Preparation method of acetic acid 2, 2-difluoroethyl ester

Abstract

The invention belongs to the technical field of organic synthesis, and discloses a preparation method of acetic acid 2, 2-difluoroethyl ester. The preparation method comprises the following steps: (1) dispersing acetate and an iodized salt catalyst in an aprotic polar solvent to obtain a mixed material 1; (2) dissolving 2-chloro-1, 1-difluoroethane and / or 2-bromo-1, 1-difluoroethane in an aprotic polar solvent, so as to obtain a mixed material 2; and (3) in a normal-pressure reflux reactor, heating the mixed material 1 to a reaction temperature, then dropwise adding the mixed material 2, after dropwise adding is completed, continuing to carry out heat preservation reaction until the reaction is completed, and separating a product to obtain the 2, 2-difluoroethyl acetate. The iodized salt is used as the catalyst for the reaction, so that the conversion rate and the yield of the reaction can be obviously improved. By optimizing a solvent and a feeding mode, the loss of reaction raw materials is reduced, the conversion rate is increased, a high-pressure reaction kettle is not needed for reaction, the requirement on equipment is low, the reaction condition is mild, and industrial production is favorably realized.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, and specifically relates to a method for preparing 2,2-difluoroethyl acetate. Background Technology

[0002] With the rapid development of new energy-related industries, higher requirements are being placed on the energy density and safety of lithium batteries. Fluorine has strong electronegativity and weak polarity, and fluorinated solvents or fluorinated additives have advantages such as low melting point, high flash point, and high oxidative decomposition voltage. 2,2-Difluoroethyl acetate (DFEA) is an important fluorinated compound with wide applications and broad prospects in the fields of electrolytes and medicine. As an additive, DFEA can improve the viscosity and conductivity of electrolytes, storage performance, cycle performance, and enhance the stability of the negative electrode.

[0003] Currently, the main methods for preparing DFEA are: (1) using 2,2-difluoroethanol and acetyl chloride as raw materials, and preparing 2,2-difluoroethyl acetate by acylation under the action of an acid scavenger. This method uses expensive 2,2-difluoroethanol as raw material, resulting in high production costs. (2) using tetrafluoroethylene and 2-chloro-1,1-difluoroethane (R142) as raw materials, the tetrafluoroethylene is first reacted to generate 1,1,2,2-tetrafluoroethyl ether, and then blended with R142 to prepare DFEA. This reaction process is complex, the process route is too long, and it is not easy to implement. (3) using R142 and alkali metal acetate as raw materials, and obtaining 2,2-difluoroethyl acetate through a one-step reaction. However, the reaction rate is slow under the condition of no catalyst, resulting in a high loss rate of low-boiling-point R142. At the same time, it has problems of low conversion rate and low yield in actual production. R142 has a boiling point below 40℃ and begins to vaporize at room temperature (25℃). It is extremely easy to vaporize during high-temperature reactions. Furthermore, R142 is a Freon derivative, and its volatilization causes serious air pollution, making post-treatment a serious problem. Summary of the Invention

[0004] In view of the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide a method for preparing 2,2-difluoroethyl acetate.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for preparing 2,2-difluoroethyl acetate includes the following preparation steps:

[0007] (1) Disperse acetate and iodide catalysts in an aprotic polar solvent to obtain mixture 1;

[0008] (2) Dissolve 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane in an aprotic polar solvent to obtain mixture 2;

[0009] (3) In an atmospheric pressure reflux reactor, the mixture 1 is heated to the reaction temperature, and then the mixture 2 is added dropwise. After the addition is completed, the reaction is kept at the temperature until the reaction is completed. After the product is separated, 2,2-difluoroethyl acetate is obtained.

[0010] Further, the acetate in step (1) is an alkali metal acetate, more preferably sodium acetate, potassium acetate, or ammonium acetate.

[0011] Furthermore, the iodine salt catalyst mentioned in step (1) is preferably potassium iodide, sodium iodide, or ammonium iodide.

[0012] Further, the aprotic polar solvent mentioned in steps (1) and (2) refers to an aprotic polar solvent containing any one or two of the three elements N, O and F, more preferably dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF) and N,N-dimethylpropionamide (DMPA).

[0013] Furthermore, the molar ratio of the acetate to 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane is preferably 0.9 to 2:1.

[0014] Furthermore, the molar ratio of the iodide catalyst to 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane is preferably 0.01 to 0.2:1.

[0015] Furthermore, the mass of the aprotic polar solvent in the mixture 1 is preferably 1 to 20 times the mass of 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane, more preferably 3 to 10 times the mass of 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane.

[0016] Furthermore, the mass of the aprotic polar solvent in the mixture 2 is preferably 1 to 3 times the mass of 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane.

[0017] Furthermore, the reaction temperature in step (3) is 60–160°C, more preferably 120–140°C.

[0018] Furthermore, the dripping time of the mixture 2 is 0 to 8 hours, more preferably 1 to 4 hours.

[0019] Furthermore, the reaction is kept at a constant temperature for 1 to 6 hours after the addition is completed.

[0020] Further, the product separation method in step (3) is as follows: after cooling the reaction solution to room temperature, filter it, and distill the filtrate under reduced pressure to obtain 2,2-difluoroethyl acetate.

[0021] The preparation method of the present invention relates to the following reaction formula:

[0022]

[0023] In the formula, X represents Cl or Br, and M represents an alkali metal element.

[0024] The principle of this invention is as follows: A nonprotic polar solvent containing N, O, and F can form strong hydrogen bonds with 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane, making them less prone to vaporization and loss during the reaction, thus increasing yield and conversion. Simultaneously, this nonprotic polar solvent favors the solvation of haloalkanes, promoting nucleophilic substitution reactions. Therefore, a larger amount of solvent is more conducive to the reaction and reduces the vaporization loss of 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane, until the solvent amount becomes too large, the system concentration decreases, and the reaction rate no longer increases. Iodide ions are excellent nucleophiles and also excellent leaving groups. By adding a small amount of iodide salt catalyst to the synthesis reaction of this application, the leaving groups of 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane, such as chloride or bromide ions, are easily attacked and lost by iodide ions to form iodoalkanes. The iodine in the iodoalkane is then easily attacked and lost by acetate nucleophiles, thus accelerating the reaction rate.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] (1) In this invention, iodine salt is used as a catalyst for the reaction of acetate with 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane, which can significantly improve the conversion rate and yield of the reaction.

[0027] (2) By selecting aprotic polar solvents containing any one or two of the three elements N, O, and F, the solvation effect of 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane can be enhanced, thus promoting the reaction. These solvents can form strong hydrogen bonds with 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane, making them less prone to vaporization loss at higher reaction temperatures.

[0028] (3) The preparation method of the present invention increases the amount of solvent and improves the feeding method (by adding 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane dropwise). It utilizes the strong hydrogen bonding between 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane and the aprotic polar solvent to make 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane less likely to vaporize and be lost during the reaction. Combined with the use of a catalyst, the yield and conversion rate are ensured and improved. The reaction does not require a high-pressure reactor, has low equipment requirements, and the reaction conditions are mild, which is conducive to industrial production. In addition, the solvent can be reused and recycled, which has a low impact on cost. Attached Figure Description

[0029] Figure 1 and Figure 2 The 1H NMR spectra of 2,2-difluoroethyl acetate obtained in the examples are shown below. 1 H-NMR and carbon spectrum 13 C-NMR). Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0031] Example 1

[0032] A method for preparing 2,2-difluoroethyl acetate includes the following preparation steps:

[0033] (1) Disperse potassium acetate and potassium iodide catalysts in DMSO solvent to obtain mixture 1; wherein the molar ratio of potassium acetate to R142 is 1:1, the molar ratio of potassium iodide to R142 is 0.1:1, and the amount of DMSO solvent is 3 times the mass of R142.

[0034] (2) Dissolve 2-chloro-1,1-difluoroethane (R142) in 1 times its mass of DMSO solvent to obtain mixture 2.

[0035] (3) In a conventional atmospheric pressure reflux reactor, mixture 1 was heated to 120℃, and then mixture 2 was added dropwise. The dropwise addition time of mixture 2 was controlled to be 0h, 0.5h, 1h, 2h, 3h, 4h and 8h respectively. After the dropwise addition was completed, the reaction was continued at the temperature for 2h. After the reaction was completed, the reaction solution was cooled to room temperature and filtered to obtain the filtrate and inorganic salts. The filtrate was then subjected to vacuum distillation to obtain high-purity 2,2-difluoroethyl acetate (DFEA). The proton NMR spectrum of the obtained 2,2-difluoroethyl acetate (DFEA) is shown in the figure. 1 H-NMR and carbon spectrum 13 C-NMR) respectively as Figure 1 and Figure 2 As shown.

[0036] Calculate the R142 loss rate (1-M) at different dropping times. 反应后R142 / M R142初始加入 ×100%), the mass of DFEA and the mass of residual R142 in the reaction solution were detected by gas chromatography (M). 残余R142 Convert the DFEA mass to R142 mass (M). DFEA折算 The mass M after the reaction was obtained. 反应后R142 =M DFEA折算 +M 残余R142 ) and conversion rate (M DFEA折算 / M 反应后R142 (×100%), the results are shown in Table 1 below.

[0037] Table 1

[0038] Dropping time / h R142 loss rate / % Conversion rate / % 0 3.86 99.12 0.5 1.21 99.32 1 0.43 99.31 2 0.22 99.32 3 0.14 99.33 4 0.1 99.32 8 0.09 99.31

[0039] As shown in Table 1, when the dropping time is 0 (i.e., R142 is added all at once for the reaction), the R142 loss rate increases significantly. This indicates that the preparation method of this invention, which uses a low-boiling-point raw material (R142) for a dropping reaction, can reduce the vaporization loss of the raw material during the reaction process. When the dropping time is controlled between 1 and 4 hours, the R142 loss rate can be controlled below 0.5%. After the dropping time exceeds 4 hours, the change in the R142 loss rate is not significant.

[0040] Example 2

[0041] A method for preparing 2,2-difluoroethyl acetate includes the following preparation steps:

[0042] (1) Disperse potassium acetate and potassium iodide catalysts in DMSO solvent to obtain mixture 1; wherein the molar ratio of potassium acetate to R142 is 1:1, the molar ratio of potassium iodide to R142 is 0.1:1, and the amount of DMSO solvent used is 1, 2, 3, 5, 10, 12, 14, 16, 18 and 20 times the mass of R142, respectively.

[0043] (2) Dissolve 2-chloro-1,1-difluoroethane (R142) in 1 times its mass of DMSO solvent to obtain mixture 2.

[0044] (3) In a conventional atmospheric pressure reflux reactor, the mixture 1 is heated to 120°C, and then the mixture 2 is added dropwise. The dropwise addition time of the mixture 2 is controlled to be 2h. After the dropwise addition is completed, the reaction is continued to be kept at the temperature for 2h. After the reaction is completed, the reaction solution is cooled to room temperature and filtered to obtain the filtrate and inorganic salt. The filtrate is then distilled under reduced pressure to obtain high-purity 2,2-difluoroethyl acetate (DFEA).

[0045] The R142 loss rate and conversion rate of mixture 1 in this embodiment under different DMSO solvent dosages are shown in Table 2 below.

[0046] Table 2

[0047] Material 1 Solvent dosage / time R142 loss rate / % Conversion rate / % 1 6.09 94.70 2 1.03 96.21 3 0.22 99.32 5 0.06 99.58 10 0.04 99.86 12 0.04 99.88 14 0.03 99.89 16 0.02 99.90 18 0.02 99.92 20 0.02 99.92

[0048] As shown in Table 2, when the solvent dosage in mixture 1 is less than 3 times the normal amount, the R142 loss rate increases significantly and the conversion rate decreases significantly. Increasing the solvent dosage to more than 10 times has little effect on the R142 loss rate and conversion rate. This is because a larger solvent dosage is more conducive to the reaction and reduces the vaporization loss of R142, until the solvent dosage becomes too large, the system concentration decreases, and the reaction rate no longer increases.

[0049] Example 3

[0050] A method for preparing 2,2-difluoroethyl acetate includes the following preparation steps:

[0051] (1) Disperse potassium acetate and potassium iodide catalysts in DMSO solvent to obtain mixture 1; wherein the molar ratio of potassium acetate to R142 is 1:1, the molar ratio of potassium iodide to R142 is 0.1:1, and the amount of DMSO solvent is 3 times the mass of R142.

[0052] (2) Dissolve 2-chloro-1,1-difluoroethane (R142) in 0, 1, 2 and 3 times the mass of DMSO solvent respectively to obtain mixture 2.

[0053] (3) In a conventional atmospheric pressure reflux reactor, the mixture 1 is heated to 120°C, and then the mixture 2 is added dropwise. The dropwise addition time of the mixture 2 is controlled to be 2h. After the dropwise addition is completed, the reaction is continued to be kept at the temperature for 2h. After the reaction is completed, the reaction solution is cooled to room temperature and filtered to obtain the filtrate and inorganic salt. The filtrate is then distilled under reduced pressure to obtain high-purity 2,2-difluoroethyl acetate (DFEA).

[0054] The R142 loss rate and conversion rate of mixture 2 in this embodiment under different DMSO solvent dosages are shown in Table 3 below.

[0055] Table 3

[0056] Material 2 Solvent dosage / time R142 loss rate / % Conversion rate / % 0 9.67 95.37 1 0.22 99.32 2 0.15 99.42 3 0.08 99.55

[0057] As shown in Table 3, when the added raw material R142 was not dissolved in solvent beforehand, the R142 loss rate increased significantly and the conversion rate decreased significantly. A lower R142 loss rate and a higher conversion rate were achieved when the amount of solvent used in the added mixture 2 was 1 to 3 times that required for the final addition.

[0058] Example 4

[0059] A method for preparing 2,2-difluoroethyl acetate includes the following preparation steps:

[0060] (1) Disperse potassium acetate and potassium iodide catalysts in DMSO solvent to obtain mixture 1; wherein the molar ratio of potassium acetate to R142 is 0.9:1, 1.5:1 and 2:1, respectively, the molar ratio of potassium iodide to R142 is 0.1:1, and the amount of DMSO solvent is 3 times the mass of R142.

[0061] (2) Dissolve 2-chloro-1,1-difluoroethane (R142) in 1 times its mass of DMSO solvent to obtain mixture 2.

[0062] (3) In a conventional atmospheric pressure reflux reactor, the mixture 1 is heated to 120°C, and then the mixture 2 is added dropwise. The dropwise addition time of the mixture 2 is controlled to be 2h. After the dropwise addition is completed, the reaction is continued to be kept at the temperature for 2h. After the reaction is completed, the reaction solution is cooled to room temperature and filtered to obtain the filtrate and inorganic salt. The filtrate is then distilled under reduced pressure to obtain high-purity 2,2-difluoroethyl acetate (DFEA).

[0063] The results of R142 loss rate and conversion rate (the conversion rate under the condition of potassium acetate:R142 being 0.9 is calculated as the actual yield of DFEA / the theoretical yield of all potassium acetate reaction) in this embodiment are shown in Table 4 below.

[0064] Table 4

[0065] Potassium acetate: R142 R142 loss rate / % Conversion rate / % 0.9 0.23 98.97 1.5 0.21 99.33 2 0.20 99.34

[0066] As can be seen from the results in Table 4, the molar ratio of acetate to halodifluoroethane has little effect on the loss rate and conversion rate of R142.

[0067] Example 5

[0068] A method for preparing 2,2-difluoroethyl acetate includes the following preparation steps:

[0069] (1) Disperse potassium acetate and potassium iodide catalysts in DMSO solvent to obtain mixture 1; wherein the molar ratio of potassium acetate to R142 is 1:1, the molar ratio of potassium iodide to R142 is 0, 0.01:1, 0.02:1, 0.05:1, 0.15:1 and 0.2:1 respectively, and the amount of DMSO solvent is 3 times the mass of R142.

[0070] (2) Dissolve 2-chloro-1,1-difluoroethane (R142) in 1 times its mass of DMSO solvent to obtain mixture 2.

[0071] (3) In a conventional atmospheric pressure reflux reactor, the mixture 1 is heated to 120°C, and then the mixture 2 is added dropwise. The dropwise addition time of the mixture 2 is controlled to be 2h. After the dropwise addition is completed, the reaction is continued to be kept at the temperature for 2h. After the reaction is completed, the reaction solution is cooled to room temperature and filtered to obtain the filtrate and inorganic salt. The filtrate is then distilled under reduced pressure to obtain high-purity 2,2-difluoroethyl acetate (DFEA).

[0072] The results of R142 loss rate and conversion rate under different catalyst dosages (potassium iodide: R142) in this embodiment are shown in Table 5 below.

[0073] Table 5

[0074]

[0075]

[0076] As can be seen from the results in Table 5, by adding iodized salt as a catalyst, the present invention can significantly improve the reaction conversion rate and reduce the R142 loss rate.

[0077] Example 6

[0078] A method for preparing 2,2-difluoroethyl acetate includes the following preparation steps:

[0079] (1) Disperse acetate and iodide catalysts in an aprotic polar solvent to obtain mixture 1; wherein the molar ratio of acetate to R142 is 1:1, the molar ratio of iodide catalyst to R142 is 0.1:1, and the amount of aprotic polar solvent is 3 times the mass of R142.

[0080] (2) Dissolve 2-chloro-1,1-difluoroethane or 2-bromo-1,1-difluoroethane in an aprotic polar solvent of equal mass to obtain mixture 2.

[0081] (3) In a conventional atmospheric pressure reflux reactor, the mixture 1 is heated to 120°C, and then the mixture 2 is added dropwise. The dropwise addition time of the mixture 2 is controlled to be 2h. After the dropwise addition is completed, the reaction is continued to be kept at the temperature for 2h. After the reaction is completed, the reaction solution is cooled to room temperature and filtered to obtain the filtrate and inorganic salt. The filtrate is then distilled under reduced pressure to obtain high-purity 2,2-difluoroethyl acetate (DFEA).

[0082] The R142 loss rate and conversion rate results of this embodiment under different acetate, catalyst, solvent and halodifluoroethane selection conditions are shown in Table 6 below.

[0083] Table 6

[0084]

[0085]

[0086] As can be seen from the results in Table 6, the present invention can achieve a low R142 loss rate and a high conversion rate under different acetate, catalyst, solvent and halodifluoroethane reaction conditions.

[0087] Example 7

[0088] A method for preparing 2,2-difluoroethyl acetate includes the following preparation steps:

[0089] (1) Disperse potassium acetate and potassium iodide catalysts in DMSO solvent to obtain mixture 1; wherein the molar ratio of potassium acetate to R142 is 1:1, the molar ratio of potassium iodide to R142 is 0.1:1, and the amount of DMSO solvent is 3 times the mass of R142.

[0090] (2) Dissolve 2-chloro-1,1-difluoroethane (R142) in 1 times its mass of DMSO solvent to obtain mixture 2.

[0091] (3) In a conventional atmospheric pressure reflux reactor, the mixture 1 was heated to 60℃, 80℃, 100℃, 120℃, 140℃ and 160℃ respectively, and then the mixture 2 was added dropwise. The dropwise addition time of the mixture 2 was controlled to be 2h. After the dropwise addition was completed, the reaction was continued to be kept at the temperature for 2h. After the reaction was completed, the reaction solution was cooled to room temperature and filtered to obtain the filtrate and inorganic salt. The filtrate was then distilled under reduced pressure to obtain high purity 2,2-difluoroethyl acetate (DFEA).

[0092] The R142 loss rate and conversion rate results of this embodiment at different reaction temperatures are shown in Table 7 below.

[0093] Table 7

[0094]

[0095]

[0096] As shown in Table 7, the conversion rate increases significantly with increasing reaction temperature. While the conversion rate remains relatively stable above 140℃, the R142 loss rate increases significantly. A high conversion rate and a low R142 loss rate can be maintained within the reaction temperature range of 120–140℃.

[0097] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing 2,2-difluoroethyl acetate, characterized in that, The preparation steps include the following: (1) Disperse acetate and iodide catalysts in an aprotic polar solvent to obtain mixture 1; (2) Dissolve 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane in an aprotic polar solvent to obtain mixture 2; (3) In an atmospheric pressure reflux reactor, the mixture 1 is heated to the reaction temperature, and then the mixture 2 is added dropwise. After the addition is completed, the reaction is kept at the temperature until the reaction is completed. After the product is separated, 2,2-difluoroethyl acetate is obtained.

2. The method for preparing 2,2-difluoroethyl acetate according to claim 1, characterized in that, The acetate in step (1) is an alkali metal acetate, including sodium acetate, potassium acetate, and ammonium acetate; the iodine catalyst is potassium iodide, sodium iodide, and ammonium iodide.

3. The method for preparing 2,2-difluoroethyl acetate according to claim 1, characterized in that, The aprotic polar solvents mentioned in steps (1) and (2) refer to aprotic polar solvents containing any one or two of the three elements N, O, and F, including dimethyl sulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide, and N,N-dimethylpropionamide.

4. The method for preparing 2,2-difluoroethyl acetate according to claim 1, characterized in that, The molar ratio of the acetate to 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane is 0.9 to 2:

1.

5. The method for preparing 2,2-difluoroethyl acetate according to claim 1, characterized in that, The molar ratio of the iodized salt catalyst to 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane is 0.01 to 0.2:

1.

6. The method for preparing 2,2-difluoroethyl acetate according to claim 3, characterized in that, The mass of the aprotic polar solvent in the mixture 1 is 1 to 20 times the mass of 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane.

7. The method for preparing 2,2-difluoroethyl acetate according to claim 3, characterized in that, The mass of the aprotic polar solvent in mixture 1 is 3 to 10 times the mass of 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane; the mass of the aprotic polar solvent in mixture 2 is 1 to 3 times the mass of 2-chloro-1,1-difluoroethane and / or 2-bromo-1,1-difluoroethane.

8. The method for preparing 2,2-difluoroethyl acetate according to claim 1, characterized in that, The reaction temperature in step (3) is 60-160℃; the dropping time of the mixture 2 is 0-8h.

9. The method for preparing 2,2-difluoroethyl acetate according to claim 1, characterized in that, The reaction temperature in step (3) is 120-140℃; the dropping time of the mixture 2 is 1-4h; and the time for continuing the reaction at a constant temperature after the dropping is completed is 1-6h.

10. The method for preparing 2,2-difluoroethyl acetate according to claim 1, characterized in that, The product separation method described in step (3) is as follows: after cooling the reaction solution to room temperature, filter it, and distill the filtrate under reduced pressure to obtain 2,2-difluoroethyl acetate.

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