Purification method and application of pentaerythritol bicyclic sulfate

Abstract

The invention provides a purification method and application of pentaerythritol bicyclosulfate, and the purification method comprises the following steps: washing and recrystallizing a pentaerythritol bicyclosulfate crude product to obtain the pentaerythritol bicyclosulfate, a washing solution for washing comprises an alkaline solution, water and an alcohol compound. According to the invention, the pentaerythritol bicyclic sulfate obtained by the purification method is high in purity, high in yield and small in product loss, and the method is simple and convenient to operate and suitable for large-scale production and industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrolyte additives, and particularly relates to a purification method and application of pentaerythritol bicyclic sulfate ester. Background Art

[0002] The electrolyte is an essential component in lithium-ion batteries, directly affecting the energy density, cycle stability, and safety of the batteries. Traditional electrolytes usually consist of lithium salts and organic solvents. However, under high-temperature or extreme conditions, the stability and safety of the electrolyte may be threatened, leading to a decline in battery performance and even thermal runaway. Therefore, developing high-performance electrolyte additives has become one of the key research directions for improving the performance of lithium-ion batteries.

[0003] Pentaerythritol bicyclic sulfate ester is a compound with multiple sulfate ester groups, and its unique molecular structure enables it to play various roles in the electrolyte. Firstly, pentaerythritol bicyclic sulfate ester can improve the ionic conductivity of the electrolyte, enhance the migration of lithium ions in the electrolyte, and thus improve the charge-discharge efficiency of the battery. Secondly, pentaerythritol bicyclic sulfate ester exhibits good thermal stability at high temperatures, can effectively inhibit the decomposition of the electrolyte, and enhance the high-temperature tolerance of the battery. In addition, pentaerythritol bicyclic sulfate ester can also form a solid electrolyte interface (SEI) film on the electrode surface. The formation of the SEI film not only reduces the reaction of lithium ions with the electrolyte in direct contact but also effectively inhibits the dendritic growth of lithium metal, reduces the risk of short circuit, improves the safety of the battery, and can also improve the cycle stability of the battery.

[0004] In practical applications, pentaerythritol bicyclic sulfate ester, as an electrolyte additive, can act together with some modifiers and functional polymers to further improve the performance of the electrolyte. In addition, its green synthesis route and low environmental impact make it show good application prospects in sustainable battery technology.

[0005] However, the pentaerythritol bicyclic sulfate ester prepared by the existing preparation methods usually contains impurities, and the presence of impurities will affect the performance of pentaerythritol bicyclic sulfate ester, thereby affecting the performance of the battery.

[0006] Therefore, developing a purification method for pentaerythritol bicyclic sulfate ester with high purity, high yield, and small product loss is an urgent problem to be solved in this field. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a purification method and application of pentaerythritol bicyclic sulfate ester. The pentaerythritol bicyclic sulfate ester obtained by the purification method has high purity, high yield, small product loss, and the method is easy to operate, suitable for large-scale production and industrial production.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for purifying pentaerythritol bicyclic sulfate, the purification method comprising the following steps: washing and recrystallizing the crude pentaerythritol bicyclic sulfate to obtain the pentaerythritol bicyclic sulfate; the washing liquid for washing comprises an alkaline solution, water and an alcohol compound.

[0010] In the present invention, after being washed with a specific washing liquid and combined with the recrystallization step, the obtained pentaerythritol bicyclic sulfate has high purity, high yield, small product loss, and the method is simple to operate, suitable for large-scale production and industrial production.

[0011] Preferably, the method for preparing the crude pentaerythritol bicyclic sulfate comprises:

[0012] (1) In the presence of a solvent, reacting pentaerythritol with thionyl chloride to obtain pentaerythritol bicyclic sulfite;

[0013] (2) In the presence of a catalyst and a solvent, reacting the pentaerythritol bicyclic sulfite obtained in step (1) with an oxidizing agent to obtain the crude pentaerythritol bicyclic sulfate.

[0014] Preferably, the solvent in step (1) comprises an aprotic organic solvent.

[0015] Preferably, the solvent in step (1) comprises dichloromethane and / or dichloroethane.

[0016] Preferably, the molar ratio of pentaerythritol to thionyl chloride in step (1) is 1:(2.1 - 4), where the specific values in (2.1 - 4) can be, for example, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, etc.

[0017] Preferably, the temperature of the reaction in step (1) is 40 - 80 °C, for example, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, etc.; the time is 1 - 10 h, for example, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h, etc.

[0018] In the present invention, after the reaction in step (1), the steps of cooling to room temperature, concentrating and washing with water are further included.

[0019] Preferably, the mass of the catalyst in step (2) is 0.01 - 1% of the mass of pentaerythritol, for example, 0.01%, 0.02%, 0.05%, 0.08%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1%, etc.

[0020] In the present invention, the catalyst includes but is not limited to ruthenium trichloride; the catalyst is added to the system in the form of an aqueous catalyst solution; the mass concentration of the aqueous catalyst solution is 0.5-2%.

[0021] Preferably, the solvent in step (2) includes acetonitrile.

[0022] Preferably, the oxidant in step (2) includes sodium hypochlorite.

[0023] Preferably, the molar ratio of pentaerythritol to the oxidant is 1:(2.4-4.2), where the specific values in (2.4-4.2) can be, for example, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, etc.

[0024] Preferably, the temperature of the reaction in step (2) is 20-30°C, for example, 20°C, 22°C, 25°C, 26°C, 28°C, 30°C, etc.; the time is 1-10 h, for example, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h, etc.

[0025] In the present invention, after the reaction in step (2), filtration is further included. The obtained filtrate is layered, and the upper organic phase is taken, and then concentrated under reduced pressure to obtain a solid, that is, the crude product of pentaerythritol bicyclic sulfate is obtained.

[0026] In the present invention, the oxidant is sodium hypochlorite, and the reaction route of the crude product of pentaerythritol bicyclic sulfate is as follows:

[0027]

[0028] Preferably, the washing includes washing successively with an alkaline solution, water, and an alcohol compound.

[0029] In the present invention, washing with an alkaline solution first and then with an alcohol compound is beneficial to removing a small amount of alcohol-soluble impurities and a large amount of water generated during the alkali washing process; thereby making the obtained pentaerythritol bicyclic sulfate have a higher purity.

[0030] Preferably, the alkaline solution includes any one or at least two of a potassium carbonate solution, a sodium carbonate solution, a sodium hydroxide solution, a potassium hydroxide solution, or a sodium bicarbonate solution, and more preferably a potassium carbonate solution.

[0031] Preferably, the mass concentration of the alkaline solution is 5-20%, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.; more preferably 8-15%.

[0032] Preferably, the mass of the alkaline solution is 2 to 5.5 times the mass of the crude pentaerythritol bicyclic sulfate, and can be, for example, 2 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, 2.6 times, 2.7 times, 2.8 times, 2.9 times, 3 times, 3.1 times, 3.2 times, 3.4 times, 3.6 times, 3.8 times, 4 times, 4.2 times, 4.4 times, 4.6 times, 4.8 times, 5 times, etc.; more preferably 2.5 to 3 times.

[0033] In the present invention, if the mass or mass concentration of the alkaline solution is too low, impurities will not be completely removed, resulting in a low purity of pentaerythritol bicyclic sulfate; if the mass or mass concentration of the alkaline solution is too high, the hydrolysis of pentaerythritol bicyclic sulfate will accelerate, resulting in a decrease in its yield.

[0034] Preferably, the temperature for washing with the alkaline solution is 10 to 50 °C, and can be, for example, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, etc.; the time is 0.5 to 2 h, and can be, for example, 0.5 h, 0.6 h, 0.8 h, 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2 h, etc.; more preferably, the temperature is 25 to 30 °C and the time is 1 to 1.5 h.

[0035] In the present invention, when the temperature and time for washing with the alkaline solution are within a specific range, the purity and yield of pentaerythritol bicyclic sulfate obtained are higher.

[0036] Preferably, the mass of the water is 2 to 5.5 times the mass of the crude pentaerythritol bicyclic sulfate, and can be, for example, 2 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, 2.6 times, 2.7 times, 2.8 times, 2.9 times, 3 times, 3.1 times, 3.2 times, 3.4 times, 3.6 times, 3.8 times, 4 times, 4.2 times, 4.4 times, 4.6 times, 4.8 times, 5 times, etc.; preferably 2.5 to 3 times.

[0037] In the present invention, if the mass of the water is too low, impurities will not be completely removed, resulting in a low purity of pentaerythritol bicyclic sulfate; if the mass of the water is too high, a small amount of pentaerythritol bicyclic sulfate will dissolve, resulting in a decrease in yield, and will also lead to an excessive amount of wastewater, increasing the treatment cost.

[0038] Preferably, the temperature for water washing is 10 - 50°C, such as 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, etc.; the time is 0.2 - 1.5 h, such as 0.2 h, 0.3 h, 0.4 h, 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, etc.; more preferably, the temperature is 25 - 30°C and the time is 0.5 - 1 h.

[0039] In the present invention, when the temperature and time for water washing are within a specific range, the purity and yield of pentaerythritol bicyclic sulfate are higher.

[0040] Preferably, the mass of the alcohol compound is 1 - 2.7 times the mass of the crude pentaerythritol bicyclic sulfate, such as 1 time, 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, etc.; preferably 1.5 - 2 times.

[0041] In the present invention, if the content of the alcohol compound is too low, it is not conducive to dissolving impurities, resulting in low product purity; if the content is too high, too much product will dissolve, which is not conducive to the precipitation of the product, resulting in low product yield.

[0042] Preferably, the alcohol compound includes any one or at least two of methanol, ethanol, ethylene glycol, propanol or isopropanol, and more preferably methanol and / or ethanol.

[0043] Preferably, the temperature for washing with the alcohol compound is 15 - 45°C, such as 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, etc.; the time is 0.2 - 1.5 h, such as 0.2 h, 0.3 h, 0.4 h, 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, etc.; more preferably, the temperature is 25 - 30°C and the time is 0.5 - 1 h.

[0044] In the present invention, when the temperature and time for washing with the alcohol compound are within a specific range, the purity and yield of pentaerythritol bicyclic sulfate are higher.

[0045] Preferably, after washing with water and the alcohol compound, the steps of filtration are independently included respectively.

[0046] Preferably, the recrystallization is carried out in an organic solvent.

[0047] Preferably, the organic solvent includes any one or at least two of acetonitrile, methanol, ethanol, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, ethylene glycol dimethyl ether, or propylene carbonate, and more preferably acetonitrile.

[0048] Preferably, the mass of the organic solvent is 3 to 9.5 times the mass of the crude product of pentaerythritol bicyclic sulfate, and can be, for example, 3 times, 3.5 times, 4 times, 4.5 times, 5 times, 5.5 times, 6 times, 6.5 times, 7 times, 7.5 times, 8 times, 8.5 times, 9 times, etc.; more preferably 4 to 6 times.

[0049] In the present invention, if the content of the organic solvent used for recrystallization is too low, it is not conducive to dissolving impurities, resulting in low product purity; if the content is too high, too much product will be dissolved, which is not conducive to the precipitation of the product, resulting in low product yield.

[0050] Preferably, the temperature of the recrystallization is 25 to 82 °C, and can be, for example, 25 °C, 26 °C, 28 °C, 30 °C, 32 °C, 35 °C, 38 °C, 40 °C, 42 °C, 45 °C, 48 °C, 50 °C, 52 °C, 55 °C, 58 °C, 60 °C, 62 °C, 65 °C, 68 °C, 70 °C, 72 °C, 75 °C, 78 °C, 80 °C, etc.; preferably 40 to 70 °C.

[0051] Preferably, the time of the recrystallization is 0.5 to 2.0 h, and can be, for example, 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2 h, etc.; more preferably 1 to 1.5 h.

[0052] In the present invention, when the temperature and time of the recrystallization are within a specific range, the purity and yield of the pentaerythritol bicyclic sulfate obtained are higher.

[0053] Preferably, after the recrystallization, it further includes the steps of filtration and drying.

[0054] In the present invention, the method of filtration includes suction filtration; the method of drying includes vacuum drying, the drying temperature is 60 to 80 °C, and the vacuum degree is 1 to 10 mbar.

[0055] As a preferred technical solution of the present invention, the purification method includes the following steps:

[0056] (S1) Wash the crude pentaerythritol bicyclic sulfate ester with an alkaline solution having a mass concentration of 5-20% at 10-50 °C for 0.5-2 h. The mass of the alkaline solution is 2-5.5 times the mass of the crude pentaerythritol bicyclic sulfate ester; then wash with water having a mass 2-5.5 times the mass of the crude pentaerythritol bicyclic sulfate ester at 10-50 °C for 0.2-1.5 h, and filter to obtain the first pentaerythritol bicyclic sulfate ester;

[0057] (S2) Wash the first pentaerythritol bicyclic sulfate ester obtained in step (S1) with an alcohol compound having a mass 1-2.7 times the mass of the crude pentaerythritol bicyclic sulfate ester at 15-45 °C for 0.2-1.5 h, and filter to obtain the second pentaerythritol bicyclic sulfate ester;

[0058] (S3) Mix the second pentaerythritol bicyclic sulfate ester obtained in step (S2) with an organic solvent. The mass of the organic solvent is 3-9.5 times the mass of the crude pentaerythritol bicyclic sulfate ester, and perform recrystallization at 25-82 °C for 0.5-2 h, filter and dry to obtain the pentaerythritol bicyclic sulfate ester.

[0059] In a second aspect, the present invention provides an application of the pentaerythritol bicyclic sulfate ester obtained by the purification method according to the first aspect in an electrolyte.

[0060] The numerical ranges described in the present invention not only include the above-listed point values, but also include any point values between the above numerical ranges not listed. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the described ranges.

[0061] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0062] The purification method of the pentaerythritol bicyclic sulfate ester provided by the present invention, after washing with a specific washing solution and combined with a recrystallization process, the obtained pentaerythritol bicyclic sulfate ester has high purity, high yield, small product loss, and the method is simple to operate, suitable for large-scale production and industrial production. Detailed Embodiments

[0063] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the described embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0064] All the reagents used in the present invention can be obtained by purchasing commercially. Unless otherwise specified, the crude pentaerythritol bicyclic sulfate ester used in the present invention is prepared by the following preparation method:

[0065] (1) Under stirring, into a 500 mL reaction device, successively add the solvent dichloromethane (200 g), pentaerythritol (40 g, 0.29 mol), heat up to 60 °C, slowly dropwise add thionyl chloride (73.4 g, 0.617 mol), after maintaining the temperature for reaction for 3 h, cool down to room temperature, concentrate the reaction solution and wash it with water to obtain pentaerythritol bicyclic sulfite (60 g, 0.263 mol).

[0066] (2) Under stirring, into a 1000 mL reaction device, add the pentaerythritol bicyclic sulfite (60 g, 0.263 mol) obtained in step (1), acetonitrile (300 g), an aqueous solution of ruthenium trichloride as a catalyst (mass concentration is 1 wt%, 4 g), sodium hypochlorite (546.75 g, 0.734 mol, mass concentration is 10 wt%), after reacting at 25 °C for 3 h, filter the reaction solution, the filtrate is layered, take the upper organic phase, concentrate it under reduced pressure to obtain a solid, that is, the crude pentaerythritol bicyclic sulfate is obtained.

[0067] Example 1

[0068] This example provides a method for purifying pentaerythritol bicyclic sulfate, which specifically includes the following steps:

[0069] (S1) Add an aqueous solution of potassium carbonate with a mass concentration of 10% (157.35 g) to the crude pentaerythritol bicyclic sulfate (60 g), stir and wash at 30 °C for 1 h, then filter by suction to obtain a filter cake; add deionized water (157.35 g) to the filter cake, stir and wash at 30 °C for 0.5 h and then filter by suction to obtain the first pentaerythritol bicyclic sulfate; the mass of the aqueous solution of potassium carbonate is 2.62 times the mass of the crude pentaerythritol bicyclic sulfate; the mass of the deionized water is 2.62 times the mass of the crude pentaerythritol bicyclic sulfate;

[0070] (S2) Add methanol (94.41 g, 2.95 mol) to the first pentaerythritol bicyclic sulfate obtained in step (S1), stir and wash at 25 °C for 0.5 h, filter by suction to obtain the second pentaerythritol bicyclic sulfate; the mass of the methanol is 1.57 times the mass of the crude pentaerythritol bicyclic sulfate;

[0071] (S3) Add acetonitrile (314.7 g, 7.666 mol) to the second pentaerythritol bicyclic sulfate obtained in step (S2), the mass of acetonitrile is 5.25 times the mass of the crude pentaerythritol bicyclic sulfate, perform recrystallization at 65 °C for 1.5 h, after cooling to room temperature, filter by suction and dry under vacuum at 70 °C, the vacuum degree is 5 mbar, to obtain the pentaerythritol bicyclic sulfate.

[0072] Example 2

[0073] This embodiment provides a method for purifying pentaerythritol bicyclic sulfate ester. The difference from Embodiment 1 is only that in step (S1), the aqueous potassium carbonate solution is replaced with an equal mass of aqueous sodium carbonate solution (mass concentration: 10%), and other components, dosages, and process parameters are the same as those in Embodiment 1.

[0074] Embodiment 3

[0075] This embodiment provides a method for purifying pentaerythritol bicyclic sulfate ester. The difference from Embodiment 1 is only that in step (S1), the masses of the aqueous potassium carbonate solution and deionized water are adjusted such that the mass of the aqueous potassium carbonate solution is 2.1 times the mass of the crude pentaerythritol bicyclic sulfate ester; the mass of the deionized water is 2.1 times the mass of the crude pentaerythritol bicyclic sulfate ester, and other components, dosages, and process parameters are the same as those in Embodiment 1.

[0076] Embodiment 4

[0077] This embodiment provides a method for purifying pentaerythritol bicyclic sulfate ester. The difference from Embodiment 1 is only that in step (S1), the masses of the aqueous potassium carbonate solution and deionized water are adjusted such that the mass of the aqueous potassium carbonate solution is 5.25 times the mass of the crude pentaerythritol bicyclic sulfate ester; the mass of the deionized water is 5.25 times the mass of the crude pentaerythritol bicyclic sulfate ester, and other components, dosages, and process parameters are the same as those in Embodiment 1.

[0078] Embodiment 5

[0079] This embodiment provides a method for purifying pentaerythritol bicyclic sulfate ester. The difference from Embodiment 1 is only that in steps (S2) and (S3), the masses of methanol and acetonitrile are adjusted such that the mass of methanol is 1.05 times the mass of the crude pentaerythritol bicyclic sulfate ester; the mass of acetonitrile is 3.15 times the mass of the crude pentaerythritol bicyclic sulfate ester, and other components, dosages, and process parameters are the same as those in Embodiment 1.

[0080] Embodiment 6

[0081] This embodiment provides a method for purifying pentaerythritol bicyclic sulfate ester. The difference from Embodiment 1 is only that in steps (S2) and (S3), the masses of methanol and acetonitrile are adjusted such that the mass of methanol is 2.62 times the mass of the crude pentaerythritol bicyclic sulfate ester; the mass of acetonitrile is 9.44 times the mass of the crude pentaerythritol bicyclic sulfate ester, and other components, dosages, and process parameters are the same as those in Embodiment 1.

[0082] Embodiment 7

[0083] This embodiment provides a method for purifying pentaerythritol bicyclic sulfate, which is only different from Embodiment 1 in that in step (S1), the temperature for washing with an aqueous potassium carbonate solution is 10°C and the time is 0.5 h; the temperature for washing with deionized water is 10°C and the time is 0.2 h; in step (S2), the temperature for washing with methanol is 15°C and the time is 0.2 h; in step (S3), the temperature for recrystallization with acetonitrile is 25°C and the time is 0.5 h; other components, dosages, and process parameters are the same as those in Embodiment 1.

[0084] Example 8

[0085] This embodiment provides a method for purifying pentaerythritol bicyclic sulfate, which is only different from Embodiment 1 in that in step (S1), the temperature for washing with an aqueous potassium carbonate solution is 50°C and the time is 2 h; the temperature for washing with deionized water is 50°C and the time is 1.5 h; in step (S2), the temperature for washing with methanol is 45°C and the time is 1.5 h; in step (S3), the temperature for recrystallization with acetonitrile is 82°C and the time is 2 h; other components, dosages, and process parameters are the same as those in Embodiment 1.

[0086] Example 9

[0087] This embodiment provides a method for purifying pentaerythritol bicyclic sulfate, which is only different from Embodiment 1 in that in step (S1), the time for washing with an aqueous potassium carbonate solution is 1.5 h; the time for washing with deionized water is 1 h; in step (S2), the temperature for washing with methanol is 30°C and the time is 1 h; in step (S3), the temperature for recrystallization with acetonitrile is 70°C and the time is 1.5 h; other components, dosages, and process parameters are the same as those in Embodiment 1.

[0088] Example 10

[0089] This embodiment provides a method for purifying pentaerythritol bicyclic sulfate, which is only different from Embodiment 1 in that in step (S1), the temperature for washing with an aqueous potassium carbonate solution is 25°C; the temperature for washing with deionized water is 25°C; in step (S3), the temperature for recrystallization with acetonitrile is 40°C and the time is 1 h; other components, dosages, and process parameters are the same as those in Embodiment 1.

[0090] Example 11

[0091] This embodiment provides a method for purifying pentaerythritol bicyclic sulfate, which specifically includes the following steps:

[0092] (S1) Add an aqueous potassium carbonate solution with a mass concentration of 14% to crude pentaerythritol bicyclic sulfate (60 g). Stir and wash at 25°C for 1.5 h, then filter by suction to obtain a filter cake. Add deionized water to the filter cake, stir and wash at 25°C for 1 h, and then filter by suction to obtain the first pentaerythritol bicyclic sulfate. The mass of the aqueous potassium carbonate solution is 3 times the mass of the crude pentaerythritol bicyclic sulfate. The mass of the deionized water is 3 times the mass of the crude pentaerythritol bicyclic sulfate.

[0093] (S2) Add methanol to the first pentaerythritol bicyclic sulfate obtained in step (S1). Stir and wash at 30°C for 1 h, then filter by suction to obtain the second pentaerythritol bicyclic sulfate. The mass of the methanol is 2 times the mass of the crude pentaerythritol bicyclic sulfate.

[0094] (S3) Add acetonitrile to the second pentaerythritol bicyclic sulfate obtained in step (S2). The mass of the acetonitrile is 4.1 times the mass of the crude pentaerythritol bicyclic sulfate. Recrystallize at 50°C for 1 h, cool to room temperature, then filter by suction and dry in vacuum at 70°C with a vacuum degree of 5 mbar to obtain the pentaerythritol bicyclic sulfate.

[0095] Example 12

[0096] This example provides a method for purifying pentaerythritol bicyclic sulfate. The difference from Example 1 is only that the mass concentration of the aqueous potassium carbonate solution in step (S1) is 3%, and other components, dosages, and process parameters are the same as those in Example 1.

[0097] Example 13

[0098] This example provides a method for purifying pentaerythritol bicyclic sulfate. The difference from Example 1 is only that the mass concentration of the aqueous potassium carbonate solution in step (S1) is 22%, and other components, dosages, and process parameters are the same as those in Example 1.

[0099] Example 14

[0100] This example provides a method for purifying pentaerythritol bicyclic sulfate. The difference from Example 1 is only that the order of steps (S1) and (S2) is reversed, that is, step (S2) is carried out first, and then step (S1), and other components, dosages, and process parameters are the same as those in Example 1.

[0101] Comparative Example 1

[0102] This comparative example provides a method for purifying pentaerythritol bicyclic sulfate. The difference from Example 1 is only that step (S2) is not carried out, that is, washing with an alcohol compound is not adopted, and step (S1) is repeated once, that is, the product obtained in step (S1) is washed again with an aqueous potassium bicarbonate solution and deionized water. Other components, dosages and process parameters are the same as those in Example 1.

[0103] Comparative Example 2

[0104] This comparative example provides a method for purifying pentaerythritol bicyclic sulfate. The difference from Example 1 is only that in step (S1), the aqueous potassium carbonate solution is replaced with an equal mass of hydrogen peroxide solution (concentration: 5 wt%), and other components, dosages and process parameters are the same as those in Example 1.

[0105] The purity and yield of the pentaerythritol bicyclic sulfate obtained by the purification methods provided in the examples and comparative examples were tested by gas chromatography (the instrument is Agilent 7890B). The test results are shown in Table 1.

[0106] Table 1

[0107] Yield (%) Purity (%) Example 1 82.3 99.96 Example 2 77.9 99.96 Example 3 80.2 99.26 Example 4 80.9 99.94 Example 5 81.6 99.17 Example 6 75.3 99.97 Example 7 80.9 98.4 Example 8 77.6 99.96 Example 9 81.8 99.93 Example 10 81.2 99.90 Example 11 81.8 99.95 Example 12 80.2 97.2 Example 13 76.2 99.82 Example 14 80.6 94.7 Comparative Example 1 73.5 96.2 Comparative Example 2 81.9 94.3

[0108] As can be seen from Table 1, for the purification method provided by the present invention, by adopting a specific washing process and recrystallization process, the purity of the obtained pentaerythritol bicyclic sulfate is ≥94.7%, and the yield is ≥75.3%. Even the effects of purity ≥99.9% and yield ≥80% can be achieved; it has high purity and relatively high yield, and the process is simple and the cost is low, which is suitable for industrial production.

[0109] The specific embodiments described above further elaborate on the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for purifying pentaerythritol bicyclic sulfate, characterized in that, The purification method includes the following steps: Washing and recrystallizing the crude pentaerythritol bicyclic sulfate to obtain the pentaerythritol bicyclic sulfate; The washing solution for the washing includes an alkaline solution, water, and an alcohol compound.

2. The purification method according to claim 1, wherein The preparation method of the crude pentaerythritol bicyclic sulfate includes: (1) In the presence of a solvent, reacting pentaerythritol with thionyl chloride to obtain pentaerythritol bicyclic sulfite; (2) In the presence of a catalyst and a solvent, reacting the pentaerythritol bicyclic sulfite obtained in step (1) with an oxidizing agent to obtain the crude pentaerythritol bicyclic sulfate.

3. The preparation method according to claim 2, characterized in that, The solvent in step (1) includes an aprotic organic solvent; Preferably, the solvent in step (1) includes dichloromethane and / or dichloroethane; Preferably, the molar ratio of pentaerythritol to thionyl chloride in step (1) is 1:(2.1 - 4); Preferably, the temperature of the reaction in step (1) is 40 - 80 °C, and the time is 1 - 10 h; Preferably, the mass of the catalyst in step (2) is 0.01 - 1% of the mass of pentaerythritol; Preferably, the solvent in step (2) includes acetonitrile; Preferably, the oxidizing agent in step (2) includes sodium hypochlorite; Preferably, the molar ratio of pentaerythritol to the oxidizing agent is 1:(2.4 - 4.2); Preferably, the temperature of the reaction in step (2) is 20 - 30 °C, and the time is 1 - 10 h.

4. The purification method according to any one of claims 1 to 3, characterized in that, The washing includes washing successively with an alkaline solution, water, and an alcohol compound.

5. The purification method according to any one of claims 1 to 4, characterized in that, The alkaline solution includes any one or at least two of potassium carbonate solution, sodium carbonate solution, sodium hydroxide solution, potassium hydroxide solution, or sodium bicarbonate solution, and more preferably potassium carbonate solution; Preferably, the mass concentration of the alkaline solution is 5 - 20%, and more preferably 8 - 15%; Preferably, the mass of the alkaline solution is 2 - 5.5 times the mass of the crude pentaerythritol bicyclic sulfate, and more preferably 2.5 - 3 times; Preferably, the temperature for washing with the alkaline solution is 10 - 50 °C, and the time is 0.5 - 2 h; more preferably, the temperature is 25 - 30 °C, and the time is 1 - 1.5 h.

6. The purification method according to any one of claims 1 to 5, characterized in that, The mass of the water is 2 - 5.5 times the mass of the crude pentaerythritol bicyclic sulfate, preferably 2.5 - 3 times; Preferably, the temperature for washing with water is 10 - 50 °C, and the time is 0.2 - 1.5 h; more preferably, the temperature is 25 - 30 °C, and the time is 0.5 - 1 h; Preferably, the mass of the alcohol compound is 1 - 2.7 times the mass of the crude pentaerythritol bicyclic sulfate, and more preferably 1.5 - 2 times; Preferably, the alcohol compound includes any one or at least two of methanol, ethanol, ethylene glycol, propanol, or isopropanol, and more preferably methanol and / or ethanol; Preferably, the temperature for washing with the alcohol compound is 15 - 45 °C, and the time is 0.2 - 1.5 h; more preferably, the temperature is 25 - 30 °C, and the time is 0.5 - 1 h; Preferably, after washing with water and the alcohol compound, each independently includes a filtration step.

7. The purification method according to any one of claims 1 to 6, characterized in that, The recrystallization is carried out in an organic solvent; Preferably, the organic solvent includes any one or at least two of acetonitrile, methanol, ethanol, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethyl acetate, ethylene glycol dimethyl ether, or propylene carbonate, and more preferably acetonitrile; Preferably, the mass of the organic solvent is 3 to 9.5 times the mass of the crude pentaerythritol bis(cyclic sulfate), and more preferably 4 to 6 times.

8. The purification method according to any one of claims 1 to 7, characterized in that, The temperature of the recrystallization is 25 to 82 °C, preferably 40 to 70 °C; Preferably, the time of the recrystallization is 0.5 to 2.0 h, and more preferably 1 to 1.5 h; Preferably, after the recrystallization, the steps of filtration and drying are further included.

9. A purification method according to any one of claims 1 to 8, characterized in that, The purification method includes the following steps: (1) The crude pentaerythritol bis(cyclic sulfate) is washed with an alkaline solution having a mass concentration of 5 to 20% at 10 to 50 °C for 0.5 to 2 h, and the mass of the alkaline solution is 2 to 5.5 times the mass of the crude pentaerythritol bis(cyclic sulfate); then it is washed with water having a mass of 2 to 5.5 times the mass of the crude pentaerythritol bis(cyclic sulfate) at 10 to 50 °C for 0.2 to 1.5 h, and filtered to obtain the first pentaerythritol bis(cyclic sulfate); (2) The first pentaerythritol bis(cyclic sulfate) obtained in step (1) is washed with an alcohol compound having a mass of 1 to 2.7 times the mass of the crude pentaerythritol bis(cyclic sulfate) at a temperature of 15 to 45 °C for 0.2 to 1.5 h, and filtered to obtain the second pentaerythritol bis(cyclic sulfate); (3) The second pentaerythritol bis(cyclic sulfate) obtained in step (2) is mixed with an organic solvent, and the mass of the organic solvent is 3 to 9.5 times the mass of the crude pentaerythritol bis(cyclic sulfate), and recrystallized at a temperature of 25 to 82 °C for 0.5 to 2 h, filtered and dried to obtain the pentaerythritol bis(cyclic sulfate).

10. Use of pentaerythritol bis(cyclic sulfate) obtained by the purification method according to any one of claims 1 to 9 in an electrolyte.

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