Preparation method of cyclic sulfate ester and non-aqueous electrolyte

Abstract

The present invention discloses a method for preparing a cyclic sulfate ester and a non-aqueous electrolyte, relating to the field of organic synthesis technology. The method for preparing the cyclic sulfate ester of the present invention comprises the following steps: Step S1: mixing a persulfate, a cyclic sulfite, a catalyst, and a first organic solvent, adjusting the pH to 4 to 8, reacting, separating the organic layer, and obtaining an organic phase; Step S2: mixing the organic phase with a second organic solvent, filtering the crystals, collecting the precipitate, and drying the resulting product; wherein the catalyst is selected from at least one of CuCo2O4 and FeCo2O4. The method for preparing the cyclic sulfate ester of the present invention is simple, low-cost, and has a high safety factor. It does not require a high-temperature or high-pressure environment and is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular to a preparation method of a cyclic sulfate and a non-aqueous electrolyte. Background Art

[0002] Cyclic sulfates are a class of organic compounds containing cyclic sulfate groups in their molecules. They can be used as additives to lithium battery electrolytes to improve the kinetic properties of electrode / electrolyte interface reactions, inhibit the decline in the battery's initial capacity, increase the initial discharge capacity, and reduce battery expansion after high-temperature storage. In addition, they can also be used to improve the battery's charge and discharge performance and cycle number.

[0003] In the related art, the preparation methods of cyclic sulfates mainly include acylation, substitution, addition, dioxane synthesis and oxidation. Among them, the oxidation method is more suitable for industrial production than other methods due to its low cost and simple preparation method. The oxidation method usually first uses alcohols and dichloride to react to generate an intermediate cyclic sulfate, which is then oxidized by an oxidant to produce the product cyclic sulfate. Currently, the main oxidation methods in the preparation of cyclic sulfates include: ① using sodium hypochlorite or sodium periodate as an oxidant and oxidizing under the catalysis of ruthenium trichloride aqueous solution; ② direct oxidation using potassium permanganate as an oxidant. However, in the actual preparation process, the precious metal ruthenium trichloride used in the former is expensive and difficult to recycle; the latter uses potassium permanganate as an oxide, which has disadvantages such as low yield and difficulty in product purification.

[0004] Therefore, there is an urgent need to provide a new method for preparing cyclic sulfates, which has a high safety factor, low cost, high yield and purity, and is suitable for industrial production. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for preparing a cyclic sulfate ester, which can improve the purity and yield of the cyclic sulfate ester, has a high safety factor, does not require a high temperature and high pressure environment, and is suitable for industrial production.

[0006] The present invention also provides an application of a cyclic sulfate in a non-aqueous electrolyte.

[0007] The first aspect of the present invention provides a method for preparing a cyclic sulfate, comprising the following steps:

[0008] Step S1, mixing a persulfate, a cyclic sulfite, a catalyst and a first organic solvent, adjusting the pH value to 4 to 8, reacting, and separating the organic layer to obtain an organic phase;

[0009] Step S2, mixing the organic phase with a second organic solvent, filtering the crystals, collecting the precipitate, and drying to obtain;

[0010] Wherein, the catalyst is selected from at least one of an iron ion-containing compound and a copper ion-containing compound.

[0011] The preparation method according to the embodiment of the present invention has at least the following beneficial effects:

[0012] (1) The present invention uses CuCo2O4 or FeCo2O4 catalysts, which can effectively improve the catalytic activity of single-metal catalysts and have the advantage of fast reaction rates. Compared with single-metal catalysts using the same metal element, they have a better oxidation-promoting effect. In addition, CuCo2O4 or FeCo2O4 has a stable structure, low cost, and is environmentally friendly.

[0013] (2) The catalyst selected by the present invention contains iron ions or copper ions. On the one hand, it has multiple oxidation states and can be transformed between different oxidation states in the catalytic cycle. The changes in these oxidation states can provide different degrees of oxidizing power, thereby enhancing the progress of the oxidation reaction. On the other hand, iron ions or copper ions have good electron transfer capabilities. In the oxidation reaction of potassium persulfate, they participate in the redox reaction and improve the oxidation effect. In addition, while ensuring excellent catalytic performance, the catalyst of the present invention is low in cost relative to the noble metal ruthenium trichloride catalyst and is more suitable for industrial production.

[0014] (3) The preparation method of the present invention has mild reaction conditions and good controllability. In the present invention, the oxidizing properties of the persulfate can be controlled by adjusting the reaction conditions (e.g., by adjusting the pH value; potassium persulfate is generally more oxidizing under acidic conditions and less oxidizing under alkaline conditions). In addition, the persulfate of the present invention itself is relatively stable under conventional conditions and is not prone to spontaneous decomposition. They can be stored and used for a long time, which is convenient for laboratory operation and industrial application.

[0015] (4) The method of the present invention is used to prepare cyclic sulfate, and the product purity is high, which can reach more than 99%, and has a good yield (greater than 85%).

[0016] In some embodiments of the present invention, in step S1, the persulfate is selected from at least one of potassium persulfate and sodium persulfate. Potassium persulfate and sodium persulfate are both strong oxidants that provide oxygen atoms or free radicals in the oxidation reaction to promote the oxidation reaction.

[0017] In some embodiments of the present invention, the cyclic sulfite is at least one of propylene sulfite, butylene sulfite, and 4-methylethylene sulfite.

[0018] In some embodiments of the present invention, the first organic solvent is a polar solvent or an aromatic hydrocarbon compound solvent.

[0019] The cyclic sulfate ester has high solubility in polar solvents or aromatic compound solvents, which can reduce the amount of solvent used and ensure that the cyclic sulfate ester is precipitated in the subsequent crystallization step.

[0020] In some embodiments of the present invention, the polar solvent includes at least one of acetone, butanone, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, propionitrile, butyronitrile, dichloromethane, chloroform, tetrachloromethane, dichloroethane, dimethyl carbonate, and diethyl carbonate.

[0021] In some embodiments of the present invention, the aromatic hydrocarbon compound solvent includes at least one of benzene, toluene, xylene, ethylbenzene, trimethylbenzene, and cumene.

[0022] In some embodiments of the present invention, the reaction time is 15 to 60 minutes; and / or the reaction temperature is 2 to 10°C.

[0023] In some embodiments of the present invention, the molar ratio of the persulfate to the cyclic sulfite is 1:(0.2-2).

[0024] In some embodiments of the present invention, the second organic solvent is a non-polar solvent;

[0025] Preferably, the second organic solvent includes at least one of propane, n-butane, isobutane, n-pentane, 2-methylbutane, 3-methylhexane, n-hexane, cyclohexane, n-octane and isooctane.

[0026] The solubility of non-polar solvents for cyclic sulfates is relatively low. In order to achieve a higher precipitation effect, the first organic solvent and the non-polar solvent used must have a certain degree of mutual solubility. If they are completely mutually soluble, the effect will be better.

[0027] In some embodiments of the present invention, the volume ratio of the second organic solvent to the organic phase is 0.5 to 10:1, preferably 2 to 4:1.

[0028] In some embodiments of the present invention, the temperature of the second organic solvent is lower than 10° C. Lower temperatures are beneficial for promoting the precipitation of cyclic sulfate.

[0029] In some embodiments of the present invention, the crystallization temperature is -5 to 5°C.

[0030] The second aspect of the present invention provides a cyclic sulfate ester, which is prepared by the preparation method of the cyclic sulfate ester described in the first aspect.

[0031] Since the cyclic sulfate includes all the technical features of the first aspect, it has at least all the advantages of the first aspect.

[0032] The third aspect of the present invention provides use of the cyclic sulfate described in the second aspect in preparing a non-aqueous electrolyte.

[0033] The application of the embodiment of the present invention has at least the following beneficial effects: the cyclic sulfate prepared by the present invention has high purity, and thus has all the advantages of the application of cyclic sulfate in non-aqueous electrolytes.

[0034] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0036] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0037] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents or instruments used, if the manufacturer is not specified, are commercially available conventional products.

[0038] Example 1

[0039] This embodiment provides a method for preparing propylene sulfate, which specifically comprises the following steps:

[0040] Weigh 122.14 g of propylene sulfite (CAS No. 4176-55-0), 270.32 g of potassium persulfate, and 0.5 g of FeCo2O4 in 300 mL of trimethylbenzene solvent, stir gently until uniform, adjust the pH to 4, and react at 5°C for 20 min. After the reaction is complete, allow the layers to stand and separate. Take the organic layer, then add 300 mL of pre-cooled n-hexane at 2°C to the organic phase. Stir until complete crystallization occurs. Filter, collect the precipitate, and dry under vacuum to obtain propylene sulfate.

[0041] After testing, the purity of propylene sulfate prepared by this method was 99.61%, and the yield was 89.54%.

[0042] Example 2

[0043] This embodiment provides a method for preparing propylene sulfate, which specifically comprises the following steps:

[0044] Weigh 136.17 g of butylene sulfite (CAS No. 4426-51-1), 270.32 g of potassium persulfate, and 0.5 g of CuCo2O4 in 300 mL of cumene solvent and slowly stir until uniform. Add potassium hydroxide solution dropwise to adjust the pH to 7. React at 4°C for 20 min. After the reaction is completed, allow the layers to separate. Take the organic layer, and then add 300 mL of pre-cooled n-butane at 4°C to the organic phase. Stir until complete crystallization occurs. Filter, collect the precipitate, and dry under vacuum to obtain butylene sulfate.

[0045] After testing, the purity of the butyl sulfate prepared by the method was 99.54%, and the yield was 88.94%.

[0046] Example 3

[0047] This embodiment provides a method for preparing propylene sulfate, which specifically comprises the following steps:

[0048] Weigh 122.14g of 4-methylvinylsulfite (CAS No. 1469-73-4), 270.32g of potassium persulfate, and 0.5g of FeCo2O4 in 300mL of xylene solvent and stir gently until uniform. Add potassium hydroxide solution dropwise to adjust the pH to 8. React at 10°C for 30 minutes. After the reaction is complete, allow the layers to separate. Take the organic layer and add 300mL of pre-cooled n-hexane at 4°C to the organic phase. Stir until complete crystallization occurs. Filter, collect the precipitate, and dry under vacuum to obtain 4-methylvinylsulfate.

[0049] After testing, the purity of 4-methyl vinyl sulfate prepared by this method is 99.42%, and the yield is 85.71%.

[0050] Comparative Example 1

[0051] This comparative example provides a method for preparing propylene sulfate, which specifically comprises the following steps:

[0052] Weigh 122.14 g of propylene sulfite (CAS No. 4176-55-0), 270.32 g of potassium persulfate, and 0.5 g of FeCo2O4 in 300 mL of trimethylbenzene solvent, stir gently until uniform, adjust the pH to 4, and react at 4°C for 20 min. After the reaction is complete, allow the layers to stand and separate. Take the organic layer, then add 300 mL of n-hexane to the organic phase. Stir at 10°C until complete crystallization. Filter, collect the precipitate, and dry under vacuum to obtain propylene sulfate.

[0053] After testing, the purity of propylene sulfate prepared by this method was 88.74% and the yield was 78.68%. As can be seen from the above, the crystallization temperature is also very important to the final purity of the product.

[0054] Comparative Example 2

[0055] This comparative example provides a method for preparing propylene sulfate, which specifically comprises the following steps:

[0056] Weigh 122.14g of propylene sulfite (CAS No. 4176-55-0), 15mL of 1M potassium permanganate solution, and 0.5g of FeCo2O4 into 300mL of trimethylbenzene solvent. Slowly stir until uniform, adjust the pH to 4, and react at 4°C for 20 minutes. After the reaction is completed, allow the layers to separate. Take the organic layer, and then add 300mL of pre-cooled n-hexane at 4°C to the organic phase. Stir until complete crystallization occurs. Filter, collect the precipitate, and dry under vacuum to obtain propylene sulfate.

[0057] Testing showed that the purity of propylene sulfate prepared by this method was 94.63% and the yield was 58.72%, which was presumably related to the production of by-products.

[0058] Comparative Example 3

[0059] This comparative example provides a method for preparing propylene sulfate, which specifically comprises the following steps:

[0060] Weigh 122.14 g of propylene sulfite (CAS No. 4176-55-0), 270.32 g of potassium persulfate, and 0.5 g of FeCo2O4 in 300 mL of trimethylbenzene solvent, stir gently until uniform, adjust the pH to 9, and react at 4°C for 45 minutes. After the reaction is complete, allow the layers to separate. Take the organic layer, and then add 300 mL of pre-cooled n-hexane at 4°C to the organic phase. Stir until complete crystallization occurs. Filter, collect the precipitate, and dry under vacuum to obtain propylene sulfate.

[0061] After testing, the purity of propylene sulfate prepared by this method was 94.74 and the yield was 75.74%. It is speculated that this is related to the generation of by-products during the reaction process. In this comparative example, the pH value is too high, which is not conducive to the oxidation reaction.

[0062] Comparative Example 4

[0063] This comparative example provides a method for preparing propylene sulfate, which specifically comprises the following steps:

[0064] Weigh 122.14g of propylene sulfite (CAS No. 4176-55-0), 270.32g of potassium persulfate, and 0.5g of FeCo2O4 in 300mL of trimethylbenzene solvent, stir gently until uniform, and then add dropwise to adjust the pH to 4. React at 4°C for 20 minutes. After the reaction is complete, allow the layers to stand and separate. Take the organic layer, stir at 0°C to allow it to crystallize, then wash twice with distilled water and dry under vacuum to obtain propylene sulfate.

[0065] After testing, the purity of propylene sulfate prepared by this method was 95.33%, and the yield was 78.41%.

[0066] Comparative Example 5

[0067] This comparative example provides a method for preparing propylene sulfate, which specifically comprises the following steps:

[0068] Weigh 122.14 g of propylene sulfite (CAS No. 4176-55-0), 270.32 g of potassium persulfate, and 0.5 g of FeCo2O4 in 300 mL of trimethylbenzene solvent, stir gently until uniform, adjust the pH to 4, and react at 4°C for 20 min. After the reaction is complete, allow the layers to stand and separate. Take the organic layer, then add 300 mL of pre-cooled ethyl acetate at 4°C to the organic phase. Stir until complete crystallization occurs. Filter, collect the precipitate, and dry under vacuum to obtain propylene sulfate.

[0069] Testing revealed that the purity of the propylene sulfate produced by this method was 98.74% and the yield was 61.77%. This is presumably related to solvent compatibility. Although ethyl acetate is a non-polar solvent, it is not very compatible with trimethylbenzene, resulting in a weak interaction between the two, which can easily lead to phase separation or precipitation, hindering the crystallization of propylene sulfate.

[0070] In summary, the present invention proposes a method for preparing a cyclic sulfate, comprising first mixing a persulfate, a cyclic sulfite, a catalyst and a first organic solvent, adjusting the pH value to 8-9, reacting, separating the organic layer to obtain an organic phase; then mixing the organic phase with a second organic solvent, crystallizing and filtering, collecting the precipitate, and drying to obtain the product; wherein the catalyst is a CuCo2O4 or FeCo2O4 catalyst, which has the advantages of fast reaction rate and good stability.

[0071] Secondly, the catalyst selected by the present invention contains iron ion or copper ion, which has multiple oxidation states on the one hand, can be transformed between different oxidation states in the catalytic cycle, and the change of these oxidation states can provide varying degrees of oxidizing power, thereby enhancing the oxidation reaction; On the other hand, iron ion or copper ion has good electron transfer ability, participates in redox reaction in the oxidation reaction of potassium persulfate, and improves oxidation effect. In addition, the catalyst of the present invention is low in cost relative to the noble metal ruthenium trichloride catalyst, and is more suitable for industrialized production.

[0072] In addition, the preparation method of the present invention has mild reaction conditions and good controllability. In the present invention, the oxidizing performance of the persulfate can be controlled by adjusting the reaction conditions (e.g., by adjusting the pH value; potassium persulfate is generally more oxidizing under acidic conditions, but less oxidizing under alkaline conditions). The sulfate of the present invention itself is relatively stable under conventional conditions, is not prone to spontaneous decomposition, can be stored and used for a long time, and is convenient for laboratory operation and industrial application.

[0073] While the embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A method for preparing a cyclic sulfate, characterized in that: The following steps are involved: Step S1, mixing a persulfate, a cyclic sulfite, a catalyst and a first organic solvent, adjusting the pH value to 4-8, reacting, and separating the organic layer to obtain an organic phase; Step S2, mixing the organic phase with a second organic solvent, filtering the crystals, collecting the precipitate, and drying to obtain; Wherein, the catalyst is selected from at least one of CuCo2O4 and FeCo2O4.

2. The preparation method according to claim 1, characterized in that In step S1, the persulfate is selected from at least one of potassium persulfate and sodium persulfate.

3. The preparation method according to claim 1, characterized in that The cyclic sulfite is at least one of propylene sulfite, butylene sulfite, and 4-methylethylene sulfite.

4. The preparation method according to claim 1, characterized in that The first organic solvent is a polar solvent or an aromatic hydrocarbon compound solvent.

5. The preparation method according to claim 4, characterized in that The polar solvent includes at least one of acetone, butanone, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, propionitrile, butyronitrile, dichloromethane, chloroform, tetrachloromethane, dichloroethane, dimethyl carbonate, and diethyl carbonate.

6. The preparation method according to claim 5, characterized in that The aromatic hydrocarbon compound solvent includes at least one of benzene, toluene, xylene, ethylbenzene, trimethylbenzene, and isopropylbenzene.

7. The preparation method according to claim 1, characterized in that The reaction time is 15-60 min; and / or the reaction temperature is 2-10°C.

8. The preparation method according to claim 1, characterized in that The molar ratio of the persulfate to the cyclic sulfite is 1:(0.2-2).

9. The preparation method according to claim 1, characterized in that The second organic solvent is a non-polar solvent.

10. The preparation method according to claim 9, characterized in that The second organic solvent includes at least one of propane, n-butane, isobutane, n-pentane, 2-methylbutane, 3-methylhexane, n-hexane, cyclohexane, n-octane, and isooctane.

11. The preparation method according to claim 9, characterized in that The temperature of the second organic solvent is lower than 10°C.