A kind of preparation method of vinylene carbonate

Abstract

The invention relates to the technical field of organic synthesis, and discloses a method for preparing vinylene carbonate, comprising the following steps: 1) mixing vinylene carbonate with an organic solvent, heating to a set temperature and stirring to dissolve, to obtain a mixed solution; 2) adding an organic amine to the mixed solution of step 1), and then continuing to stir and react; 3) adding a reducing agent to the reaction solution of step 2) in batches, and continuing to stir and react; 4) performing solid-liquid separation on the liquid after the reaction in step 3), and then performing vacuum distillation and cooling crystallization to obtain a finished vinylene carbonate product. In the present invention, a reducing agent is additionally added in the late stage of the reaction of vinylene carbonate and organic amine, and the generated organic amine hydrochloride is reduced to the organic amine, so as to realize the recovery and application of part of the organic amine hydrochloride solid in the reaction process.

Description

Technical Field

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

[0002] Vinylene carbonate is an important organic synthesis intermediate and is currently mainly used in the electrolyte of lithium batteries. During the use of the battery, it will form a tight structural layer without increasing impedance, which can prevent the electrolyte from further decomposing into a SEI film. It can effectively improve the high and low temperature resistance of lithium-ion electrolytes, and can improve the flame retardancy of lithium-ion electrolytes, thereby increasing the battery cycle life and significantly improving the safety performance of the battery.

[0003] At present, the main method for preparing vinylene carbonate is: adding organic amine to chloroethylene carbonate as a substrate, mixing and reacting to generate a mixture containing vinylene carbonate, and then filtering, separating, desolventizing and distilling to obtain high-purity vinylene carbonate. The above method has the following disadvantages: the method will produce a large amount of organic amine hydrochloride solids; in addition, vinylene carbonate will self-polymerize, and the self-polymer will mix with the organic amine hydrochloride to generate a black viscous substance. On the one hand, vinylene carbonate will be contained in the viscous substance, which is not conducive to the subsequent reaction and further purification. On the other hand, the treatment of a large amount of organic amine hydrochloride by-products increases economic and environmental pressures. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art, provide a method for preparing vinylene carbonate, reduce the amount of organic amine used and the amount of organic amine hydrochloride generated, increase reaction efficiency, and improve the economy and environmental protection of the reaction.

[0005] In order to achieve the above object, the technical solution of the present invention is: a method for preparing vinylene carbonate, characterized in that it comprises the following steps:

[0006] 1) mixing ethylene chlorocarbonate and an organic solvent, heating to a set temperature and stirring to dissolve, to obtain a mixed solution;

[0007] 2) adding an organic amine to the mixed solution of step 1), and then continuing to stir the reaction at a set temperature;

[0008] 3) adding a reducing agent to the reaction solution of step 2) in batches to keep the pH of the solution at 7 to 8, and stirring the reaction at a set temperature;

[0009] 4) The liquid after the reaction in step 3) is subjected to solid-liquid separation, and then subjected to vacuum distillation and cooling crystallization to obtain the finished vinylene carbonate product.

[0010] Furthermore, in step 1), the mass ratio of ethylene chlorocarbonate to the organic solvent is 1:(1-10), and the set temperature is 40-70°C.

[0011] Further; the organic solvent in step 1) is selected from one or more combinations of ethyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, MTBE, dichloromethane, dichloroethane, acetonitrile, methyl propyl ether, dipropyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, tetrahydrofuran, n-hexane, n-heptane, petroleum ether, toluene, and xylene.

[0012] Further; in step 2), the molar ratio of ethylene chlorocarbonate to organic amine is 1: (0.5-1.5), and the reaction is stirred for 30 minutes.

[0013] Furthermore, the organic amine in step 2) is selected from one of monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine and aniline.

[0014] Furthermore, in step 3), the molar ratio of the reducing agent to the organic amine is 1:(1-5), and the reaction is stirred for 4-7 hours.

[0015] Furthermore, in step 3), the reducing agent is selected from one of sodium hydroxide, calcium oxide and anhydrous magnesium sulfate.

[0016] Furthermore, in step 3), the reducing agent is added every 15 to 30 minutes, with 0.5 to 1 g added each time.

[0017] Further; in step 4), the fraction at 72°C / 32mmHg is collected in the vacuum distillation, and the cooling crystallization temperature is 10 to 20°C.

[0018] Beneficial effects of the present invention:

[0019] The present invention adds a reducing agent in the later stage of the reaction between ethylene chlorocarbonate and organic amine to reduce the generated organic amine hydrochloride to organic amine, thereby realizing the recovery and reuse of part of the organic amine hydrochloride solid in the reaction process, thereby reducing the usage of organic amine and the generation of organic amine hydrochloride.

[0020] Since the strong alkaline reducing agent will undergo a hydrolysis reaction with chloroethylene carbonate, capture the chlorine and hydrogen therein and release a large amount of heat, the reducing agent of the present invention is added in batches, so that the alkalinity of the reaction system can be maintained at a relatively low level, the pH is kept at 7-8, and the temperature fluctuation is small and negligible. At the same time, due to the presence of the organic amine / organic amine hydrochloride buffer system, a large amount of decomposition of the raw materials can be avoided. DETAILED DESCRIPTION

[0021] Content: Calculated by subtraction method, that is, by subtracting the sum of the contents of each impurity in the product from 100%.

[0022] Embodiment 1:

[0023] A method for preparing vinylene carbonate comprises the following steps: adding 100g of chloroethylene carbonate (content 75%, 0.61mol) and 100g of dimethyl carbonate into a flask respectively, fixing a reflux condenser device just above the flask, connecting an acid gas absorption device (the gas generated by the reaction is hydrogen chloride, which is absorbed by a sodium bicarbonate solution), heating to 50°C, stirring for 30min to dissolve, and the stirring speed is 300r / min, then dropping 31.29g of triethylamine (content 99%, 0.31mol), stirring at 50°C for 30min. Then, 12g of sodium hydroxide (0.3mol) is added to the reaction solution in batches, once every 15min, 0.5g is added each time, and the pH value of the solution is maintained at 7-8. After the addition is completed, stirring is continued at 50°C for 4h, and then sampling is taken to detect that the content of chloroethylene carbonate is 0.3%, the reaction mixture is suction filtered, the obtained filtrate is subjected to vacuum distillation, and the 72°C / 32mmHg fraction is collected to obtain a vinylene carbonate crude product. Finally, the crude vinylene carbonate was cooled to 10° C. to obtain 47 g of crystalline vinylene carbonate product with a purity of 99.5% and a yield of 90%.

[0024] Embodiment 2:

[0025] A method for preparing vinylene carbonate comprises the following steps: adding 100g of chloroethylene carbonate (content 75%, 0.61mol) and 100g of dimethyl carbonate into a flask respectively, fixing a reflux condenser device just above the flask, connecting an acid gas absorption device (the gas generated by the reaction is hydrogen chloride, which is absorbed by a sodium bicarbonate solution), heating to 50°C, stirring for 30min to dissolve, and the stirring speed is 300r / min, then dropping 31.29g of triethylamine (content 99%, 0.31mol), stirring at 50°C for 30min. Then, 17g of calcium oxide (0.3mol) is added to the reaction solution in batches, once every 15min, 1g is added each time, and the pH value of the solution is maintained at 7-8. After the addition is completed, stirring is continued at 50°C for 4h, then sampling is taken to detect that the content of chloroethylene carbonate is 0.3%, the reaction mixture is suction filtered, the obtained filtrate is subjected to vacuum distillation, and the fraction of 72°C / 32mmHg is collected to obtain a vinylene carbonate crude product. Finally, the crude vinylene carbonate was cooled to 10° C. to obtain 47 g of crystalline vinylene carbonate product with a purity of 99.5% and a yield of 80%.

[0026] Embodiment 3:

[0027] A method for preparing vinylene carbonate comprises the following steps: adding 100g of chloroethylene carbonate (content 75%, 0.61mol) and 100g of dimethyl carbonate into a flask respectively, fixing a reflux condenser device just above the flask, connecting an acid gas absorption device (the gas generated by the reaction is hydrogen chloride, which is absorbed by a sodium bicarbonate solution), heating to 50°C, stirring for 30min to dissolve, and stirring at a speed of 300r / min, then dropping 43.8g of triethylamine (content 99%, 0.42mol), stirring at 50°C for 30min. Then, adding 7g of sodium hydroxide (0.175mol) in batches into the reaction solution, adding once every 30min, adding 1g each time, and keeping the pH value of the solution at 7-8. After the addition is completed, stirring is continued at 50°C for 4h, then sampling is taken to detect that the content of chloroethylene carbonate is 0.3%, the reaction mixture is suction filtered, the obtained filtrate is subjected to vacuum distillation, and the fraction of 72°C / 32mmHg is collected to obtain a vinylene carbonate crude product. Finally, the crude vinylene carbonate was cooled to 10° C. to obtain 44 g of crystalline vinylene carbonate product with a purity of 99.5% and a yield of 85%.

[0028] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A method for preparing vinylene carbonate, characterized in that: The following steps are involved: 1) mixing ethylene chlorocarbonate with an organic solvent, heating to a set temperature and stirring to dissolve, to obtain a mixed solution; the organic solvent is selected from one or more combinations of ethyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, MTBE, dichloromethane, dichloroethane, acetonitrile, methyl propyl ether, dipropyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, tetrahydrofuran, n-hexane, n-heptane, petroleum ether, toluene, and xylene; 2) adding an organic amine to the mixed solution of step 1), and then continuing to stir and react at a set temperature; the organic amine is selected from one of monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, and aniline; 3) Adding a reducing agent to the reaction solution of step 2) in batches to keep the pH of the solution at 7-8, and stirring the reaction at a set temperature; the reducing agent is selected from sodium hydroxide and calcium oxide; 4) The liquid after the reaction in step 3) is subjected to solid-liquid separation, and then subjected to vacuum distillation and cooling crystallization to obtain the finished vinylene carbonate product.

2. The method for preparing vinylene carbonate according to claim 1, wherein: In step 1), the mass ratio of ethylene chlorocarbonate to the organic solvent is 1:(1-10), and the set temperature is 40-70°C.

3. The method for preparing vinylene carbonate according to claim 1, wherein: In step 2), the molar ratio of ethylene chlorocarbonate to organic amine is 1: (0.5-1.5), and the reaction is stirred for 30 minutes.

4. The method for preparing vinylene carbonate according to claim 1, wherein: In step 3), the molar ratio of the reducing agent to the organic amine is 1: (1-5), and the reaction is stirred for 4-7 hours.

5. The method for preparing vinylene carbonate according to claim 1, wherein: The reducing agent in step 3) is added every 15 to 30 minutes, with 0.5 to 1 g added each time.

6. The method for preparing vinylene carbonate according to claim 1, wherein: In step 4), the fraction at 72°C / 32 mmHg is collected in the vacuum distillation, and the cooling crystallization temperature is 10-20°C.