A process for the preparation of ethyl difluoroacetate

Abstract

The application relates to the technical field of organic synthesis, in particular to a preparation method of ethyl difluoroacetate, which comprises the following steps: S1, 2,2-difluoro-1,1-dichloroethyl ethyl ether is added into a reaction kettle, concentrated sulfuric acid is added dropwise under stirring at a certain reaction temperature, after the dropwise addition is completed, the reaction is continuously kept for reaction completion, and a compound shown in formula I is obtained; S2, water is added into a reaction container, the compound shown in formula I prepared in the step S1 is added dropwise into the reaction container for hydrolysis reaction at a certain temperature, after the reaction is completed, the reaction is allowed to stand and is separated into layers, and the lower organic layer is ethyl difluoroacetate; the application has the advantages of simple process, easily obtained raw materials, mild reaction conditions, easy control, high product yield, few by-products, reaction condition detection at any time, one-time reaction completion, secondary recovery treatment avoidance, raw material loss reduction and easy industrialized production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic synthesis, and particularly relates to a preparation method of ethyl difluoroacetate. BACKGROUND

[0002] Ethyl difluoroacetate has a CAS number of 454-31-9, a boiling point of 99 DEG C, is a colorless transparent liquid, and has an alcohol smell.

[0003] Ethyl difluoroacetate is an important fluorine-containing fine chemical intermediate, and is mainly used to prepare fluorine-containing pesticides and pharmaceutical products, such as five fluorine sulcotrione, pyrazole amide fungicides, new nicotine insecticides, chloramphenicol derivatives, pyrazolo thiazine drugs and the like. In recent years, ethyl difluoroacetate is also used as an electrolyte of a lithium battery.

[0004] At present, there are many methods for synthesizing the compound, and the methods mainly include the following:

[0005] 1. Tetrafluoroethyl ethyl ether is subjected to high-temperature catalytic cracking to obtain difluoroacetyl fluoride, and then subjected to esterification reaction with ethanol to obtain the target product ethyl difluoroacetate. This method adopts a high-temperature cracking reaction of a catalyst, and has harsh reaction conditions, many side reactions, and poor product selectivity.

[0006] 2. Difluoroacetonitrile is subjected to catalytic hydrolysis and alcoholysis to obtain ethyl difluoroacetate. This method uses raw materials which are not easy to obtain, and needs to be completed under catalytic conditions.

[0007] 3. Difluoroacetic acid is subjected to esterification reaction with ethanol to obtain ethyl difluoroacetate. This method needs to be reacted under an acid catalyst, has low reaction yield, large raw material loss, and complicated three-waste treatment.

[0008] 4. Dichloroacetyl chloride reacts with diethylamine to generate dichloroacetyl diethylamine, which is subjected to fluorination to obtain difluoroacetyl diethylamine, and then subjected to acid catalysis alcoholysis to obtain the target product. In this method, cyclobutane sulfone is used as a solvent in fluorination, and sulfur trioxide gas is easily generated, which is not conducive to the environment. Meanwhile, the recovery of diethylamine, a reaction raw material, is difficult, and is not conducive to cost reduction. The above synthesis methods all have various defects. SUMMARY

[0009] The present application aims to provide a preparation method of ethyl difluoroacetate, which is used to overcome at least one of the above technical problems.

[0010] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0011] A preparation method of ethyl difluoroacetate, the preparation method comprising the following steps:

[0012] S1 adds 2, 2-difluoro-1, 1-dichloroethyl ethyl ether into a reaction kettle, adds concentrated sulfuric acid dropwise under stirring at a certain reaction temperature, continues to react until the reaction is complete after the dropwise addition is completed, and a compound shown in formula I is obtained;

[0013]

[0014] S2 adds water into a reaction container, hydrolyzes the compound shown in formula I prepared in step S1 dropwise into the reaction container at a certain temperature, and the lower organic layer is ethyl difluoroacetate after the reaction is completed and the layers are separated.

[0015] Further, the reaction temperature is controlled to be 10-100 DEG C when the concentrated sulfuric acid is added dropwise in step S1, the concentration of the concentrated sulfuric acid is 90%-98%, and the reaction temperature is controlled to be 30 DEG C after the dropwise addition of the concentrated sulfuric acid is completed.

[0016] Further, the reaction temperature is controlled to be 20-60 DEG C when the concentrated sulfuric acid is added dropwise in step S1, and the concentration of the concentrated sulfuric acid is 90%-96%.

[0017] Further, the molar ratio of the 2, 2-difluoro-1, 1-dichloroethyl ethyl ether and the 95% concentrated sulfuric acid is 1:1-2.

[0018] Further, the molar ratio of the 2, 2-difluoro-1, 1-dichloroethyl ethyl ether and the 95% concentrated sulfuric acid is 1:1.5.

[0019] Further, the temperature of the hydrolysis reaction in step S2 is less than 30 DEG C.

[0020] The beneficial effects of the technical scheme of the present application are as follows:

[0021] Compared with the preparation method of the ethyl difluoroacetate described above, the preparation method in the present application has the advantages of simple process, easily available raw materials, mild reaction conditions, easy control, high product yield, and less by-products, the reaction condition can be detected at any time, the reaction is completely reacted at one time to avoid secondary recovery treatment, the loss of raw materials is reduced, and the industrial production is easy.

[0022] The sulfuric acid used in the present application is a reactant, participates in a chemical reaction, and generates a stable sulfate compound, so that the whole reaction can be carried out at a lower temperature and under normal pressure, and the reaction is complete and the yield is high. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The figure is a mass spectrum of the ethyl difluoroacetate compound prepared in the present application.

[0024] Figure 2 The figure is a gas chromatogram of the ethyl difluoroacetate compound prepared in example 1. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the specific embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0026] The raw materials in the present application are all ordinary commercial products.

[0027] 2,2-difluoro-1,1-dichloroethyl ethyl ether 99% (Jinjingle (Hunan) Chemical Co., Ltd., Jiangsu Blue Star Environmental Protection Technology Co., Ltd.).

[0028] A preparation method of ethyl difluoroacetate, the preparation method comprising the following steps:

[0029] S1, 2,2-difluoro-1,1-dichloroethyl ethyl ether is added to a reaction kettle, concentrated sulfuric acid is added dropwise under stirring at a certain reaction temperature, after the dropwise addition is completed, the reaction is continued to be kept at a certain temperature until the reaction is completed, to obtain a compound shown in formula I; the reaction formula is as follows:

[0030]

[0031] S2, water is added to a reaction container, the compound shown in formula I prepared in step S1 is added dropwise into the reaction container to perform a hydrolysis reaction at a certain temperature, after the reaction is completed, the reaction container is allowed to stand and separate into layers, and the lower organic layer is ethyl difluoroacetate. The hydrolysis principle is as follows:

[0032]

[0033] Reaction formula (2) and reaction formula (3) disclose the principle of the process that the sulfate compound generated in reaction formula (1) is added into water to generate ethyl difluoroacetate.

[0034] The above three reaction formulas completely illustrate the principle that 2,2-difluoro-1,1-dichloroethyl ethyl ether reacts with concentrated sulfuric acid to generate a corresponding sulfate compound, the sulfate compound is added into water and further reacts to generate an ester compound, which theoretically provides a basis for improving the production efficiency of the reaction.

[0035] Figure 1 The mass spectrum of the ethyl difluoroacetate compound prepared in the present application is shown in the following figure.

[0036] Figure 2 The gas chromatogram of the ethyl difluoroacetate compound prepared in Example 1 is shown in the following figure.

[0037] Example 1

[0038] Into a 1 liter stirred carbon steel reaction vessel, 179 grams of 2,2-difluoro-l,l- dichloroethyl ethyl ether was added, and 155 grams of 95% concentrated sulfuric acid was added dropwise while stirring, controlling the reaction temperature to be below 80°C. After the dropwise addition was completed, the temperature was maintained at about 30°C and the reaction was stirred for 4 hours to obtain a sulfate product at a yield of 99%. During the reaction, the off-gas was absorbed with water.

[0039] Into a 1 liter stirred carbon steel reaction vessel, 179 grams of 2,2-difluoro-l,l- dichloroethyl ethyl ether was added, and 155 grams of 95% concentrated sulfuric acid was added dropwise while stirring, controlling the reaction temperature to be below 80°C. After the dropwise addition was completed, the temperature was maintained at about 30°C and the reaction was stirred for 4 hours to obtain a sulfate product at a yield of 99%. During the reaction, the off-gas was absorbed with water.

[0040] Example 2

[0041] Into a 1 liter stirred carbon steel reaction vessel, 179 grams of 2,2-difluoro-l,l- dichloroethyl ethyl ether was added, and 155 grams of 95% concentrated sulfuric acid was added dropwise while stirring, controlling the reaction temperature to be below 80°C. After the dropwise addition was completed, the temperature was maintained at about 30°C and the reaction was stirred for 4 hours to obtain a sulfate product at a yield of 99%. During the reaction, the off-gas was absorbed with water.

[0042] Into a 1 liter stirred carbon steel reaction vessel, 179 grams of 2,2-difluoro-l,l- dichloroethyl ethyl ether was added, and 155 grams of 95% concentrated sulfuric acid was added dropwise while stirring, controlling the reaction temperature to be below 80°C. After the dropwise addition was completed, the temperature was maintained at about 30°C and the reaction was stirred for 4 hours to obtain a sulfate product at a yield of 99%. During the reaction, the off-gas was absorbed with water.

[0043] Example 3

[0044] Into a 1 liter stirred carbon steel reaction vessel, 179 grams of 2,2-difluoro-l,l- dichloroethyl ethyl ether was added, and 155 grams of 95% concentrated sulfuric acid was added dropwise while stirring, controlling the reaction temperature to be below 80°C. After the dropwise addition was completed, the temperature was maintained at about 30°C and the reaction was stirred for 4 hours to obtain a sulfate product at a yield of 99%. During the reaction, the off-gas was absorbed with water.

[0045] Into a 1 liter stirred carbon steel reaction vessel, 179 grams of 2,2-difluoro-l,l- dichloroethyl ethyl ether was added, and 155 grams of 95% concentrated sulfuric acid was added dropwise while stirring, controlling the reaction temperature to be below 80°C. After the dropwise addition was completed, the temperature was maintained at about 30°C and the reaction was stirred for 4 hours to obtain a sulfate product at a yield of 99%. During the reaction, the off-gas was absorbed with water.

[0046] Example 4

[0047] In a 5 liter agitated internal Teflon lined tank reactor, 2000 g of 2,2-difluoro-l,l- dichloroethyl ethyl ether was charged and 1730 g of 98% concentrated sulfuric acid was added dropwise while stirring, controlling the reaction temperature below 60°C. After the addition was completed, the temperature was maintained at about 30°C and the reaction was stirred for 2 hours. The reaction apparatus was then converted to a distillation apparatus, and 210 g of water was added dropwise to the stirred tank reactor while maintaining the temperature at 40°C. After the addition was completed, the stirring was continued for 2 hours, and then the temperature was raised for distillation. 1340 g of ethyl difluoroacetate having a boiling point of 99°C was collected, and the purity was 98.8%. The sulfuric acid in the stirred tank reactor was cooled and could be used as a raw material for the production of sulfuric acid ester compounds.

[0048] Furthermore, it should be understood that although the description herein is made on the basis of the embodiments, not every embodiment contains only one independent right scheme, and the description herein is only for the sake of clarity, and those skilled in the art should consider the description as a whole, and the technical schemes in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A process for the preparation of ethyl difluoroacetate, characterized in that: The preparation method comprises the following steps: S1: 2,2-difluoro-1,1-dichloroethyl ethyl ether is added into a reaction kettle, concentrated sulfuric acid is added dropwise under stirring at a certain reaction temperature, after the dropwise addition is completed, the reaction is continued to be kept at a certain temperature until the reaction is completed, and a compound shown in formula I is obtained; S2: water is added into a reaction container, the compound shown in formula I prepared in step S1 is added dropwise into the reaction container for hydrolysis reaction at a certain temperature, after the reaction is completed, the reaction is allowed to stand and separate, and the lower organic layer is the ethyl difluoroacetate.

2. A process for the preparation of ethyl difluoroacetate according to claim 1, characterized in that: In the step S1, the reaction temperature is controlled to be 10-100 DEG C during the dropwise addition of the concentrated sulfuric acid, the concentration of the concentrated sulfuric acid is 90-98%, and the reaction temperature is controlled to be 30 DEG C after the dropwise addition of the concentrated sulfuric acid is completed.

3. A process for the preparation of ethyl difluoroacetate according to claim 2, characterized by: In the step S1, the reaction temperature is controlled to be 20-60 DEG C during the dropwise addition of the concentrated sulfuric acid, and the concentration of the concentrated sulfuric acid is 90-96%.

4. The process for the preparation of ethyl difluoroacetate as claimed in claim 1, wherein: The molar ratio of the 2,2-difluoro-1,1-dichloroethyl ethyl ether to the 95% concentrated sulfuric acid is 1:1-2.

5. A process for the preparation of ethyl difluoroacetate according to claim 4, characterized in that: The molar ratio of the 2,2-difluoro-1,1-dichloroethyl ethyl ether to the 95% concentrated sulfuric acid is 1:1.

5.

6. The process for the preparation of ethyl difluoroacetate as claimed in claim 1, wherein: In the step S2, the temperature of the hydrolysis reaction is less than 30 DEG C.

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