A method for preparing anhydrous N,N-dimethylaminosulfonyl fluoride by a solvent-free method

Abstract

The application discloses a method for preparing anhydrous N,N-dimethylaminosulfonyl fluoride by a solvent-free method, and comprises the following steps: adding anhydrous N,N-dimethylaminosulfonyl chloride into a reaction container, adding an anhydrous phase transfer catalyst under stirring, then adding anhydrous potassium fluoride into the reaction container in batches, and carrying out a nucleophilic substitution reaction under a solvent-free condition to obtain a mixture containing N,N-dimethylaminosulfonyl fluoride; filtering the obtained mixture containing N,N-dimethylaminosulfonyl fluoride, separating out a solid by-product potassium chloride, then carrying out vacuum rectification on the filtrate, collecting a distillate, and obtaining anhydrous N,N-dimethylaminosulfonyl fluoride. The application realizes preparation of N,N-dimethylaminosulfonyl fluoride by a phase transfer catalysis one-step method under the mild conditions of anhydrous, normal pressure and solvent-free, uses cheap potassium fluoride as a fluorine source, and has the technical effects of low cost, high safety, simple post-treatment, no three wastes, and high product yield and purity.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, specifically to a solvent-free method for preparing anhydrous N,N-dimethylaminosulfonyl fluoride. Background Technology

[0002] Fluorosulfonyl imides exhibit excellent electrochemical and thermal stability due to their unique molecular structure. The sulfonyl imide group in these compounds possesses a strong electron-withdrawing effect, effectively improving the oxidative stability of the molecule. Simultaneously, the introduction of fluorine atoms enhances the bond energy of the molecular chemical bonds, further improving their oxidation resistance under high-voltage environments. Based on these properties, N,N-dimethylaminosulfonyl fluoride shows broad application prospects as a lithium-ion battery electrolyte or electrolyte additive.

[0003] Currently, the publicly disclosed synthetic methods for N,N-dimethylaminosulfonyl fluoride mainly include the following: Method 1: Sulfonyl fluoride gas is passed into a dimethylamine organic solution, followed by the addition of triethylamine to prepare the product. This method yields a high yield, but the sulfuryl fluoride gas is highly toxic, requiring high levels of equipment sealing and pressure resistance, which increases the difficulty and safety risks of industrial implementation.

[0004] Method 2: Bismuth trifluoride and N,N-dimethylaminosulfonyl chloride are reacted under inert gas protection and heated to prepare the solution. However, this method involves expensive bismuth trifluoride, resulting in high material costs, and the bismuth compound poses potential environmental risks.

[0005] Method 3: Preparation by reacting N,N-dimethylaminosulfonyl chloride with potassium fluoride in an aqueous phase. The presence of water in this method can corrode the reaction equipment, and the resulting product has a high water content, making it difficult to meet the stringent moisture requirements of lithium-ion battery electrolytes.

[0006] Method 4: Using N,N-dimethylaminosulfonyl chloride and hydrogen fluoride as raw materials, the reaction is carried out at a low temperature of -78℃ and then gradually heated to 100℃. This method involves hydrogen fluoride, a highly hazardous and toxic chemical, and the low-temperature reaction consumes a lot of energy and requires harsh operating conditions, which is not conducive to industrial production and poses a high environmental risk.

[0007] In summary, existing technologies suffer from drawbacks such as high equipment requirements, high material costs, high product moisture content, and significant safety hazards. Therefore, there is an urgent need to develop a method for preparing N,N-dimethylaminosulfonyl fluoride that is anhydrous, low-cost, high-purity, and suitable for industrial production. Summary of the Invention

[0008] To address the aforementioned technical problems, the present invention aims to provide a solvent-free method for preparing anhydrous N,N-dimethylaminosulfonyl fluoride. This invention achieves a one-step preparation of high-purity N,N-dimethylaminosulfonyl fluoride using inexpensive potassium fluoride as the fluorine source under mild, anhydrous, atmospheric pressure, and solvent-free conditions via phase transfer catalysis. This method offers advantages such as low cost, high safety, simple post-processing, no waste generation, and high product yield and purity.

[0009] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution: A solvent-free method for preparing anhydrous N,N-dimethylaminosulfonyl fluoride includes the following steps: Step (1): Add anhydrous N,N-dimethylaminosulfonyl chloride to the reaction vessel, add anhydrous phase transfer catalyst under stirring, and then add anhydrous potassium fluoride in batches. Under solvent-free conditions, carry out nucleophilic substitution reaction to obtain a mixture containing N,N-dimethylaminosulfonyl fluoride. Step (2): Filter the mixture containing N,N-dimethylaminosulfonyl fluoride obtained in step (1) to separate the solid byproduct potassium chloride. Then, distill the filtrate under reduced pressure and collect the fraction to obtain anhydrous N,N-dimethylaminosulfonyl fluoride.

[0010] In the above preparation method, N,N-dimethylaminosulfonyl chloride reacts with potassium fluoride in an anhydrous system via a nucleophilic substitution reaction, where chlorine atoms are replaced by fluorine atoms, generating the target product N,N-dimethylaminosulfonyl fluoride and potassium chloride as a byproduct. This reaction exhibits good selectivity and few impurities. After the reaction, potassium chloride precipitates as a solid, which can be separated by filtration; the filtrate is then subjected to vacuum distillation to obtain the high-purity product. This method introduces no water from raw materials and reaction to post-treatment, effectively controlling the moisture content of the product.

[0011] Preferably, the anhydrous phase transfer catalyst in step (1) is selected from at least one of quaternary ammonium salt catalysts, crown ether catalysts, or polyether catalysts. The phase transfer catalyst enhances the nucleophilic reactivity of fluoride ions in potassium fluoride, enabling the solid-liquid heterogeneous reaction to proceed smoothly under solvent-free conditions. Preferably, the quaternary ammonium salt catalyst is selected from at least one of tetrabutylammonium bromide, benzyltriethylammonium chloride, benzyltrimethylammonium chloride, and tetrabutylammonium chloride; the crown ether catalyst is selected from 18-crown-6 or 15-crown-5; and the polyether catalyst is selected from polyethylene glycol.

[0012] Furthermore, in step (1), potassium fluoride is added in batches 2 to 10 times. Batch addition helps control the reaction rate and avoids excessively high local concentrations and violent exothermic reactions caused by adding a large amount of potassium fluoride at once.

[0013] Further, in step (1), the molar ratio of N,N-dimethylaminosulfonyl chloride to potassium fluoride is 1:(1.2~1.7). Increasing the amount of potassium fluoride can improve the reaction conversion rate and reaction rate.

[0014] Furthermore, the nucleophilic substitution reaction in step (1) is carried out at a temperature of 70-120°C. Too low a temperature results in a slow reaction rate and insufficient conversion; too high a temperature may trigger side reactions. Preferably, the reaction temperature is 90-120°C.

[0015] Furthermore, the nucleophilic substitution reaction in step (1) takes 1 to 2 hours. Preferably, the reaction time is 1 hour.

[0016] Furthermore, the pressure of the vacuum distillation in step (2) is 2~8 kPa.

[0017] The beneficial effects of this invention are as follows: (1) The raw material cost is low and no waste is generated. The present invention uses potassium fluoride as the fluorine source. This raw material is widely available and inexpensive. Compared with materials such as bismuth trifluoride and hydrogen fluoride, it can reduce the production cost. At the same time, the reaction byproduct is only potassium chloride, which can be recycled. The entire process has no waste gas, waste liquid and waste residue emissions.

[0018] (2) The reaction has good safety. The reaction of the present invention is carried out under normal pressure conditions, the operating conditions are mild, the use of high pressure gas and highly toxic chemicals is avoided, there are no special requirements for the sealing and pressure resistance of the equipment, and the safety risks in the production process are reduced.

[0019] (3) The post-processing steps are relatively simple. Since no external solvent is required in the reaction system, the byproduct potassium chloride precipitates in solid form after the reaction is completed. It can be separated by filtration, eliminating the solvent recovery process. The filtrate can be distilled under reduced pressure to obtain a high-purity product. The operation process is relatively short, which helps to reduce separation energy consumption.

[0020] (4) Product moisture content can be effectively controlled. This invention does not introduce water throughout the entire process from raw materials and reaction to post-processing, eliminating the product drying step. The moisture content of the resulting product can meet the requirements for use in lithium battery electrolytes or additives. Attached Figure Description

[0021] Figure 1 This is the N,N-dimethylaminosulfonyl fluoride proton NMR spectrum of Example 1 of the present invention.

[0022] Figure 2 This is the N,N-dimethylaminosulfonyl fluoride NMR fluorine spectrum of Example 1 of the present invention. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. 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.

[0024] This invention provides a solvent-free method for preparing anhydrous N,N-dimethylaminosulfonyl fluoride, comprising the following steps: Anhydrous N,N-dimethylaminosulfonyl chloride is added to a reaction vessel (e.g., a three-necked flask), and stirring is started. Anhydrous phase-transfer catalyst is added under stirring. After the catalyst is evenly dispersed, anhydrous potassium fluoride is added to the reaction system in batches. After the addition is complete, the reaction system is heated to the set temperature to carry out a nucleophilic substitution reaction. After the reaction is complete, a mixture containing N,N-dimethylaminosulfonyl fluoride is obtained.

[0025] The mixture was filtered to separate the solid byproduct potassium chloride. The filtrate was collected and subjected to vacuum distillation to obtain anhydrous N,N-dimethylaminosulfonyl fluoride.

[0026] For example, the anhydrous phase transfer catalyst in step (1) can be selected from one or more of quaternary ammonium salt catalysts, crown ether catalysts, or polyether catalysts. The role of the phase transfer catalyst is to enhance the nucleophilic reactivity of fluoride ions in potassium fluoride, so that the solid-liquid heterogeneous reaction can proceed smoothly under solvent-free conditions. Preferably, the quaternary ammonium salt catalyst can be selected from one or more of tetrabutylammonium bromide, benzyltriethylammonium chloride, benzyltrimethylammonium chloride, or tetrabutylammonium chloride; the crown ether catalyst can be selected from 18-crown-6 or 15-crown-5; and the polyether catalyst can be selected from polyethylene glycol. The above catalysts have good dispersibility and catalytic activity in anhydrous systems.

[0027] For example, the amount of phase transfer catalyst can be adjusted according to the reaction scale. Generally, based on the mass of the raw material N,N-dimethylaminosulfonyl chloride, an amount of 0.01% to 1% can achieve a good catalytic effect.

[0028] In step (1), potassium fluoride is added in batches, typically 2 to 10 times. Adding in batches helps control the reaction rate and avoids excessively high local concentrations and concentrated exothermic reactions caused by adding a large amount of potassium fluoride at once. Preferably, adding it in 10 batches ensures a more stable reaction process. Stirring is maintained after each addition to ensure sufficient contact between the potassium fluoride and N,N-dimethylaminosulfonyl chloride.

[0029] In step (1), the molar ratio of N,N-dimethylaminosulfonyl chloride to potassium fluoride is, for example, 1:1.2 to 1:1.7. Within this range, the amount of potassium fluoride used is sufficient to ensure the reaction conversion rate while avoiding excess and waste. Preferably, the molar ratio is 1:1.7.

[0030] In step (1), the reaction temperature for the nucleophilic substitution reaction is, for example, 70-120°C. If the temperature is too low, the reaction rate is slow and the conversion rate is insufficient; if the temperature is too high, side reactions or product decomposition may occur. Preferably, the reaction temperature is 90-120°C.

[0031] In step (1), the nucleophilic substitution reaction typically takes 1 to 2 hours. Within this time range, the reaction can proceed sufficiently, achieving a high conversion rate. Preferably, the reaction time is 1 hour.

[0032] In step (2), the pressure of vacuum distillation is exemplarily 2-8 kPa. Within this pressure range, the boiling point of N,N-dimethylaminosulfonyl fluoride is suitable, enabling effective separation from small amounts of unreacted raw materials and other impurities.

[0033] In the above preparation method, N,N-dimethylaminosulfonyl chloride reacts with potassium fluoride in an anhydrous system via a nucleophilic substitution reaction, where chlorine atoms are replaced by fluorine atoms, generating the target product N,N-dimethylaminosulfonyl fluoride and potassium chloride as a byproduct. This reaction exhibits good selectivity and few impurities. After the reaction, potassium chloride precipitates as a solid, which can be separated by filtration; the filtrate is then subjected to vacuum distillation to obtain the high-purity product. This method introduces no water from raw materials and the reaction process to post-treatment, effectively controlling the moisture content of the product.

[0034] The present invention will be further described below through specific embodiments.

[0035] The anhydrous N,N-dimethylaminosulfonyl chloride used in this invention is a commercially available product (purity ≥98%), and was not further processed before use. The moisture content of the obtained N,N-dimethylaminosulfonyl fluoride was determined by the Karl Fischer method, and the results were all below 100 ppm.

[0036] Example 1

[0037] The preparation method of this embodiment 1 includes the following steps: (1) Add 50g of N,N-dimethylaminosulfonyl chloride to a three-necked flask, start stirring, add 0.025g of tetrabutylammonium bromide, and then add 34.35g of potassium fluoride in 10 portions to N,N-dimethylaminosulfonyl chloride. During the batch addition process, the reaction temperature is controlled at 120℃. After the reaction is completed in 1 hour, a mixture containing N,N-dimethylaminosulfonyl fluoride is obtained. (2) The mixture containing N,N-dimethylaminosulfonyl fluoride was filtered to separate the solid, and then the filtrate was subjected to vacuum distillation to obtain 35.12 g of the target product; the structure of the obtained product was confirmed by 1H NMR and fluorine NMR (spectroscopy, see below). Figure 1 , Figure 2 ).

[0038] According to gas chromatography analysis and calculation, the yield of N,N-dimethylaminosulfonyl fluoride was 79.3%, and the purity was 99%.

[0039] Example 2

[0040] The preparation method of this Example 2 includes the following steps: (1) Add 50g of N,N-dimethylaminosulfonyl chloride to a three-necked flask, start stirring, add 0.025g of benzyltriethylammonium chloride, and then add 34.35g of potassium fluoride to N,N-dimethylaminosulfonyl chloride in 5 portions. During the batch addition process, the reaction temperature is controlled at 120℃. After the reaction is completed in 1 hour, a mixture containing N,N-dimethylaminosulfonyl fluoride is obtained. (2) The mixture containing N,N-dimethylaminosulfonyl fluoride was filtered to separate the solid, and then the filtrate was subjected to vacuum distillation to obtain 34g of the target product.

[0041] According to gas chromatography analysis and calculation, the yield of N,N-dimethylaminosulfonyl fluoride was 76.8%, and the purity was 98.1%.

[0042] Example 3

[0043] The preparation method of this embodiment 3 includes the following steps: (1) Add 50g of N,N-dimethylaminosulfonyl chloride to a three-necked flask, start stirring, add 0.025g of tetrabutylammonium chloride, and then add 31.18g of potassium fluoride in 10 portions to N,N-dimethylaminosulfonyl chloride. During the batch addition process, the reaction temperature is controlled at 120℃. After the reaction is completed in 1 hour, a mixture containing N,N-dimethylaminosulfonyl fluoride is obtained. (2) The mixture containing N,N-dimethylaminosulfonyl fluoride was filtered to separate the solid, and then the filtrate was subjected to vacuum distillation to obtain 33.46 g of the target product.

[0044] According to gas chromatography analysis and calculation, the yield of N,N-dimethylaminosulfonyl fluoride was 75.6%, and the purity was 99%.

[0045] Example 4

[0046] The preparation method of this Example 4 includes the following steps: (1) Add 50g of N,N-dimethylaminosulfonyl chloride to a three-necked flask, start stirring, add 0.025g of tetrabutylammonium chloride, and then add 34.35g of potassium fluoride in 10 portions to N,N-dimethylaminosulfonyl chloride. During the batch addition process, the reaction temperature is controlled at 90℃. After the reaction is completed in 1 hour, a mixture containing N,N-dimethylaminosulfonyl fluoride is obtained. (2) The mixture containing N,N-dimethylaminosulfonyl fluoride was filtered to separate the solid, and then the filtrate was subjected to vacuum distillation to obtain 34.13g of the target product.

[0047] According to gas chromatography analysis and calculation, the yield of N,N-dimethylaminosulfonyl fluoride was 77.1%, and the purity was 97.6%.

[0048] Example 5

[0049] The preparation method of this embodiment 5 includes the following steps: (1) Add 50g of N,N-dimethylaminosulfonyl chloride to a three-necked flask, start stirring, add 0.025g of benzyltrimethylammonium chloride, and then add 34.35g of potassium fluoride in 10 portions to N,N-dimethylaminosulfonyl chloride. During the batch addition process, the reaction temperature is controlled at 120℃. After the reaction is completed for 2 hours, a mixture containing N,N-dimethylaminosulfonyl fluoride is obtained. (2) The mixture containing N,N-dimethylaminosulfonyl fluoride was filtered to separate the solid, and then the filtrate was subjected to vacuum distillation to obtain 33.91g of the target product.

[0050] According to gas chromatography analysis and calculation, the yield of N,N-dimethylaminosulfonyl fluoride was 76.7%, and the purity was 96.1%.

[0051] Comparative Example 1 The preparation method of Comparative Example 1 includes the following steps: (1) Add 50g of N,N-dimethylaminosulfonyl chloride to a three-necked flask, add ethyl acetate as solvent, start stirring, add 0.025g of tetrabutylammonium bromide, and then add 34.35g of potassium fluoride in 10 portions to N,N-dimethylaminosulfonyl chloride. During the batch addition process, the reaction temperature is controlled at 80℃. After the reaction is completed for 3 hours, a mixed solution containing N,N-dimethylaminosulfonyl fluoride is obtained. (2) The above mixed solution was filtered to separate the solid, and then the filtrate was subjected to vacuum distillation to recover ethyl acetate and obtain 33.21g of the target product.

[0052] According to gas chromatography analysis and calculation, the yield of N,N-dimethylaminosulfonyl fluoride was 75.13%, and the purity was 95%.

[0053] Comparing Comparative Example 1 with the Example, the results show that after introducing the solvent, the product yield and purity are both lower than those of Example 1 (yield 79.3%, purity 99%) using the solvent-free method of the present invention. Furthermore, the addition of a solvent recovery step makes the post-processing more complex, demonstrating the superiority of the solvent-free method of the present invention.

[0054] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0055] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A solvent-free method for preparing anhydrous N,N-dimethylaminosulfonyl fluoride, characterized in that, Includes the following steps: Step (1): Add anhydrous N,N-dimethylaminosulfonyl chloride to the reaction vessel, add anhydrous phase transfer catalyst under stirring, and then add anhydrous potassium fluoride in batches. Under solvent-free conditions, carry out nucleophilic substitution reaction to obtain a mixture containing N,N-dimethylaminosulfonyl fluoride. Step (2): Filter the mixture containing N,N-dimethylaminosulfonyl fluoride obtained in step (1) to separate the solid byproduct potassium chloride. Then, distill the filtrate under reduced pressure and collect the fraction to obtain anhydrous N,N-dimethylaminosulfonyl fluoride.

2. The method according to claim 1, characterized in that, The anhydrous phase transfer catalyst mentioned in step (1) is selected from at least one of quaternary ammonium salt catalysts, crown ether catalysts, or polyether catalysts.

3. The method according to claim 2, characterized in that, The quaternary ammonium salt catalyst is selected from at least one of tetrabutylammonium bromide, benzyltriethylammonium chloride, benzyltrimethylammonium chloride, and tetrabutylammonium chloride; the crown ether catalyst is selected from 18-crown-6 or 15-crown-5; and the polyether catalyst is selected from polyethylene glycol.

4. The method according to claim 1, characterized in that, In step (1), potassium fluoride is added in batches 2 to 10 times.

5. The method according to claim 1, characterized in that, In step (1), the molar ratio of N,N-dimethylaminosulfonyl chloride to potassium fluoride is 1:(1.2~1.7).

6. The method according to claim 1, characterized in that, The reaction temperature for the nucleophilic substitution reaction described in step (1) is 70~120℃.

7. The method according to claim 1, characterized in that, The reaction time for the nucleophilic substitution reaction described in step (1) is 1 to 2 hours.

8. The method according to claim 1, characterized in that, In step (1), the reaction temperature is 90~120℃ and the reaction time is 1 hour.

9. The method according to claim 1, characterized in that, The pressure of vacuum distillation in step (2) is 2~8 kPa.

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