A method for synthesizing a bisfluorosulfimide

Abstract

The application provides a synthesis method of difluorosulfimide. The method comprises the following steps: under nitrogen protection, fluorosulfonic acid, aminosulfonic acid and a catalyst are added into a reaction container, stirring is performed, and the temperature is raised to a reaction temperature; then sulfuryl fluoride is introduced, and the reaction is kept under temperature while the sulfuryl fluoride is introduced; after the reaction is completed, the difluorosulfimide is obtained through rectification. The method is simple in process, can quickly and efficiently synthesize difluorosulfimide, and the obtained difluorosulfimide has high yield and high purity.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of fluorinated chemicals and chemical synthesis, and particularly relates to a synthesis method of difluorosulfonyl imide. BACKGROUND

[0002] Difluorosulfonyl imide lithium has the advantages of high conductivity, high thermal stability, excellent low-temperature resistance and good hydrolytic stability, and is the best choice to replace lithium hexafluorophosphate at present. Difluorosulfonyl imide is an important raw material for synthesizing difluorosulfonyl imide lithium.

[0003] At present, the most commonly used synthesis method of difluorosulfonyl imide is a two-step method, also known as the chlorosulfonic acid method. The first step is to synthesize dichlorosulfonyl imide acid by using chlorosulfonic acid, chlorosulfonyl isocyanate and sulfamic acid. The second step is to synthesize difluorosulfonyl imide acid by using dichlorosulfonyl imide acid and a fluorinating agent (mainly hydrogen fluoride, and also a fluorine-containing salt). The reaction route is shown below. However, the above method has problems of long process, many by-products and high cost.

[0004]

[0005] In addition, there are other reports on the synthesis method of difluorosulfonyl imide, mainly including the following methods: (1) first, dichlorosulfonyl imide acid is synthesized by using chlorosulfonic acid and chlorosulfonyl isocyanate; then, difluorosulfonyl imide acid is synthesized by using dichlorosulfonyl imide acid and a fluorinating agent (mainly hydrogen fluoride, and also a fluorine-containing salt); (2) difluorosulfonyl imide acid is synthesized by using fluorosulfonic acid and urea; (3) difluorosulfonyl imide acid is synthesized by using fluorosulfonic acid and fluorosulfonyl isocyanate. However, the above methods all have problems of too long reaction time and high cost. Therefore, it is of great social significance and economic value to develop a method for rapidly and efficiently synthesizing difluorosulfonyl imide.

[0006] Therefore, it is of greater social significance and higher economic value to develop a method for rapidly and efficiently synthesizing difluorosulfonyl imide with high conversion rate and simple process. For this purpose, the present application is proposed. SUMMARY

[0007] In view of the deficiencies of the prior art, the present application provides a synthesis method of difluorosulfonyl imide. The method of the present application can rapidly and efficiently synthesize difluorosulfonyl imide, and the obtained difluorosulfonyl imide has high yield and high purity.

[0008] The technical scheme of the present application is as follows:

[0009] A synthesis method of difluorosulfonyl imide comprises the following steps:

[0010] Under the protection of nitrogen, fluorosulfonic acid, aminosulfonic acid, a catalyst are added into a reaction container, and stirred to be heated to a reaction temperature, and then heated and stirred; after that, sulfuryl fluoride is introduced, and heated and reacted while the sulfuryl fluoride is being introduced; after the reaction is completed, distillation is performed to obtain difluorosulfonyl imide.

[0011] According to the application, the molar ratio of the fluorosulfonic acid, the aminosulfonic acid and the sulfuryl fluoride is 1:1:5-10.

[0012] According to the application, the catalyst is one or a combination of two or more of cuprous iodide, chromium fluoride, cesium fluoride, Raney nickel and iron acetylacetonate, and is further preferably chromium fluoride and / or cesium fluoride, and more preferably a combination of chromium fluoride and cesium fluoride, and the molar ratio of the chromium fluoride and the cesium fluoride in the combination is 1:1.

[0013] According to the application, the molar number of the catalyst is 0.5-5% of the molar number of the aminosulfonic acid.

[0014] According to the application, the reaction temperature is 100-165℃, and the time for heating and stirring before the introduction of the sulfuryl fluoride is 1-3 hours.

[0015] According to the application, the time for the introduction of the sulfuryl fluoride is controlled to be 5-12 hours.

[0016] According to the application, the pressure for the distillation is 4-6kPa, and the temperature is 90-110℃.

[0017] The reaction route of the application is shown as follows:

[0018]

[0019] The technical features and advantages of the application are as follows:

[0020] 1. The synthesis method of difluorosulfonyl imide of the application is a one-step reaction, and the process is simple, the synthesis method is more efficient, and the yield and purity of the obtained difluorosulfonyl imide are high.

[0021] 2. The synthesis method of difluorosulfonyl imide of the application uses a specific type of catalyst for catalysis, so that the reaction condition is more mild, the reaction time is shortened, the reaction efficiency is improved, the generation of by-products is reduced, the impurities are less, the cost is reduced, and especially after the addition of the catalyst in the synthesis step, the reaction can reach a higher conversion rate in a short time, and the yield and purity of the obtained difluorosulfonyl imide are greatly improved. DETAILED DESCRIPTION

[0022] The application will be further described in conjunction with specific embodiments, but the application is not limited to these specific embodiments. Those skilled in the art should recognize that the application encompasses all alternatives, modifications and equivalents within the scope of the claims.

[0023] Example 1

[0024] A method for synthesizing a bis-fluorosulfone imide comprises the following steps:

[0025] Under nitrogen protection, fluorosulfonic acid is added to a dry polytetrafluoroethylene four-neck flask, stirring is started, then an equal molar amount of sulfamic acid to the fluorosulfonic acid is added, a catalyst cuprous iodide is added, the molar amount of cuprous iodide is 1% of the molar amount of sulfamic acid, the temperature is raised to 120°C, and the mixture is stirred for 1 hour; then the slow introduction of sulfuryl fluoride gas is started, the total molar amount of sulfuryl fluoride gas introduced is 5 times the molar amount of sulfamic acid, the flow rate is controlled so that the introduction time is controlled to be 5 hours, and the reaction is carried out at 120°C while the sulfuryl fluoride is being introduced; the entire synthesis process is carried out under nitrogen protection; after the reaction is completed, the material is transferred to a rectification device, and the fraction with a temperature of 90-110°C is collected under a pressure of 5 kPa to obtain the bis-fluorosulfone imide.

[0026] Example 2

[0027] A method for synthesizing a bis-fluorosulfone imide comprises the following steps:

[0028] Under nitrogen protection, fluorosulfonic acid is added to a dry polytetrafluoroethylene four-neck flask, stirring is started, then an equal molar amount of sulfamic acid to the fluorosulfonic acid is added, a catalyst cuprous iodide is added, the molar amount of cuprous iodide is 1% of the molar amount of sulfamic acid, the temperature is raised to 120°C, and the mixture is stirred for 1 hour; then the slow introduction of sulfuryl fluoride gas is started, the total molar amount of sulfuryl fluoride gas introduced is 5 times the molar amount of sulfamic acid, the flow rate is controlled so that the introduction time is controlled to be 5 hours, and the reaction is carried out at 120°C while the sulfuryl fluoride is being introduced; the entire synthesis process is carried out under nitrogen protection; after the reaction is completed, the material is transferred to a rectification device, and the fraction with a temperature of 90-110°C is collected under a pressure of 5 kPa to obtain the bis-fluorosulfone imide.

[0029] Example 3

[0030] A method for synthesizing a bis-fluorosulfone imide comprises the following steps:

[0031] Under the protection of nitrogen, fluorosulfonic acid is added into a dry polytetrafluoroethylene four-neck flask, stirring is started, then an equimolar amount of sulfamic acid is added, and a catalyst, acetylacetone iron, is added, the molar amount of acetylacetone iron being 1% of the molar amount of sulfamic acid, the temperature is raised to 120°C, and the mixture is stirred for 1 hour; then the slow introduction of sulfuryl fluoride gas is started, the total molar amount of sulfuryl fluoride gas introduced being 5 times the molar amount of sulfamic acid, the flow rate is controlled so that the introduction time is controlled to be 5 hours, and the reaction is carried out at 120°C while the sulfuryl fluoride is being introduced; the entire synthesis process is carried out under the protection of nitrogen; after the reaction is completed, the material is transferred to a rectification device, and the fraction collected at 90-110°C under a pressure of 5 kPa is the difluorosulfurylimide.

[0032] Example 4

[0033] A method for synthesizing difluorosulfurylimide, comprising the following steps:

[0034] Under the protection of nitrogen, fluorosulfonic acid is added into a dry polytetrafluoroethylene four-neck flask, stirring is started, then an equimolar amount of sulfamic acid is added, and a catalyst, chromium fluoride, is added, the molar amount of chromium fluoride being 1% of the molar amount of sulfamic acid, the temperature is raised to 120°C, and the mixture is stirred for 1 hour; then the slow introduction of sulfuryl fluoride gas is started, the total molar amount of sulfuryl fluoride gas introduced being 5 times the molar amount of sulfamic acid, the flow rate is controlled so that the introduction time is controlled to be 5 hours, and the reaction is carried out at 120°C while the sulfuryl fluoride is being introduced; the entire synthesis process is carried out under the protection of nitrogen; after the reaction is completed, the material is transferred to a rectification device, and the fraction collected at 100°C under a pressure of 5 kPa is the difluorosulfurylimide.

[0035] Example 5

[0036] A method for synthesizing difluorosulfurylimide, comprising the following steps:

[0037] Under the protection of nitrogen, fluorosulfonic acid is added into a dry polytetrafluoroethylene four-neck flask, stirring is started, then an equimolar amount of sulfamic acid is added, and a catalyst, cesium fluoride, is added, the molar amount of cesium fluoride being 1% of the molar amount of sulfamic acid, the temperature is raised to 120°C, and the mixture is stirred for 1 hour; then the slow introduction of sulfuryl fluoride gas is started, the total molar amount of sulfuryl fluoride gas introduced being 5 times the molar amount of sulfamic acid, the flow rate is controlled so that the introduction time is controlled to be 5 hours, and the reaction is carried out at 120°C while the sulfuryl fluoride is being introduced; the entire synthesis process is carried out under the protection of nitrogen; after the reaction is completed, the material is transferred to a rectification device, and the fraction collected at 90-110°C under a pressure of 5 kPa is the difluorosulfurylimide.

[0038] Example 6

[0039] A method for synthesizing difluorosulfurylimide, comprising the following steps:

[0040] Under nitrogen protection, fluorosulfonic acid was added into a dry polytetrafluoroethylene four-neck flask, stirring was started, then an equimolar amount of sulfamic acid was added, followed by the addition of a catalyst composed of chromium fluoride and cesium fluoride (molar ratio of chromium fluoride to cesium fluoride in the composition was 1:1), the molar amount of the catalyst was 1% of the molar amount of sulfamic acid, the temperature was raised to 120°C, and the mixture was stirred for 1 hour; then the slow introduction of sulfuryl fluoride gas was started, the total molar amount of sulfuryl fluoride gas introduced was 5 times the molar amount of sulfamic acid, the flow rate was controlled so that the introduction time was controlled to be 5 hours, and the reaction was carried out at 120°C while the sulfuryl fluoride was being introduced; the entire synthesis process was carried out under nitrogen protection; after the reaction was completed, the material was transferred to a rectification device, and the fraction with a boiling point of 90-110°C was collected under a pressure of 5 kPa to obtain bis-fluorosulfonylimide.

[0041] Example 7

[0042] A method for synthesizing bis-fluorosulfonylimide was as described in Example 6, except that the molar amount of the catalyst was 3% of the molar amount of sulfamic acid.

[0043] Example 8

[0044] A method for synthesizing bis-fluorosulfonylimide was as described in Example 6, except that the total molar amount of sulfuryl fluoride gas introduced was 7 times the molar amount of sulfamic acid.

[0045] Example 9

[0046] A method for synthesizing bis-fluorosulfonylimide was as described in Example 6, except that the introduction time of sulfuryl fluoride gas was controlled to be 8 hours.

[0047] Comparative Example 1

[0048] Bis-fluorosulfonylimide was synthesized by using the most commonly used two-step synthesis method, i.e., the chlorosulfonic acid method, and the specific steps were as follows:

[0049] (1) Under nitrogen protection, sulfamic acid and thionyl chloride (molar ratio was 1:3) were sequentially added into a dry polytetrafluoroethylene four-neck flask, stirring was started, the temperature was controlled to be 60°C, and the mixture was stirred for 2 hours to ensure that the sulfamic acid and thionyl chloride were completely miscible. Then the temperature was gradually raised to 100°C, and chlorosulfonic acid was started to be added dropwise, the dropwise addition time was 6 hours, and the mixture was stirred for 24 hours after the dropwise addition of chlorosulfonic acid was completed; finally, bis-chlorosulfonylimide was distilled out by vacuumizing to 5 kPa and heating to 100°C.

[0050] (2) Under nitrogen protection, dichlorosulfimide was added into a dry polytetrafluoroethylene four-neck flask, and stirring was started. The reaction temperature was 60°C, the operation pressure was 0.5 MPa, and excess HF gas was introduced for fluorination reflux reaction for 8 hours. After the reaction was completed, the material was continuously heated to reflux to remove the residual HF. Since HF and bisfluorosulfimide acid form an azeotrope, the residual HF is not easy to remove, and needs to be removed twice. The first removal temperature was 80°C, and the time was 6 hours. The second removal temperature was 100°C, and the time was 4 hours. Finally, bisfluorosulfimide was obtained.

[0051] Comparative Example 2

[0052] A method for synthesizing bisfluorosulfimide is as described in Example 6, except that no catalyst is added.

[0053] Comparative Example 3

[0054] A method for synthesizing bisfluorosulfimide is as described in Example 6, except that the catalyst is bismuth trifluoride.

[0055] Comparative Example 4

[0056] A method for synthesizing bisfluorosulfimide is as described in Example 6, except that the catalyst is chromium oxide.

[0057] Comparative Example 5

[0058] A method for synthesizing bisfluorosulfimide is as described in Example 6, except that the catalyst is aluminum fluoride.

[0059] Comparative Example 6

[0060] A method for synthesizing bisfluorosulfimide is as described in Example 6, except that the catalyst is antimony trifluoride.

[0061] Conversion rate comparison of examples and comparative examples

[0062] The purity of bisfluorosulfimide is tested by potentiometric titration.

[0063] The calculation method of conversion rate is as follows: taking the mass fraction of sulfamic acid as the basis, and taking the percentage of the actual obtained mass fraction of bisfluorosulfimide in the theoretical mass fraction of bisfluorosulfimide as the conversion rate. The comparison data are shown in Table 1.

[0064] Table 1

[0065] Item Purity % Conversion % Reaction time h Example 1 97.6 93.1 6 Example 2 97.8 92.6 6 Example 3 97.4 93.4 6 Example 4 98.2 93.2 6 Example 5 97.9 93.6 6 Example 6 97.6 94.2 6 Example 7 97.8 94.5 6 Example 8 98.0 94.6 6 Example 9 97.9 94.5 9 Comparative Example 1 97.0 90.2 50 Comparative Example 2 97.1 85.6 6 Comparative Example 3 97.4 90.4 6 Comparative Example 4 97.0 91.6 6 Comparative Example 5 97.2 90.6 6 Comparative Example 6 97.4 90.5 6

[0066] Note: The reaction time includes the holding time before the introduction of sulfuryl fluoride, but does not include the rectification time.

[0067] From the final test result data: the conversion rate of the product in the comparative example 1 is greatly lower, and the production efficiency is greatly reduced due to the long time consumption; from the comparison between the comparative example 2 and the examples, it can be seen that the conversion rate of the product is the lowest without adding the catalyst, which indicates that the catalyst has a positive effect on improving the conversion rate of the product; from the comparison between the comparative examples 3-6 and the examples, it can be seen that the catalyst selected in the application has a better effect on improving the conversion rate of the product than other types of catalysts. From the data of the examples 1-9, it can be seen that the fluorine-containing catalyst (chromium fluoride and cesium fluoride) is more effective than other catalysts (cuprous iodide, Raney nickel and iron acetylacetonate) in improving the conversion rate of the product, and the combination of the chromium fluoride and the cesium fluoride catalyst has a more obvious effect on improving the conversion rate of the product; meanwhile, increasing the amount of the catalyst can improve the conversion rate. However, excessively increasing the amount of the sulfuryl fluoride gas and excessively slowing down the feeding rate cannot greatly improve the purity and the conversion rate of the product, and the catalyst selection, the amount of the catalyst, the amount of the sulfuryl fluoride gas and the feeding rate need to be further adjusted in consideration of the comprehensive cost.

Claims

1. A method for synthesizing difluorosulfonylimide, comprising the following steps: Under nitrogen protection, fluorosulfonic acid, aminosulfonic acid, and catalyst were added to the reaction vessel, stirred and heated to the reaction temperature, and kept at the temperature while stirring. Then, sulfuryl fluoride was introduced while keeping the temperature constant. After the reaction was completed, distillation was performed to obtain difluorosulfonyl imide. The molar ratio of fluorosulfonic acid, aminosulfonic acid, and sulfuryl fluoride is 1:1:5~10; the catalyst is one or a combination of two or more of cuprous iodide, chromium fluoride, cesium fluoride, Raney nickel, and iron acetylacetonate.

2. The method for synthesizing difluorosulfonylimide according to claim 1, characterized in that, The catalyst is chromium fluoride and / or cesium fluoride.

3. The method for synthesizing difluorosulfonylimide according to claim 1, characterized in that, The catalyst is a composition of chromium fluoride and cesium fluoride, wherein the molar ratio of chromium fluoride to cesium fluoride in the composition is 1:

1.

4. The method for synthesizing difluorosulfonylimide according to claim 1, characterized in that, The number of moles of the catalyst is 0.5 to 5% of the number of moles of aminosulfonic acid.

5. The method for synthesizing difluorosulfonylimide according to claim 1, characterized in that, The reaction temperature is 100~165℃, and the stirring time before introducing sulfuryl fluoride is 1~3 hours.

6. The method for synthesizing difluorosulfonylimide according to claim 1, characterized in that, The time for introducing sulfuryl fluoride should be controlled between 5 and 12 hours.

7. The method for synthesizing difluorosulfonylimide according to claim 1, characterized in that, The distillation process is carried out at a pressure of 4-6 kPa and a temperature of 90-110℃.

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