Preparation method of vinylene carbonate

Abstract

The invention relates to the technical field of synthesis of vinylene carbonate, in particular to a preparation method of vinylene carbonate, which comprises the following steps: S1, preparing a chloroethylene carbonate solution and a dehalogenating agent solution; wherein the dehalogenating agent is a polymer of which the molecular structure contains a plurality of primary amino groups or secondary amino groups and also contains a plurality of carboxylic acids or carboxylate; s2, preheating a chloroethylene carbonate solution and a dehalogenating agent solution to 30 DEG C, then respectively inputting the preheated chloroethylene carbonate solution and dehalogenating agent solution into a microchannel of a microchannel reactor for mixed reaction, and after the reaction is finished, enabling a product to flow out from an outlet of the microchannel reactor to obtain a solution A; s3, the solution A is transferred into a rectifying still for rectification, and vinylene carbonate is obtained; by-products of the dechlorination reaction of the chloroethylene carbonate are reduced, and the yield of the vinylene carbonate is improved.

Description

Technical Field

[0001] The present application relates to the technical field of vinylene carbonate synthesis, and in particular to a method for preparing vinylene carbonate. Background Art

[0002] Vinylene carbonate, also known as 1,3-dioxol-2-one, ethylene carbonate, etc., is currently used more in batteries. Vinylene carbonate can undergo polymerization reaction on the surface of the negative electrode of the lithium battery during the initial charge and discharge of the battery to generate polyalkyl lithium carbonate compounds. The formation of this substance can effectively inhibit the embedding of solvent molecules and the bloating of lithium batteries. In addition, the polymerization reaction of vinylene carbonate can form a layer of SEI (solid electrolyte interface) film on the negative electrode of the battery, which can minimize the degree of decomposition of graphite battery electrolysis, thereby effectively improving the cycle life of lithium batteries. Therefore, based on the fact that vinylene carbonate is currently the most ideal, most effective, and most widely used electrolyte additive, its demand has increased greatly, which makes the research on the synthesis process of vinylene carbonate also have very important practical significance.

[0003] At present, in the traditional process of synthesizing vinylene carbonate in industry, such as CN201510922630.9, chloroethylene carbonate is basically subjected to a dechlorination reaction to obtain a crude product, and then the crude product is purified to obtain a fine vinylene carbonate. Its preparation process is relatively complicated and cumbersome, with more by-products and higher moisture content, resulting in a low yield of the crude product. After refining, especially after the recrystallization process, its yield is even lower. There are many reasons that make the preparation cost of vinylene carbonate high. Summary of the invention

[0004] In order to reduce the byproducts of the dechlorination reaction of vinyl chlorocarbonate and improve the yield of vinylene carbonate, the present application provides a method for preparing vinylene carbonate.

[0005] The present application provides a method for preparing vinylene carbonate, which adopts the following technical scheme: A method for preparing vinylene carbonate comprises the following steps: S1. preparing a chloroethylene carbonate solution and a dehalogenating agent solution; wherein the dehalogenating agent is a polymer having a plurality of primary or secondary amine groups and a plurality of carboxylic acids or carboxylates in its molecular structure; S2, preheating the ethylene chlorocarbonate solution and the dehalogenating agent solution to 30°C, then respectively inputting the preheated ethylene chlorocarbonate solution and the dehalogenating agent solution into the microchannel of the microchannel reactor for mixed reaction, controlling the temperature to 47-55°C, the mixed reaction for 7-15min, the flow rate of the ethylene chlorocarbonate solution to 0.2-0.4mL / min, and the flow rate of the dehalogenating agent solution to make the mass of the dehalogenating agent 4-6 times that of ethylene chlorocarbonate, after the reaction is completed, the product flows out through the outlet of the microchannel reactor to obtain solution A; S3. Transfer solution A into a distillation kettle for distillation to obtain vinylene carbonate.

[0006] By adopting the above technical scheme, the reaction of the present application is carried out in a microchannel reactor. Compared with the traditional process, the reaction mass transfer and heat release efficiency is higher, the raw material contact is more complete, and the reaction is safer; and the dehalogenating agent of the present application adopts a polymer containing an amino group, which can be dissolved in the same solvent and fully contact with vinyl carbonate, thereby promoting the dechlorination reaction; and through experimental research, the purity of the vinyl carbonate prepared is above 99.99%, and the yield is 91.0% and above. Different from the traditional dehalogenating agent triethylamine, it is almost non-volatile and not easy to enter the vinyl carbonate product. In addition, based on the presence of carboxylate and amino groups in the dehalogenating agent, it has a higher polarity and can be separated from the reaction system by adjusting the polarity of the solvent, recovered by reaction with an alkali, and reused; compared with triethylamine which is not easy to recover, the dehalogenating agent of the present application has more advantages.

[0007] Preferably, the solvents of the ethylene chlorocarbonate solution and the dehalogenating agent solution are both dimethyl carbonate, and the mass ratio of the ethylene chlorocarbonate to the dimethyl carbonate is 1:5; the mass ratio of the dehalogenating agent to the dimethyl carbonate is 1:3.

[0008] By adopting the above technical solution and this ratio, the reactants can have good solubility, and the dehalogenating agent has a low viscosity at this concentration and is not easy to generate micelles in the solution to embed the amino group, thereby affecting its dehalogenation effect.

[0009] As a preference: the preparation method of the dehalogenating agent is as follows: S1. Add 15 g of enamine to tetrahydrofuran, stir until dissolved, heat to 50-60° C., dropwise add epichlorohydrin in an amount equimolar to the enamine, stir to react, then add sodium hydroxide solution, wherein the amount of sodium hydroxide is 1.1-1.3 times the amount of epichlorohydrin added. After the reaction is completed, adjust the pH to neutral, remove the solvent, and obtain solid A; S2. Add iminodiacetonitrile and polyamino small molecules in a molar ratio of (1-3):1 to tetrahydrofuran, wherein the total molar amount of iminodiacetonitrile and polyamino small molecules is the same as that of epichlorohydrin, stir until dissolved, add solid A, raise the temperature to 55-65°C, remove the solvent after the reaction is completed, obtain a solid, and then add the solid to a sodium hydroxide solution for hydrolysis to obtain product B; S3. Under nitrogen atmosphere, product B is dissolved in DMF, and then a free radical initiator is added, wherein the molar amount of the free radical initiator is 0.8-1.2% of the enamine, and a dehalogenating agent is obtained by free radical polymerization at a temperature of 60-70°C.

[0010] By adopting the above technical scheme, two monomer molecules containing double bonds can be prepared by reacting enamine with epichlorohydrin and then reacting with iminodiacetonitrile or polyamino small molecules. Epichlorohydrin plays a role in connecting enamine and iminodiacetonitrile or polyamino small molecules. Then, after the polymerization reaction, it is hydrolyzed in an alkaline environment, and the acetonitrile group is hydrolyzed to obtain a carboxyl group. Part of the carboxyl group reacts with sodium hydroxide to obtain a sodium carboxylate group. The carboxyl group and the sodium carboxylate group can increase the polarity of the dehalogenating agent, so that it can be more easily dissolved in dimethyl carbonate, which is convenient for the dehalogenation reaction with vinyl chlorocarbonate. In addition, the increase in its polarity is conducive to more complete recovery of the dehalogenating agent.

[0011] Preferably, the molar ratio of the iminodiacetonitrile to the polyamino small molecule is 2:1.

[0012] By adopting the above technical scheme, the polyamino small molecules are beneficial to the dehalogenation reaction, the acetonitrile group is beneficial to the polarity of the dehalogenating agent, and its polarity has a great influence on its recovery rate from the reaction system. When the molar ratio of iminodiacetonitrile and polyamino small molecules is 2:1, it can better take into account the dehalogenation effect and recovery rate, which is a better ratio.

[0013] Preferably, the polyamino small molecule is one or more of L-arginine, p-phenylenediamine, m-phenylenediamine, and 2,3-diaminopyridine.

[0014] By adopting the above technical solutions, these molecules can theoretically achieve technical effects similar to those of the present application, which are not explored one by one in the examples.

[0015] Preferably, the free radical initiator is azobisisobutyronitrile or azobisisoheptanenitrile.

[0016] By adopting the above technical scheme, azobisisobutyronitrile or azobisisoheptanenitrile can achieve a good polymerization effect, and a dehalogenating agent with excellent dehalogenating effect can be prepared.

[0017] Preferably, the enamine is one or both of allylamine and diallylamine.

[0018] By adopting the above technical solution, allylamine and diallylamine both have an amino group and a double bond and can fully react with epichlorohydrin.

[0019] As a preference: the method for recovering the dehalogenating agent is as follows: Ether is added dropwise to the solution A after distillation until the precipitate no longer increases, the precipitate is filtered to obtain the precipitate, sodium hydroxide solution is added dropwise after the precipitate is dried, the reaction is stirred at 45-55° C., ether is added dropwise again until the precipitate no longer increases, and the precipitate is filtered to obtain the recovered dehalogenating agent.

[0020] By adopting the above technical scheme and utilizing the principle of like dissolves like, the dehalogenating agent can be separated from the reaction system by changing the polarity of the solvent, and then the amino group can be restored by reacting in a strong base, thereby regaining the dehalogenating effect and achieving the technical effect of reuse.

[0021] In summary, the present application includes at least one of the following beneficial technical effects: 1. The reaction of the present application is carried out in a microchannel reactor. Compared with the traditional process, the reaction mass transfer and heat release efficiency is higher, the raw material contact is more complete, and the reaction is safer; and the dehalogenating agent of the present application adopts a polymer containing an amino group, which can be dissolved in the same solvent and fully contact with chloroethylene carbonate, thereby promoting the dechlorination reaction; and through experimental exploration, the purity of the obtained vinylene carbonate is above 99.99%, and the yield is 90.4% and above. Different from the traditional dehalogenating agent triethylamine, it is almost non-volatile and not easy to enter the vinylene carbonate product. In addition, based on the presence of carboxylate and amino groups in the dehalogenating agent, it has a higher polarity and can be separated from the reaction system by adjusting the polarity of the solvent, recovered by reaction with an alkali, and reused; compared with triethylamine which is not easy to recover, the dehalogenating agent of the present application has more advantages.

[0022] 2. The purity of vinylene carbonate obtained by the preparation method of the present application can reach 99.99%, and the yield can be 91.0% or above, and the highest can reach 95.9%; and the recovery rate of the dehalogenating agent is 90.4% or above, and the highest can reach 98.1%. DETAILED DESCRIPTION

[0023] The present application is further described in detail below in conjunction with the specific contents.

[0024] raw material The raw materials in the preparation examples and embodiments of the present application were all purchased from commercial sources and were all analytically pure.

[0025] Preparation Example Preparation Example 1 A dehalogenating agent, the preparation method of which is as follows: S1. Add 15 g of diallylamine to 500 g of tetrahydrofuran, stir until dissolved, heat to 55 ° C, add epichlorohydrin in an amount equimolar to diallylamine, the addition rate is 1 mL / min, and stir while adding. After the addition is complete, stir and react for 4 h, then add a 40% sodium hydroxide aqueous solution, wherein the amount of sodium hydroxide is 1.2 times the amount of epichlorohydrin added, and stir and react for 1 h, then adjust the pH to 7 with hydrochloric acid, and remove the solvent by rotary evaporation to obtain solid A; S2, in 500g of tetrahydrofuran, add iminodiacetonitrile and L-arginine in a molar ratio of 2: 1, the total molar amount of iminodiacetonitrile and L-arginine is the same as that of epichlorohydrin, stir until dissolved, add solid A, heat to 60 ° C, stir and react for 8h, and remove the solvent by rotary evaporation to obtain a solid, which is then added to a sodium hydroxide solution with a mass fraction of 4% for hydrolysis, the molar amount of sodium hydroxide is 2.5 times the molar amount of iminodiacetonitrile, the temperature is maintained at 60 ° C, the hydrolysis reaction is carried out for 2h, and then the solvent is removed by rotary evaporation to obtain product B; S3. Under nitrogen atmosphere, dissolve product B in 150 g of DMF, then add azobisisobutyronitrile, the molar amount of azobisbutyronitrile being 1% of diallylamine, raise the temperature to 65°C, stir while raising the temperature, react for 15 hours, evaporate and concentrate to remove the solvent, and the dehalogenating agent can be obtained.

[0026] Preparation Example 2 A dehalogenating agent, which is different from Preparation Example 1 in that the molar ratio of iminodiacetonitrile to L-arginine in S2 is 1:1, and the remaining steps are the same as Preparation Example 1.

[0027] Preparation Example 3 A dehalogenating agent, which is different from Preparation Example 1 in that the molar ratio of iminodiacetonitrile to L-arginine in S2 is 3:1, and the remaining steps are the same as Preparation Example 1. Example

[0028] Example 1 A method for preparing vinylene carbonate comprises the following steps: S1, dissolving ethylene chlorocarbonate in dimethyl carbonate, the mass ratio of ethylene chlorocarbonate to dimethyl carbonate is 1:5, to obtain ethylene chlorocarbonate solution; dissolving a dehalogenating agent in dimethyl carbonate, the mass ratio of the dehalogenating agent to dimethyl carbonate is 1:3, to obtain a dehalogenating agent solution; wherein the dehalogenating agent is from Preparation Example 1; S2, the ethylene chlorocarbonate solution and the dehalogenating agent solution are respectively input into the preheater through the metering pump for preheating, and both are preheated to 30 ℃, and then the preheated ethylene chlorocarbonate solution and the dehalogenating agent solution are respectively input into the microchannel of the microchannel reactor for mixed reaction, the temperature is controlled to be 50 ℃, the mixed reaction is 8min, the flow rate of the ethylene chlorocarbonate solution is 0.3mL / min, and the flow rate of the dehalogenating agent solution is controlled to make the mass of the dehalogenating agent 5 times that of ethylene chlorocarbonate. After the reaction is completed, the product flows out through the outlet of the microchannel reactor to obtain solution A; S3, transferring solution A into a distillation kettle for distillation, the pressure of the distillation kettle is 10 mmHg, the temperature of the distillate is 35-45°C, sampling and analyzing the obtained distillate, the purity of vinylene carbonate is 99.99%, the yield is 95.6%, the water content is 0.1 ppm, and the free acid content is 0.1 ppm; S4, the recovery steps of the dehalogenating agent are as follows: Ether was added dropwise to the remaining mixture after distillation of solution A until the precipitate stopped increasing, filtered, dried, and then a 5% by mass sodium hydroxide solution was added dropwise to the precipitate so that the mass of the precipitate was 3 times the mass of the sodium hydroxide. The temperature was raised to 50° C., stirred for reaction for 1 h, and ether was added dropwise until the precipitate stopped increasing to obtain a recovered dehalogenating agent. The ammonium salt groups of the recovered dehalogenating agent were restored to amino and imino groups and could be reused. The recovery rate of the dehalogenating agent was 97.3%.

[0029] Example 2 A method for preparing vinylene carbonate, which is different from Example 1 in that the dehalogenating agent comes from Preparation Example 2, and the remaining steps are the same as those of Example 1; the obtained fractions are sampled and analyzed, and the purity of the vinylene carbonate is 99.99%, the yield is 95.9%, the water content is 0.1 ppm, and the free acid content is 0.1 ppm; the recovery rate of the dehalogenating agent is 90.8%.

[0030] Example 3 A method for preparing vinylene carbonate, which is different from Example 1 in that the dehalogenating agent comes from Preparation Example 3, and the remaining steps are the same as those of Example 1; the obtained fractions are sampled and analyzed, and the purity of vinylene carbonate is 99.99%, the yield is 92.1%, the water content is 0.1 ppm, and the free acid content is 0.1 ppm; the recovery rate of the dehalogenating agent is 98.1%.

[0031] Example 4 A method for preparing vinylene carbonate, which is different from Example 1 in that the dehalogenating agent is from the dehalogenating agent recovered in Example 1, and the remaining steps are the same as those in Example 1; the obtained fraction is sampled and analyzed, and the purity of vinylene carbonate is 99.99%, the yield is 95.5%, the water content is 0.1 ppm, and the free acid content is 0.1 ppm; the recovery rate of the dehalogenating agent is 97.2%; It can be seen from the measured experimental data that the dehalogenating agent prepared in Preparation Example 1 performs better in terms of the yield of vinylene carbonate and the recovery rate of the dehalogenating agent, and the dehalogenating effect of the dehalogenating agent after recovery is also better.

[0032] Example 5 A method for preparing vinylene carbonate, which is different from Example 2 in that the dehalogenating agent is from the dehalogenating agent recovered in Example 2, and the remaining steps are the same as those in Example 2; the obtained fraction is sampled and analyzed, and the purity of vinylene carbonate is 99.99%, the yield is 95.7%, the water content is 0.1 ppm, and the free acid content is 0.1 ppm; the recovery rate of the dehalogenating agent is 90.4%; It can be seen from the measured experimental data that, although the dehalogenation effect of the dehalogenation agent prepared in Preparation Examples 1-3 is the best, that is, the yield of vinylene carbonate is higher, the recovery rate of the dehalogenation agent in Preparation Example 2 is lower. When preparing the dehalogenation agent, the recovery of the dehalogenation agent should be considered, and the addition ratio of iminodiacetonitrile should not be too small. In actual production, it can also be adjusted according to production costs.

[0033] Example 6 A method for preparing vinylene carbonate, which is different from Example 3 in that the dehalogenating agent is from the dehalogenating agent recovered in Example 2, and the remaining steps are the same as those in Example 3; the obtained fraction is sampled and analyzed, and the purity of vinylene carbonate is 99.99%, the yield is 91.0%, the water content is 0.1 ppm, and the free acid is 0.1 ppm; the recovery rate of the dehalogenating agent is 97.9%; The measured data show that, although the dehalogenating agent is easy to recover when a large amount of iminodiacetonitrile is added during preparation, its amino content is relatively small and its dehalogenating effect is poor, resulting in a decrease in the yield of ethylene carbonate.

[0034] Comparative Example Comparative Example 1 A method for preparing vinylene carbonate, which is different from that in Example 1, the molar ratio of iminodiacetonitrile to L-arginine is 0.5:1 during the preparation of the dehalogenating agent, and the remaining steps are the same as those in Example 1; the obtained fraction is sampled and analyzed, and the purity of the vinylene carbonate is 99.99%, the yield is 94.4%, the water content is 0.1 ppm, and the free acid content is 0.1 ppm; the recovery rate of the dehalogenating agent is 78.6%; The yield of vinylene carbonate in Comparative Example 1 decreases, which is considered to be because there are more amino groups in the dehalogenating agent and more hydrogen bonds between its molecules, which makes it easy to form micelles in the solution, reducing its dehalogenation effect to a certain extent; and the recovery rate of the dehalogenating agent is greatly reduced, which may be due to the low content of carboxyl groups, which reduces its polarity and is therefore not easy to precipitate from the reaction system.

[0035] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A method for preparing vinylene carbonate, characterized in that: It includes the following steps: S1. preparing a chloroethylene carbonate solution and a dehalogenating agent solution; wherein the dehalogenating agent is a polymer having a plurality of primary or secondary amine groups and a plurality of carboxylic acids or carboxylates in its molecular structure; S2, preheating the ethylene chlorocarbonate solution and the dehalogenating agent solution to 30°C, then respectively inputting the preheated ethylene chlorocarbonate solution and the dehalogenating agent solution into the microchannel of the microchannel reactor for mixed reaction, controlling the temperature to 47-55°C, the mixed reaction for 7-15min, the flow rate of the ethylene chlorocarbonate solution to 0.2-0.4mL / min, and the flow rate of the dehalogenating agent solution to make the mass of the dehalogenating agent 4-6 times that of ethylene chlorocarbonate, after the reaction is completed, the product flows out through the outlet of the microchannel reactor to obtain solution A; S3. Transfer solution A into a distillation kettle for distillation to obtain vinylene carbonate.

2. A method for preparing vinylene carbonate according to claim 1, characterized in that: The solvents of the ethylene chlorocarbonate solution and the dehalogenating agent solution are both dimethyl carbonate, and the mass ratio of the ethylene chlorocarbonate to the dimethyl carbonate is 1:5; the mass ratio of the dehalogenating agent to the dimethyl carbonate is 1:

3.

3. A method for preparing vinylene carbonate according to claim 2, characterized in that: The preparation method of the dehalogenating agent is as follows: S1. Add 15 g of enamine to tetrahydrofuran, stir until dissolved, heat to 50-60° C., dropwise add epichlorohydrin in an amount equimolar to the enamine, stir to react, then add sodium hydroxide solution, wherein the amount of sodium hydroxide is 1.1-1.3 times the amount of epichlorohydrin added. After the reaction is completed, adjust the pH to neutral, remove the solvent, and obtain solid A; S2. Add iminodiacetonitrile and polyamino small molecules in a molar ratio of (1-3):1 to tetrahydrofuran, wherein the total molar amount of iminodiacetonitrile and polyamino small molecules is the same as that of epichlorohydrin, stir until dissolved, add solid A, raise the temperature to 55-65°C, remove the solvent after the reaction is completed, obtain a solid, and then add the solid to a sodium hydroxide solution for hydrolysis to obtain product B; S3. Under nitrogen atmosphere, product B is dissolved in DMF, and then a free radical initiator is added, wherein the molar amount of the free radical initiator is 0.8-1.2% of the enamine, and a dehalogenating agent is obtained by free radical polymerization at a temperature of 60-70°C.

4. A method for preparing vinylene carbonate according to claim 3, characterized in that: The molar ratio of the iminodiacetonitrile to the polyamino small molecule is 2:

1.

5. A method for preparing vinylene carbonate according to claim 3, characterized in that: The polyamino small molecule is one or more of L-arginine, p-phenylenediamine, m-phenylenediamine, and 2,3-diaminopyridine.

6. A method for preparing vinylene carbonate according to claim 3, characterized in that: The free radical initiator is azobisisobutyronitrile or azobisisoheptanenitrile.

7. The method for preparing vinylene carbonate according to claim 1, wherein: The enamine is one or both of allylamine and diallylamine.

8. A method for preparing vinylene carbonate according to claim 1, characterized in that: The recovery method of the dehalogenating agent is as follows: Ether is added dropwise to the solution A after distillation until the precipitate no longer increases, the precipitate is filtered to obtain the precipitate, sodium hydroxide solution is added dropwise after the precipitate is dried, the reaction is stirred at 45-55° C., ether is added dropwise again until the precipitate no longer increases, and the precipitate is filtered to obtain the recovered dehalogenating agent.