Method for preparing high-purity methylsulfonyl fluoride through two-step method

Abstract

The invention relates to the technical field of fine chemical engineering, in particular to a method for preparing high-purity methylsulfonyl fluoride by a two-step method, which comprises the following steps: sequentially adding methylsulfonyl chloride and anhydrous metal fluoride into a reactor, then adding anhydrous methylsulfonyl fluoride as a dispersing agent, and reacting to obtain a reaction product; and carrying out vacuum filtration on the reaction product to obtain a reaction solution, slowly adding the reaction solution into a fixed bed packed column filled with anhydrous metal fluoride solid particles, heating the fixed bed packed column, and discharging to obtain a product, namely the high-purity methylsulfonyl fluoride. The method disclosed by the invention has the beneficial effect that the methylsulfonyl fluoride is prepared by adopting an anhydrous system two-step method. According to the method, the reaction is performed under the anhydrous condition, and the fixed bed reactor is combined for further reaction, so that the fluorination reaction time can be shortened to a certain extent, the reaction efficiency is improved, and meanwhile, a higher-purity methylsulfonyl fluoride product is obtained.

Description

Technical Field

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

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

[0003] Trifluoromethanesulfonic acid is generally prepared by electrofluorination of methylsulfonyl fluoride, acidification with inorganic acid and other processes. Methylsulfonyl fluoride is the main raw material for preparing trifluoromethanesulfonic acid. At present, the main preparation method of methylsulfonyl fluoride is to hydrolyze and fluorinate 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 hydrolysis 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 more than 99%, but at the same time there are problems such as 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 methyl sulfonyl fluoride, which can shorten the fluorination reaction time, improve the reaction efficiency and obtain a methyl sulfonyl fluoride product with higher purity.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is: to provide 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: 280-500ppm; Then, anhydrous methyl sulfonyl fluoride is added as a dispersant for reaction, wherein the molar ratio of anhydrous methyl sulfonyl fluoride to methyl sulfonyl chloride is (0.8-1):1; after stirring, the materials are fully dispersed, the temperature of the reaction system is increased to 70-100° C., and the reaction is kept warm for 5-6 hours to obtain a reaction product, wherein the conversion rate of methyl sulfonyl chloride of the obtained reaction product is ≥90%; The reaction product is vacuum filtered to obtain a reaction liquid, and the reaction liquid is slowly added into a fixed bed filling column filled with anhydrous metal fluoride solid particles. The fixed bed filling column is heated (the fixed bed filling column is provided with a heating device to control the temperature of the fixed bed), and the product obtained by discharging is high-purity methyl sulfonyl fluoride.

[0010] Furthermore, in the above two-step method for preparing high-purity methylsulfonyl fluoride, the discharge rate of the discharge material is 1 g / min.

[0011] Furthermore, in the above two-step method for preparing high-purity methylsulfonyl fluoride, the heating temperature of the fixed bed filling column is 30-50°C.

[0012] 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.

[0013] 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.

[0014] Furthermore, in the above two-step method for preparing high-purity methylsulfonyl fluoride, the water content of the methylsulfonyl chloride is 280 ppm.

[0015] Furthermore, in the above two-step method for preparing high-purity methylsulfonyl fluoride, the stirring speed is 300-500 rpm.

[0016] Furthermore, in the above two-step method for preparing high-purity methylsulfonyl fluoride, the stirring speed is 400 rpm.

[0017] The beneficial effect of the present invention is that the present invention adopts a two-step method of anhydrous system to prepare methyl sulfonyl fluoride. The method reacts under anhydrous conditions and further reacts 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 methyl sulfonyl fluoride product with higher purity. The method of the present invention uses methyl sulfonyl chloride as a raw material. At a higher temperature, methyl sulfonyl chloride can react directly with metal fluoride without solvent dissolving metal fluoride. At the same time, a dispersant (methyl sulfonyl fluoride) is added to adjust the viscosity of the system to avoid excessive concentration of the reaction product, resulting in system viscosity, uneven reaction degree, and violent local reaction. The present invention can control the fixed bed temperature. The discharge speed is controlled by the discharge control valve at the lower end of the filling column to control the residence time of the reaction liquid in the filling column. The discharge product is subjected to gas phase detection, and the product content is required to be ≥99.9%. Specifically, the present invention is divided into two steps of reaction. Since it is an anhydrous system, methylsulfonyl chloride, metal fluoride (potassium fluoride) and methylsulfonyl fluoride as a dispersant, if a single batch reaction is performed, the reaction process will generate severe heat. After the reaction, KCl will be produced and wrapped on the surface of KF, causing KF to be inactivated. The continuous reaction cannot disperse the materials in the initial stage. By adopting this batch reaction + fixed bed combination, 95-97% is converted in the batch reaction and then transferred to the fixed bed. Because the reaction products in the fixed bed are continuously extracted, the reaction can be promoted to proceed in the forward direction, the final product has high purity, and the overall reaction is faster. DETAILED DESCRIPTION

[0018] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in conjunction with the implementation modes.

[0019] The key concept of the present invention is: the present invention proposes a method for preparing methylsulfonyl fluoride without water. 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 in the presence of a solvent, such as water. JP1993005524 also believes that the undissolved part of the metal fluoride does not react with methylsulfonyl chloride, and proposes to increase the amount of water added to the reaction system so as to complete the reaction between the metal fluoride and methylsulfonyl chloride in a short time. However, the inventors found that at a higher temperature, methylsulfonyl chloride can directly react with the metal fluoride without the need for a solvent to dissolve the metal fluoride, and that the simultaneous addition of methylsulfonyl fluoride can effectively control the reaction process and avoid problems such as excessive local reaction.

[0020] The system of the present application is anhydrous and does not have the problem of hydrolysis. Anhydrous methyl sulfonyl fluoride can be added as a dispersant. Because the reaction product methyl sulfonyl chloride is liquid and anhydrous potassium fluoride is solid powder, the reaction system cannot be fully dispersed and appears viscous, resulting in a rapid termination of the reaction. Methyl sulfonyl fluoride is added, on the one hand, as a dispersant to adjust the viscosity of the system, and on the other hand, it is also a product itself and does not need to be separated after the reaction.

[0021] The invention has the following advantages: 1. The three wastes of the reaction are greatly reduced. 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. The problem of the existence of acyl chloride and acyl fluoride hydrolysis side reactions in the traditional hydrolysis fluorination reaction is solved. 3. Under anhydrous conditions, the reaction activity of metal fluorides is high, which can improve the reaction efficiency and the utilization rate of raw materials. The conversion rate of the raw material methylsulfonyl chloride can reach more than 99.7%. 4. Different from the traditional homogeneous reaction, the 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.

[0022] Example 1: A two-step method for preparing high-purity methylsulfonyl fluoride comprises the following steps: 300 g of methylsulfonyl chloride (water content 280 ppm) was added to a 1L three-necked flask, and then 166.4 g of anhydrous potassium fluoride was added thereto. After the potassium fluoride was added, 240 g of anhydrous methylsulfonyl fluoride was added to the flask as a dispersant. Stirring was started, and the stirring speed was gradually adjusted to 400 rpm. After the materials were fully dispersed, the temperature was raised to 70 ° C, and the reaction was kept warm for 5 hours. After the reaction was completed, a reaction mixture 1 was obtained. Using the GC method, the content of methylsulfonyl chloride in the liquid phase of the reaction solution was determined to be 90.9%.

[0023] The reaction mixture 1 was vacuum filtered to obtain the reaction liquid phase, and the reaction liquid was slowly added to the fixed bed packed column filled with potassium fluoride solid powder particles, and the fixed bed heating temperature was set to 30-50°C. When the packed column began to discharge, the discharge control valve was adjusted to control the discharge rate to about 1g / min. The product content was determined by GC method to be 99.93%.

[0024] Example 2: A two-step method for preparing high-purity methylsulfonyl fluoride comprises the following steps: 300 g of methylsulfonyl chloride (water content 280 ppm) was added to a 1L three-necked flask, and then 196.8 g of anhydrous potassium fluoride was added thereto. After the potassium fluoride was added, 240 g of anhydrous methylsulfonyl fluoride was added to the flask as a dispersant. Stirring was started, and the stirring speed was gradually adjusted to 400 rpm. After the materials were fully dispersed, the temperature was turned on, the temperature of the reaction system was raised to 100 ° C, and the reaction was kept warm for 6 hours. After the reaction was completed, a reaction mixture 2 was obtained. Using the GC method, the content of methylsulfonyl chloride in the liquid phase of the reaction solution was determined to be 98.3%.

[0025] The reaction mixture 2 was vacuum filtered to obtain the reaction liquid phase, and the reaction liquid was slowly added to the fixed bed filling column filled with potassium fluoride solid powder particles, and the fixed bed heating temperature was set to 50°C. When the filling column began to discharge, the discharge control valve was adjusted to control the discharge rate to about 1g / min. The product content was determined by GC method to be 99.99%.

[0026] Example 3: A two-step method for preparing high-purity methylsulfonyl fluoride comprises the following steps: 300 g of methylsulfonyl chloride (water content 280 ppm) was added to a 1L three-necked flask, and then 166.4 g of anhydrous potassium fluoride was added thereto. After the potassium fluoride was added, 240 g of anhydrous methylsulfonyl fluoride was added to the flask as a dispersant. Stirring was started, and the stirring speed was gradually adjusted to 400 rpm. After the materials were fully dispersed, the temperature was increased, the temperature of the reaction system was increased to 100 ° C, and the reaction was kept warm for 6 hours. After the reaction was completed, a reaction mixture 3 was obtained. Using the GC method, the content of methylsulfonyl chloride in the liquid phase of the reaction solution was determined to be 93.7%.

[0027] The reaction mixture 3 was vacuum filtered to obtain a reaction liquid phase, and the reaction liquid was slowly added to a fixed bed column filled with potassium fluoride solid powder particles, and the fixed bed heating temperature was set to 40°C. When the filling column began to discharge, the discharge control valve was adjusted to control the discharge rate to about 1g / min. The product content was determined by GC method to be 99.93%.

[0028] Example 4: A two-step method for preparing high-purity methylsulfonyl fluoride comprises the following steps: 300 g of methylsulfonyl chloride (water content 280 ppm) was added to a 1L three-necked flask, and then 181.7 g of anhydrous potassium fluoride was added thereto. After the potassium fluoride was added, 240 g of anhydrous methylsulfonyl fluoride was added to the flask as a dispersant. Stirring was started, and the stirring speed was gradually adjusted to 400 rpm. After the materials were fully dispersed, the temperature was raised to 80 ° C, and the reaction was kept warm for 5 hours. After the reaction was completed, a reaction mixture 4 was obtained. Using the GC method, the content of methylsulfonyl chloride in the liquid phase of the reaction solution was determined to be 95.2%.

[0029] The reaction mixture 4 was vacuum filtered to obtain a reaction liquid phase, and the reaction liquid was slowly added to a fixed bed column filled with potassium fluoride solid powder particles, and the fixed bed heating temperature was set to 45°C. When the filling column began to discharge, the discharge control valve was adjusted to control the discharge rate to about 1g / min. The product content was determined by GC method to be 99.97%.

[0030] Example 5: A two-step method for preparing high-purity methylsulfonyl fluoride comprises the following steps: 300 g of methylsulfonyl chloride (water content 280 ppm) was added to a 1L three-necked flask, and then 181.7 g of anhydrous potassium fluoride was added thereto. After the potassium fluoride was added, 240 g of anhydrous methylsulfonyl fluoride was added to the flask as a dispersant. Stirring was started, and the stirring speed was gradually adjusted to 400 rpm. After the materials were fully dispersed, the temperature was increased to 100 ° C, and the reaction was kept warm for 6 hours. After the reaction was completed, a reaction mixture 5 was obtained. Using the GC method, the content of methylsulfonyl chloride in the liquid phase of the reaction solution was determined to be 97.8%.

[0031] The reaction mixture 5 was vacuum filtered to obtain a reaction liquid phase, and the reaction liquid was slowly added to a fixed bed column filled with potassium fluoride solid powder particles, and the fixed bed heating temperature was set to 45°C. When the filling column began to discharge, the discharge control valve was adjusted to control the discharge rate to about 1g / min. The product content was determined by GC method to be 99.99%.

[0032] Example 6: A two-step method for preparing high-purity methylsulfonyl fluoride comprises the following steps: 300 g of methylsulfonyl chloride (water content 280 ppm) was added to a 1L three-necked flask, and then 181.7 g of anhydrous potassium fluoride was added thereto. After the potassium fluoride was added, 240 g of anhydrous methylsulfonyl fluoride was added to the flask as a dispersant. Stirring was started, and the stirring speed was gradually adjusted to 400 rpm. After the materials were fully dispersed, the temperature was raised to 90 ° C, and the reaction was kept warm for 4 hours. After the reaction was completed, a reaction mixture 6 was obtained. Using the GC method, the content of methylsulfonyl chloride in the liquid phase of the reaction solution was determined to be 95.7%.

[0033] The reaction mixture 1 was vacuum filtered to obtain the reaction liquid phase, and the reaction liquid was slowly added to the fixed bed filling column filled with potassium fluoride solid powder particles, and the fixed bed heating temperature was set to 50°C. When the filling column began to discharge, the discharge control valve was adjusted to control the discharge rate to about 1g / min. The product content was determined by GC method to be 99.97%.

[0034] Comparative Example 1 A method for preparing methylsulfonyl fluoride comprises the following steps: Add 300g of methylsulfonyl chloride (water content 280ppm) and 213g of anhydrous potassium fluoride into a 1L three-necked flask. Start stirring, gradually increase the speed to 400rpm, start heating, raise the temperature of the reaction system to 100℃, and keep the temperature for 8 hours. After the reaction is completed, the system is viscous, the reaction system cannot be fully dispersed, the product separation is difficult, and the conversion rate is ~60%.

[0035] Comparative Example 2 A method for preparing methylsulfonyl fluoride comprises the following steps: Put 300g of methylsulfonyl chloride (water content 280ppm) and 202g of anhydrous potassium fluoride into a 1L three-necked flask. After completion, add 230g of anhydrous methylsulfonyl fluoride into the flask. Turn on the stirring, gradually adjust the speed to 400rpm, and after the material is fully dispersed, turn on the temperature increase, raise the temperature of the reaction system to 60°C, and keep the reaction for 4 hours. After the reaction is completed, the material is vacuum filtered to obtain the methylsulfonyl fluoride product. After the reaction of comparative example 2, KCl will be wrapped on the surface of KF, causing KF to be inactivated, and the continuous reaction cannot disperse the material in the early stage. The reaction conversion rate is 70.7%.

[0036] 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 high-purity methylsulfonyl fluoride, characterized in that: The method comprises 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; Then, anhydrous methyl sulfonyl fluoride is added as a dispersant for reaction, wherein the molar ratio of anhydrous methyl sulfonyl fluoride to methyl sulfonyl chloride is (0.8-1):1; after stirring, the materials are fully dispersed, the temperature of the reaction system is increased to 70-100° C., and the reaction is kept warm for 5-6 hours to obtain a reaction product, wherein the conversion rate of methyl sulfonyl chloride of the obtained reaction product is ≥90%; The reaction product is vacuum filtered to obtain a reaction liquid, and the reaction liquid is slowly added into a fixed bed column filled with anhydrous metal fluoride solid particles. The fixed bed column is heated, and the product obtained by discharging is high-purity methyl sulfonyl fluoride.

2. The method for preparing high-purity methylsulfonyl fluoride by two steps according to claim 1, characterized in that: The discharging speed of the discharging material is 1 g / min.

3. The method for preparing high-purity methylsulfonyl fluoride by two steps according to claim 1, characterized in that: The heating temperature of the fixed bed packed column is 30-50°C.

4. The method for preparing high-purity methylsulfonyl fluoride by two steps according to claim 1, characterized in that: The anhydrous metal fluoride is potassium fluoride, sodium fluoride or cesium fluoride.

5. The method for preparing high-purity methylsulfonyl fluoride by two steps according to claim 1, characterized in that: The anhydrous metal fluoride is potassium fluoride, and the potassium fluoride is in the form of powder, sphere or cylinder.

6. The method for preparing high-purity methylsulfonyl fluoride by two steps according to claim 1, characterized in that: The water content of the methanesulfonyl chloride was 280 ppm.

7. The method for preparing high-purity methylsulfonyl fluoride by two steps according to claim 1, characterized in that: The stirring speed is 300-500 rpm.

8. The method for preparing high-purity methylsulfonyl fluoride by two steps according to claim 1, characterized in that: The stirring speed is 400 rpm.

Images