled in the art without departing from the principles and spirit of the application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing battery-grade lithium trifluoromethanesulfinate, comprising the following steps: reacting sodium trifluoromethanesulfinate with a benzyl halide in a solvent to prepare benzyl trifluoromethyl sulfone, hydrogenating and reducing benzyl trifluoromethyl sulfone under a catalyst to prepare trifluoromethanesulfinic acid, distilling and purifying the obtained battery-grade trifluoromethanesulfinic acid, and reacting the obtained trifluoromethanesulfinic acid with a battery-grade lithium salt to prepare lithium trifluoromethanesulfinate; The synthetic route is as follows: in, X is chlorine or bromine; 2. The method for preparing battery-grade lithium trifluoromethanesulfinate according to claim 1, wherein: The solvent for the reaction of sodium trifluoromethanesulfinate and benzyl halide comprises any one of water, ethyl acetate, propyl acetate, butyl acetate, dichloromethane, 1,2-dichloroethane, chloroform, carbon tetrachloride, tetrahydrofuran, dioxane, acetone, acetonitrile, ethylene glycol dimethyl ether, toluene, xylene, N,N-dimethylformamide and N,N-dimethylacetamide, or a mixed solvent of two thereof.

3. The method for preparing battery-grade lithium trifluoromethanesulfinate according to claim 1, wherein: The catalyst is any one of palladium carbon, platinum carbon, palladium chloride, palladium sulfate, platinum dioxide, nickel and nickel chloride.

4. The method for preparing battery-grade lithium trifluoromethanesulfinate according to claim 1, wherein: The battery-grade lithium salt includes any one of lithium carbonate, lithium hydroxide, lithium chloride, lithium bromide, and lithium iodide.

5. The method for preparing battery-grade lithium trifluoromethanesulfinate according to claim 1, wherein: The distillation is vacuum distillation, the distillation pressure is 10-300 Pa, and the temperature is 40-60°C.

6. The method for preparing battery-grade lithium trifluoromethanesulfinate according to claim 1, wherein: The molar ratio of the sodium trifluoromethanesulfinate to the benzyl halide is 3:1 to 1.2:

1.

7. The method for preparing battery-grade lithium trifluoromethanesulfinate according to claim 1, wherein: The pressure of the hydrogenation reduction is 0.1 MPa to 1 MPa.

8. The method for preparing battery-grade lithium trifluoromethanesulfinate according to claim 1, wherein: The temperature of the hydrogenation reduction is 20-120°C.

9. The method for preparing battery-grade lithium trifluoromethanesulfinate according to claim 1, wherein: The solvent for hydrogenation reduction is any one of toluene, xylene, ethylbenzene, methanol, ethanol, isopropanol, n-butanol, tert-butanol, tetrahydrofuran and dioxane.

Images