CN115960072A - Preparation method of chlorinated ethylene carbonate - Google Patents
Preparation method of chlorinated ethylene carbonate Download PDFInfo
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- CN115960072A CN115960072A CN202310045709.2A CN202310045709A CN115960072A CN 115960072 A CN115960072 A CN 115960072A CN 202310045709 A CN202310045709 A CN 202310045709A CN 115960072 A CN115960072 A CN 115960072A
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Abstract
The invention belongs to the field of chlorinated ethylene carbonate, and particularly relates to a preparation method of chlorinated ethylene carbonate. The preparation method comprises the following steps: (1) Preparing chlorinated ethylene carbonate by adopting an ethylene carbonate chlorination method, and terminating the reaction before the end of the chlorination reaction to obtain a reaction solution; (2) Cooling and crystallizing the reaction liquid obtained in the step (1), and separating out ethylene carbonate crystals to obtain a chlorinated ethylene carbonate solution; (3) And (3) rectifying the chloroethylene carbonate solution to remove dichloroethylene carbonate to obtain a chloroethylene carbonate product. The preparation method of the chloroethylene carbonate stops the reaction before the end point of the chlorination reaction, thereby reducing the generation of byproducts; ethylene carbonate is separated by crystallization, and then ethylene dichlorocarbonate as a byproduct is removed by rectification, so that the problem that the ethylene chlorocarbonate and the ethylene carbonate are difficult to separate due to azeotropy is solved, the utilization rate of raw materials is improved, and the production cost is reduced.
Description
Technical Field
The invention belongs to the field of chlorinated ethylene carbonate, and particularly relates to a preparation method of chlorinated ethylene carbonate.
Background
With the increasing demand of the market for lithium ion batteries, the requirements on the performance of the lithium ion Chi Xing are more and more strict. The electrolyte is an important component in the lithium ion battery and is an important factor for determining the performance of the lithium ion battery. Fluoroethylene carbonate and vinylene carbonate are electrolyte additives which are widely used at present, play a very important role in improving the performance of batteries, are both cyclic carbonates, are produced by taking chloroethylene carbonate as an essential intermediate in industrial production, and have higher requirements on the productivity of chloroethylene carbonate along with the increase of the demand of fluoroethylene carbonate and vinylene carbonate.
The prior preparation process of chlorinated ethylene carbonate mainly comprises a sulfonyl chloride method and a chlorine method. By any method, the main content of the chloroethylene carbonate obtained after the chlorination reaction is about 80%, the content of the byproduct dichloroethylene carbonate is 7-8%, and the content of the raw material ethylene carbonate is 6-7%. The direct use of the reaction product can cause the waste of raw materials, and the continuous chlorination can cause the increase of byproducts, thereby influencing the purity and the yield of the chlorinated ethylene carbonate product. For example, after further chlorination, the crude content of ethyl chlorocarbonate can be about 86%, but the content of dichloroethylene carbonate as a by-product is also increased to about 10%, and the content of dichloroethylene carbonate as a by-product is undesirably high.
How to realize the economical efficiency of the production process of the chloroethylene carbonate becomes an important problem for the practical production of the products. The Chinese invention patent application with the application publication number of CN115043813A discloses a high conversion rate preparation method of chlorinated ethylene carbonate, which is characterized in that Ethylene Carbonate (EC) and benzoyl peroxide are put into a reaction device, the reaction device is irradiated by an ultraviolet lamp after the temperature is raised, chlorine is introduced, and the Chlorinated Ethylene Carbonate (CEC) is generated through reaction; stopping introducing chlorine when the reaction is carried out until the content of Ethylene Carbonate (EC) is close to 50 percent, and introducing nitrogen at the constant temperature to obtain a reaction product; rectifying the obtained product, and collecting fractions to obtain a chloroethylene carbonate (CEC) finished product; continuously rectifying the residual material, and recovering to obtain Ethylene Carbonate (EC); the bottom charge, ethylene Dichlorocarbonate (DCEC), was periodically discharged. By the method, the generation of byproducts can be reduced, the utilization rate of the raw material ethylene carbonate is improved, and the purity of the chloroethylene carbonate reaches about 98 percent.
Although the above production method of vinyl chlorocarbonate is improved in terms of reducing the production of by-products and improving the utilization rate of the raw material vinyl carbonate, the purity of the vinyl chlorocarbonate still needs to be further improved.
Disclosure of Invention
The invention aims to provide a preparation method of chlorinated ethylene carbonate, which aims to solve the problem that the purity of the chlorinated ethylene carbonate needs to be improved while ensuring that the generation of byproducts is reduced and the utilization of raw material ethylene carbonate is improved in the existing production method.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a preparation method of chlorinated ethylene carbonate comprises the following steps:
(1) Preparing chlorinated ethylene carbonate by adopting an ethylene carbonate chlorination method, and terminating the reaction before the end of the chlorination reaction to obtain a reaction solution;
(2) Cooling and crystallizing the reaction liquid obtained in the step (1), and separating out ethylene carbonate crystals to obtain a chlorinated ethylene carbonate solution;
(3) And (3) rectifying the chloroethylene carbonate solution to remove dichloroethylene carbonate to obtain a chloroethylene carbonate product.
The preparation method of the chloroethylene carbonate stops the reaction before the chlorination reaction end point, thereby reducing the generation of byproducts; ethylene carbonate is separated by crystallization, and then ethylene dichlorocarbonate as a byproduct is removed by rectification, so that the problem that the ethylene chlorocarbonate and the ethylene carbonate are difficult to separate due to azeotropy is solved, the utilization rate of raw materials is improved, and the production cost is reduced. Because of the pre-separation of the ethylene carbonate, the purity of the chlorinated ethylene carbonate product prepared by the method is more than 99 percent, and the product quality is further improved.
In the prior art CN115043813A, the reaction is stopped when the EC content is close to 50%, which is based on the rectification separation requirement, although the utilization rate of EC is increased to a certain extent, the idle running degree of EC is large, the load of the rectification equipment is increased, and the production efficiency is different. In order to solve this problem, it is preferable that the content of vinyl chlorocarbonate is 60 to 80% in the step (1) for terminating the reaction. More preferably, in the step (1), the content of vinyl chlorocarbonate is 60 to 70% when the reaction is terminated. Under this condition, the production economy is higher and the idling of the raw materials is greatly reduced, which further proves the process rationality of the method of the invention. The chlorination reaction end point is that the content of chloroethylene carbonate is not less than 75%.
In order to further improve the utilization rate of raw materials, it is further preferable that the content of ethylene dichlorocarbonate in the step (1) is less than 2% when the reaction is terminated.
In order to further promote the effective precipitation of the ethylene carbonate crystals, the temperature of the temperature-reducing crystallization in the step (2) is preferably-10 to-60 ℃.
From the comprehensive consideration of the crystal precipitation efficiency and the energy efficiency, in the step (2), the temperature of the cooling crystallization is preferably-40 to-50 ℃. The crystallization time is preferably 4 to 10 hours, more preferably 5 to 9 hours, most preferably 6 to 8 hours. The filtered ethylene carbonate crystal is used as raw material to react again.
Preferably, in the step (1), the ethylene carbonate chlorination method comprises reacting an ethylene carbonate raw material with chlorine under ultraviolet irradiation. The chlorination method of chlorine under ultraviolet irradiation is adopted, the production process is mature, and the stability is good during mass production.
Drawings
FIG. 1 is a process flow diagram for preparing chlorinated ethylene carbonate according to the invention.
Detailed Description
In order to solve the problems of raw material waste caused by low purity of chlorinated ethylene carbonate products, high byproduct content along with the improvement of product purity during reaction, high requirement on equipment during purification and the like in the prior art, the invention provides the following preparation scheme of chlorinated ethylene carbonate:
1) Under the irradiation of ultraviolet light, ethylene carbonate raw material and chlorine gas are reacted at 40-80 ℃, preferably, the reaction is stopped when the content of chloroethylene carbonate in reaction liquid is 60-70% and the content of dichloroethylene carbonate is less than 2%, and tail gas is absorbed by alkali liquor.
2) And (3) cooling and crystallizing the reaction liquid in low-temperature refrigeration equipment to obtain a Chlorinated Ethylene Carbonate (CEC) solution, and returning the crystalline ethylene carbonate to the reaction kettle for continuous reaction after remelting.
3) And (3) carrying out nitrogen blowing pretreatment on the chloroethylene carbonate solution, and then removing dichloroethylene carbonate (DCEC) through rectification to obtain a high-purity chloroethylene carbonate product.
The reaction involved in step 1) is as follows:
in step 1), the molar ratio of ethylene carbonate to chlorine gas is preferably 1 (1.0 to 1.4), more preferably 1:1.2.
in step 1), the reaction temperature is preferably 40 to 80 ℃, more preferably 50 to 70 ℃, and most preferably 60 to 65 ℃. The tail gas absorbing alkali solution may be sodium hydroxide aqueous solution.
In step 2), the crystallization temperature is preferably-10 to-60 ℃, more preferably-30 to-50 ℃, and most preferably-40 to-50 ℃, the crystallization time is preferably 4 to 10 hours, more preferably 5 to 9 hours, and most preferably 6 to 8 hours, and the filtered crystals are re-reacted as a raw material.
In the step 3), the rectification process parameters can be set as follows: the temperature of the bottom of the tower is 90-95 ℃, the temperature of the top of the tower is 35-50 ℃, and the vacuum degree is 300-750 Pa. The byproduct ethylene dichlorocarbonate can be used for preparing other accessory products, such as ethylene difluorocarbonate. In the step, because the rectification mainly realizes the separation of CEC and DCEC, the boiling points of the CEC and DCEC are greatly different, the DCEC is easily separated, and the boiling point of the rest CEC is high (at the bottom), namely the product. The whole required rectifying column height does not need to be too high, the required temperature does not need to be very high, the energy consumption is low, and the separation degree is high.
The following describes the practice of the present invention in detail with reference to specific examples.
Example 1
The preparation method of chloroethylene carbonate of the embodiment, as shown in fig. 1, comprises the following steps:
(1) Adding 330g of ethylene carbonate into a glass reaction kettle with a thermometer, a stirring device and a condensing device, heating to 60 ℃, introducing chlorine gas under the irradiation of ultraviolet light for reacting for 8 hours, and absorbing tail gas by using a sodium hydroxide aqueous solution; the reaction is monitored by a gas chromatograph in the whole reaction process, and the reaction is stopped when the content of chloroethylene carbonate in the reaction liquid is 60.38% and the content of dichloroethylene carbonate is 1.25%, so as to obtain the reaction liquid.
(2) And (3) reducing the temperature of the reaction liquid in a low-temperature refrigeration device in a gradient manner to-40 ℃ at a cooling speed of 5 ℃/h, then maintaining for 6h to finish crystallization to obtain a mixed filtrate of 87.16% chlorinated ethylene carbonate and 11.05% dichloroethylene carbonate in purity, and returning the crystal ethylene carbonate to the reaction kettle for continuous reaction after re-melting.
(3) After the mixed filtrate is pretreated by nitrogen blowing, dichloroethylene carbonate is removed by rectification (the bottom temperature is 90 ℃, the top temperature is 35 ℃ and the vacuum degree is 300 Pa) to obtain 337.3g of chloroethylene carbonate products with the purity of 99.47 percent, and the yield is 73.5 percent.
Example 2
The preparation method of chloroethylene carbonate comprises the following steps:
(1) Adding 400g of ethylene carbonate into a glass reaction kettle with a thermometer, a stirring device and a condensing device, heating to 65 ℃, introducing chlorine gas under the irradiation of ultraviolet light to react for 10.4 hours, and absorbing tail gas by using a sodium hydroxide aqueous solution; the reaction is monitored by a gas chromatograph in the whole reaction process, and the reaction is stopped when the content of chloroethylene carbonate in the reaction liquid is 65.20% and the content of dichloroethylene carbonate is 1.44%, so as to obtain the reaction liquid.
(2) And (3) reducing the temperature of the reaction liquid in a low-temperature refrigeration device in a gradient manner to-45 ℃ at a cooling speed of 5 ℃/h and keeping the temperature for 7h to obtain a mixed filtrate of 88.82% of purity chloroethylene carbonate and 9.51% of dichloroethylene carbonate, and returning the crystal ethylene carbonate to the reaction kettle for continuous reaction after re-melting.
(3) After the mixed filtrate was pretreated by nitrogen bubbling, dichloroethylene carbonate was removed by rectification (column bottom temperature 95 ℃, column top temperature 50 ℃ and vacuum degree 750 Pa) to obtain 427.4g of a chloroethylene carbonate product with a purity of 99.61%, with a yield of 76.8%.
Example 3
The preparation method of chloroethylene carbonate comprises the following steps:
(1) Adding 415g of ethylene carbonate into a glass reaction kettle with a thermometer, a stirring device and a condensing device, heating to 65 ℃, introducing chlorine gas under the irradiation of ultraviolet light to react for 11.5 hours, and absorbing tail gas by using a sodium hydroxide aqueous solution; the reaction is monitored by a gas chromatograph in the whole reaction process, and the reaction is stopped when the content of chloroethylene carbonate in the reaction liquid is 69.62 percent and the content of dichloroethylene carbonate is 1.67 percent, so as to obtain the reaction liquid.
(2) The reaction liquid is cooled in a low-temperature refrigeration device in a gradient manner, the temperature is reduced to-50 ℃ at the cooling speed of 5 ℃/h and is kept for 8h, mixed filtrate of 90.19% purity chloroethylene carbonate and 8.26% dichloroethylene carbonate is obtained, and the crystal ethylene carbonate is re-melted and then returns to the reaction kettle for continuous reaction.
(3) After the mixed filtrate is pretreated by nitrogen blowing, dichloroethylene carbonate is removed by rectification (the bottom temperature is 92 ℃, the top temperature is 40 ℃ and the vacuum degree is 600 Pa) to obtain 462.5g of chloroethylene carbonate products with the purity of 99.75 percent, and the yield is 80.1 percent.
Example 4
The difference between the method for preparing chloroethylene carbonate in the embodiment and the embodiment 1 is that:
in the step (2), the temperature is reduced to-10 ℃ at the speed of 5 ℃/h and kept for 6h to obtain a mixed filtrate of 67.23% of purity chloroethylene carbonate and 21.11% of dichloroethylene carbonate, and the crystal ethylene carbonate is re-melted and then returns to the reaction kettle for continuous reaction.
In the step (3), after the mixed filtrate is pretreated by nitrogen blowing, dichloroethylene carbonate is removed by rectification (the bottom temperature is 90 ℃, the top temperature is 35 ℃, and the vacuum is 300 Pa), and chloroethylene carbonate 195.3g with the purity of 98.91 percent is obtained, and the yield is 57.6 percent.
Example 5
The difference between the method for preparing chloroethylene carbonate in the embodiment and the embodiment 1 is that:
in the step (2), the temperature is reduced to minus 30 ℃ at the speed of 5 ℃/h and kept for 6h to obtain a mixed filtrate of 75.36% of purity chloroethylene carbonate and 15.32% of dichloroethylene carbonate, and the crystal ethylene carbonate is returned to the reaction kettle for continuous reaction after being re-melted.
In the step (3), after the mixed filtrate is pretreated by nitrogen blowing, dichloroethylene carbonate is removed by rectification (the bottom temperature is 90 ℃, the top temperature is 35 ℃ and the vacuum is 300 Pa), so that 226.7g of chloroethylene carbonate with the purity of 99.03 percent is obtained, and the yield is 66.9 percent.
Example 6
The preparation method of chloroethylene carbonate comprises the following steps:
(1) Adding 330g of ethylene carbonate into a glass reaction kettle with a thermometer, a stirring device and a condensing device, heating to 60 ℃, introducing chlorine gas under the irradiation of ultraviolet light for reaction for 12 hours, absorbing tail gas by using a sodium hydroxide aqueous solution, monitoring the reaction by using a gas chromatograph in the whole reaction process, and stopping the reaction to obtain a reaction solution when the content of chloroethylene carbonate in the reaction solution is 69.2 percent and the content of dichloroethylene carbonate in the reaction solution is 4.35 percent.
(2) The reaction liquid is cooled in a low-temperature refrigeration device in a gradient way, crystallized for 6 hours at the temperature of minus 30 ℃ to obtain mixed filtrate of 68.36 percent of purity chloroethylene carbonate and 30.19 percent of dichloroethylene carbonate, and the crystal ethylene carbonate is returned to the reaction kettle for continuous reaction after being re-melted.
(3) After the mixed filtrate is pretreated by nitrogen blowing, dichloroethylene carbonate is removed by rectification (the bottom temperature is 90 ℃, the top temperature is 35 ℃, and the vacuum is 300 Pa), and the chloroethylene carbonate with the purity of 99.03 percent, 204.7g is obtained, and the yield is 60.4 percent.
Example 7
The preparation method of chloroethylene carbonate comprises the following steps:
(1) Adding 330g of ethylene carbonate into a glass reaction kettle with a thermometer, a stirring device and a condensing device, heating to 60 ℃, introducing chlorine gas under the irradiation of ultraviolet light for reacting for 18 hours, absorbing tail gas by using a sodium hydroxide aqueous solution, monitoring the reaction by using a gas chromatograph in the whole reaction process, and stopping the reaction to obtain a reaction solution when the content of chloroethylene carbonate in the reaction solution is 76.9 percent and the content of dichloroethylene carbonate in the reaction solution is 7.3 percent.
(2) And (3) reducing the temperature of the reaction liquid in a low-temperature refrigeration device in a gradient manner, crystallizing for 6 hours at the temperature of minus 30 ℃ to obtain a mixed filtrate of chloroethylene carbonate with the purity of 57.36 percent and 38.19 percent dichloroethylene carbonate, and returning the crystal ethylene carbonate to the reaction kettle for continuous reaction after remelting.
(3) After pretreatment of the mixed filtrate by nitrogen bubbling, ethylene dichlorocarbonate was removed by rectification (bottom temperature 90 ℃, top temperature 35 ℃, vacuum 300 Pa) to obtain 156.5g of ethylene chlorocarbonate with a purity of 99.05% in a yield of 46.2%.
Comparative example
The preparation method of the chloroethylene carbonate of the comparative example comprises the following steps:
(1) Adding 330g of ethylene carbonate into a glass reaction kettle with a thermometer, a stirring device and a condensing device, heating to 60 ℃, introducing chlorine gas under ultraviolet irradiation for reacting for 36 hours, absorbing tail gas by using a sodium hydroxide aqueous solution, monitoring the reaction by using a gas chromatograph in the whole reaction process, and stopping the reaction to obtain a reaction solution when the content of chloroethylene carbonate in the reaction solution is 80.6 percent and the content of dichloroethylene carbonate is 10.8 percent.
(2) After pretreatment of the mixed filtrate by nitrogen blowing, dichloroethylene carbonate is removed by rectification (vacuum 300 Pa), and then temperature rise rectification is carried out again to obtain 141.6g of chloroethylene carbonate with purity of 89.63 percent, and the yield is 37.6 percent.
Claims (7)
1. The preparation method of chlorinated ethylene carbonate is characterized by comprising the following steps:
(1) Preparing chlorinated ethylene carbonate by adopting an ethylene carbonate chlorination method, and terminating the reaction before the end of the chlorination reaction to obtain a reaction solution;
(2) Cooling and crystallizing the reaction liquid obtained in the step (1), and separating out ethylene carbonate crystals to obtain a chlorinated ethylene carbonate solution;
(3) And (3) rectifying the chloroethylene carbonate solution to remove dichloroethylene carbonate to obtain a chloroethylene carbonate product.
2. The process for producing ethylene chlorocarbonate according to claim 1, wherein in the step (1), the content of ethylene chlorocarbonate is 60 to 80% when the reaction is terminated.
3. The process for producing ethylene chlorocarbonate according to claim 2, wherein in the step (1), the content of ethylene chlorocarbonate is 60 to 70% when the reaction is terminated.
4. The process for producing ethylene chlorocarbonate according to claim 2, wherein in the step (1), the content of ethylene dichlorocarbonate is less than 2% when the reaction is terminated.
5. The method for preparing chlorinated ethylene carbonate according to claim 1, wherein in the step (2), the temperature of the cooling crystallization is-10 to-60 ℃.
6. The method for preparing chlorinated ethylene carbonate according to claim 5, wherein in the step (2), the temperature for reducing the temperature and crystallizing is-40 to-50 ℃.
7. The method for preparing chlorinated ethylene carbonate according to any one of claims 1 to 6, wherein in the step (1), the ethylene carbonate chlorination method comprises the reaction of ethylene carbonate raw materials and chlorine gas under the irradiation of ultraviolet light.
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