Preparation method of high-purity methanesulfonic anhydride
By controlling the reaction temperature, time, and vacuum level, combined with specific crystallization solvents and drying treatment, the problems of high equipment corrosion and low yield in the preparation of methanesulfonic anhydride in the past have been solved, and high-purity, high-yield, and low-cost methanesulfonic anhydride preparation has been achieved.
Patent Information
- Application Number
- CN202511012104.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-22
- Publication Date
- 2025-11-07
AI Technical Summary
Existing methods for preparing methanesulfonic anhydride suffer from problems such as high equipment corrosion, complex operation, low yield, and high cost, and traditional processes are also environmentally unfriendly.
Using methanesulfonic acid and thionyl chloride as raw materials, by controlling the reaction temperature and time, and combining vacuum distillation and crystallization steps, excess thionyl chloride is distilled off, crystallized using a specific crystallization solvent, and finally vacuum dried to obtain high-purity methanesulfonic anhydride.
The preparation of high-purity (over 99.5%) methanesulfonic anhydride has been achieved with high yield, simple operation, low cost, and environmental friendliness, making it suitable for industrial production.
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing high-purity methanesulfonic anhydride, belonging to the technical field of methanesulfonic anhydride preparation. Background Technology
[0002] Methanesulfonic anhydride is a white, prismatic crystal with corrosive and highly hygroscopic properties. It is soluble in chloroform, benzene, and diethyl ether. Methanesulfonic anhydride is an important organic synthesis reagent, widely used in organic synthesis, medicine, agriculture, and other fields.
[0003] There are various methods for preparing methanesulfonic anhydride, but existing processes have some shortcomings. For example, one traditional method involves reacting methanesulfonic acid with phosphorus pentoxide to synthesize methanesulfonic anhydride. The reaction mixture is then extracted, distilled, and recrystallized to obtain the methanesulfonic anhydride product. To avoid the formation of the byproduct phosphoric acid-methanesulfonic acid mixed anhydride, phosphorus pentoxide is added in multiple batches. Because phosphorus pentoxide is highly corrosive and toxic, it places high demands on the safety of equipment and operators. Furthermore, the process generates waste residue, increasing the complexity of subsequent reprocessing and environmental pressure.
[0004] Other synthetic routes for methanesulfonic anhydride include the methanesulfonic acid-methanesulfonyl chloride method, the methanesulfonyl chloride-metal oxide method, the sodium methanesulfonate-methanesulfonyl chloride method, and the sodium methanesulfonate-thionyl chloride method. However, the yield of methanesulfonic anhydride obtained by the above methods is generally less than 20%, the production cost is high, and there is a lack of industrialization value.
[0005] This application is submitted in response to the above-mentioned issues. Summary of the Invention
[0006] The purpose of this invention is to overcome the shortcomings of the aforementioned background technology and provide a relatively simple route for producing high-purity methanesulfonic anhydride. While ensuring yield and conversion rate, it avoids problems such as low yield and cumbersome operation, offering simple operation, easy control, and high product yield and purity.
[0007] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing high-purity methanesulfonic anhydride, comprising the following steps:
[0008] S1: Add methanesulfonic acid and thionyl chloride to the reaction system, heat the reactants, and when the temperature of the reaction system reaches 70°C, reflux begins to occur. Continue to raise the temperature to 80°C and maintain this temperature for 8-16 hours to allow the methanesulfonic acid to react completely.
[0009] S2: After the reaction is complete, transfer the reaction system into a rotary evaporator to distill off the excess thionyl chloride in the reaction system. When the distillate no longer appears at the set temperature, continue vacuum distillation for 20 minutes to distill off as much thionyl chloride as possible.
[0010] S3: Then add the same volume of crystallization solvent to the system, and block-shaped crystals appear in the system. Dissolve the crystals by heating and refluxing, and then slowly cool down at a rate of 1℃ / 5min. Finally, cool down to 25℃, and crystallize for 30min;
[0011] S4: After filtration, high-purity methyl sulfonic anhydride product is obtained, which is eluted with a crystallization solvent and dried in a vacuum drying oven at room temperature.
[0012] Preferably, the molar ratio of methyl sulfonic acid to thionyl chloride in step S1 is 1:1.5-3.5.
[0013] By using the above technical solution, when the excess thionyl chloride is evaporated in the reaction, the vacuum distillation temperature is set to 50℃, which is gradually increased to 80℃, while ensuring that the vacuum degree is greater than 0.09MPa, so that the excess thionyl chloride is completely evaporated, and the evaporated thionyl chloride can be recycled.
[0014] The key points of the present application are as follows: (1) The temperature and time of the heating reaction in step S1 must be in place, otherwise the yield will be reduced; (2) In the distillation process of step S2, the thionyl chloride must be evaporated as much as possible to improve the purity of the product; (3) In the vacuum distillation process of step S2, the higher the vacuum degree, the better, and the optimal vacuum degree is greater than 0.09MPa, so that the excess thionyl chloride can be distilled out, and the reaction system must be sealed well, otherwise the water in the air will affect the purity of the product.
[0015] Preferably, the crystallization solvent for cooling and crystallization in step S3 is methyl tert-butyl ether-toluene, petroleum ether-ethyl acetate or benzene-isopropyl ether.
[0016] Preferably, in the methyl tert-butyl ether-toluene, the volume ratio of the two is 1:1; in the petroleum ether-ethyl acetate, the volume ratio of the two is 1:1; in the benzene-isopropyl ether, the volume ratio of the two is 1:1.
[0017] Preferably, the subsequent drying treatment in step S3 is: after filtering or centrifuging the solvent and the product, the product is placed in a vacuum oven and dried at room temperature for 2-4h to obtain the finished product high-purity methyl sulfonic anhydride.
[0018] Preferably, the crystallization solvent, mother liquor and washing liquid after separation in step S3 are treated and reused.
[0019] By using the above technical solution, after the reaction is completed, the excess thionyl chloride in the system must be evaporated. By means of vacuum distillation, the excess thionyl chloride can be easily removed from the reaction system. The more complete the evaporation of thionyl chloride, the higher the purity of methyl sulfonic anhydride, and the longer the storage time.
[0020] The beneficial effects of the present application are as follows:
[0021] The preparation method of the present application for preparing methanesulfonic anhydride has high product purity (up to 99.5% or more), can be stored at room temperature, has no by-products, high yield, simple operation, relatively low cost, and can produce qualified high-purity methanesulfonic anhydride products. DETAILED DESCRIPTION
[0022] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the present application is further described below in combination with specific embodiments.
[0023] Example 1
[0024] A preparation method of high-purity methanesulfonic anhydride, comprising the following steps:
[0025] S1: Methyl sulfonic acid (content of 99%) and thionyl chloride are added into a three-necked flask according to a molar ratio of 1:2, a condensation reflux and tail gas absorption device are connected, the reaction system is warmed, and the temperature is set to 70°C. When the system temperature is 50°C, there are obvious gas and bubbles in the reaction system and the tail of the tail gas absorption device. When the reaction temperature is 70°C, reflux begins to appear. The reaction temperature is continuously increased to 80°C, the reaction is carried out for 16h, and after the tail gas absorption device basically has no gas, the reaction is complete.
[0026] S2: The reaction liquid is moved into a rotary evaporation flask, and the excess thionyl chloride is evaporated. The initial evaporation temperature is set to 50°C, the amount of distillate is reduced, the temperature is continuously increased to 70°C, and finally the temperature is increased to 80°C until basically no distillate appears. The evaporation is continuously carried out for 20min to ensure that the thionyl chloride is completely evaporated.
[0027] S3: The crystallization solvent methyl tert-butyl ether-toluene (volume ratio of 1:1) is added into the system, the temperature is increased to 60°C to keep reflux for 20min, then the temperature is decreased, the decreasing rate is controlled at 1°C / 5min, the final crystallization temperature is 25°C, and the temperature is kept for 30min, and the crystallization is completed.
[0028] S4: The methanesulfonic anhydride product is filtered, washed with 80ml of methyl tert-butyl ether, dried in a vacuum oven at room temperature for 2h to obtain the methanesulfonic anhydride finished product, which is vacuum packaged after weighing. The purity of the methanesulfonic anhydride product is measured to be 99.70%.
[0029] Example 2
[0030] A preparation method of high-purity methanesulfonic anhydride, comprising the following steps:
[0031] S1: Methyl sulfonic acid (content of 99%) and thionyl chloride were added into a three-necked flask according to a molar ratio of 1:2.5, a condensation reflux and tail gas absorption device were connected, the reaction system was warmed, and the temperature was set to 70°C. When the system temperature was 50°C, obvious gas and bubbles appeared in the reaction system and the tail of the tail gas absorption device. When the reaction temperature was 70°C, reflux began to appear. The reaction temperature was continuously increased to 80°C, and the reaction was carried out for 10h. After no gas appeared in the tail gas absorption device, the reaction was complete.
[0032] S2: The reaction liquid was moved into a rotary flask, and the excess thionyl chloride was distilled off. The initial distillation temperature was set to 50°C. When the distillate amount became small, the temperature was continuously increased to 70°C, and finally increased to 80°C until no distillate appeared. The distillation was continuously carried out for 20min to ensure that the thionyl chloride was completely distilled off.
[0033] S3: The crystallization solvent petroleum ether-ethyl acetate (volume ratio 1:1) was added into the system, and the temperature was increased to 60°C under reflux for 20min. Then the temperature was decreased at a rate of 1°C / 5min, and the final temperature was 25°C. The temperature was kept for 30min, and the crystallization was completed.
[0034] S4: The methyl sulfonic anhydride product was filtered, washed with 80ml of petroleum ether, and dried in a vacuum oven at room temperature for 2h to obtain the finished methyl sulfonic anhydride product. The product was weighed and vacuum packaged. The purity of the methyl sulfonic anhydride product was measured to be 99.65%.
[0035] Example 3
[0036] A method for preparing high-purity methyl sulfonic anhydride, comprising the following steps:
[0037] S1: Methyl sulfonic acid (content of 99%) and thionyl chloride were added into a three-necked flask according to a molar ratio of 1:3.5, a condensation reflux and tail gas absorption device were connected, the reaction system was warmed, and the temperature was set to 70°C. When the system temperature was 50°C, obvious gas and bubbles appeared in the reaction system and the tail of the tail gas absorption device. When the reaction temperature was 70°C, reflux began to appear. The reaction temperature was continuously increased to 80°C, and the reaction was carried out for 16h. After no gas appeared in the tail gas absorption device, the reaction was complete.
[0038] S2: The reaction liquid was moved into a rotary flask, and the excess thionyl chloride was distilled off. The initial distillation temperature was set to 50°C. When the distillate amount became small, the temperature was continuously increased to 70°C, and finally increased to 80°C until no distillate appeared. The distillation was continuously carried out for 20min to ensure that the thionyl chloride was completely distilled off.
[0039] S3: Add crystallization solvent benzene-isopropyl ether (volume ratio 1:1) into the system, keep 60°C under reflux for 20 min, then start to cool down, control the cooling rate at 1°C / 5 min, the final temperature is 25°C, keep for 30 min, the crystallization is finished.
[0040] S4: Filter the product of methylsulfonic anhydride, rinse with 80 ml isopropyl ether, dry in vacuum oven at room temperature for 2 h, get the product of methylsulfonic anhydride, weigh and vacuum package. Measure the purity of the product of methylsulfonic anhydride, which is 99.75%.
[0041] Test Example 1
[0042] (1) Keep the temperature at 60°C, 70°C, 80°C, 90°C, 100°C in step S1 for 16 h, other same as Example 1. The test results are shown in Table 1.
[0043] Table 1: Effect of different temperatures on product yield
[0044] Temperature / °C 60℃ 70℃ 80℃ 90℃ 100℃ Product yield 55.60％ 67.80％ 91.20％ 92.10％ 92.10％
[0045] According to Table 1, the product yield gradually increases with the increase of temperature.
[0046] (2) Keep the temperature at 80°C in step S1 for 2 h, 8 h, 12 h, 16 h, 20 h, other same as Example 1. The test results are shown in Table 2.
[0047] Table 2: Effect of different time on product yield
[0048] Time / h 2h 8h 12h 16h 20h Product yield 25.30％ 75.80％ 80.20％ 91.20％ 91.20％
[0049] According to Table 2, the product yield gradually increases with the increase of time.
[0050] (3) In the process of vacuum distillation in step S2, the vacuum degree is adjusted to 0.04 MPa, 0.06 MPa, 0.08 MPa, 0.09 MPa, 0.1 MPa, other same as Example 1. The test results are shown in Table 3.
[0051] Table 3: Effect of different vacuum degrees on product purity
[0052] Vacuum / Mpa 0.04 0.06 0.08 0.09 0.1 Product purity 99.90％ 99.95％ 99.96％ 99.96％ 99.98％
[0053] According to Table 3, the higher the vacuum degree, the higher the product purity.
[0054] The foregoing merely illustrates the principles of the application and application of its leading features. This application is not limited to the exact details shown above and described herein, and obvious modifications will occur to those skilled in the art. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and without intent that the application be limited to the subjects shown or described, the scope of the application being indicated by the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.
[0055] Furthermore, it should be understood that although the description above is based on embodiments, not every embodiment contains only one independent technical solution, and the description above is only for the sake of clarity, and those skilled in the art should understand the description as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.
Claims
1. A process for the preparation of high purity methanesulfonic anhydride, characterized in that, The method comprises the following steps: S1: adding methylsulfonic acid and thionyl chloride into a reaction system, heating the reactants, and starting reflux when the temperature of the reaction system reaches 70 DEG C, and then heating to 80 DEG C, and maintaining the temperature for 8-16 hours; S2: after the reaction is completed, the reaction system is moved into a rotary evaporation flask, and when no distillate is obtained, vacuum distillation is continued for 20 minutes; S3: then the same volume of a crystallization solvent is added into the system, and blocky crystals appear in the system, the crystals are dissolved by heating to reflux, and then the temperature is slowly decreased at a rate of 1 DEG C / 5 minutes, and finally the temperature is decreased to 25 DEG C, and the crystals are separated for 30 minutes; S4: after filtration, high-purity methylsulfonic anhydride is obtained, and the crystallization solvent is used for elution, and the product is dried in a vacuum drying box at room temperature.
2. The method for preparing high-purity methanesulfonic anhydride as described in claim 1, characterized in that, The molar ratio of methylsulfonic acid to thionyl chloride in step S1 is 1:1.5-3.
5.
3. The method for preparing high-purity methanesulfonic anhydride as described in claim 1, characterized in that, The crystallization solvent for temperature decreasing and crystallization in step S3 is methyl tert-butyl ether-toluene, petroleum ether-ethyl acetate or benzene-isopropyl ether.
4. The method for preparing high-purity methanesulfonic anhydride as described in claim 3, characterized in that, In the methyl tert-butyl ether-toluene, the volume ratio of the two is 1:1; in the petroleum ether-ethyl acetate, the volume ratio of the two is 1:1; and in the benzene-isopropyl ether, the volume ratio of the two is 1:
1.
5. The method for preparing high-purity methanesulfonic anhydride as described in claim 1, characterized in that, The subsequent drying treatment in step S4 is as follows: after the solvent and the product are separated by filtration or centrifugation, the product is dried in a vacuum oven at room temperature for 2-4 hours to obtain the finished product high-purity methylsulfonic anhydride.
6. The method for preparing high-purity methanesulfonic anhydride as described in claim 1, characterized in that, The crystallization solvent, mother liquor and washing liquid separated in step S4 are treated and reused.