Purification method of intermediate in mannitol carbonate sulfate preparation process

Abstract

The invention relates to the technical field of purification of fine chemical intermediates, in particular to a purification method of a mannitol carbonate sulfate preparation process intermediate, which comprises the following steps: S1, synthesizing diacetone-D-mannitol; s2, preparing an organic solution containing solids; s3, performing deprotection reaction to prepare a solid crude product; s4, removing unreacted solids; s5, extracting and separating by-product solids; and S6, purifying the target product solid and recovering mannitol. Through system separation and multi-component recovery, preparation of a high-purity product and cyclic utilization of unreacted substances, byproducts and raw materials are realized, the yield is remarkably improved, the cost is reduced, and the quality of a final product is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of fine chemical intermediate purification technology, specifically a method for purifying intermediates in the preparation of mannitol sulfate carbonate. Background Technology

[0002] Mannitol sulfate carbonate is a novel, high-efficiency film-forming additive for lithium-ion battery electrolytes, belonging to organic compounds containing cyclic sulfate structures. Due to the strong electronegativity of the central sulfur atom in its molecule, this compound exhibits higher reduction reactivity on the graphite anode surface than conventional carbonate solvents. Therefore, it can preferentially reduce at the electrode interface, forming a more uniform, dense, and stable solid electrolyte interphase (SEI) film. Introducing mannitol sulfate carbonate as an additive into lithium-ion battery electrolytes can effectively suppress initial capacity decay, increase first-discharge capacity, significantly reduce battery gas accumulation during high-temperature storage, and simultaneously improve battery charge-discharge performance and cycle life.

[0003] Currently, a mainstream process has been developed to prepare mannitol sulfate carbonate using mannitol and dimethyl carbonate as raw materials through transesterification, cyclization, and oxidation reactions (such as CN 120441561 A, which discloses a method for preparing mannitol sulfate carbonate). Although this process can achieve large-scale production of the final product and claims that the purity of the final product can reach more than 99.6%, in actual production, it only focuses on optimizing the synthesis conditions of the final product and does not carry out targeted purification treatment of the intermediates generated in the "transesterification-cyclization" stage. These intermediates are often accompanied by unreacted mannitol, solid by-products (such as protective agent derivatives), and isomer impurities, which become potential hidden dangers for subsequent processes.

[0004] However, the final quality and performance of this additive are highly dependent on the purity of its intermediates. Impurities in the intermediates can not only interfere with subsequent synthesis reactions, leading to a decrease in product yield, but also affect the batch stability of the final product, thereby increasing production costs. Therefore, efficient purification of mannitol carbonate sulfate intermediates to effectively remove impurities and improve purity has become a key technical step in ensuring product quality and optimizing battery performance.

[0005] Therefore, in view of this situation, there is an urgent need to develop a purification method for intermediates in the preparation of mannitol sulfate carbonate to overcome the shortcomings in current practical applications. Summary of the Invention

[0006] The purpose of this invention is to provide a method for purifying intermediates in the preparation of mannitol sulfate carbonate, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions: A method for purifying intermediates in the preparation of mannitol sulfate carbonate includes the following steps: S1. Mannitol is dissolved in the protective reagent dimethoxypropane, a catalyst is added, and the mixture is stirred at 60℃~80℃ for 1~4 hours. After the reaction is completed, the mixture is concentrated and dried to obtain diacetone-D-mannitol; wherein the amount of the catalyst is 0.1%~2% of the mass of mannitol, and the mass ratio of mannitol to dimethoxypropane is 1:(2~6); the catalyst is stannous chloride; S2. The diacetone-D-mannitol obtained in step S1 is mixed with an organic solvent at a mass ratio of 1:(2-10). After thorough stirring, an alkaline catalyst is added, and the mixture is reacted in a water bath at 40℃-70℃ for 4-10 hours to obtain a product containing intermediates. The organic solvent is selected from dimethyl carbonate, diethyl carbonate, or methyl ethyl carbonate; the alkaline catalyst is anhydrous potassium carbonate, and the amount of alkaline catalyst added is 0.1% to 2% of the mass of diacetone-D-mannitol; S3, the contents obtained in step S2 Trifluoroacetic acid was added to an organic solution, the amount of which was 1% to 20% of the mass of diacetone-D-mannitol, to carry out a deprotection reaction. After the reaction was completed, the solution was concentrated and dried to obtain a product containing impurities. crude product; S4. Obtained from step S3 The crude product is mixed with water at a mass ratio of 1:(5-50), stirred thoroughly to dissolve, and then vacuum filtered. The filter residue is dried to obtain recyclable material. ; S5. Extract the filtrate from step S4 with organic solvent II at a mass ratio of 1:(1-10). After separation, collect the organic phase, concentrate and dry to obtain the by-product solid. The organic solvent is selected from dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, or ethyl acetate.

[0008] S6. Concentrate and dry the aqueous phase extracted in step S5 to obtain a residual solid. Dissolve the residual solid in ethylene glycol dimethyl ether at a mass ratio of 1:(1-10) to solvent, and filter to remove insoluble matter. Concentrate and dry the filtrate to obtain a solid. Mannitol was recovered after the filter residue was dried.

[0009] As a further aspect of the present invention: in step S4, the dried solid Purity ≥ 99.5%. As a further aspect of the present invention: in step S5, the obtained by-product solid... Purity ≥ 98%.

[0010] As a further aspect of the present invention: in step S6, the obtained solid The purity is ≥99.5%, and the recovered mannitol has a purity of ≥98%. Compared with the prior art, the beneficial effects of the embodiments of the present invention are: This invention utilizes crude solid containing impurities after deprotection reaction. Through steps such as washing, extraction, separation, concentration, and recrystallization, the target product was successfully obtained in solid form. It is prepared with high purity (>99.5%); at the same time, unreacted high-purity solids can be effectively recovered during the purification process. (>99.5%) and raw material mannitol (>98%), and by-products recyclable solids. (>98%), which significantly improved the utilization rate of raw materials and the yield of products, and reduced production costs.

[0011] This process not only solves the key problem of intermediate impurities affecting the performance of the final product and improves the quality and stability of subsequent synthesis of mannitol sulfate carbonate, but also realizes the recycling of resources. It has the advantages of reasonable process, simple operation, green environmental protection and easy industrial promotion, and can be widely used in the preparation of high-purity organic intermediates in the fields of medicine, food additives and high-performance battery materials.

[0012] In summary, this invention achieves the preparation of high-purity products and the recycling of unreacted substances, byproducts and raw materials through systematic separation and multi-component recovery, significantly improving yield, reducing costs and ensuring the quality of the final product. Attached Figure Description

[0013] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0014] Figure 1 intermediate solid Predicted carbon spectra; Figure 2 intermediate solid Experimental carbon spectrum; Figure 3 intermediate solid The predicted proton spectrum; Figure 4 intermediate solid Experimental proton spectrum; Figure 5 The image shows the IR spectrum of the byproduct mannitol. Detailed Implementation

[0015] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Diacetone-D-mannitol can be converted into a solid intermediate product under the action of a protective agent and a catalyst. Its purity is usually above 99%, which is already quite high and basically requires no further purification. However, in subsequent reactions using trifluoroacetic acid as the reaction condition for the solid... Deprotection preparation of intermediate solids During the process, various side reactions often occur, generating byproducts such as solids. Mannitol and unreacted solids If these impurities are not effectively removed, they will generate more byproducts in subsequent cyclization and oxidation reactions, seriously affecting the purity, quality, and electrochemical performance of the final product, mannitol sulfate carbonate.

[0017] The core of this invention lies in: the preparation of intermediate solids In the key steps, targeted removal of byproduct solids is crucial. Mannitol and residual solids This significantly improves the solid The purity of the precursors ensures high purity for subsequent reactions, effectively guaranteeing the quality and performance stability of the final product, mannitol sulfate.

[0018] The overall reaction process is as follows: .

[0019] like Figure 1 and Figure 2 As shown, for intermediate solids The structure is determined by NMR analysis: the shifts in the C and H spectra and the content of different C and H atoms can be used to determine its structural formula. For example... Figure 3 As shown, infrared detection of the byproduct mannitol and comparison with the infrared spectrum of mannitol revealed that their infrared spectra were essentially identical. Therefore, it can be determined that the generated byproduct is mannitol. Since the byproduct is a solid... It is unstable at room temperature and transforms into a solid upon contact with water. The solid can be deduced from the hydrolysis reaction mechanism. solid The intermediate transition state is obtained, thus yielding its structural formula. Based on the above description, this invention provides a method for purifying intermediates in the preparation of mannitol sulfate carbonate, namely, purifying intermediate solids. This includes the following steps: S1. Synthesis of diacetone-D-mannitol (solid) (precursor) Mannitol was dissolved in the protective reagent dimethoxypropane, and a catalyst (stannous chloride or p-toluenesulfonic acid) was added. The mixture was stirred at 60℃~80℃ for 1~4 hours. After the reaction was completed, the mixture was concentrated and dried to obtain diacetone-D-mannitol with a purity greater than 99%. The amount of catalyst used was 0.1%~2% of the mass of mannitol, and the mass ratio of mannitol to dimethoxypropane was 1:(2~6). S2. Preparation of solid... organic solutions The above-mentioned diacetone-D-mannitol was mixed with an organic solvent at a mass ratio of 1:(2-10), and after thorough stirring, an alkaline catalyst was added. The mixture was then reacted in a water bath at 40℃-70℃ for 4-10 hours to produce a solid containing intermediate products. The organic solvent used can be selected from dimethyl carbonate, diethyl carbonate, or methyl ethyl carbonate; the alkaline catalyst can be anhydrous potassium carbonate, sodium carbonate, or aluminum oxide, and the amount added is 0.1% to 2% of the mass of diacetone-D-mannitol.

[0020] S3, Deprotection reaction to prepare solid crude product To contain solid Trifluoroacetic acid (1%–20% of the mass of diacetone-D-mannitol) was added to an organic solution to carry out a deprotection reaction. After the reaction was completed, the solution was concentrated and dried to obtain a solid containing impurities. Crude product.

[0021] S4. Remove unreacted solids.

[0022] solid The crude product is mixed with water at a mass ratio of 1:(5-50), and after thorough stirring and dissolution, it is filtered under vacuum. The filter residue consists of unreacted solids. After drying, its purity can reach over 99.5%, and it can be recycled and reused.

[0023] S5. Extraction and separation of byproduct solids

[0024] The above filtrate was extracted with organic solvent II at a mass ratio of 1:(1-10). After separation, the organic phase was collected, concentrated, and dried to obtain a by-product solid with a purity greater than 98%. The organic solvent used can be selected from dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, or ethyl acetate.

[0025] S6. Purify the target product solid. And recover mannitol The extracted aqueous phase was concentrated and dried to obtain a residual solid. Ethylene glycol dimethyl ether was added at a solid-to-solvent mass ratio of 1:(1-10) to dissolve the solid, and the insoluble matter was removed by filtration. The filtrate was concentrated and dried to obtain a high-purity solid with a purity greater than 99.5%. The filter residue can be dried to recover mannitol with a purity greater than 99%.

[0026] Example 1 An embodiment of the present invention provides a method for purifying intermediates in the preparation of mannitol sulfate, comprising the following steps: 1) Dissolve 30g of mannitol in 60g of dimethoxypropane, add 0.6g of stannous chloride as a catalyst, and stir the reaction at 70℃ for 4 hours. After the reaction is complete, concentrate and dry to obtain diacetone-D-mannitol with a purity of 99.4%.

[0027] 2) Take 20g of the above product and mix it with 40g of dimethyl carbonate. After stirring thoroughly, add 0.02g of anhydrous potassium carbonate and heat in a water bath at 70℃ for 10 hours to obtain a product containing solid... Organic solutions.

[0028] 3) Add 0.2 g of trifluoroacetic acid to the organic solution to carry out a deprotection reaction. After the reaction is completed, concentrate and dry to obtain a solid. Crude product.

[0029] 4) Take 10g of solid The crude product is mixed with 50g of water, stirred thoroughly to dissolve, then vacuum filtered and dried. The filter residue is an unreacted solid. The purity reaches 99.5%.

[0030] 5) Extract 40g of the filtrate with 40g of ethyl acetate, separate the liquid from the filtrate, concentrate and dry the organic phase to obtain a byproduct solid with a purity of 98.2%. .

[0031] 6) The extracted aqueous phase was concentrated and dried to a solid state. An equal mass (1:1) of ethylene glycol dimethyl ether was added to dissolve the solid. After filtration, the filtrate was concentrated and dried to obtain a solid with a purity of 99.5%. The filter residue was dried and then recovered to obtain mannitol with a purity of 98.3%.

[0032] Example 2 An embodiment of the present invention provides a method for purifying intermediates in the preparation of mannitol sulfate, comprising the following steps: 1) Dissolve 30g of mannitol in 120g of dimethoxypropane, add 0.03g of stannous chloride as a catalyst, stir and react at 60℃ for 3 hours, concentrate and dry after the reaction is complete to obtain diacetone-D-mannitol with a purity of 99.5%.

[0033] 2) Take 20g of the above product and mix it with 100g of diethyl carbonate. Add 0.2g of anhydrous potassium carbonate and heat in a water bath at 50℃ for 8 hours to obtain a product containing solid... Organic solutions.

[0034] 3) Add 2g of trifluoroacetic acid to the solution to carry out the deprotection reaction. After the reaction is completed, concentrate and dry to obtain a solid. Crude product.

[0035] 4) Take 10g of solid The crude product was mixed with 300g of water, stirred thoroughly to dissolve, then vacuum filtered and dried. The filter residue was an unreacted solid. The purity reaches 99.7%.

[0036] 5) Extract 40g of the filtrate with 200g of dimethyl carbonate. After separation, concentrate and dry the organic phase to obtain a byproduct solid with a purity of 98.7%. .

[0037] 6) Concentrate and dry the extracted aqueous phase into a solid, dissolve it in 5 times its weight of ethylene glycol dimethyl ether, filter, and then concentrate and dry the filtrate to obtain a solid with a purity of 99.7%. The filter residue was dried and then recovered to obtain mannitol with a purity of 98.5%.

[0038] Example 3

[0039] 1) Dissolve 30g of mannitol in 180g of dimethoxypropane, add 0.06g of stannous chloride as a catalyst, stir and react at 60℃ for 1 hour, concentrate and dry after the reaction is complete to obtain diacetone-D-mannitol with a purity of 99.7%.

[0040] 2) Take 20g of the above product and mix it with 200g of methyl ethyl carbonate, add 0.4g of anhydrous potassium carbonate, and heat in a water bath at 40℃ for 4 hours to obtain a product containing solid... Organic solutions.

[0041] 3) Add 4g of trifluoroacetic acid to the solution to carry out the deprotection reaction. After the reaction is completed, concentrate and dry to obtain a solid. Crude product.

[0042] 4) Take 10g of solid The crude product is mixed with 500g of water, stirred thoroughly to dissolve, then vacuum filtered and dried. The filter residue is an unreacted solid. The purity reaches 99.76%.

[0043] 5) Extract 40g of the filtrate with 400g of dimethyl carbonate. After separation, concentrate and dry the organic phase to obtain a byproduct solid with a purity of 99.2%. .

[0044] 6) Concentrate and dry the extracted aqueous phase into a solid, dissolve it in 10 times its weight of ethylene glycol dimethyl ether, filter, and then concentrate and dry the filtrate to obtain a solid with a purity of 99.8%. The filter residue was dried to recover mannitol with a purity of 98.3%. Table 1 below shows the intermediate solids of the example and the unpurified form. Purity data comparison. Unpurified intermediate solid. The purity was only 90%, but through the purification process provided by this invention (including steps such as washing, extraction, separation, concentration, and drying), the purity was significantly increased to over 99.5% in all three embodiments. This demonstrates that the purification method is highly efficient in removing impurities.

[0045] Table 1. Solid intermediates in the examples and before purification Purity data

[0046] The above embodiments of the present invention provide a method for purifying intermediates in the preparation of mannitol sulfate, by using solid... After dissolving in an organic solvent and then adding trifluoroacetic acid for deprotection, a crude solid product is obtained. After further steps such as washing, extraction, separation, concentration, and drying, a high-purity solid with a purity greater than 99.5% is finally obtained. . crude solid After washing with water, the filter residue is dried to obtain a solid with a purity greater than 99.5%. This high-purity solid Can be used as a solid for the next synthesis The raw materials effectively save costs and improve solids The yield was determined by the following method: The filtrate after washing with water was subjected to a two-stage extraction with an organic solvent. The organic phase was then concentrated and dried to obtain a byproduct solid with a purity greater than 98%. .solid It can be further reacted with trifluoroacetic acid to prepare a solid. This improves the overall solid The yield.

[0047] The aqueous phase after extraction and separation was concentrated and dried into a solid, dissolved in ethylene glycol dimethyl ether, and filtered. The filter residue was dried to obtain mannitol with a purity greater than 98%. High-purity mannitol can be used to prepare diacetone-D-mannitol, significantly reducing production costs and increasing the yield of diacetone-D-mannitol.

[0048] This invention removes impurities from mannitol sulfate carbonate intermediates using specific process methods, ensuring high purity of the final product. It achieves effective separation and recovery of the crude product, the target product, and byproducts, improving raw material utilization and reducing production costs. This invention not only improves the solid content of the target product... The yield was improved, and the overall economic benefits were further enhanced by the reuse of by-products, providing high-quality raw materials for the subsequent synthesis of high-value-added end products.

[0049] In summary, this invention, through its innovative purification process, not only ensures product quality but also achieves efficient resource utilization, possessing significant practical application value and broad market prospects.

[0050] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these should also be considered within the scope of protection of the present invention. These will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for purifying intermediates in the preparation of mannitol sulfate, characterized in that, Includes the following steps: S1. Mannitol is dissolved in the protective reagent dimethoxypropane, a catalyst is added, and the mixture is stirred at 60℃~80℃ for 1~4 hours. After the reaction is completed, the mixture is concentrated and dried to obtain diacetone-D-mannitol; wherein the amount of the catalyst is 0.1%~2% of the mass of mannitol, and the mass ratio of mannitol to dimethoxypropane is 1:(2~6); the catalyst is stannous chloride; S2. The diacetone-D-mannitol obtained in step S1 is mixed with an organic solvent at a mass ratio of 1:(2-10). After thorough stirring, an alkaline catalyst is added, and the mixture is reacted in a water bath at 40℃-70℃ for 4-10 hours to obtain a product containing intermediates. An organic solution; the organic solvent is selected from dimethyl carbonate, diethyl carbonate, or methyl ethyl carbonate; the alkaline catalyst is anhydrous potassium carbonate, and the amount of the alkaline catalyst added is 0.1% to 2% of the mass of diacetone-D-mannitol; S3, to the solution obtained in step S2 containing... Trifluoroacetic acid was added to an organic solution, the amount of which was 1% to 20% of the mass of diacetone-D-mannitol, to carry out a deprotection reaction. After the reaction was completed, the solution was concentrated and dried to obtain a product containing impurities. crude product; S4. Obtained from step S3 The crude product is mixed with water at a mass ratio of 1:(5-50), stirred thoroughly to dissolve, and then vacuum filtered. The filter residue is dried to obtain recyclable material. ; S5. Extract the filtrate from step S4 with organic solvent II at a mass ratio of 1:(1-10). After separation, collect the organic phase, concentrate and dry to obtain the by-product solid. The organic solvent is selected from dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, or ethyl acetate; S6, the aqueous phase after extraction in step S5 is concentrated and dried to obtain a residual solid, which is then dissolved in ethylene glycol dimethyl ether at a mass ratio of residual solid to solvent of 1:(1-10), and the insoluble matter is removed by filtration; the filtrate is concentrated and dried to obtain a solid. Mannitol was recovered after the filter residue was dried.

2. The method for purifying the intermediate in the preparation of mannitol sulfate according to claim 1, characterized in that, In step S4, the dried solid Purity ≥ 99.5%.

3. The method for purifying the intermediate in the preparation of mannitol sulfate according to claim 2, characterized in that, In step S5, the obtained by-product solid Purity ≥ 98%.

4. The method for purifying the intermediate in the preparation of mannitol sulfate according to claim 3, characterized in that, In step S6, the obtained solid The purity is ≥99.5%, and the purity of the recovered mannitol is ≥98%.

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