Preparation method of acetic acid 2, 2-difluoroethyl ester

Abstract

The invention relates to a preparation method of 2, 2-difluoroethyl acetate, and belongs to the field of preparation of 2, 2-difluoroethyl acetate. The preparation method comprises the following steps: reacting bromomethyl acetate with (difluoromethyl) trimethylsilane in an organic solvent in the presence of alkali and a cuprous iodide catalyst to prepare the 2, 2-difluoroethyl acetate. According to the invention, the method for preparing the acetic acid 2, 2-difluoroethyl ester by reacting the bromomethyl acetate with the (difluoromethyl) trimethylsilane is provided for the first time. The raw materials are stable in physical state at high temperature, are not easy to leak, have low requirements on air tightness and pressure resistance of a reaction device, and are convenient to realize; and the reaction raw materials have stable chemical properties, are not easy to decompose and are convenient to store and use.

Description

Technical Field

[0001] The present invention relates to a preparation method of 2,2-difluoroethyl acetate, belonging to the field of the preparation of 2,2-difluoroethyl acetate. Background Art

[0002] 2,2-Difluoroethyl acetate is an important fluorine-containing compound, and its main uses can be used as battery electrolyte additives, chemical reagents, fine chemicals, pharmaceutical intermediates and material intermediates. It has a wide range of uses, good market prospects and high development value.

[0003] Electrolyte additives usually do not participate in the electrode reaction of the battery, but can significantly improve the electrochemical performance of the electrolyte. Commonly used electrolyte additives include film-forming agents, overcharge protection agents, high and low temperature performance improvers, neutralizing agents and flame retardants, etc. Among them, film-forming agents such as fluoroethylene carbonate are commonly used additives.

[0004] The boiling point of 2,2-difluoroethyl acetate is 105°C, and the density is 1.203 g / cm 3 . Its characteristics of high boiling point and density enable it to maintain a stable physical state in a high-temperature environment, which helps to improve the high-temperature cycle performance of the battery. As an additive for battery electrolytes, 2,2-difluoroethyl acetate can significantly improve the charge and discharge efficiency, cycle performance and capacity retention rate of lithium batteries. In high-performance lithium-ion batteries, 2,2-difluoroethyl acetate can replace traditional fluoroethylene carbonate solvents to improve the conductivity and capacity retention rate of the electrolyte. Therefore, in order to better develop and utilize 2,2-difluoroethyl acetate, the synthesis process of 2,2-difluoroethyl acetate is crucial.

[0005] The Chinese patent application with the publication number CN116969837A discloses a preparation method of electronic-grade 2,2-difluoroethyl acetate. Using 2-chloro-1,1-difluoroethane (R142) as the raw material and potassium acetate as the base, a high-temperature reaction is carried out in dimethyl sulfoxide solvent. After the reaction is completed, 2,2-difluoroethyl acetate is obtained by distillation. The reaction temperature is 120°C, which is higher than the boiling point of 2-chloro-1,1-difluoroethane, that is, R142 participates in the reaction in a gaseous form during the reaction process, which easily leads to raw material leakage during the reaction process, and has high requirements for the airtightness and pressure resistance of the reaction device, which is not conducive to large-scale popularization and application.

[0006] The Chinese patent application with the publication number CN113698295A discloses a synthesis method of 2,2-difluoroethyl acetate. By reacting 2,2-difluoroethanol with acetyl chloride under the action of an acid scavenger, it is obtained through an acylation reaction. The reaction process is simple and mild, but the reaction raw material acetyl chloride is extremely easy to hydrolyze when encountering water, and its chemical properties are unstable, and it needs to be prepared and used immediately, resulting in complex operations and easy waste. Summary of the Invention

[0007] The object of the present invention is to provide a preparation method of 2,2-difluoroethyl acetate, so as to solve the problems of easy leakage of reaction raw materials and unstable chemical properties in the synthesis of 2,2-difluoroethyl acetate in the prior art.

[0008] In order to achieve the above object, the technical solution of the present invention is as follows:

[0009] A preparation method of 2,2-difluoroethyl acetate, comprising the following steps: reacting bromomethyl acetate with (difluoromethyl) trimethylsilane in an organic solvent in the presence of a base and a copper iodide catalyst to obtain 2,2-difluoroethyl acetate.

[0010] The preparation method of 2,2-difluoroethyl acetate of the present invention is an exploratory invention. The present invention firstly proposes to react bromomethyl acetate with (difluoromethyl) trimethylsilane to prepare 2,2-difluoroethyl acetate. The raw materials of the present invention have stable physical states at high temperatures, are not easy to leak, have low requirements for the airtightness and pressure resistance of the reaction device, and are easy to implement; moreover, the chemical properties of the reaction raw materials are stable and not easy to decompose, which is convenient for storage and use.

[0011] In order to further improve the yield and purity of 2,2-difluoroethyl acetate, preferably, the reaction conditions further include a nucleophilic catalyst, and the nucleophilic catalyst is 4-dimethylaminopyridine.

[0012] In order to improve the efficiency of difluoromethylation, preferably, the molar ratio of bromomethyl acetate to (difluoromethyl) trimethylsilane is 1:(3-6).

[0013] In order to improve the reaction efficiency and ensure complete reaction, preferably, the reaction temperature is 120-130°C and the time is 18-24 h.

[0014] In order to further improve the yield and purity of 2,2-difluoroethyl acetate, preferably, the organic solvent is any one of N-methylpyrrolidone, N,N-dimethylformamide.

[0015] Preferably, the molar ratio of bromomethyl acetate to the base is 1:(1-3.5).

[0016] Preferably, the base is any one of cesium fluoride and potassium fluoride.

[0017] Preferably, the molar ratio of bromomethyl acetate to copper iodide is 1:(1-1.1).

[0018] Preferably, the molar ratio of bromomethyl acetate to 4-dimethylaminopyridine is 1:(0.02-0.1). Brief Description of the Drawings

[0019] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the product obtained in Example 2 of the present invention. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further described below in conjunction with specific implementation methods.

[0021] The invention prepares 2,2-difluoroethyl acetate by reacting bromomethyl acetate with (difluoromethyl)trimethylsilane to difluoromethylate the bromomethyl acetate. The reaction conditions are mild, the operation is simple, and the large-scale promotion and application are convenient.

[0022] The reaction formula of the method for preparing 2,2-difluoroethyl acetate of the present invention is as follows:

[0023]

[0024] 1. The specific embodiment of the preparation method of 2,2-difluoroethyl acetate of the present invention is as follows:

[0025] Example 1

[0026] The preparation method of 2,2-difluoroethyl acetate in this embodiment adopts the following steps:

[0027] Under nitrogen protection, 1L NMP (N-methylpyrrolidone), 15.3g bromomethyl acetate, 45.3g cesium fluoride, 19g cuprous iodide, and 71g (difluoromethyl)trimethylsilane were added to a 2L three-necked flask in sequence, and the mixture was reacted at 120°C for 24h. After the reaction, the mixture was filtered and the filtrate was distilled at 80°C under normal pressure to obtain 2,2-difluoroethyl acetate (FEA). The purity of the filtrate was measured to be 98.9% and the yield was 89.5%.

[0028] Example 2

[0029] The preparation method of 2,2-difluoroethyl acetate in this embodiment adopts the following steps:

[0030] Under nitrogen protection, 1L NMP (N-methylpyrrolidone), 15.3g bromomethyl acetate, 45.3g cesium fluoride, 19g cuprous iodide, 1.22g 4-dimethylaminopyridine, and 71g (difluoromethyl)trimethylsilane were added to a 2L three-necked flask in sequence. The mixture was reacted at 120°C for 24h. After the reaction, the mixture was filtered and the filtrate was distilled at 80°C under normal pressure to obtain 2,2-difluoroethyl acetate (FEA). The purity of the product was 99.9% and the yield was 99.5%. The results of the H NMR spectrum of the product are as follows: Figure 1 As shown, it is illustrated that the method of this embodiment successfully synthesized 2,2-difluoroethyl acetate.

[0031] Example 3

[0032] The preparation method of 2,2-difluoroethyl acetate in this example adopts the following steps:

[0033] Under the condition of nitrogen protection, 1 L of DMF (N,N-dimethylformamide), 15.3 g of bromomethyl acetate, 17.4 g of potassium fluoride, 19 g of cuprous iodide, 1.22 g of 4-dimethylaminopyridine, and 71 g of (difluoromethyl)trimethylsilane are successively added into a 2 L three-necked flask, and the reaction is carried out at 120 °C for 24 h. After the reaction is completed, filtration is carried out, and the obtained filtrate is distilled under normal pressure at 80 °C to obtain 2,2-difluoroethyl acetate (FEA). Its purity is measured to be 99.2%, and the yield is 97.3%.

[0034] Example 4

[0035] The preparation method of 2,2-difluoroethyl acetate in this example adopts the following steps:

[0036] Under the condition of nitrogen protection, 1 L of NMP (N-methylpyrrolidone), 15.3 g of bromomethyl acetate, 45.3 g of cesium fluoride, 19 g of cuprous iodide, 1.22 g of 4-dimethylaminopyridine, and 71 g of (difluoromethyl)trimethylsilane are successively added into a 2 L three-necked flask, and the reaction is carried out at 130 °C for 24 h. After the reaction is completed, filtration is carried out, and the obtained filtrate is distilled under normal pressure at 80 °C to obtain 2,2-difluoroethyl acetate (FEA). Its purity is measured to be 98.2%, and the yield is 95.9%.

[0037] Example 5

[0038] The preparation method of 2,2-difluoroethyl acetate in this example adopts the following steps:

[0039] Under the condition of nitrogen protection, 1 L of NMP (N-methylpyrrolidone), 15.3 g of bromomethyl acetate, 45.3 g of cesium fluoride, 19 g of cuprous iodide, 1.22 g of 4-dimethylaminopyridine, and 71 g of (difluoromethyl)trimethylsilane are successively added into a 2 L three-necked flask, and the reaction is carried out at 120 °C for 18 h. After the reaction is completed, filtration is carried out, and the obtained filtrate is distilled under normal pressure at 80 °C to obtain 2,2-difluoroethyl acetate (FEA) with a purity of 98.3% and a yield of 96.2%.

[0040] Example 6

[0041] The preparation method of 2,2-difluoroethyl acetate in this example adopts the following steps:

[0042] Under nitrogen protection, 1 L of NMP (N-methylpyrrolidone), 15.3 g of bromomethyl acetate, 45.3 g of cesium fluoride, 20.9 g of cuprous iodide, 1.22 g of 4-dimethylaminopyridine, and 71 g of (difluoromethyl)trimethylsilane were successively added to a 2 L three-necked flask, and the reaction was carried out at 120 °C for 24 h. After the reaction was completed, filtration was carried out, and the obtained filtrate was distilled under normal pressure at 80 °C to obtain 2,2-difluoroethyl acetate (FEA) with a purity of 99.6% and a yield of 99.5%.

[0043] Example 7

[0044] The preparation method of 2,2-difluoroethyl acetate in this example comprises the following steps:

[0045] Under nitrogen protection, 1 L of NMP (N-methylpyrrolidone), 15.3 g of bromomethyl acetate, 45.3 g of cesium fluoride, 20.9 g of cuprous iodide, 0.34 g of 4-dimethylaminopyridine, and 71 g of (difluoromethyl)trimethylsilane were successively added to a 2 L three-necked flask, and the reaction was carried out at 120 °C for 24 h. After the reaction was completed, filtration was carried out, and the obtained filtrate was distilled under normal pressure at 80 °C to obtain 2,2-difluoroethyl acetate (FEA) with a purity of 99.6% and a yield of 99.5%.

[0046] II. Comparative Example

[0047] Comparative Example 1

[0048] The preparation method of 2,2-difluoroethyl acetate in this comparative example comprises the following steps:

[0049] Under nitrogen protection, 1 L of NMP (N-methylpyrrolidone), 15.3 g of bromomethyl acetate, 12.6 g of sodium fluoride, 19 g of cuprous iodide, 1.22 g of 4-dimethylaminopyridine, and 71 g of (difluoromethyl)trimethylsilane were successively added to a 2 L three-necked flask, and the reaction was carried out at 120 °C for 24 h. After the reaction was completed, filtration was carried out, and the obtained filtrate was distilled under normal pressure at 80 °C to obtain 2,2-difluoroethyl acetate (FEA) with a purity of 95.3% and a yield of 78.5%.

[0050] Compared with Examples 2 and 3, when cesium fluoride and potassium fluoride were replaced with the same molar amount of sodium fluoride, the yield of 2,2-difluoroethyl acetate prepared was significantly reduced, which proved the importance of the selection of cesium fluoride and potassium fluoride.

[0051] Comparative Example 2

[0052] The preparation method of 2,2-difluoroethyl acetate in this comparative example comprises the following steps:

[0053] Under nitrogen protection, 1 L of DMF-DMA, 15.3 g of bromomethyl acetate, 45.3 g of cesium fluoride, 19 g of cuprous iodide, 1.22 g of 4-dimethylaminopyridine, and 71 g of (difluoromethyl)trimethylsilane were successively added to a 2 L three-necked flask, and the reaction was carried out at 120 °C for 24 h. After the reaction was completed, filtration was carried out, and the obtained filtrate was distilled under atmospheric pressure at 80 °C to obtain 2,2-difluoroethyl acetate (FEA) with a purity of 93.7% and a yield of 50.8%. In this comparative example, the solvent was replaced with DMF-DMA (N,N-dimethylformamide dimethyl acetal), which reduced the yield of the final product FEA.

[0054] Comparative Example 3

[0055] The preparation method of 2,2-difluoroethyl acetate in this comparative example comprises the following steps:

[0056] Under nitrogen protection, 1 L of DMSO, 15.3 g of bromomethyl acetate, 45.3 g of cesium fluoride, 19 g of cuprous iodide, 1.22 g of 4-dimethylaminopyridine, and 71 g of (difluoromethyl)trimethylsilane were successively added to a 2 L three-necked flask, and the reaction was carried out at 120 °C for 24 h. After the reaction was completed, filtration was carried out, and the obtained filtrate was distilled under atmospheric pressure at 80 °C to obtain 2,2-difluoroethyl acetate (FEA) with a purity of 95.8% and a yield of 58.4%. In this comparative example, the solvent was replaced with DMSO (dimethyl sulfoxide), which reduced the yield of the final product FEA.

Claims

1. A method for preparing 2,2-difluoroethyl acetate, characterized in that, Comprising the following steps: React bromomethyl acetate with (difluoromethyl)trimethylsilane in an organic solvent in the presence of a base and a copper(I) iodide catalyst to obtain 2,2-difluoroethyl acetate.

2. The preparation method of 2,2-difluoroethyl acetate according to claim 1, wherein The reaction conditions further include a nucleophilic catalyst, and the nucleophilic catalyst is 4-dimethylaminopyridine.

3. The method for preparing 2,2-difluoroethyl acetate according to claim 1, wherein The molar ratio of bromomethyl acetate to (difluoromethyl)trimethylsilane is 1:(3-6).

4. The preparation method of 2,2-difluoroethyl acetate according to any one of claims 1-3, characterized in that, The temperature of the reaction is 120-130 °C and the time is 18-24 h.

5. The method for preparing 2,2-difluoroethyl acetate according to any one of claims 1-3, characterized in that, The organic solvent is any one of N-methylpyrrolidone, N,N-dimethylformamide.

6. The method for preparing 2,2-difluoroethyl acetate according to any one of claims 1-3, characterized in that, The molar ratio of bromomethyl acetate to the base is 1:(1-3.5).

7. The method for preparing 2,2-difluoroethyl acetate according to claim 6, wherein, The base is any one of cesium fluoride and potassium fluoride.

8. The method for preparing 2,2-difluoroethyl acetate according to any one of claims 1-3, characterized in that, The molar ratio of bromomethyl acetate to copper(I) iodide is 1:(1-1.1).

9. The method for preparing 2,2-difluoroethyl acetate according to claim 2, wherein The molar ratio of bromomethyl acetate to 4-dimethylaminopyridine is 1:(0.02-0.1).

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