Synthetic method of trifluoroethyl acetate, trifluoroethyl acetate and application of trifluoroethyl acetate

Abstract

The invention discloses a synthesis method of trifluoroethyl acetate, the trifluoroethyl acetate and application of the trifluoroethyl acetate, and the synthesis method at least comprises the following operation steps: S11) adding acetic anhydride and a catalyst into a reactor, dropwise adding trifluoroethanol into the reactor, and reacting the acetic anhydride with the trifluoroethanol to obtain a reaction liquid; and S12) transferring the reaction liquid prepared in the step S11) into a rectifying tower for rectification and purification, and extracting and collecting a trifluoroethyl acetate product from the rectifying tower, according to the method, the trifluoroethyl acetate product with extremely low water content can be obtained, the reaction condition is mild, and the reaction selectivity is high; meanwhile, the prepared trifluoroethyl acetate product is high in purity, extremely low in acetic acid content and basically free of three wastes, and is very suitable for being used as an additive of a battery electrolyte (especially a lithium battery electrolyte).

Description

Technical Field

[0001] The invention belongs to the field of preparation of battery electrolyte additives, and in particular relates to a method for synthesizing trifluoroethyl acetate. The invention also relates to the trifluoroethyl acetate obtained by the synthesis method and application thereof. Background Art

[0002] New energy batteries (especially lithium batteries) have achieved rapid development. As an indispensable raw material for battery electrolyte, electrolyte solvent is also one of the important factors affecting battery performance. However, the solvent of lithium battery electrolyte is still mainly carbonate-based, which has defects such as poor binding performance with new electrodes, poor negative electrode stability under high voltage, incompatibility with lithium metal, poor temperature tolerance, and serious safety problems.

[0003] Existing technologies have been devoted to exploring new electrolytes to adapt to high energy density lithium battery systems. Common strategies include molecular structure engineering of solvents, ionic liquids, and synthetic solid electrolytes. In contrast, the development of new electrolytes is more conducive to rapid commercialization. Introducing functional groups or unique components into the electrolyte solvent molecules can obtain high-performance electrolytes. Studies have found that electrolytes containing fluorinated solvents can overcome many problems associated with traditional electrolytes. Specifically, electrolytes containing trifluoroethyl acetate can form high Li on the graphite surface. + The conductive SEI film reduces the delithiation polarization potential of graphite at low temperatures and increases the low-temperature delithiation capacity. At the same time, the electrolyte can enable LiCoO2 graphite batteries to maintain good cycle performance at 333K (60°C). Therefore, trifluoroethyl acetate is suitable as a co-solvent for wide-temperature electrolytes for lithium-ion batteries.

[0004] However, trifluoroethyl acetate (chemical formula: C4H5F3O2) in the prior art is mainly used in the fields of medicine, pesticides, and organic intermediates. The product purity is relatively poor and cannot meet the current demand for battery electrolytes.

[0005] Therefore, the applicant hopes to seek a synthesis method of trifluoroethyl acetate suitable as a battery electrolyte additive. Summary of the invention

[0006] In view of this, the object of the present invention is to provide a synthesis method of trifluoroethyl acetate, trifluoroethyl acetate and application thereof, which can obtain a trifluoroethyl acetate product with extremely low water content, mild reaction conditions and high reaction selectivity; at the same time, the prepared trifluoroethyl acetate product has high purity, extremely low acetic acid content, and (basically) no three wastes are generated, and is very suitable as an additive for battery electrolyte (especially lithium battery electrolyte).

[0007] The technical solution adopted by the present invention is as follows: A method for synthesizing trifluoroethyl acetate comprises at least the following steps: S11), adding acetic anhydride and a catalyst into a reactor, and dripping trifluoroethanol into the reactor, wherein the acetic anhydride and trifluoroethanol react according to the following reaction formula to obtain a reaction solution; ; S12), transferring the reaction solution prepared in the above step S11) into a distillation tower for distillation and purification, and extracting and collecting the trifluoroethyl acetate product from the distillation tower.

[0008] Preferably, in the step S11), the catalyst includes an acid catalyst or a base catalyst, wherein the acid catalyst includes any one of concentrated sulfuric acid, hydrochloric acid, p-toluenesulfonic acid, methanesulfonic acid, phosphoric acid, nitric acid, ammonium phosphate, ammonium chloride, ammonium sulfate, zinc chloride, titanium tetrachloride, aluminum oxide, and aluminum chloride, or a mixture thereof; the base catalyst includes any one of sodium methoxide, sodium ethoxide, triethylamine, N,N-dimethylaniline, N,N-diisopropylethylamine, pyridine, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, lithium carbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, calcium hydroxide, lithium oxide, sodium oxide, potassium oxide, magnesium oxide, and calcium oxide, or a mixture thereof.

[0009] Preferably, in the step S11), the amount of the catalyst added is 0.05%-10% of the amount of trifluoroethanol added; and / or the mass ratio of the trifluoroethanol to the acetic anhydride is 1:0.5-3.0.

[0010] Preferably, in the step S11), the acetic anhydride and trifluoroethanol are reacted under a target temperature condition; wherein the target temperature range is 0°C-100°C, preferably 60°C-80°C; and / or the reaction time is 3-8 hours, more preferably 4-6 hours.

[0011] Preferably, in the step S11), during the process of adding acetic anhydride and the catalyst into the reactor, the temperature of the reactor is controlled at 0°C-20°C; during the process of dropwise adding trifluoroethanol into the reactor, the temperature of the reactor is controlled at 0°C-30°C.

[0012] Preferably, in the distillation purification process of step S12), the bottom temperature of the distillation tower is controlled to be 80°C-100°C in the early stage, and the trifluoroethyl acetate sample is taken out. After the moisture content and purity of the sample are tested to be qualified, the temperature is gradually increased to start collecting the sample, and the top of the distillation tower is in a reflux state during the collection and collection process, and the sample collection is stopped when the acidity of the sample exceeds the standard.

[0013] Preferably, the conditions for starting to collect samples include: the water content of the sample is less than 20 ppm, the purity of trifluoroethyl acetate is greater than 99.9%, and the acidity is less than 10 ppm; the condition for stopping collecting samples is: the acidity of the sample is greater than 20 ppm; wherein, it is preferred to use an acid-base titration method to test the acidity of the sample; wherein the acidity test method is: using a triethylamine / dimethyl carbonate solution of known concentration to titrate the acid solution to be tested, and judging the titration end point by the color change of the phenolphthalein indicator, thereby calculating the acidity of the product.

[0014] Preferably, the height of the distillation tower is greater than 1.2 meters, and the sample collection port is located on one side of the distillation tower, and is at a height position of 60-75% of the total height of the distillation tower.

[0015] Preferably, trifluoroethyl acetate is prepared by the above-mentioned synthesis method of trifluoroethyl acetate; wherein the water content of the trifluoroethyl acetate is less than 20 ppm, the purity is greater than 99.9%, and the acidity is less than 10 ppm.

[0016] Preferably, an application of the above trifluoroethyl acetate is provided, wherein the trifluoroethyl acetate is used as an additive for battery electrolyte, preferably as an additive for lithium battery electrolyte.

[0017] It should be noted that, when implementing step S11), the present application may have: acetic acid self-condensation reaction and acetic acid and trifluoroethanol esterification reaction, these reactions will not have a negative impact on the main reaction, the specific reaction formula is: Acetic acid self-condensation reaction: ; Esterification reaction of acetic acid and trifluoroethanol: .

[0018] The present application uses acetic anhydride as an acylating agent to react with trifluoroethanol under catalyst conditions. In the entire reaction process, substantially no water is generated, and the water in the system is removed by azeotropic distillation of trifluoroethyl acetate and water in the distillation stage, so that a trifluoroethyl acetate product with extremely low water content can be obtained. The reaction conditions are mild and the reaction selectivity is high. The reaction by-product is acetic acid, which can be well separated from trifluoroethyl acetate through the distillation process, which is beneficial to ensure that the obtained trifluoroethyl acetate product has high purity, extremely low acetic acid content, and (substantially) no three wastes are generated, and is very suitable as an additive for battery electrolytes (especially lithium battery electrolytes). BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flowchart of the preparation steps of the synthesis method of trifluoroethyl acetate in a specific embodiment of the present invention; Figure 2 The GC chromatogram of the trifluoroethyl acetate product collected in Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0020] See also Figure 1 As shown, this embodiment provides a method for synthesizing trifluoroethyl acetate, which at least includes the following steps: S11), adding acetic anhydride and a catalyst into a reactor, and dropping trifluoroethanol into the reactor, and the acetic anhydride and trifluoroethanol react according to the following reaction formula to obtain a reaction solution; ; Preferably, in this step S11), the catalyst includes an acid catalyst or a base catalyst, wherein the acid catalyst includes any one or a mixture of concentrated sulfuric acid, hydrochloric acid, p-toluenesulfonic acid, methanesulfonic acid, phosphoric acid, nitric acid, ammonium phosphate, ammonium chloride, ammonium sulfate, zinc chloride, titanium tetrachloride, aluminum oxide, and aluminum chloride; the base catalyst includes any one or a mixture of sodium methoxide, sodium ethoxide, triethylamine, N,N-dimethylaniline, N,N-diisopropylethylamine, pyridine, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, lithium carbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, calcium hydroxide, lithium oxide, sodium oxide, potassium oxide, magnesium oxide, and calcium oxide.

[0021] Preferably, in order to facilitate sufficient reaction, in this step S11), the amount of catalyst added is 0.05%-10% of the amount of trifluoroethanol added; and / or the mass ratio of trifluoroethanol to acetic anhydride is 1:0.5-3.0.

[0022] Preferably, in order to facilitate sufficient reaction, in this step S11), acetic anhydride and trifluoroethanol are kept warm for reaction under target temperature conditions; wherein the target temperature range is 0°C-100°C, preferably 60°C-80°C; and / or the reaction time is 3-8 hours, more preferably 4-6 hours.

[0023] Preferably, in order to facilitate sufficient reaction, in this step S11), during the process of adding acetic anhydride and the catalyst into the reactor, the temperature of the reactor is controlled at 0°C-20°C, more preferably 15°C-20°C; during the process of dropwise adding trifluoroethanol into the reactor, the temperature of the reactor is controlled at 0°C-30°C, more preferably 20°C-30°C.

[0024] S12), transferring the reaction solution prepared in the above step S11) into a distillation tower for distillation and purification, and extracting and collecting the trifluoroethyl acetate product from the distillation tower; preferably, the height of the distillation tower is greater than 1.2 meters, and the sample extraction and collection port is located on one side of the distillation tower, and it is at a height position of 60-75% of the total height of the distillation tower; Preferably, in the distillation purification process of this step S12), the bottom temperature of the distillation tower is controlled to be 80°C-100°C in the early stage, and the trifluoroethyl acetate sample (mainly the azeotrope of trifluoroethyl acetate and water) is taken out. After the moisture content and purity of the sample are tested to be qualified, the temperature is gradually increased to start collecting the sample, and the top of the distillation tower is in a reflux state during the collection and collection process, and the sample collection is stopped until the acidity of the sample exceeds the standard; Preferably, in this embodiment, the conditions for starting to collect samples include: the water content of the sample is less than 20ppm, the purity of trifluoroethyl acetate is greater than 99.9%, and the acidity is less than 10ppm, more preferably less than 5ppm; the condition for stopping collecting samples is: the acidity of the sample is greater than 20ppm, more preferably greater than 15ppm; wherein, in this embodiment, the acid-base titration method is used to test the acidity of the sample; wherein the acidity test method is: using a triethylamine / dimethyl carbonate solution of known concentration to titrate the acid solution to be tested, and judging the titration end point by the color change of the phenolphthalein indicator, thereby calculating the acidity of the product (that is, the side sample product). Of course, the acidity can also be tested by other test methods, and this embodiment does not impose the sole limitation on this.

[0025] Preferably, this embodiment also proposes a trifluoroethyl acetate, which is prepared by the synthesis method of trifluoroethyl acetate described above; wherein the water content of trifluoroethyl acetate is less than 20 ppm, the purity is greater than 99.9%, and the acidity is less than 10 ppm, more preferably less than 5 ppm.

[0026] Preferably, this embodiment also proposes an application of trifluoroethyl acetate as described above, wherein trifluoroethyl acetate is used as an additive for battery electrolyte, preferably as an additive for lithium battery electrolyte.

[0027] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only 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 should fall within the scope of protection of the present invention.

[0028] On the basis of the above implementation contents, in order to verify the technical effects achieved by the present application, the present application further proposes the following embodiments and comparative examples: Example 1

[0029] Add 411.6 g (4.0 mol) of acetic anhydride and 1.0 g of 80% concentrated sulfuric acid into a 1000 ml reaction bottle; control the temperature at 18°C, add 400.2 g (4.0 mol) of trifluoroethanol dropwise into the reactor, control the temperature at 25°C during the addition, raise the temperature to 60°C after the addition is completed, and keep the temperature for 5 hours to obtain a reaction liquid; detect the reaction liquid by GC (gas chromatography) (excluding acetic acid), and the test results show: acetic anhydride content: 0.3%, trifluoroethanol content: 5.2%, trifluoroethyl acetate content: 93.83%, and unknown impurities totaling 0.67%.

[0030] The reaction solution prepared above was transferred to a distillation tower for distillation and purification, wherein the height of the distillation tower was selected to be 1.5 meters, and a sample collection port was set on one side at a height of 1 meter; the temperature of the tower bottom was controlled to be 90°C, and the azeotrope of trifluoroethyl acetate, water and trifluoroethanol was extracted by distillation, and a total of 153g was extracted; the side sample GC test showed that the water content of the extracted sample was 20ppm, and the purity of trifluoroethyl acetate was 99.91%; at this time, the temperature was raised and the sample (the product of this embodiment 1) was collected. During the extraction and collection process, the top of the distillation tower was in a reflux state; until the acidity of the extracted sample was found to be greater than 10ppm, the sample collection was stopped, and a total of 381g of trifluoroethyl acetate product was collected; The trifluoroethyl acetate product obtained above was subjected to GC detection (see the spectrum for Figure 2 As shown in the figure, the purity of trifluoroethyl acetate is 99.93%, the water content is 18ppm, the acidity is less than 10ppm, and the retention time of trifluoroethyl acetate is 2.669min. Example 2

[0031] Add 823.2g (8.0mol) of acetic anhydride and 1.0g of concentrated sulfuric acid with a concentration of 80% to a 1000ml reaction bottle; control the temperature at 15°C, add 400.2g (4.0mol) of trifluoroethanol to the reactor, control the temperature at 20°C during the addition, heat to 60°C after the addition, and keep the temperature for 5 hours to obtain a reaction solution; detect the reaction solution (excluding acetic acid) by GC (gas chromatography), and the test results show: acetic anhydride content: 53.56%, trifluoroethanol content: 0.1%, trifluoroethyl acetate content: 45.83%, and unknown impurities totaling 0.51%.

[0032] The reaction solution prepared above was transferred to a distillation tower for distillation purification, wherein the height of the distillation tower was selected to be 1.5 meters, and a sample collection port was set on one side at a height of 1 meter; the temperature of the tower bottom was controlled to be 80°C, and the azeotrope of trifluoroethyl acetate and water was extracted by distillation, and a total of 28g was extracted; the GC detection of the side sample showed that the water content of the extracted sample was 17ppm, and the purity of trifluoroethyl acetate was 99.97%; at this time, the temperature was raised and the sample (the product of Example 2) was collected, and the top of the distillation tower was in a reflux state during the extraction and collection process; the sample collection was stopped until the acidity of the extracted sample was found to be greater than 10ppm, and a total of 499g of trifluoroethyl acetate product was collected; The trifluoroethyl acetate product obtained above was subjected to GC detection: the purity of trifluoroethyl acetate was 99.96%, the water content was 11 ppm, and the acidity was less than 5 ppm. Example 3

[0033] Add 823.2 g (8.0 mol) of acetic anhydride and 1.0 g of hydrochloric acid to a 1000 ml reaction bottle; control the temperature at 20°C, add 400.2 g (4.0 mol) of trifluoroethanol to the reactor, control the temperature at 30°C during the addition, raise the temperature to 60°C after the addition is completed, and keep the temperature for 5 hours to obtain a reaction solution; detect the reaction solution by GC (gas chromatography) (excluding acetic acid), and the test results show: acetic anhydride content: 51.28%, trifluoroethanol content: 0.53%, trifluoroethyl acetate content: 47.96%, and unknown impurities totaling 0.23%.

[0034] The reaction solution prepared above was transferred to a distillation tower for distillation purification, wherein the height of the distillation tower was selected to be 1.5 meters, and a sample collection port was set on one side at a height of 1 meter; the temperature of the tower bottom was controlled to be 100° C., and the azeotrope of trifluoroethyl acetate and water was extracted by distillation, and a total of 63 g was extracted; the GC detection of the side sample showed that the water content of the extracted sample was 18 ppm, and the purity of trifluoroethyl acetate was 99.93%, at which time the temperature was raised and the sample (the product of Example 3) was collected, and the top of the distillation tower was in a reflux state during the extraction and collection process; the sample collection was stopped until the acidity of the extracted sample was found to be greater than 10 ppm, and a total of 452 g of trifluoroethyl acetate product was collected; The trifluoroethyl acetate product obtained above was tested by GC: the purity of trifluoroethyl acetate was 99.94%, the water content was 17 ppm, and the acidity was less than 10 ppm.

[0035] Comparative Example 1: The remaining technical solutions of this comparative example 1 are the same as those of Example 1, except that, in this comparative example 1, 1.0 g of concentrated sulfuric acid having a concentration of 80% is not added; a total of 352 g of trifluoroethyl acetate product is collected through the distillation tower; and the purity of trifluoroethyl acetate is 99.2%.

[0036] Comparative Example 2: In this comparative example 2, ethyl trifluoroacetate prepared by the scheme of Example 1 of the previously disclosed CN118496097A was used; after GC detection, the purity of ethyl trifluoroacetate was less than 96%.

[0037] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0038] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for synthesizing trifluoroethyl acetate, characterized in that, At least the following steps are included: S11), adding acetic anhydride and a catalyst into a reactor, and dripping trifluoroethanol into the reactor, wherein the acetic anhydride and trifluoroethanol react according to the following reaction formula to obtain a reaction solution; ； S12), transferring the reaction solution prepared in the above step S11) into a distillation tower for distillation and purification, and extracting and collecting the trifluoroethyl acetate product from the distillation tower.

2. The synthetic method of trifluoroethyl acetate according to claim 1, characterized in that: In the step S11), the catalyst includes an acid catalyst or a base catalyst, wherein the acid catalyst includes any one of concentrated sulfuric acid, hydrochloric acid, p-toluenesulfonic acid, methanesulfonic acid, phosphoric acid, nitric acid, ammonium phosphate, ammonium chloride, ammonium sulfate, zinc chloride, titanium tetrachloride, aluminum oxide, and aluminum chloride, or a mixture thereof; the base catalyst includes any one of sodium methoxide, sodium ethoxide, triethylamine, N,N-dimethylaniline, N,N-diisopropylethylamine, pyridine, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, lithium carbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, calcium hydroxide, lithium oxide, sodium oxide, potassium oxide, magnesium oxide, and calcium oxide, or a mixture thereof.

3. The synthetic method of trifluoroethyl acetate according to claim 1 or 2, characterized in that, In the step S11), the amount of the catalyst added is 0.05%-10% of the amount of trifluoroethanol added; and / or the mass ratio of the trifluoroethanol to the acetic anhydride is 1:0.5-3.

0.

4. The synthetic method of trifluoroethyl acetate according to claim 1, characterized in that: In the step S11), the acetic anhydride and trifluoroethanol are reacted under a target temperature condition; wherein the target temperature range is 0°C-100°C, preferably 60°C-80°C; and / or the reaction time is 3-8 hours, more preferably 4-6 hours.

5. The method for synthesizing trifluoroethyl acetate according to claim 1 or 4, characterized in that: In the step S11), during the process of adding acetic anhydride and the catalyst into the reactor, the temperature of the reactor is controlled at 0°C-20°C; during the process of dripping trifluoroethanol into the reactor, the temperature of the reactor is controlled at 0°C-30°C.

6. The synthetic method of trifluoroethyl acetate according to claim 1, characterized in that: In the distillation purification process of step S12), the bottom temperature of the distillation tower is controlled to be 80°C-100°C in the early stage, and the trifluoroethyl acetate sample is taken out. After the moisture content and purity of the sample are tested to be qualified, the temperature is gradually increased to start collecting the sample. During the collection and collection process, the top of the distillation tower is in a reflux state until the acidity of the sample exceeds the standard and the sample collection is stopped.

7. The method for synthesizing trifluoroethyl acetate according to claim 1 or 6, characterized in that: The conditions for starting to collect samples include: the water content of the sample is less than 20 ppm, the purity of trifluoroethyl acetate is greater than 99.9%, and the acidity is less than 10 ppm; the condition for stopping collecting samples is: the acidity of the sample is greater than 20 ppm; wherein, it is preferred to use an acid-base titration method to test the acidity of the sample; wherein, the acidity test method is: using a triethylamine / dimethyl carbonate solution of known concentration to titrate the acid solution to be tested, and judging the titration end point by the color change of the phenolphthalein indicator, thereby calculating the acidity of the product.

8. The method for synthesizing trifluoroethyl acetate according to claim 1, characterized in that: The height of the distillation tower is greater than 1.2 meters, and the sample collection port is located on one side of the distillation tower, and is at a height position of 60-75% of the total height of the distillation tower.

9. A trifluoroethyl acetate, characterized in that The trifluoroethyl acetate is prepared by the synthesis method of trifluoroethyl acetate according to any one of claims 1 to 8; wherein the water content of the trifluoroethyl acetate is less than 20 ppm, the purity is greater than 99.9%, and the acidity is less than 10 ppm.

10. A use of trifluoroethyl acetate according to claim 9, characterized in that: The trifluoroethyl acetate is used as an additive for battery electrolyte, preferably as an additive for lithium battery electrolyte.

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