Preparation method of ethylene sulfate

Abstract

The invention discloses a preparation method of ethylene sulfate, which comprises the following steps: mixing silicon dioxide, alkali and a villiaumite catalyst in ethylene glycol, carrying out heating reaction, distilling, filtering and drying to obtain an ethylene glycol siloxane intermediate; mixing the ethylene glycol siloxane intermediate, sulfuric acid diester and an ionic liquid catalyst in ethylene glycol, carrying out heating reaction, filtering, concentrating and drying to obtain ethylene sulfate. According to the method, the ethylene glycol siloxane intermediate prepared from the cheap ethylene glycol and the sulfuric acid diester are subjected to ester exchange to generate the ethylene sulfate, so that the use of a noble metal catalyst and complex reaction equipment is avoided, and meanwhile, a preparation reference route is provided for synthesizing the compounds; the method has the advantages of mild conditions, no use of strong acid, oxidizing agent and high-temperature and high-pressure reaction conditions, easily available raw materials in the market, simple process, safety, stability and suitableness for industrial scale amplification.

Description

Technical Field

[0001] The invention relates to the technical field of lithium battery additive materials, and in particular to a method for preparing vinyl sulfate. Background Art

[0002] Ethylene sulfate (CAS No: 1072-53-3), white crystals or crystalline powder. Ethylene sulfate is an important chemical raw material, widely used in medicine, plastics, coatings, dyes, inks and other fields. With the development of new energy technology, ethylene sulfate (DTD) has also become an excellent lithium battery electrolyte additive. Ethylene sulfate can be decomposed on the surface of graphite negative electrode in preference to electrolyte solvent ethylene carbonate to generate organic sulfonates with good ion conductivity, thereby reducing interface impedance. Generally, its addition ratio is about 0.5%, and it can be effectively used in lithium iron phosphate, lithium cobalt oxide, and ternary material batteries. As an electrolyte additive for lithium-ion batteries, ethylene sulfate (DTD) can be used to inhibit the decrease of the initial capacity of the battery, increase the initial discharge capacity, reduce the expansion of the battery after high temperature placement, and improve the charge and discharge performance and cycle number of the battery. It can also be used as a raw material for synthetic surfactants and pharmaceutical intermediates.

[0003] At present, there are two main production processes for vinyl sulfate. One process is to prepare vinyl sulfate by catalytic reaction of ethylene oxide and sulfur trioxide or chlorosulfonic acid, such as the catalytic reaction of sulfur trioxide and ethylene oxide in Chinese patent CN108658928. This method requires high temperature, high pressure, and harsh conditions of anhydrous and oxygen-free conditions, with a large number of by-products, and the raw material sulfur trioxide is a highly dangerous and highly corrosive substance, and ethylene oxide is a highly dangerous chemical; Chinese patent CN114539211 is a catalytic reaction of halosulfonic acid and ethylene oxide, and the raw material of this method also uses ethylene oxide, which is a highly dangerous chemical; the other process is to use ethylene glycol and dichlorothionyl to undergo a cyclization reaction to prepare vinyl sulfite Then, an oxidation reaction is performed to generate vinyl sulfate (Chinese patents CN118496194A, CN118496195A, CN118561806A, CN118373802A, CN118388444A, etc.). Such processes require precious metal catalysts during the oxidation process, which is costly. Moreover, although such processes use different process flows, such as tubular reactor oxidation reaction systems, fixed bed oxidation systems, continuous flow oxidation systems, electrochemical in-situ oxidation systems, etc., the investment in the reaction equipment required is relatively large, and the equipment requirements are relatively high. From the perspective of process feasibility and cost, they are not suitable for large-scale industrial production. Summary of the invention

[0004] The present invention provides a method for preparing vinyl sulfate to solve the above problems. The present invention uses ethylene glycol, silicon dioxide and alkali as raw materials to prepare an ethylene glycol siloxane intermediate under the action of a fluoride salt catalyst; the ethylene glycol siloxane intermediate and a sulfuric acid diester generate vinyl sulfate under the catalysis of an ionic liquid. The route of the present invention is overall reasonable and is carried out in two steps, providing a simple and effective new path for the preparation of vinyl sulfate.

[0005] The technical solution of the present invention is:

[0006] A method for preparing vinyl sulfate comprises the following steps:

[0007] S1: Mix silica, alkali and fluoride salt catalyst in ethylene glycol and heat them.

[0008] The reaction generates an ethylene glycol siloxane intermediate; the reaction formula is shown in formula (1);

[0009]

[0010] S2: Mixing the ethylene glycol siloxane intermediate, the sulfuric acid diester and the ionic liquid catalyst in ethylene glycol, and reacting them under elevated temperature to generate vinyl sulfate, the reaction formula is shown in formula (2).

[0011]

[0012] Furthermore, the alkali is sodium hydroxide or potassium hydroxide.

[0013] Furthermore, the fluoride salt catalyst is sodium fluoride or potassium fluoride.

[0014] Furthermore, in S1, the molar ratio of the alkali, silicon dioxide and fluoride salt catalyst is 1.0-1.1:1:0.01-0.03.

[0015] Furthermore, in S2, the molar ratio of the sulfuric acid diester, the ethylene glycol siloxane intermediate and the ionic liquid catalyst is 1:1.2-1.3:0.005-0.01.

[0016] Further, in S1, the temperature range of the heating condition is 190-195°C;

[0017] In S2, the temperature range of the heating condition is 50-65°C.

[0018] Furthermore, in S2, the sulfuric acid diester is any one of dimethyl sulfate, diethyl sulfate, and dibutyl sulfate.

[0019] Furthermore, in S2, the sulfuric acid diester is diethyl sulfate.

[0020] Furthermore, in S2, the ionic liquid catalyst is any one of 1,3-dimethylimidazole methyl sulfate and 1-ethyl-3-methylimidazole ethyl sulfate.

[0021] Furthermore, in S2, the ionic liquid catalyst is 1-ethyl-3-methylimidazolium ethyl sulfate.

[0022] The beneficial effects of the present invention are:

[0023] (1) In the first step of the present invention, silicon dioxide and ethylene glycol are used as raw materials to prepare the ethylene glycol siloxane intermediate, and the reaction yield is high, which is conducive to ensuring a high yield of the subsequent preparation of vinyl sulfate, and the excess ethylene glycol can be recycled and reused, which can not only reduce the waste of raw materials, but also reduce the pollution to the environment;

[0024] (2) In the second step of the present invention, an ethylene glycol siloxane intermediate prepared from cheap ethylene glycol is used to undergo ester exchange with a sulfuric acid diester to generate vinyl sulfate, thereby avoiding the use of precious metal catalysts and complex reaction equipment, and also providing a preparation reference route for the synthesis of such compounds;

[0025] (3) The conditions required for this method are mild, avoiding the use of strong acids, oxidants, and high temperature and high pressure reaction conditions. The raw materials used are readily available in the market, the process is simple, safe and stable, and is suitable for industrial scale expansion. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The key principles involved in this application are:

[0028] The ionic liquid catalyst acts on the silicon atom of ethylene glycol siloxane to form ethylene glycol oxygen anions, which then attack the sulfur atom of the sulfate diester to exchange the alcohol of the sulfate diester to form vinyl sulfate. The exchanged alcohol combines with the silicon atom to regenerate siloxane. The reaction formula is shown in formula (3):

[0029]

[0030] Embodiment 1:

[0031] A method for preparing vinyl sulfate comprises the steps of:

[0032] S1: Under nitrogen protection, in a reaction bottle, 6.0g (0.1mol) of silicon dioxide, 4.2g (0.1mol) of sodium hydroxide and 0.084g (0.002mol) of sodium fluoride were mixed in 120mL of ethylene glycol, heated to 195°C, reacted for 8 hours, and the generated water was separated by a water separator during reflux. After the reaction was completed, ethylene glycol was slowly distilled out under reflux until solids precipitated, cooled to room temperature, filtered, and the product was slurried with 60mL of acetonitrile, filtered, and dried to obtain 32.2g of ethylene glycol siloxane intermediate, with a yield of 80%. 1HNMR (400MHz, CD3OD): 3.64 (s, 20H) verified that the product was ethylene glycol siloxane intermediate;

[0033] S2: Under nitrogen protection, in a reaction bottle, 15.4g (0.1mol) of diethyl sulfate, 52.2g (0.13mol) of ethylene glycol siloxane intermediate and 0.19g (0.8mmol) of 1-ethyl-3-methylimidazole ethyl sulfate were mixed in 60mL of ethylene glycol, heated to 60-65°C, reacted for 6 hours, cooled to room temperature, filtered, and concentrated under reduced pressure to obtain a crude product, which was slurried with ice water and dried to obtain 9.3g of product vinyl sulfate, with a yield of 75% and a chemical purity of 99.7%. 1HNMR (400MHz, CDCl3): 4.76 (s, 4H) verified that the product was vinyl sulfate.

[0034] Embodiment 2:

[0035] Under nitrogen protection, in a reaction bottle, 6.0 g (0.1 mol) of silicon dioxide, 5.6 g (0.1 mol) of potassium hydroxide and 0.058 g (0.001 mol) of potassium fluoride were mixed in 100 mL of ethylene glycol, heated to 195° C., and reacted for 5 hours. During the reflux process, the generated water was separated with a water separator. After the reaction was completed, ethylene glycol was slowly distilled out under reflux until solids precipitated, cooled to room temperature, filtered, and the product was slurried with 60 mL of acetonitrile, filtered, and dried to obtain 30.6 g of ethylene glycol siloxane intermediate with a yield of 76%.

[0036] Under nitrogen protection, in a reaction bottle, 12.6 g (0.1 mol) of dimethyl sulfate, 48.3 g (0.12 mol) of ethylene glycol siloxane intermediate and 0.2 g (1 mmol) of 1,3-dimethylimidazole methyl sulfate were mixed in 50 mL of ethylene glycol, heated to 50-55 ° C, reacted for 5 hours, cooled to room temperature, filtered, and concentrated under reduced pressure to obtain a crude product, which was slurried with ice water and dried to obtain 8.8 g of product vinyl sulfate with a yield of 71% and a chemical purity of 99.6%.

[0037] Embodiment 3:

[0038] Under nitrogen protection, in a reaction bottle, 6.0 g (0.1 mol) of silicon dioxide, 4.4 g (0.11 mol) of sodium hydroxide and 0.13 g (0.003 mol) of sodium fluoride were mixed in 140 mL of ethylene glycol, heated to 195 ° C under reflux conditions, and reacted for 6 hours. During the reflux process, the generated water was separated with a water separator. After the reaction was completed, ethylene glycol was slowly distilled out under reflux until solids precipitated, cooled to room temperature, filtered, and the product was slurried with 60 mL of acetonitrile, filtered, and dried to obtain 31.0 g of ethylene glycol siloxane intermediate with a yield of 77%.

[0039] Under nitrogen protection, in a reaction bottle, 15.4 g (0.1 mol) of diethyl sulfate, 48.3 g (0.12 mol) of ethylene glycol siloxane intermediate and 0.19 g (0.8 mmol) of 1-ethyl-3-methylimidazole ethyl sulfate were mixed in 70 mL of ethylene glycol, heated to 60-65 ° C, reacted for 7 hours, cooled to room temperature, filtered, concentrated under reduced pressure, dried, and the crude product was slurried with ice water to obtain 8.7 g of vinyl sulfate product with a yield of 70% and a chemical purity of 99.7%.

[0040] Embodiment 4:

[0041] Under nitrogen protection, in a reaction bottle, 6.0 g (0.1 mol) of silicon dioxide, 6.2 g (0.11 mol) of potassium hydroxide and 0.12 g (0.002 mol) of potassium fluoride were mixed in 100 mL of ethylene glycol, heated to 195 ° C and reacted under reflux for 5 hours. The generated water was separated by a water separator during the reflux process. After the reaction was completed, ethylene glycol was slowly distilled out under reflux until solids precipitated, cooled to room temperature, filtered, and the product was slurried with 60 mL of acetonitrile, filtered, and dried to obtain 31.4 g of ethylene glycol siloxane intermediate with a yield of 78%.

[0042] Under nitrogen protection, in a reaction bottle, 21g (0.1mol) of dibutyl sulfate, 52.2g (0.13mol) of ethylene glycol siloxane intermediate and 0.19g (0.8mmol) of 1-ethyl-3-methylimidazole ethyl sulfate were mixed in 50mL of ethylene glycol, heated to 55-60°C, reacted for 9 hours, cooled to room temperature, filtered, and concentrated under reduced pressure to obtain a crude product, which was slurried with ice water and dried to obtain 8.1g of product vinyl sulfate, with a yield of 65% and a chemical purity of 99.6%.

[0043] In summary, the yield of vinyl sulfate prepared by the method is high and the product purity is high; the method prepares vinyl sulfate by ester exchange reaction between ethylene glycol siloxane intermediate generated by silicon dioxide and ethylene glycol in the presence of alkali and fluoride salt catalyst and sulfuric acid diester, thereby providing a concise and effective new path for the preparation of vinyl sulfate; the preparation method has a simple process, mild conditions, cheap and easily available raw materials, no need for special reaction equipment, low production cost, and is suitable for industrial expansion production of vinyl sulfate.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing vinyl sulfate, characterized in that: The following steps are involved: S1: mixing silica, alkali and fluoride salt catalyst in ethylene glycol, performing a temperature-raising reaction, and obtaining an ethylene glycol siloxane intermediate after distillation, filtration and drying; S2: Mixing the ethylene glycol siloxane intermediate, the sulfuric acid diester and the ionic liquid catalyst in ethylene glycol, performing a temperature-raising reaction, and obtaining vinyl sulfate after filtering, concentrating and drying.

2. The method for preparing vinyl sulfate according to claim 1, characterized in that: The alkali is sodium hydroxide or potassium hydroxide.

3. The method for preparing vinyl sulfate according to claim 1, characterized in that: The fluoride salt catalyst is sodium fluoride or potassium fluoride.

4. The method for preparing vinyl sulfate according to claim 1, characterized in that: In S1, the molar ratio of the base, silicon dioxide and fluoride salt catalyst is 1.0-1.1:1:0.01-0.

03.

5. The method for preparing vinyl sulfate according to claim 1, characterized in that: In S2, the molar ratio of the sulfuric acid diester, the ethylene glycol siloxane intermediate and the ionic liquid catalyst is 1:1.2-1.3:0.005-0.

01.

6. The method for preparing vinyl sulfate according to claim 1, characterized in that: In S1, the temperature range of the heating condition is 190-195°C; In S2, the temperature range of the heating condition is 50-65°C.

7. The method for preparing vinyl sulfate according to claim 1, characterized in that: In S2, the sulfuric acid diester is any one of dimethyl sulfate, diethyl sulfate, and dibutyl sulfate.

8. The method for preparing vinyl sulfate according to claim 7, characterized in that: In S2, the sulfuric acid diester is diethyl sulfate.

9. The method for preparing vinyl sulfate according to claim 1, characterized in that: In S2, the ionic liquid catalyst is any one of 1,3-dimethylimidazole methyl sulfate and 1-ethyl-3-methylimidazole ethyl sulfate.

10. The method for preparing vinyl sulfate according to claim 9, characterized in that: In S2, the ionic liquid catalyst is 1-ethyl-3-methylimidazolium ethyl sulfate.

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