Preparation method of difluoroethylene sulfate

Abstract

The preparation method of the ethylene difluorosulfate comprises the following steps: step 1, adding a solvent into ethylene difluorosulfate under a nitrogen protection condition to dissolve the ethylene difluorosulfate, and adding anhydrous fluoride after the ethylene difluorosulfate is completely dissolved; 2, carrying out a reaction at a temperature of 20 to 90 DEG C for 2 to 20 h; and 3, removing the generated chloride and the fluoride which is not completely reacted, and rectifying the reaction liquid to obtain the difluoroethylene sulfate. Various byproducts of monofluoro, difluoro and trifluoro are not generated in the preparation process, so that the rectification difficulty is greatly reduced, and the cost investment of equipment is reduced; meanwhile, fluorides and by-product chlorides used in the invention can be removed by using a filtering method, so that the post-treatment operation is simplified, the process of decomposing hydrogen fluoride is avoided, and the safety and environmental protection are improved; the prepared difluoroethylene sulfate is high in purity and yield, the process is simple, the cost is low, electrolysis operation is avoided, and industrial production is easy to carry out.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of difluorosulfuric acid ethylene ester, an additive for lithium-ion battery electrolyte, and more specifically, to a preparation method of difluorosulfuric acid ethylene ester. Background Art

[0002] Vinyl sulfate is a new type of additive for lithium-ion battery electrolyte, which is used to inhibit the initial capacity decline of the battery, reduce the battery swelling after high-temperature storage, and improve the charge-discharge performance and cycle times of the battery. Its difluoro derivative, difluorosulfuric acid ethylene ester (whose molecular formula is as Figure 1 shown), can effectively reduce the battery impedance, improve the specific capacity of the battery, and enhance the safety and service life of the battery. Therefore, difluorosulfuric acid ethylene ester is being widely promoted and applied.

[0003] However, the existing preparation process of difluorosulfuric acid ethylene ester is relatively complex. For example, the synthesis process in the existing patent (CN113215600A) is to mix vinyl sulfate and hydrogen fluoride, perform fluorination after electrolysis, and then obtain the product through rectification. The products after electrolysis are relatively complex, increasing the difficulty of rectification; hydrogen fluoride is a highly toxic substance with strong corrosiveness, posing potential hazards in terms of safety and environmental protection; and the electrolysis equipment is not easy to be industrialized. Summary of the Invention

[0004] The present invention provides a preparation method of difluorosulfuric acid ethylene ester to solve the defects in the prior art.

[0005] The present invention is achieved through the following technical solutions:

[0006] A preparation method of difluorosulfuric acid ethylene ester, comprising the following steps:

[0007] Step 1: Dichlorosulfuric acid ethylene ester is added to a solvent for dissolution under nitrogen protection, and after complete dissolution, an anhydrous fluoride is added;

[0008] Step 2: React at 20 - 90 °C for 2 - 20 h;

[0009] Step 3: Remove the generated chlorides and the unreacted fluorides completely, and rectify the reaction solution to obtain difluorosulfuric acid ethylene ester.

[0010] In the preparation method of difluorosulfuric acid ethylene ester as described above, the reaction temperature in Step 2 is 70 - 90 °C, the reaction duration is 4 - 5 h, and the molar ratio of the anhydrous fluoride to dichlorosulfuric acid ethylene ester is 1:2 - 3.

[0011] In the preparation method of difluorosulfuric acid ethylene ester as described above, the solvent is any one of acetonitrile, ethyl acetate, N,N-dimethylformamide, dichloroethane, and ethylene glycol dimethyl ether.

[0012] The preparation method of vinyl bis(fluorosulfate) as described above, wherein the water content in the solvent is not higher than 50 ppm.

[0013] The preparation method of vinyl bis(fluorosulfate) as described above, wherein the anhydrous fluoride is anhydrous potassium fluoride or anhydrous sodium fluoride.

[0014] The advantages of the present invention are as follows: various by-products such as monofluoro-, difluoro-, and trifluoro- are not generated during the preparation process of the present invention, greatly reducing the difficulty of rectification and reducing the equipment cost investment; at the same time, the fluoride and by-product potassium chloride used in the present invention can be removed by filtration, simplifying the post-treatment operation and avoiding the process of decomposing hydrogen fluoride, improving in terms of safety and environmental protection; the vinyl bis(fluorosulfate) prepared by the present invention has high purity and yield, simple process, low cost, avoids electrolysis operation, and is easy to carry out industrial production. Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 is the molecular formula of vinyl bis(fluorosulfate) of the present invention. Detailed Embodiments

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0018] Example 1

[0019] Under nitrogen protection, 500 ml of anhydrous acetonitrile was added to a 1 L reaction flask, 0.5 mol of vinyl bis(chlorosulfate) was added, and stirred for 10 min to dissolve. 1.2 mol of anhydrous potassium fluoride was slowly added, mixed evenly, and stirred at room temperature for 15 min. The temperature was raised to 80 °C and reacted for 4 h. When the residue of vinyl bis(chlorosulfate) was detected to be less than 0.1%, the reaction was stopped. The temperature was lowered to room temperature, and the excessive potassium fluoride and the generated potassium chloride were removed by filtration. The mother liquor was rectified to recover the acetonitrile solvent, and 77.4 g of vinyl bis(fluorosulfate) was obtained. The purity detected by GC was 99.76%, and the yield was 96.75%.

[0020] Example 2

[0021] Under nitrogen protection, 500 ml of anhydrous acetonitrile was added to a 1 L reaction flask, and 0.5 mol of vinyl bis(chlorosulfate) was added. After stirring for 10 min to dissolve, 1.1 mol of anhydrous potassium fluoride was slowly added, and the mixture was stirred evenly and then stirred at room temperature for 15 min. The temperature was raised to 85 °C and reacted for 4 h. After detecting that the residue of vinyl bis(chlorosulfate) was less than 0.1%, the reaction was stopped. The temperature was lowered to room temperature, and the excess potassium fluoride and the generated potassium chloride were removed by filtration. The mother liquor was rectified to recover the acetonitrile solvent, and 78.5 g of vinyl bis(fluorosulfate) was obtained. The purity detected by GC was 99.82%, and the yield was 98.12%.

[0022] Example 3

[0023] Under nitrogen protection, 600 ml of anhydrous ethyl acetate was added to a 1 L reaction flask, and 0.6 mol of vinyl bis(chlorosulfate) was added. After stirring for 10 min to dissolve, 1.5 mol of anhydrous potassium fluoride was slowly added, and the mixture was stirred evenly and then stirred at room temperature for 15 min. The temperature was raised to 80 °C and reacted for 5 h. After detecting that the residue of vinyl bis(chlorosulfate) was less than 0.1%, the reaction was stopped. The temperature was lowered to room temperature, and the excess potassium fluoride and the generated potassium chloride were removed by filtration. The mother liquor was rectified to recover the ethyl acetate solvent, and 92.02 g of vinyl bis(fluorosulfate) was obtained. The purity detected by GC was 99.53%, and the yield was 95.85%.

[0024] Example 4

[0025] Under nitrogen protection, 600 ml of anhydrous N,N-dimethylformamide was added to a 1 L reaction flask, and 0.6 mol of vinyl bis(chlorosulfate) was added. After stirring for 10 min to dissolve, 1.5 mol of anhydrous sodium fluoride was slowly added, and the mixture was stirred evenly and then stirred at room temperature for 10 min. The temperature was raised to 90 °C and reacted for 6 h. After detecting that the residue of vinyl bis(chlorosulfate) was less than 0.1%, the reaction was stopped. The temperature was lowered to room temperature, and the excess sodium fluoride and the generated sodium chloride were removed by filtration. The mother liquor was rectified to recover the N,N-dimethylformamide solvent, and 95.13 g of vinyl bis(fluorosulfate) was obtained. The purity detected by GC was 99.64%, and the yield was 99.09%.

[0026] Example 5

[0027] Under nitrogen protection, 600 ml of anhydrous dichloroethane was added to a 1 L reaction flask, and 0.5 mol of vinyl bis(chlorosulfate) was added. After stirring for 10 min to dissolve, 1.2 mol of anhydrous sodium fluoride was slowly added, and the mixture was stirred evenly and then stirred at room temperature for 10 min. The temperature was raised to 80 °C and reacted for 6 h. After detecting that the residue of vinyl bis(chlorosulfate) was less than 0.1%, the reaction was stopped. The temperature was lowered to room temperature, and the excess sodium fluoride and the generated sodium chloride were removed by filtration. The mother liquor was rectified to recover the dichloroethane solvent, and 76.19 g of vinyl bis(fluorosulfate) was obtained. The purity detected by GC was 99.57%, and the yield was 95.24%.

[0028] As can be seen from Examples 1-5, the preparation method of the present invention is simple to operate, and the obtained vinyl bis(fluorosulfate) has high purity and high yield, thus facilitating the popularization and application of vinyl bis(fluorosulfate).

[0029] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the present invention in each example.

Claims

1. A method for preparing vinyl bis(fluorosulfate), characterized in that: It includes the following steps: Step 1: Vinyl bis(chlorosulfate) is added to a solvent for dissolution under nitrogen protection. After complete dissolution, anhydrous fluoride is added; Step 2: The reaction is carried out at 20 - 90 °C for 2 - 20 h; Step 3: The reaction-generated chlorides and unreacted fluorides are removed by filtration, and the reaction solution is rectified to remove the solvent to obtain vinyl bis(fluorosulfate).

2. The preparation method of vinyl bis(fluorosulfate) according to claim 1, wherein: In Step 2, the reaction temperature is 70 - 90 °C, the reaction duration is 4 - 5 h, and the molar ratio of anhydrous fluoride to vinyl bis(chlorosulfate) is 1:2 - 3.

3. The preparation method of vinyl bis(fluorosulfate) according to claim 1, wherein: The solvent is any one of acetonitrile, ethyl acetate, N,N-dimethylformamide, dichloroethane, and ethylene glycol dimethyl ether.

4. The preparation method of vinyl bis(fluorosulfate) according to claim 1, wherein: The water content in the solvent is not higher than 50 ppm.

5. The preparation method of vinyl bis(fluorosulfate) according to claim 1, wherein: The anhydrous fluoride is anhydrous potassium fluoride or anhydrous sodium fluoride.

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