A method for synthesizing high purity methanedisulfonic acid methylene ester

Abstract

The application discloses a synthesis method of high-purity methanedisulfonic acid methylene ester, which comprises the following steps: 100 parts of methanedisulfonic acid methylene ester is taken, 150-200 parts of fuming sulfuric acid is added dropwise at a specified temperature, and stirring is conducted; polyformaldehyde is added in batches, and then dehydration reaction is conducted; after the reaction is completed, temperature is lowered, and quenching, water washing, concentration and crystallization are conducted, so that high-purity methanedisulfonic acid methylene ester is obtained. The production method has the advantages of mild reaction condition and fast reaction rate, the conversion rate of methanedisulfonic acid reaches 95%, the process is simple, the cost is low, the product quality is good, the yield is high, the production method is suitable for industrial production, the purity of methanedisulfonic acid methylene ester prepared by the production method can reach 99.9%, the moisture content is less than 100 ppm, and the acid value is less than 30 ppm, which has important significance for promoting the development of the lithium ion power battery industry.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis, and in particular relates to a method for synthesizing high-purity methane disulfonate methylene ester. Background Technology

[0002] With the development of new energy technologies, lithium-ion batteries, as a relatively mature technology in electronic energy storage, have a wide range of applications. Methylene methane disulfonate (MMDS) is one of the world's most advanced cathode film-forming additives, which can be added to the electrolyte, the "blood" of lithium-ion batteries, to improve their high-temperature cycle performance.

[0003] MMDS, as an electrolyte additive for lithium batteries, enables batteries to exhibit excellent high-temperature cycle performance, making it suitable for power batteries, especially those using lithium manganese oxide as the cathode material. Methylene methane disulfonate (MMDS) decomposes on the LiMn₂O₄ electrode surface to form a protective film. This film effectively reduces electrolyte decomposition and the dissolution of manganese ions in the electrolyte, significantly improving the thermal stability of the LiMn₂O₄ cathode material. It also prevents the adsorption of molten Mn on the anode surface at high temperatures, suppressing impedance rise and effectively improving cycle characteristics, thus greatly increasing cycle life. With the increasing market share of lithium manganese oxide batteries, the market size of MMDS will gradually expand, indicating a promising market prospect.

[0004] Patent WO85 / 03075 describes the reaction of silver methane disulfonate and diiodomethane to obtain methylene methane disulfonate, but this method has a very low yield, high cost, and the product contains a high concentration of metal ions.

[0005] Patent JP2005336155A describes the preparation of methane disulfonic acid methylene ester by cyclization reaction of methane disulfonic acid and methylene diacetate. However, there is no method for the batch preparation of methylene diacetate as a raw material for this reaction, and the product has many impurities and is not easy to purify.

[0006] Patent CN101426776 describes a solvent-free cyclization reaction between methane disulfonic acid and paraformaldehyde in the presence of a dehydrating agent to prepare methane disulfonic acid methylene ester. However, this method suffers from drawbacks such as incomplete reaction and difficulty in controlling the reaction during large-scale production due to the solid-phase nature of the reaction. The resulting reaction solution is very dark and viscous, making it difficult to extract the product. Furthermore, it has disadvantages such as low yield, high wastewater content, and formaldehyde pollution. The resulting product has poor color, many impurities, and low purity.

[0007] Patent CN101511782A describes the preparation of methanedisulfonate methylene ester by reacting pyridine ruthenium salt of methanedisulfonate with methylene bis(chlorosulfonate). However, this method generates a large amount of organic waste, pyridine ruthenium salt of chlorosulfonate. Even after recrystallization, residual organic alkali and pyridine salts (pyridine ruthenium salt of methanedisulfonate and / or pyridine ruthenium salt of chlorosulfonate) remain in the product. If washed with water, the product will be partially hydrolyzed or dissolved, and it is difficult to remove water, resulting in the residual water content of the product failing to meet the qualified standards. Moreover, the wastewater containing organic matter will increase significantly, and the resulting product will have poor color, many impurities, and a purity not exceeding 99%, making it unsuitable as an additive for lithium battery electrolytes. Summary of the Invention

[0008] This invention discloses a method for synthesizing high-purity methylene disulfonate, so as to achieve efficient purification of methylene disulfonate.

[0009] This invention discloses a method for synthesizing high-purity methylene disulfonate, comprising:

[0010] Step 1: Take 100 parts by weight of methylene disulfonate, add 150-200 parts by weight of fuming sulfuric acid dropwise at a specified temperature, and stir.

[0011] Step 2: Add paraformaldehyde in batches and then carry out a dehydration reaction;

[0012] Step 3: After the reaction is complete, the temperature is lowered, quenched, washed with water, and then concentrated and crystallized to obtain high-purity methane disulfonate.

[0013] Furthermore, step 2 specifically includes:

[0014] Step 2.1: Add paraformaldehyde in batches. After the addition is complete, keep the mixture warm for 3-4 hours to allow the reaction to proceed.

[0015] Step 2.2: Add 20-100 parts by weight of phosphorus pentoxide to the mixture after the heat preservation reaction for further dehydration reaction, continue to keep warm for 2-3 hours, and the reaction is completed.

[0016] Furthermore, step 3 specifically includes:

[0017] Step 3.1. Quenching process: Turn off the heating and allow the system to cool naturally to 40-50℃. Slowly add the dissolving solvent dropwise to the system, and stir to dissolve after the addition is complete.

[0018] Step 3.2. Extraction process: Slowly drop the above system into ice water; separate the liquid and collect the upper organic phase, and wash with deionized water;

[0019] Step 3.3. Crystallization process: Collect the organic phase, pass it through a desiccant, collect the organic phase, remove the solvent, slowly cool to 5-10℃, add the crystallization solvent dropwise, after the addition is complete, keep warm and stir for 1 hour, and then filter to obtain a white solid;

[0020] Step 3.4. Refining process: The white solid is dissolved in a solvent and dehydrated using a feed column filled with a dehydrating agent. After desolventizing, it is cooled and crystallized, then filtered to obtain wet methane disulfonate. Vacuum drying yields high-purity methane disulfonate.

[0021] Furthermore, the temperature specified in step 1 is 60-80℃, preferably 65-75℃.

[0022] Furthermore, the solvent used in step 3 is one of diethyl carbonate, dimethyl carbonate, or ethyl methyl carbonate, preferably dimethyl carbonate.

[0023] Furthermore, the desiccant used in step 3 is one or more of magnesium sulfate, sodium sulfate, aluminum oxide, and silica gel, with aluminum oxide being preferred.

[0024] Furthermore, the solvent used for crystallization in step 3 is one of methanol, dichloromethane, and isopropanol, with isopropanol being preferred.

[0025] Furthermore, the material feed column used for drying in step 3 is made of glass, with a length of 60cm, a diameter of φ24mm, and a discharge glass valve at the bottom.

[0026] Furthermore, the solvent used in step 3, the refining process, is dimethyl carbonate.

[0027] Furthermore, the dehydrating agent used in step 3 is one or two of alumina and silica gel, preferably silica gel.

[0028] Compared with the prior art, the production method disclosed in this invention has the advantages of mild reaction conditions and fast reaction rate, achieving a methane disulfonic acid conversion rate of 95%. The process is simple, the cost is low, the product quality is good, and the yield is high, making it suitable for industrial production. The methane disulfonic acid methylene ester produced by this method can achieve a purity of 99.9%, with moisture content <100ppm and acid value <30ppm, which is of great significance for promoting the development of the lithium-ion power battery industry. Attached Figure Description

[0029] Figure 1 This is a process flow diagram of an embodiment of the present invention. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0031] Methylene methane disulfonate (MMDS), used as an electronic-grade reagent in lithium-ion battery electrolytes, is a high-end ultrapure chemical. It requires high purity, manifested as a white powder or white crystals, with a chemical purity of at least 99.9%, free of alcohol solvent residues, a moisture content below 100 ppm, and an acid value below 30 ppm. Therefore, further development of methods for preparing high-purity MMDS is of great significance for promoting the development of the lithium-ion power battery industry.

[0032] The purpose of this invention is to provide a method for synthesizing high-purity methylene disulfonate, which has the advantages of high conversion efficiency, high product purity, low moisture and acid value, and low environmental pollution.

[0033] To achieve the above objectives, the present invention adopts the following technical solution:

[0034] This invention synthesizes methylene disulfonic acid (MMDS) from methanedisulfonic acid and paraformaldehyde. It innovatively selects alumina as a desiccant and silica gel as a dehydrating agent to obtain a high-yield, high-purity MMDS product (99.9% purity, moisture <100ppm, acid value <30ppm). The raw materials are inexpensive and readily available, generate no waste, and the process is simple and low-cost, making it suitable for industrial production.

[0035] Methylene methane disulfonate was synthesized using methane disulfonic acid and paraformaldehyde.

[0036] The reaction formula is as follows:

[0037]

[0038] The specific method for synthesizing methylene disulfonate according to the embodiments of the present invention includes:

[0039] Step 1: Take 100 parts by weight of methylene disulfonate, add 150-200 parts by weight of fuming sulfuric acid dropwise at a specified temperature, and stir.

[0040] Step 2: Add paraformaldehyde in batches and then carry out a dehydration reaction;

[0041] Specifically, step 2 includes: step 2.1: adding paraformaldehyde in batches, and keeping it warm for 3-4 hours after the addition is complete; step 2.2: adding 20-100 parts by weight of phosphorus pentoxide to the mixture after the warm reaction for further dehydration reaction, and continuing to keep it warm for 2-3 hours until the reaction ends.

[0042] Step 3: After the reaction is complete, the temperature is lowered, quenched, washed with water, and then concentrated and crystallized to obtain high-purity methane disulfonate.

[0043] Specifically, step 3 is as follows: Step 3.1. Quenching process: Turn off the heating, allow it to cool naturally to 40-50℃, slowly add the dissolving solvent to the system, and stir to dissolve after the addition is complete; Step 3.2. Extraction process: Slowly add the above system to ice water; separate the liquid and collect the upper organic phase, and wash with deionized water; Step 3.3. Crystallization process: Collect the organic phase, pass it through a desiccant, collect the organic phase, remove the solvent, slowly cool to 5-10℃, add the crystallization solvent, keep warm and stir for 1 hour after the addition is complete, and then filter to obtain a white solid; Step 3.4. Purification process: Dissolve the white solid in solvent, and dehydrate it using a feed column filled with a dehydrating agent. After removing the solvent, cool and crystallize, filter to obtain wet methanedisulfonate, and vacuum dry to obtain high-purity methanedisulfonate.

[0044] Optionally, the specified temperature in step 1 is 60-80℃, preferably 65-75℃. The solvent used in step 3 is one of diethyl carbonate, dimethyl carbonate, or methyl ethyl carbonate, preferably dimethyl carbonate. The desiccant used in step 3 is one or more of magnesium sulfate, sodium sulfate, alumina, or silica gel, preferably alumina. The solvent used for crystallization in step 3 is one of methanol, dichloromethane, or isopropanol, preferably isopropanol. The feed column used for drying in step 3 is made of glass window material, 60cm long, φ24mm in diameter, and equipped with a discharge glass valve at the bottom. The solvent used for purification in step 3 is dimethyl carbonate. The dehydrating agent used for purification in step 3 is one or two of alumina and silica gel, preferably silica gel.

[0045] To illustrate the specific implementation of the embodiments of the present invention, Examples 1-6 are listed below to demonstrate the effects of the synthesis method of the embodiments of the present invention.

[0046] Example 1

[0047] 136.2 g of methanedisulfonic acid (96% purity) was added to a four-necked flask equipped with a mechanical stirrer and a thermometer. The temperature was raised to 70°C, and 250 g of fuming sulfuric acid was added dropwise. The mixture was stirred for 0.5 h, and paraformaldehyde was added in batches. After the addition was complete, the reaction was maintained at this temperature for 3-4 h. Then, 50 g of phosphorus pentoxide was added for further dehydration. The reaction was maintained at this temperature for another 2-3 h until the reaction was complete. The heating was turned off, and the mixture was allowed to cool naturally to 40-50°C. 600 g of dimethyl carbonate was slowly added dropwise to the system, and the mixture was stirred to dissolve after each addition. The mixture was then slowly added dropwise into ice water. The mixture was separated, and the upper organic phase was collected and washed with deionized water. The organic phase was collected, passed through a 50 g alumina column, and the solvent was removed. The temperature was slowly lowered to 5-10°C. 320 g of isopropanol was added dropwise, and after the addition was complete, the mixture was kept at this temperature and stirred for 1 h. The mixture was then filtered to obtain a white solid. The white solid was then dissolved in 640g of dimethyl carbonate, dehydrated and desolventized by passing it through a silica gel column, cooled and crystallized, and filtered to obtain wet methane disulfonate. After vacuum drying at 30℃, 109.3g of the finished product was obtained, with a purity of 99.91%, a moisture content of 85ppm, an acid value of 25ppm, and a yield of 78.26%.

[0048] Example 2

[0049] 136.2 g of methanedisulfonic acid (96% purity) was added to a four-necked flask equipped with a mechanical stirrer and a thermometer. The temperature was raised to 70°C, and 250 g of fuming sulfuric acid was added dropwise. The mixture was stirred for 0.5 h, and paraformaldehyde was added in batches. After the addition was complete, the reaction was maintained at this temperature for 3-4 h. Then, 50 g of phosphorus pentoxide was added for further dehydration. The reaction was maintained at this temperature for another 2-3 h until the reaction was complete. The heating was turned off, and the mixture was allowed to cool naturally to 40-50°C. 600 g of dimethyl carbonate was slowly added dropwise to the system, and the mixture was stirred to dissolve after each addition. The mixture was then slowly added dropwise into ice water. The mixture was separated, and the upper organic phase was collected and washed with deionized water. The organic phase was collected, passed through an 80 g alumina column, and the solvent was removed. The temperature was slowly lowered to 5-10°C. 320 g of isopropanol was added dropwise, and after the addition was complete, the mixture was kept at this temperature and stirred for 1 h. The mixture was then filtered to obtain a white solid. The white solid was dissolved in 640g of dimethyl carbonate, dehydrated and desolventized by passing it through a silica gel column, and then cooled to crystallize. The solution was filtered to obtain wet methane disulfonate, which was then dried under vacuum at 30°C to obtain 110.5g of the final product with a purity of 99.93%, a moisture content of 50ppm, an acid value of 27ppm, and a yield of 79.11%.

[0050] Example 3

[0051] 136.2 g of methanedisulfonic acid (96% purity) was added to a four-necked flask equipped with a mechanical stirrer and a thermometer. The temperature was raised to 70°C, and 250 g of fuming sulfuric acid was added dropwise. The mixture was stirred for 0.5 h, and paraformaldehyde was added in batches. After the addition was complete, the reaction was maintained at this temperature for 3-4 h. Then, 50 g of phosphorus pentoxide was added for further dehydration. The reaction was maintained at this temperature for another 2-3 h until the reaction was complete. The heating was turned off, and the mixture was allowed to cool naturally to 40-50°C. 600 g of dimethyl carbonate was slowly added dropwise to the system, and the mixture was stirred to dissolve after each addition. The mixture was then slowly added dropwise to ice water. The mixture was separated, and the upper organic phase was collected and washed with deionized water. The organic phase was collected, passed through a 100 g alumina column, and the solvent was removed. The temperature was slowly lowered to 5-10°C. 320 g of isopropanol was added dropwise, and after the addition was complete, the mixture was kept at this temperature and stirred for 1 h. The mixture was then filtered to obtain a white solid. The white solid was then dissolved in 640g of dimethyl carbonate, dehydrated and desolventized by passing it through a silica gel column, cooled and crystallized, and filtered to obtain wet methane disulfonate. After vacuum drying at 30℃, 110g of the finished product was obtained with a purity of 99.90%, a moisture content of 49ppm, an acid value of 28ppm, and a yield of 78.76%.

[0052] Example 4

[0053] 136.2 g of methanedisulfonic acid (96% purity) was added to a four-necked flask equipped with a mechanical stirrer and a thermometer. The temperature was raised to 70°C, and 250 g of fuming sulfuric acid was added dropwise. The mixture was stirred for 0.5 h, and paraformaldehyde was added in batches. After the addition was complete, the reaction was maintained at this temperature for 3-4 h. Then, 50 g of phosphorus pentoxide was added for further dehydration. The reaction was maintained at this temperature for another 2-3 h until the reaction was complete. The heating was turned off, and the mixture was allowed to cool naturally to 40-50°C. 600 g of dimethyl carbonate was slowly added dropwise to the system, and the mixture was stirred to dissolve after each addition. The mixture was then slowly added dropwise into ice water. The mixture was separated, and the upper organic phase was collected and washed with deionized water. The organic phase was collected, passed through an 80 g alumina column, and the solvent was removed. The temperature was slowly lowered to 5-10°C. 320 g of isopropanol was added dropwise, and after the addition was complete, the mixture was kept at this temperature and stirred for 1 h. The mixture was then filtered to obtain a white solid. The white solid was then dissolved in 640g of dimethyl carbonate, dehydrated and desolventized by passing it through a silica gel column, cooled and crystallized, and filtered to obtain wet methane disulfonate. After vacuum drying at 30℃, 110.9g of the finished product was obtained, with a purity of 99.92%, a moisture content of 55ppm, an acid value of 20ppm, and a yield of 79.40%.

[0054] Example 5

[0055] 136.2 g of methanedisulfonic acid (96% purity) was added to a four-necked flask equipped with a mechanical stirrer and a thermometer. The temperature was raised to 70°C, and 250 g of fuming sulfuric acid was added dropwise. The mixture was stirred for 0.5 h, and paraformaldehyde was added in batches. After the addition was complete, the reaction was maintained at this temperature for 3-4 h. Then, 50 g of phosphorus pentoxide was added for further dehydration. The reaction was maintained at this temperature for another 2-3 h until the reaction was complete. The heating was turned off, and the mixture was allowed to cool naturally to 40-50°C. 600 g of dimethyl carbonate was slowly added dropwise to the system, and the mixture was stirred to dissolve after each addition. The mixture was then slowly added dropwise into ice water. The mixture was separated, and the upper organic phase was collected and washed with deionized water. The organic phase was collected, passed through an 80 g alumina column, and the solvent was removed. The temperature was slowly lowered to 5-10°C. 320 g of isopropanol was added dropwise, and after the addition was complete, the mixture was kept at this temperature and stirred for 1 h. The mixture was then filtered to obtain a white solid. The white solid was dissolved in 640g of dimethyl carbonate, dehydrated and desolventized by passing it through a silica gel column, and then cooled to crystallize. After pressure filtration, wet methane disulfonate was obtained, and then vacuum dried at 30℃ to obtain 110.9g of the finished product with a purity of 99.90%, a moisture content of 55ppm, an acid value of 19ppm, and a yield of 79.40%.

[0056] Example 6

[0057] 136.2 g of methanedisulfonic acid (96% purity) was added to a four-necked flask equipped with a mechanical stirrer and a thermometer. The temperature was raised to 70°C, and 250 g of fuming sulfuric acid was added dropwise. The mixture was stirred for 0.5 h, and paraformaldehyde was added in batches. After the addition was complete, the reaction was maintained at this temperature for 3-4 h. Then, 50 g of phosphorus pentoxide was added for further dehydration. The reaction was maintained at this temperature for another 2-3 h until the reaction was complete. The heating was turned off, and the mixture was allowed to cool naturally to 40-50°C. 600 g of dimethyl carbonate was slowly added dropwise to the system, and the mixture was stirred to dissolve after each addition. The mixture was then slowly added dropwise into ice water. The mixture was separated, and the upper organic phase was collected and washed with deionized water. The organic phase was collected, passed through an 80 g alumina column, and the solvent was removed. The temperature was slowly lowered to 5-10°C. 320 g of isopropanol was added dropwise, and after the addition was complete, the mixture was kept at this temperature and stirred for 1 h. The mixture was then filtered to obtain a white solid. The white solid was dissolved in 640g of dimethyl carbonate, dehydrated and desolventized by passing it through a column of 90g silica gel, and then cooled to crystallize. After pressure filtration, wet methane disulfonate was obtained, and then vacuum dried at 30℃ to obtain 110.8g of the finished product with a purity of 99.93%, a moisture content of 49ppm, an acid value of 18ppm, and a yield of 79.35%.

[0058] The production methods provided in Examples 1-6 of this invention have mild reaction conditions, fast reaction rates, and the final methane disulfonate methylene ester purity reaches over 99%, with moisture content <100ppm, acid value <30ppm, and methane disulfonate conversion rate over 75%. The process is simple, low-cost, produces high-quality products with high yields, and is suitable for industrial production, meeting the needs of the lithium-ion power battery industry.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this application specification, they can still modify or make equivalent substitutions to the specific implementation of the present invention, but these modifications or changes do not depart from the protection scope of the pending claims of the present invention.

Claims

1. A method for synthesizing high-purity methylene disulfonate, characterized in that, include: Step 1: Take 100 parts by weight of methanedisulfonic acid, add 150-200 parts by weight of fuming sulfuric acid dropwise at 60-80℃, and stir. Step 2: Add paraformaldehyde in batches and then carry out a dehydration reaction; Step 3: After the reaction is complete, the temperature is lowered, quenched, washed with water, and then concentrated and crystallized to obtain high-purity methane disulfonate. Step 2 specifically includes: Step 2.1: Add paraformaldehyde in batches. After the addition is complete, keep the mixture warm for 3-4 hours to allow the reaction to proceed. Step 2.2: Add 20-100 parts by weight of phosphorus pentoxide to the mixture after the heat preservation reaction for further dehydration reaction, continue to keep warm for 2-3 hours, and the reaction is completed; Step 3 specifically includes: Step 3.

1. Quenching process: Turn off the heating and allow the system to cool naturally to 40-50℃. Slowly add the dissolving solvent dropwise to the system, and stir to dissolve after the addition is complete. The dissolving solvent is one of diethyl carbonate, dimethyl carbonate, or methyl ethyl carbonate. Step 3.

2. Extraction process: Slowly drop the above system into ice water; separate the liquid and collect the upper organic phase, and wash with deionized water; Step 3.

3. Crystallization process: Collect the organic phase, place the alumina column, the weight ratio of alumina to methanedisulfonic acid is 80:130.752, collect the organic phase, remove the solvent, slowly cool to 5-10℃, add the crystallization solvent dropwise, after the addition is complete, keep warm and stir for 1 hour, and then filter to obtain a white solid. Step 3.

4. Refining process: The white solid is dissolved in a solvent and dehydrated using a feed column filled with a dehydrating agent. After desolventizing, it is cooled and crystallized, then filtered to obtain wet methane disulfonate. Vacuum drying yields high-purity methane disulfonate.

2. The method for synthesizing high-purity methane disulfonate methylene ester according to claim 1, characterized in that, The solvent used for crystallization in step 3.3 is one of methanol, dichloromethane, or isopropanol.

3. The method for synthesizing high-purity methane disulfonate methylene ester according to claim 1, characterized in that, The feed column in step 3.4 is made of glass, with a length of 60cm, a diameter of φ24mm, and a feed glass valve at the bottom.

4. The method for synthesizing high-purity methane disulfonate methylene ester according to claim 1, characterized in that, The solvent used in step 3.4, refining, is dimethyl carbonate.

5. The method for synthesizing high-purity methane disulfonate methylene ester according to claim 1, characterized in that, The dehydrating agent used in step 3.4 is one or two of alumina and silica gel.

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