A two-step method for preparing high-purity methylsulfonyl fluoride

Abstract

The present invention relates to the field of fine chemical technology, and in particular to a method for preparing high-purity methyl sulfonyl fluoride by a two-step method, comprising the steps of: sequentially adding methyl sulfonyl chloride and anhydrous metal fluoride into a reactor, then adding anhydrous methyl sulfonyl fluoride as a dispersant to react to obtain a reaction product; vacuum filtering the reaction product to obtain a reaction solution, slowly adding the reaction solution to a fixed bed packed column filled with anhydrous metal fluoride solid particles, heating the fixed bed packed column, and discharging the resulting product as high-purity methyl sulfonyl fluoride. The beneficial effect of the present invention is that the present invention adopts an anhydrous system two-step method to prepare methyl sulfonyl fluoride. The method is further reacted under anhydrous conditions in combination with a fixed bed reactor, which can shorten the fluorination reaction time to a certain extent, improve the reaction efficiency, and obtain a higher purity methyl sulfonyl fluoride product.

Description

Technical Field

[0001] The present invention relates to the technical field of fine chemicals, and in particular to a two-step method for preparing high-purity methylsulfonyl fluoride. Background Art

[0002] Trifluoromethanesulfonic acid is an organic superacid widely used in the pharmaceutical, chemical, materials, electronics, and electroplating industries. It is also one of the main raw materials for the preparation of lithium trifluoromethanesulfonate and lithium bis(trifluoromethanesulfonyl)imide, both of which are important raw materials for lithium battery electrolytes.

[0003] Trifluoromethanesulfonic acid is generally prepared from methylsulfonyl fluoride through processes such as electrofluorination and inorganic acid acidification. Methanesulfonyl fluoride is the main raw material for the preparation of trifluoromethanesulfonic acid. Currently, the main method for preparing methylsulfonyl fluoride is the hydrolysis and fluorination of methylsulfonyl chloride in an aqueous solution of a fluorinating agent such as potassium fluoride or sodium fluoride.

[0004]

[0005] This method has the advantages of simple process and fast reaction speed; however, it also has the problem of hydrolysis side reactions of acyl chloride and acyl fluoride, resulting in low yield and environmental pollution.

[0006] At present, the reaction yield of hydrolytic fluorination is generally less than 95%. At the same time, the water in the product needs to be removed to meet the water requirements of subsequent electrolytic fluorination and other operations. The wastewater discharged during the separation process will also have adverse effects on the environment.

[0007] The use of an anhydrous system can increase the reaction yield to over 99%, but at the same time there are problems of long reaction time and low overall efficiency. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a two-step method for preparing high-purity methylsulfonyl fluoride, which can shorten the fluorination reaction time, improve the reaction efficiency and obtain a methylsulfonyl fluoride product with higher purity.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is: providing a two-step method for preparing high-purity methylsulfonyl fluoride, comprising the following steps: sequentially adding methylsulfonyl chloride and anhydrous metal fluoride into a reactor, wherein the molar ratio of the anhydrous metal fluoride to methylsulfonyl chloride is (1.1-1.3):1; the water content of the methylsulfonyl chloride is: 280-500 ppm;

[0010] Anhydrous methylsulfonyl fluoride is then added as a dispersant for reaction, wherein the molar ratio of the anhydrous methylsulfonyl fluoride to methylsulfonyl chloride is (0.8-1):1; after stirring and fully dispersing the materials, the temperature of the reaction system is raised to 70-100° C. and kept at this temperature for reaction for 5-6 hours to obtain a reaction product, wherein the conversion rate of methylsulfonyl chloride of the obtained reaction product is ≥90%;

[0011] The reaction product is vacuum filtered to obtain a reaction liquid, which is slowly added to a fixed bed packed column filled with anhydrous metal fluoride solid particles. The fixed bed packed column is heated (the fixed bed packed column is equipped with a heating device to control the fixed bed temperature), and the product obtained by discharging is high-purity methylsulfonyl fluoride.

[0012] Furthermore, in the above two-step method for preparing high-purity methylsulfonyl fluoride, the discharge rate of the discharge material is 1 g / min.

[0013] Furthermore, in the above two-step method for preparing high-purity methylsulfonyl fluoride, the heating temperature of the fixed bed packed column is 30-50°C.

[0014] Furthermore, in the above two-step method for preparing high-purity methylsulfonyl fluoride, the anhydrous metal fluoride is potassium fluoride, sodium fluoride or cesium fluoride.

[0015] Furthermore, in the above two-step method for preparing high-purity methylsulfonyl fluoride, the anhydrous metal fluoride is potassium fluoride, and the potassium fluoride is in powder, spherical or cylindrical form.

[0016] Furthermore, in the above two-step method for preparing high-purity methylsulfonyl fluoride, the water content of the methylsulfonyl chloride is 280 ppm.

[0017] Furthermore, in the above two-step method for preparing high-purity methylsulfonyl fluoride, the stirring speed is 300-500 rpm.

[0018] Furthermore, in the above two-step method for preparing high-purity methylsulfonyl fluoride, the stirring speed is 400 rpm.

[0019] The present invention has the beneficial effect of preparing methylsulfonyl fluoride using a two-step anhydrous process. This process, through reaction under anhydrous conditions and further reaction in a fixed-bed reactor, can shorten the fluorination reaction time to a certain extent, improve reaction efficiency, and simultaneously produce a methylsulfonyl fluoride product of higher purity. The method uses methylsulfonyl chloride as a raw material. At a relatively high temperature, methylsulfonyl chloride reacts directly with the metal fluoride without the need for a solvent to dissolve the metal fluoride. A dispersant (methylsulfonyl fluoride) is added to adjust the viscosity of the system to avoid excessive concentration of the reaction product, which can lead to problems such as system viscosity, uneven reaction, and intense localized reactions. The present invention can control the fixed-bed temperature. The discharge rate is controlled by a discharge control valve at the lower end of the packed column to control the residence time of the reaction liquid in the packed column. The discharged product undergoes gas phase testing, requiring a product content of ≥99.9%. Specifically, the present invention uses a two-step reaction. Since it is an anhydrous system, methylsulfonyl chloride, metal fluoride (potassium fluoride), and methylsulfonyl fluoride as a dispersant would generate severe heat during the reaction if reacted in batches alone. KCl would be produced after the reaction and coated on the surface of KF, causing KF inactivation. A continuous reaction would not be able to disperse the materials in the initial stage. This batch reaction + fixed bed combination achieves a conversion of 95-97% in the batch reaction before transferring to the fixed bed. Because the reaction products are continuously withdrawn from the fixed bed, the reaction can be driven forward, resulting in a high purity final product and a faster overall reaction. DETAILED DESCRIPTION

[0020] To explain the technical content, achieved objectives and effects of the present invention in detail, the following describes them in conjunction with the implementation methods.

[0021] The key concept of the present invention is that the present invention proposes a method for preparing methylsulfonyl fluoride in an anhydrous manner. The prior art generally believes that methylsulfonyl fluoride is obtained by mixing a metal fluoride, such as potassium fluoride (KF), with methylsulfonyl chloride and then reacting the mixture in the presence of a solvent, such as water. JP1993005524 also believes that the undissolved portion of the metal fluoride does not react with the methylsulfonyl chloride and proposes increasing the amount of water added to the reaction system to complete the reaction between the metal fluoride and the methylsulfonyl chloride in a short time. However, the inventors have discovered that at higher temperatures, methylsulfonyl chloride can react directly with the metal fluoride without the need for a solvent to dissolve the metal fluoride. Furthermore, the simultaneous addition of methylsulfonyl fluoride can effectively control the reaction process and avoid problems such as excessive local reactions.

[0022] The system of the present application is anhydrous and does not have the problem of hydrolysis. Anhydrous methylsulfonyl fluoride can be added as a dispersant. Because the reaction product methylsulfonyl chloride is liquid and anhydrous potassium fluoride is a solid powder, the reaction system cannot be fully dispersed and becomes viscous, resulting in a rapid termination of the reaction. The addition of methylsulfonyl fluoride, on the one hand, acts as a dispersant to adjust the viscosity of the system, and on the other hand, it is itself a product and does not need to be separated after the reaction.

[0023] The present invention has the following advantages: 1. It greatly reduces the three wastes generated in the reaction. The method is an anhydrous reaction and does not generate wastewater. When methylsulfonyl fluoride is selected as the dispersant, it can be reused, thereby improving environmental benefits and reducing production costs. 2. It solves the problem of acyl chloride and acyl fluoride hydrolysis side reactions in traditional hydrolysis fluorination reactions. 3. Under anhydrous conditions, the reaction activity of metal fluorides is high, which can improve reaction efficiency and raw material utilization. The conversion rate of raw material methylsulfonyl chloride can reach more than 99.7%. 4. Different from traditional homogeneous reactions, the present method is a solid-liquid reaction, which is convenient for introducing fixed bed and other reaction equipment for continuous production, and is suitable for the industrial preparation of methylsulfonyl fluoride.

[0024] Example 1:

[0025] A two-step method for preparing high-purity methylsulfonyl fluoride comprises the following steps:

[0026] To a 1L three-necked flask, add 300g of methylsulfonyl chloride (water content 280ppm) and then 166.4g of anhydrous potassium fluoride. After the potassium fluoride is added, add 240g of anhydrous methylsulfonyl fluoride as a dispersant. Stirring is initiated and gradually increased to 400rpm. Once the materials are fully dispersed, the temperature of the reaction system is raised to 70°C and maintained for 5 hours. After completion of the reaction, a reaction mixture 1 is obtained. GC analysis of the reaction mixture reveals a methylsulfonyl chloride content of 90.9%.

[0027] The reaction mixture 1 was vacuum filtered to obtain a liquid phase. This phase was then slowly added to a fixed-bed column filled with potassium fluoride solid powder particles. The fixed-bed heating temperature was set between 30°C and 50°C. When the column began to discharge material, the discharge control valve was adjusted to maintain a discharge rate of approximately 1 g / min. The product content was determined by GC to be 99.93%.

[0028] Example 2:

[0029] A two-step method for preparing high-purity methylsulfonyl fluoride comprises the following steps:

[0030] To a 1L three-necked flask, add 300g of methylsulfonyl chloride (water content 280ppm) and then 196.8g of anhydrous potassium fluoride. After the potassium fluoride is added, add 240g of anhydrous methylsulfonyl fluoride as a dispersant. Stirring is initiated and gradually increased to 400rpm. Once the materials are fully dispersed, the temperature of the reaction system is raised to 100°C and maintained for 6 hours. After completion of the reaction, a reaction mixture 2 is obtained. GC analysis of the reaction mixture reveals a methylsulfonyl chloride content of 98.3%.

[0031] After vacuum filtration of the reaction mixture 2, the resulting liquid phase was slowly added to a fixed-bed column filled with potassium fluoride solid powder particles. The fixed-bed heating temperature was set at 50°C. When the column began to discharge material, the discharge control valve was adjusted to maintain a discharge rate of approximately 1 g / min. The product content was determined by GC to be 99.99%.

[0032] Example 3:

[0033] A two-step method for preparing high-purity methylsulfonyl fluoride comprises the following steps:

[0034] To a 1L three-necked flask, add 300g of methylsulfonyl chloride (water content 280ppm) and then 166.4g of anhydrous potassium fluoride. After the potassium fluoride is added, add 240g of anhydrous methylsulfonyl fluoride as a dispersant. Stirring is initiated and gradually increased to 400rpm. Once the materials are fully dispersed, the temperature of the reaction system is raised to 100°C and maintained for 6 hours. After completion of the reaction, a reaction mixture 3 is obtained. GC analysis of the reaction mixture reveals a methylsulfonyl chloride content of 93.7%.

[0035] The reaction mixture 3 was vacuum filtered to obtain a liquid phase. This phase was then slowly added to a fixed-bed column filled with potassium fluoride solid powder particles. The fixed-bed was heated to 40°C. When the column began to discharge material, the discharge control valve was adjusted to maintain a discharge rate of approximately 1 g / min. The product content was determined by GC to be 99.93%.

[0036] Example 4:

[0037] A two-step method for preparing high-purity methylsulfonyl fluoride comprises the following steps:

[0038] To a 1L three-necked flask, add 300g of methylsulfonyl chloride (water content 280ppm) and then 181.7g of anhydrous potassium fluoride. After the potassium fluoride is added, add 240g of anhydrous methylsulfonyl fluoride as a dispersant. Stirring is initiated and gradually increased to 400rpm. Once the materials are fully dispersed, the temperature of the reaction system is raised to 80°C and maintained for 5 hours. After completion of the reaction, a reaction mixture 4 is obtained. GC analysis of the reaction mixture reveals a methylsulfonyl chloride content of 95.2%.

[0039] The reaction mixture 4 was vacuum filtered to obtain a liquid phase. This phase was then slowly added to a fixed-bed column filled with potassium fluoride solid powder particles. The fixed-bed heating temperature was set at 45°C. When the column began to discharge material, the discharge control valve was adjusted to maintain a discharge rate of approximately 1 g / min. The product content was determined by GC to be 99.97%.

[0040] Example 5:

[0041] A two-step method for preparing high-purity methylsulfonyl fluoride comprises the following steps:

[0042] To a 1L three-necked flask, add 300g of methylsulfonyl chloride (water content 280ppm) and then 181.7g of anhydrous potassium fluoride. After the potassium fluoride is added, add 240g of anhydrous methylsulfonyl fluoride as a dispersant. Stirring is initiated and gradually increased to 400rpm. Once the materials are fully dispersed, the temperature of the reaction system is raised to 100°C and maintained for 6 hours. After completion of the reaction, a reaction mixture 5 is obtained. GC analysis of the reaction mixture reveals a methylsulfonyl chloride content of 97.8%.

[0043] The reaction mixture 5 was vacuum filtered to obtain a liquid phase. This phase was then slowly added to a fixed-bed column filled with potassium fluoride solid powder particles. The fixed-bed was heated to 45°C. When the column began to discharge material, the discharge control valve was adjusted to maintain a discharge rate of approximately 1 g / min. The product content was determined by GC to be 99.99%.

[0044] Example 6:

[0045] A two-step method for preparing high-purity methylsulfonyl fluoride comprises the following steps:

[0046] To a 1L three-necked flask, add 300g of methylsulfonyl chloride (water content 280ppm) and then 181.7g of anhydrous potassium fluoride. After the potassium fluoride is added, add 240g of anhydrous methylsulfonyl fluoride as a dispersant. Stirring is initiated and gradually increased to 400rpm. Once the materials are fully dispersed, the temperature of the reaction system is raised to 90°C and maintained for 4 hours. After completion of the reaction, a reaction mixture 6 is obtained. GC analysis of the reaction mixture reveals a methylsulfonyl chloride content of 95.7%.

[0047] The reaction mixture 1 was vacuum filtered to obtain a liquid phase. This phase was then slowly added to a fixed-bed column filled with potassium fluoride solid powder particles. The fixed-bed was heated to 50°C. When the column began to discharge material, the discharge control valve was adjusted to maintain a discharge rate of approximately 1 g / min. The product content was determined by GC to be 99.97%.

[0048] Comparative Example 1

[0049] A method for preparing methylsulfonyl fluoride comprises the following steps:

[0050] In a 1L three-necked flask, add 300g of methanesulfonyl chloride (water content 280ppm) and 213g of anhydrous potassium fluoride. Stirring was initiated, and the speed was gradually increased to 400rpm. The temperature of the reaction system was raised to 100°C and maintained for 8 hours. Upon completion of the reaction, the system was viscous, and the reaction system could not be fully dispersed, making product isolation difficult. The conversion rate was approximately 60%.

[0051] Comparative Example 2

[0052] A method for preparing methylsulfonyl fluoride comprises the following steps:

[0053] To a 1L three-necked flask, add 300g of methylsulfonyl chloride (water content 280ppm) and 202g of anhydrous potassium fluoride. After completion, add 230g of anhydrous methylsulfonyl fluoride to the flask. Stirring was initiated and the speed gradually increased to 400rpm. After the materials were fully dispersed, the temperature of the reaction system was raised to 60°C and maintained for 4 hours. After the reaction was complete, the material was vacuum filtered to obtain the methylsulfonyl fluoride product. In Comparative Example 2, KCl formed on the surface of the potassium fluoride (KF), deactivating it. This prevented the material from being dispersed in the initial stages of the reaction. The reaction conversion rate was 70.7%.

[0054] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A two-step method for preparing methylsulfonyl fluoride, characterized in that: The method comprises the following steps: sequentially adding methanesulfonyl chloride and anhydrous metal fluoride into a reactor, wherein the anhydrous metal fluoride is potassium fluoride, sodium fluoride or cesium fluoride; The molar ratio of the anhydrous metal fluoride to methanesulfonyl chloride is (1.1-1.3):1; the water content of the methanesulfonyl chloride is: 280-500 ppm; Anhydrous methylsulfonyl fluoride is then added as a dispersant for reaction, wherein the molar ratio of the anhydrous methylsulfonyl fluoride to methylsulfonyl chloride is (0.8-1):1; after stirring and fully dispersing the materials, the temperature of the reaction system is raised to 70-100° C. and kept at this temperature for reaction for 5-6 hours to obtain a reaction product, wherein the conversion rate of methylsulfonyl chloride of the obtained reaction product is ≥90%; The reaction product is vacuum filtered to obtain a reaction liquid, which is slowly added into a fixed bed packed column filled with anhydrous metal fluoride solid particles. The fixed bed packed column is heated, and the product obtained by discharging is methylsulfonyl fluoride.

2. The method for preparing methylsulfonyl fluoride by a two-step process according to claim 1, wherein The discharging speed of the discharging material is 1 g / min.

3. The method for preparing methylsulfonyl fluoride by a two-step process according to claim 1, wherein The heating temperature of the fixed bed packed column is 30-50°C.

4. The method for preparing methylsulfonyl fluoride by a two-step process according to claim 1, wherein The anhydrous metal fluoride is potassium fluoride, and the potassium fluoride is in the form of powder, sphere or cylinder.

5. The method for preparing methylsulfonyl fluoride by a two-step process according to claim 1, wherein The water content of the methanesulfonyl chloride was 280 ppm.

6. The method for preparing methylsulfonyl fluoride by a two-step process according to claim 1, wherein The stirring speed is 300-500 rpm.

7. The method for preparing methylsulfonyl fluoride by a two-step process according to claim 1, wherein The stirring speed is 400 rpm.

Images