A cyclic sulfate and its preparation method

Abstract

This invention relates to the field of organic synthesis technology, specifically disclosing a cyclic sulfate ester and its preparation method. The method involves reacting a cyclic sulfite ester with an oxidant in the presence of a catalyst and a reaction solvent to obtain the cyclic sulfate ester. This invention features mild reaction conditions, simple operation, high yield, excellent product purity, low waste volume, and is environmentally friendly, making it suitable for industrial production. The obtained cyclic sulfate ester has a purity ≥99.3% and can be directly used as an additive in lithium-ion battery electrolytes.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and in particular to a cyclic sulfate ester and its preparation method. Background Technology

[0002] Cyclic sulfates are important additives in lithium-ion battery electrolytes, significantly improving battery cycle performance and safety. However, existing preparation processes generally suffer from high raw material costs, demanding reaction conditions, low product yields, and complex waste treatment, limiting their industrial production and application.

[0003] Cyclic sulfates, as additives in lithium-ion battery electrolytes, can effectively improve the charge-discharge performance and cycle life of batteries, and enhance the high and low temperature cycling performance of lithium-ion batteries. However, current methods for synthesizing cyclic sulfates have several drawbacks: (1) Acylation method: Cyclic sulfate esters are prepared by reacting diol compounds with thioyl fluoride or thioyl chloride. Although the raw materials are cheap, the yield of this method is low and the raw materials are highly corrosive to the reaction equipment. The safety of large-scale production cannot be guaranteed. (2) Substitution method: By reacting dibromoethane with silver sulfate, cyclic sulfate esters are generated. Not only is the yield low, but the silver salt required for large-scale production will also significantly increase the economic cost. (3) Addition method: There are multiple addition routes. Although the raw materials are cheap and readily available, the feasibility of industrialization is not high due to the harsh preparation conditions. (4) Oxidation method: There are four mainstream oxidation methods, but the production process has problems such as large amount of waste, low product purity, and complicated purification.

[0004] Therefore, developing a method for synthesizing cyclic sulfates that uses inexpensive raw materials, has a simple process, high yield, and is environmentally friendly not only conforms to the current green and environmentally friendly concept, but also has important industrial application value. Summary of the Invention

[0005] To address the technical problems existing in the background art, the present invention proposes a method for preparing cyclic sulfates, comprising the following steps: mixing cyclic sulfite, organic solvent and catalyst, then adding oxidant, carrying out oxidation reaction, filtering and washing the filter cake with water, and drying the filter cake to obtain cyclic sulfates; Preferably, the catalyst is selected from at least one of sodium tungstate, tungsten oxide, sodium molybdate, ammonium molybdate, phosphomolybdic acid, and molybdenum oxide; Preferably, the oxidant is selected from at least one of sodium hypochlorite, sodium periodate, hydrogen peroxide, tert-butyl hydroperoxide, ammonium persulfate, potassium persulfate, potassium peroxymonosulfate, sodium perborate, sodium percarbonate, and m-chloroperoxybenzoic acid. More preferably, the catalyst is selected from sodium tungstate; More preferably, the oxidant is selected from tert-butyl hydroperoxide; More preferably, the concentration of the tert-butyl hydroperoxide is 70 wt%.

[0006] This invention employs a catalytic oxidation method to prepare cyclic sulfates. A catalyst is used to activate the oxidant, releasing reactive oxygen species that electrophilically oxidize the tetravalent sulfur (S(IV)) in the cyclic sulfite molecule, converting it into a hexavalent sulfur (S(VI)) cyclic sulfate. After filtration, the residue (containing the target product) is obtained by washing with water. Impurities such as residual tungstate and tert-butyl hydrogen peroxide are removed during washing. The washed target product, the cyclic sulfate, is then dried and desolventized to obtain a high-purity cyclic sulfate. This preparation method is simple to operate, environmentally friendly, and suitable for industrial production.

[0007] Preferably, the cyclic sulfite is selected from at least one of vinyl sulfite, 3,3'-diethylene sulfite, mannitol carbonate disulfite, spiropropylene sulfite, and 5,5'-dipropylene sulfite.

[0008] In this invention, the oxidation method for preparing cyclic sulfates has a wide range of raw material selection. Whether it is a monocyclic sulfite, a bicyclic dimer, a spirocyclic, or a polyheterocyclic complex molecule, all can be oxidized into the corresponding cyclic sulfate, and the yield and purity are both high. For preferred raw material selection, please refer to the following structural diagram: .

[0009] Preferably, the organic solvent is selected from at least one of acetonitrile, tetrahydrofuran, methyl tert-butyl ether, methanol, ethanol, isopropanol, tert-butanol, n-butanol, formic acid, acetic acid, ethylene glycol monomethyl ether, and ethylene glycol dimethyl ether. In this invention, the choice of organic solvents, oxidants and catalysts is diverse and inexpensive. When this preparation method is applied to industrial production, it can avoid the limitations of a single specific reagent or expensive reagent, which is conducive to the promotion of the process.

[0010] Preferably, the organic solvent is selected from acetonitrile; the catalyst is selected from sodium tungstate; and the oxidant is selected from tert-butyl hydroperoxide. In this invention, when the concentration of tert-butyl hydroperoxide is 70 wt%, it is safe and readily available as one of the raw materials. Its tert-butyl group reacts to generate tert-butanol without introducing difficult-to-remove metal ions or acidic impurities, which is beneficial to ensuring product purity. This preferred combination achieves high yield (≥83%) and high purity (≥99.3%), with stable reaction and simple post-processing, as shown in the specific data in Examples 1-5.

[0011] Preferably, based on the sulfite groups within the cyclic sulfite molecule, the molar ratio of sulfite groups to oxidant is 1:1-5; More preferably, based on the sulfite groups within the cyclic sulfite molecule, the molar ratio of sulfite groups to oxidant is 1:1.1-3.

[0012] Preferably, the catalyst is 0.1-5 wt% of a cyclic sulfite. Preferably, the catalyst is 0.5-2 wt% of a cyclic sulfite. More preferably, the catalyst is 0.5 wt% of a cyclic sulfite.

[0013] In this invention, theoretically, 1 mole of sulfite group requires 1 mole of oxidant. However, in practice, due to the decomposition loss of oxidant, a slight excess is required. But if the excess is too much, it will increase the burden of post-processing. The amount of catalyst used is in the thousands, which reduces the residue of metal catalyst in the product, reduces raw material costs, and is environmentally friendly.

[0014] Preferably, the oxidation reaction is carried out at a temperature of 30-80°C for 3-10 hours. More preferably, the oxidation reaction is carried out at a temperature of 40-60°C for 5-7 hours. More preferably, the oxidation reaction is carried out at a temperature of 50°C for 6 hours.

[0015] In this invention, cyclic sulfates are easily hydrolyzed and open under trace acidic conditions at high temperatures, therefore the oxidation reaction temperature should not be too high.

[0016] Preferably, the purity of the cyclic sulfate ester obtained by the above preparation method is ≥99.3%.

[0017] The oxidation method of the present invention for preparing cyclic sulfates, due to the use of mild catalytic oxidation and simple water washing-filtration post-treatment, produces products free of strong acid residues and heavy metal contaminants, and exhibits high batch-to-batch stability.

[0018] Beneficial effects of this invention: (1) The oxidation method of the present invention has mild reaction conditions and can be carried out at normal pressure and medium and low temperature, and has high safety.

[0019] It requires less catalyst, exhibits high selectivity, and has fewer side reactions; (2) The cyclic sulfate ester prepared by the oxidation method of the present invention has a high yield (above 83%) and high purity (≥99.3%), which can meet the requirements of battery grade. It does not require complicated purification treatment and can be directly applied to the electrolyte of lithium-ion batteries. (3) The post-treatment process of the oxidation method of the present invention is simple, produces little waste, is environmentally friendly, and is suitable for industrial production. Attached Figure Description

[0020] Figure 1 The reaction formula for preparing vinyl sulfate in Example 1 of this invention; Figure 2 The reaction formula for preparing 3,3'-ethylene disulfate in Example 2 of this invention; Figure 3 The reaction formula for preparing mannitol carbonate bisulfate in Example 3 of this invention; Figure 4 The reaction formula for preparing spiropropyl sulfate in Example 4 of this invention; Figure 5 The reaction formula for preparing 5,5'-propenyl disulfate in Example 5 of this invention is shown. Detailed Implementation

[0021] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0023] The technical solution of the present invention will now be described more clearly and completely with reference to specific embodiments and comparative examples.

[0024] Example 1 This embodiment proposes a method for preparing cyclic sulfates, comprising the following steps: At 25°C, 10.0 g of vinyl sulfite, 0.05 g of sodium tungstate, and 30 mL of acetonitrile were added to a 250 mL four-necked flask. After stirring evenly, the temperature was raised to 50°C, and then 14.3 g of 70% tert-butyl hydrogen peroxide was added dropwise over a period of 0.5-1 h. After the addition was complete, the reaction was kept at this temperature for 6 hours. After the reaction was completed, the reaction product was cooled to room temperature. A large amount of white solid precipitated in the reaction solution. The product was filtered, and the filter cake was washed with deionized water in small amounts several times. The residual tungstate and tert-butyl hydrogen peroxide were removed by washing the filter cake with water, resulting in a wet vinyl sulfite material. The wet vinyl sulfite material was dried to obtain 11.0 g of white powdered vinyl sulfite. Based on the amount of raw materials input, the product obtained in Example 1 had a purity of 99.6% and a yield of 95.4%.

[0025] Example 2 This embodiment proposes a method for preparing cyclic sulfates, comprising the following steps: At 25°C, 10.0 g of 3,3'-vinyl disulfite, 0.05 g of sodium tungstate, and 30 mL of acetonitrile were added to a 250 mL four-necked flask. After stirring evenly, the temperature was raised to 50°C, and then 15.0 g of 70% tert-butyl hydroperoxide was added dropwise over a period of 0.5-1 h. After the addition was complete, the reaction was maintained at this temperature for 6 hours. After the reaction was completed, the reaction product was cooled to room temperature. A large amount of white solid precipitated in the reaction solution. The product was filtered, and the filter cake was washed with deionized water in small amounts several times. The residual tungstate and tert-butyl hydroperoxide were removed by washing the filter cake with water, resulting in a wet 3,3'-vinyl disulfite. The wet 3,3'-vinyl disulfite was dried at 50°C to obtain 10.4 g of white powder 3,3'-vinyl disulfite. Based on the amount of raw materials used, the product obtained in Example 2 had a purity of 99.5% and a yield of 90.0%.

[0026] Example 3 This embodiment proposes a method for preparing cyclic sulfates, comprising the following steps: At 25°C, 10.0 g of mannitol carbonate bisulfite, 0.05 g of sodium tungstate, and 30 mL of acetonitrile were added to a 250 mL four-necked flask. After stirring evenly, the temperature was raised to 50°C, and then 10.7 g of 70% tert-butyl hydroperoxide was added dropwise over a period of 0.5-1 h. After the addition was complete, the reaction was kept at this temperature for 6 hours. After the reaction was completed, the reaction product was cooled to room temperature. A large amount of white solid precipitated in the reaction solution. The product was filtered, and the filter cake was washed with deionized water in small amounts several times. The residual tungstate and tert-butyl hydroperoxide were removed by washing the filter cake with water, resulting in a wet mannitol carbonate bisulfite. The wet mannitol carbonate bisulfite was dried to obtain 10.3 g of white powdered mannitol carbonate bisulfite. Based on the amount of raw materials used, the product obtained in Example 3 had a purity of 99.5% and a yield of 92.6%.

[0027] Example 4 This embodiment proposes a method for preparing cyclic sulfates, comprising the following steps: At 25°C, 10.0g of spiropropylene sulfite, 0.05g of sodium tungstate, and 30mL of acetonitrile were added to a 250mL four-necked flask. After stirring evenly, the temperature was raised to 50°C, and then 14.1g of 70% tert-butyl hydrogen peroxide was added dropwise over a period of 0.5-1h. After the addition was complete, the reaction was kept at this temperature for 6 hours. After the reaction was completed, the reaction product was cooled to room temperature. A large amount of white solid precipitated in the reaction solution. The product was filtered, and the filter cake was washed with deionized water in small amounts several times. The residual tungstate and tert-butyl hydrogen peroxide were removed by washing the filter cake with water, resulting in a wet spiropropylene sulfite. The wet spiropropylene sulfite was dried to obtain 9.8g of white powdered spiropropylene sulfite. Based on the amount of raw materials used, the product obtained in Example 4 had a purity of 99.3% and a yield of 85.3%.

[0028] Example 5 This embodiment proposes a method for preparing cyclic sulfates, comprising the following steps: At 25°C, 10.0 g of 5,5'-propenyl 5,5'-disulfite, 0.05 g of sodium tungstate, and 30 mL of acetonitrile were added to a 250 mL four-necked flask. After stirring evenly, the temperature was raised to 50°C, and then 13.3 g of 70% tert-butyl hydroperoxide was added dropwise over a period of 0.5-1 h. After the addition was complete, the reaction was maintained at this temperature for 6 hours. After the reaction was completed, the reaction product was cooled to room temperature. A large amount of white solid precipitated in the reaction solution. The product was filtered, and the filter cake was washed with deionized water in small amounts several times. The residual tungstate and tert-butyl hydroperoxide were removed by washing the filter cake with water, resulting in a wet 5,5'-disulfite. The wet 5,5'-disulfite was dried to obtain 9.5 g of white powder 5,5'-disulfite. Based on the amount of raw materials used, the product obtained in Example 5 had a purity of 99.5% and a yield of 83.5%.

[0029] Comparative Example 1 This embodiment proposes a method for preparing cyclic sulfates, comprising the following steps: At 25℃, 10.0g of vinyl sulfite, 0.05g of sodium tungstate, and 30mL of dichloroethane were added to a 250mL four-necked flask. After stirring evenly, the temperature was raised to 50℃, and then 14.3g of 70% tert-butyl hydrogen peroxide was added dropwise over a period of 0.5-1h. After the addition was complete, the reaction was maintained at this temperature for 6 hours. After the reaction was completed, the reaction product was cooled to room temperature. A large amount of white solid precipitated in the lower organic phase. The product was filtered, and the filter cake was washed with deionized water in small amounts several times. The residual tungstate and tert-butyl hydrogen peroxide were removed by washing the filter cake with water, resulting in a wet vinyl sulfite material. The wet vinyl sulfite material was dried to obtain 8.3g of white powdered vinyl sulfite. Based on the amount of raw materials used, the product obtained in Comparative Example 1 had a purity of 96.1% and a yield of 69.5%.

[0030] The purity of the cyclic sulfates prepared in the above examples and comparative examples was obtained by quantitative analysis using high performance liquid chromatography.

[0031] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a cyclic sulfate ester, characterized in that, The process includes the following steps: mixing cyclic sulfite, organic solvent and catalyst, then adding oxidant, carrying out oxidation reaction, filtering and washing the filter cake with water, and drying the filter cake to obtain cyclic sulfite; The catalyst is selected from sodium tungstate; The oxidant is selected from tert-butyl hydroperoxide; The concentration of the tert-butyl hydroperoxide is 70 wt%.

2. The method for preparing the cyclic sulfate ester according to claim 1, characterized in that, The cyclic sulfite is selected from at least one of vinyl sulfite, 3,3'-diethylene sulfite, mannitol carbonate disulfite, spiropropylene sulfite, and 5,5'-dipropylene sulfite.

3. The method for preparing the cyclic sulfate ester according to claim 1 or 2, characterized in that, The organic solvent is selected from at least one of acetonitrile, tetrahydrofuran, methyl tert-butyl ether, methanol, ethanol, isopropanol, tert-butanol, n-butanol, formic acid, acetic acid, ethylene glycol monomethyl ether, and ethylene glycol dimethyl ether.

4. The method for preparing the cyclic sulfate ester according to claim 1 or 2, characterized in that, The organic solvent is selected from acetonitrile; the catalyst is selected from sodium tungstate; and the oxidant is selected from tert-butyl hydroperoxide.

5. The method for preparing the cyclic sulfate ester according to claim 1, characterized in that, Based on the sulfite groups within the cyclic sulfite molecule, the molar ratio of sulfite groups to oxidant is 1:1-5.

6. The method for preparing the cyclic sulfate ester according to claim 1, characterized in that, The catalyst is 0.5 wt% of cyclic sulfite.

7. The method for preparing the cyclic sulfate ester according to claim 1, characterized in that, The oxidation reaction was carried out at a temperature of 50°C for 6 hours.

8. The method for preparing the cyclic sulfate ester according to claim 1 or 2, characterized in that, The purity of the cyclic sulfate ester obtained by the preparation method is ≥99.3%.

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