阅读说明：本技术 一种含氟碳酸乙烯酯的制备方法 (Preparation method of fluorine-containing ethylene carbonate ) 是由 汪许诚 王小龙 于 2020-12-21 设计创作，主要内容包括：本发明公开了一种含氟碳酸乙烯酯的制备方法,该制备方法包括如下步骤：在保护气体保护下,将碳酸乙烯酯熔化,得熔化的碳酸乙烯酯；在紫外光照射下、在保护气体保护下,同时向所述熔化的碳酸乙烯酯中通入氯气和氟化氢,反应,生成含氟碳酸乙烯酯；该方法能够在无溶剂条件下一锅法制成含氟碳酸乙烯酯,操作简单,转化率高,所得的含氟碳酸乙烯酯纯度高,副产少,适合于工业化生产。(The invention discloses a preparation method of fluorine-containing ethylene carbonate, which comprises the following steps: under the protection of protective gas, melting ethylene carbonate to obtain molten ethylene carbonate; under the irradiation of ultraviolet light and under the protection of protective gas, simultaneously introducing chlorine and hydrogen fluoride into the molten ethylene carbonate, and reacting to generate fluorine-containing ethylene carbonate; the method can prepare the fluorine-containing ethylene carbonate by a one-pot method under the solvent-free condition, has simple operation and high conversion rate, and the obtained fluorine-containing ethylene carbonate has high purity and few byproducts, and is suitable for industrial production.)

1. The preparation method of fluorine-containing ethylene carbonate is characterized by comprising the following steps:

under the protection of protective gas, melting ethylene carbonate to obtain molten ethylene carbonate;

under the irradiation of ultraviolet light and under the protection of protective gas, chlorine and hydrogen fluoride are simultaneously introduced into the melted ethylene carbonate to react to generate fluorine-containing ethylene carbonate.

2. The method for preparing fluoroethylene carbonate according to claim 1, wherein the reaction is carried out at 38 to 45 ℃.

3. The method for producing fluoroethylene carbonate according to claim 2, wherein the reaction is carried out by heating in a water bath.

4. The method for preparing fluorine-containing ethylene carbonate as claimed in claim 1, wherein the ultraviolet light irradiation is carried out at a wavelength of 280-380 nm.

5. The method for preparing fluorine-containing ethylene carbonate according to claim 1, wherein the chlorine gas is dried chlorine gas dried by concentrated sulfuric acid, and the hydrogen fluoride is anhydrous hydrogen fluoride.

6. The method according to claim 1, wherein the chlorine gas and the hydrogen fluoride are separately introduced into the molten ethylene carbonate from the bottom.

7. The method according to claim 1, wherein the ethylene carbonate, the chlorine gas and the hydrogen fluoride are fed in a molar ratio of 1: 1 to 2.5.

8. The method for preparing fluorine-containing ethylene carbonate according to claim 1, wherein the method further comprises a post-treatment step, the post-treatment step comprises vacuum distillation and vacuum rectification which are sequentially carried out, and the vacuum distillation is carried out by using a reboiler.

9. The method for preparing fluorine-containing ethylene carbonate according to claim 8, wherein the process for preparing fluorine-containing ethylene carbonate is carried out in a one-pot method.

10. The method for preparing fluorine-containing ethylene carbonate according to claim 1, wherein the specific implementation manner of preparing fluorine-containing ethylene carbonate is as follows: adding molten ethylene carbonate into a tetrafluoro reaction kettle preheated in a water bath under the replacement of protective gas, starting an ultraviolet lamp, introducing dry chlorine and anhydrous hydrogen fluoride from the bottom of the kettle, controlling the temperature of the kettle to be 38-45 ℃, controlling the flow rate of the dry chlorine and the anhydrous hydrogen fluoride to be completely introduced within 4-8h, carrying out heat preservation reaction until the content of the ethylene carbonate in a sample after the reaction is lower than 1%, increasing the flow of the protective gas after the reaction is finished, exhausting other gases, carrying out reduced pressure distillation to obtain a fluorine-containing ethylene carbonate crude product, and then carrying out reduced pressure rectification to prepare the purified fluorine-containing ethylene carbonate.

Technical Field

The invention belongs to the technical field of organic film forming additives of lithium battery electrolytes, particularly relates to fluorine-containing ethylene carbonate, and particularly relates to a preparation method of fluorine-containing ethylene carbonate.

Background

Fluorine-containing ethylene carbonate such as ethylene carbonate FEC (forward error correction) and ethylene carbonate DFEC (double-sided fluoride carbonate) are lithium ion battery electrolyte additives, the performance of an SEI (solid electrolyte interphase) film is better, a compact structure layer is formed, impedance is not increased, the electrolyte can be prevented from being further decomposed, and the low-temperature performance of the electrolyte is improved.

The current synthesis of fluorine-containing ethylene carbonate is mainly carried out by a halogen exchange method, direct fluorination and electrochemical fluorination. The direct fluorination method generally refers to that fluorine gas and inert gas are mixed at a certain temperature and directly carry out fluorine substitution reaction with ethylene carbonate. Fluorine gas is directly used for replacing reaction to prepare fluorine-containing ethylene carbonate, so that more byproducts are produced, the equipment requirement is higher, the later purification is more complicated, and the environmental pollution is greater; the halogen exchange method needs to use a large amount of solvent (the solvent has the functions of improving the dispersibility of the dispersed mixture and improving the reaction efficiency and effect), and the solvent needs to be removed firstly and then further purified in the later purification process; the electrochemical fluorination conditions are also harsh, liquid hydrogen fluoride needs to be electrolyzed, and environmental equipment is also required to be higher.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide an improved preparation method of fluorine-containing ethylene carbonate, the method can prepare fluorine-containing ethylene carbonate by a one-pot method under the solvent-free condition, the operation is simple, the conversion rate is high, the purity of the obtained fluorine-containing ethylene carbonate is high, few byproducts are generated, and the method is suitable for industrial production.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a preparation method of fluorine-containing ethylene carbonate comprises the following steps:

under the protection of protective gas, melting ethylene carbonate to obtain molten ethylene carbonate;

under the irradiation of ultraviolet light and under the protection of protective gas, chlorine and hydrogen fluoride are simultaneously introduced into the melted ethylene carbonate to react to generate fluorine-containing ethylene carbonate.

According to some preferred aspects of the invention, the reaction is carried out at 38-45 ℃.

According to some preferred aspects of the invention, the reaction is carried out by heating in a water bath.

According to some preferred aspects of the present invention, the ultraviolet light irradiation is performed at a wavelength of 280-380 nm.

According to some preferred aspects of the invention, the chlorine gas is dried chlorine gas after drying by concentrated sulfuric acid, and the hydrogen fluoride is Anhydrous Hydrogen Fluoride (AHF).

According to some preferred aspects of the present invention, the chlorine gas and the hydrogen fluoride are respectively introduced into the molten ethylene carbonate from the bottom, so that the chlorine gas and the hydrogen fluoride can be maximally utilized and prevented from being carried away by the protective gas.

According to some preferred aspects of the present invention, the feed molar ratio of the ethylene carbonate, the chlorine gas and the hydrogen fluoride is 1: 1-2.5.

According to some preferred aspects of the invention, the preparation method further comprises a post-treatment step, wherein the post-treatment step comprises vacuum distillation and vacuum rectification which are sequentially carried out, and the vacuum distillation is carried out by using a reboiler, so that the increment is increased, and carbonization is prevented. The generated waste gas firstly passes through a saturated calcium chloride absorption tank (for absorbing excessive hydrogen fluoride), and then sequentially passes through a water absorption tank (for recovering HCl) and an alkali liquor absorption tank (for preventing excessive absorption of protective gas).

According to the invention, after post-treatment, the purity of the purified fluorine-containing ethylene carbonate can be more than or equal to 99.95%, the acidity is less than 10ppm, the chroma is less than 10Hazen, and the moisture is less than 10 ppm.

According to the invention, no solvent is used, the crude product is directly distilled under reduced pressure after the reaction is finished, and then the crude product is rectified to obtain the high-purity fluorine-containing ethylene carbonate, the conversion efficiency is high, the operation is simple, the obtained main byproducts are hydrogen chloride and redundant hydrogen fluoride, the hydrogen fluoride is removed through a saturated calcium chloride absorption pool, and the hydrogen chloride can be used for preparing the industrial hydrochloric acid.

According to some preferred aspects of the present invention, the process for preparing fluoroethylene carbonate is carried out in a one-pot process.

According to some preferred aspects of the present invention, the specific embodiments for preparing fluorine-containing ethylene carbonate are as follows: adding molten ethylene carbonate into a tetrafluoro reaction kettle preheated in a water bath under the replacement of protective gas, starting an ultraviolet lamp, introducing dry chlorine and anhydrous hydrogen fluoride from the bottom of the kettle, controlling the temperature of the kettle to be 38-45 ℃, controlling the flow rate of the dry chlorine and the anhydrous hydrogen fluoride to be completely introduced within 4-8h, carrying out heat preservation reaction until the content of the ethylene carbonate in a sample after the reaction is lower than 1%, increasing the flow of the protective gas after the reaction is finished, exhausting other gases, carrying out reduced pressure distillation to obtain a fluorine-containing ethylene carbonate crude product, and then carrying out reduced pressure rectification to prepare the purified fluorine-containing ethylene carbonate.

According to the invention, the ethylene carbonate, chlorine and anhydrous hydrogen fluoride are commercially available, and the purity of the ethylene carbonate is more than or equal to 99.5%.

In the present invention, the structural formula of the monofluoroethylene carbonate FEC is as follows:the structural formula of the difluoroethylene carbonate DFEC is as follows:

in the invention, the reaction process for preparing fluorine-containing ethylene carbonate is shown as follows:

due to the implementation of the technical scheme, compared with the prior art, the invention has the following advantages:

based on the defects that the process for preparing the fluorine-containing ethylene carbonate in the prior art is complex and needs to adopt an organic solvent, the invention innovatively provides a method for preparing the fluorine-containing ethylene carbonate by a one-pot method under the solvent-free condition, the method adopts molten ethylene carbonate as a raw material, then chlorine and hydrogen fluoride gas are introduced simultaneously, so that chlorination and halogen exchange are carried out simultaneously, the solvent is not needed in the whole process, the excellent reaction yield is still obtained, the conversion rate of ethylene carbonate EC is more than 90%, and the yield of the fluorine-containing ethylene carbonate is more than 85%.

Detailed Description

The present invention will be described in further detail with reference to specific examples. It is to be understood that these examples are for the purpose of illustrating the general principles, essential features and advantages of the present invention, and the present invention is not limited by the following examples. The implementation conditions used in the examples can be further adjusted according to specific requirements, and the implementation conditions not indicated are generally the conditions in routine experiments.

In the following examples, all starting materials are either commercially available or prepared by conventional methods unless otherwise specified. The ethylene carbonate, chlorine and anhydrous hydrogen fluoride are commercially available, and the purity of the ethylene carbonate is 99.5%.

Example 1

Downward water bath 40 under nitrogen displacement protectionA1000 ml tetrafluoro reaction kettle (with tetrafluoro stirring machine set, saturated calcium chloride absorption tank, water absorption tank and alkali liquor absorption tank) preheated by 1000 deg.C is added with 400 g (4.318mol) of molten ethylene carbonate (content 99.5%), an ultraviolet lamp (wavelength 280nm) is started, and chlorine (Cl) is introduced into the kettle bottom₂)307 g (4.32mol), Anhydrous Hydrogen Fluoride (AHF)90 g (4.6mol), and a pot temperature of 40 ℃. Controlling the flow rates of chlorine and anhydrous hydrogen fluoride, finishing aeration after 6 hours, keeping the temperature at 45 ℃ for 4 hours for reaction, sampling, and regarding the content of the vinyl carbonate in the sample as 0.82 percent (less than 1 percent) as the end of the reaction. The nitrogen flow is increased, the redundant gas in the kettle is discharged to an absorption cell, 421.31 g of crude monofluoroethylene carbonate is distilled under reduced pressure, GC is 95.6 percent, and the yield is 87.99 percent.

Example 2

Under the protection of nitrogen displacement, 400 g (4.318mol) of molten ethylene carbonate (content: 99.5%) is added into a 1000ml tetrafluoro reaction kettle (with tetrafluoro stirring machine set and saturated calcium chloride absorption tank, water absorption tank and alkali liquor absorption tank) preheated in water bath at 40 ℃, an ultraviolet lamp (wavelength: 280nm) is started, and chlorine (Cl) is introduced into the kettle bottom₂)614 g (8.64mol), Anhydrous Hydrogen Fluoride (AHF)180 g (9.2mol) and a kettle temperature of 40 ℃. Controlling the flow rates of chlorine and anhydrous hydrogen fluoride, finishing aeration after 6 hours, keeping the temperature at 45 ℃ for 4 hours for reaction, sampling, and regarding the content of the vinyl carbonate in the sample as 0.78% (less than 1%) as the end of the reaction. The nitrogen flow is increased, the redundant gas in the kettle is discharged to an absorption cell, 507.35 g of crude difluoroethylene carbonate is distilled under reduced pressure, GC93.64 percent and the yield is 88.72 percent.

Example 3

Under the protection of nitrogen displacement, 4000 g (43.18mol) of molten ethylene carbonate (with the content of 99.5%) is added into a 5000ml tetrafluoro reaction kettle (with a tetrafluoro stirring unit, a saturated calcium chloride absorption tank, a water absorption tank and an alkali liquor absorption tank) preheated in a water bath at 40 ℃, an ultraviolet lamp (with the wavelength of 280nm) is started, and chlorine (Cl) is introduced into the kettle bottom₂)3070 g (43.2mol), Anhydrous Hydrogen Fluoride (AHF)900 g (46mol), and a pot temperature of 40 ℃. Controlling the flow rates of chlorine and anhydrous hydrogen fluoride, finishing aeration after 6 hours, keeping the temperature at 45 ℃ for 6 hours, sampling, and regarding the content of the vinyl carbonate in the sample as 0.58% (less than 1%) as the end of the reaction. Increasing nitrogen flow and discharging excessive gas in the kettleThe product was discharged to an absorption cell, and 4308.6 g of crude monofluoroethylene carbonate was distilled under reduced pressure, GC 96.64% and yield 90.97%.

Further, the crude product is rectified, and 75-88 ℃ fractions are collected under the pressure of 5mmHg, so that 3852.8 g of monofluoroethylene carbonate, 99.975% of GC, 8.5ppm of acidity HFH, 5Hazen of chroma and 7.28ppm of moisture are obtained.

The present invention is described in detail in order to make those skilled in the art understand the content and practice the invention, and the invention is not limited to the above embodiments, and all equivalent changes or modifications made according to the spirit of the invention should be covered by the scope of the invention.