Preparation method of fluoro-ether

Abstract

The invention relates to a preparation method of fluoro-ether, which comprises the following steps: providing a first reaction system which comprises paratoluensulfonyl chloride, fluorine-containing alcohol, an alkali metal hydroxide aqueous solution, a phase transfer catalyst and an organic solvent which is insoluble in water; performing a first reaction on the first reaction system to generate p-toluenesulfonate, then standing for layering, and taking an organic phase; providing a second reaction system, wherein the second reaction system comprises the organic phase, fluorine-containing alcohol and an alkali metal hydroxide aqueous solution; and carrying out a second reaction on the second reaction system to generate fluoroether. The preparation method is simple in operation steps, does not need or reduces the steps of extraction, separation and the like, and has the advantage of saving reagent cost.

Description

Technical Field

[0001] The present application relates to the technical field of chemical synthesis, and in particular to a method for preparing fluoroether. Background Art

[0002] Fluoroethers, also known as hydrofluoroethers, are a new class of chlorofluorocarbon (CFC) substitutes. With zero ODP, a low GWP, and a short atmospheric residence time, they are considered an ideal CFC replacement. In addition to their excellent environmental properties, fluoroethers also possess low toxicity, are non-corrosive, and are easy to store and transport. They are widely used in foaming agents, cleaning agents, solvents, battery electrolytes, and liquid coolants.

[0003] In the prior art, the preparation method of fluoroether is relatively complicated and involves multiple extraction and separation steps. Summary of the Invention

[0004] The purpose of the present application is to provide a method for preparing fluoroethers, which has simple operation steps, does not require or reduces steps such as extraction and separation, and has the advantage of saving reagent costs.

[0005] To this end, the present application provides a method for preparing a fluoroether, which comprises:

[0006] Providing a first reaction system comprising p-toluenesulfonyl chloride, a fluorinated alcohol, an aqueous alkali metal hydroxide solution, a phase transfer catalyst, and an organic solvent that is insoluble in water; subjecting the first reaction system to a first reaction to generate p-toluenesulfonate, then allowing the system to stand for separation and collecting an organic phase;

[0007] A second reaction system is provided, comprising the organic phase, a fluorine-containing alcohol and an alkali metal hydroxide aqueous solution; and the second reaction system is subjected to a second reaction to generate a fluoroether.

[0008] By adopting the above-described first reaction system, the reaction proceeds at a relatively fast rate. Furthermore, the prepared p-toluenesulfonate product dissolves in the organic solvent, while impurities (such as alkali byproducts) dissolve in the aqueous phase. After the first reaction, no extraction is required; the organic phase obtained by stratification can be directly used in the second reaction system. Furthermore, the second reaction system does not require the addition or replacement of additional organic solvents, simplifying the process and facilitating subsequent separation and purification.

[0009] In any embodiment, the organic solvent includes at least one of toluene, benzene, carbon tetrachloride, ethyl acetate, cyclohexane, n-hexane, and 1,2-dichloroethane.

[0010] The above organic solvent has a relatively high boiling point and can still be used in the second reaction when the second reaction has a relatively high reaction temperature, thereby eliminating the need to add new organic solvents to the second reaction system, allowing the reaction to proceed smoothly.

[0011] In any embodiment, before the second reaction, a phase transfer catalyst is added to the second reaction system.

[0012] After the first reaction is complete, some phase transfer catalyst may remain in the aqueous phase, making the content of phase transfer catalyst in the organic phase insufficient for the second reaction. Therefore, adding additional phase transfer catalyst to the second reaction system can help increase the reaction rate of the second reaction.

[0013] In any embodiment, the concentration of the phase transfer catalyst in the first reaction system is 2% to 5%; or,

[0014] The concentration of the phase transfer catalyst in the first reaction system is less than 2%, and a certain amount of phase transfer catalyst is added to the second reaction system before the second reaction.

[0015] When the concentration of the phase transfer catalyst in the first reaction system is high (2% to 5%), the phase transfer catalyst retained in the organic phase can better meet the requirements of the second reaction, and additional phase transfer catalyst can be added to the second reaction system. When the concentration of the phase transfer catalyst in the first reaction system is low (less than 2%), the phase transfer catalyst retained in the organic phase may not be sufficient for the second reaction. Therefore, adding a certain amount of phase transfer catalyst to the second reaction system is beneficial to improving the efficiency of the second reaction.

[0016] In any embodiment, the phase transfer catalyst includes at least one of tetrabutylammonium bromide, trioctylmethylammonium chloride, tetrabutylammonium chloride, and 18-crown-6.

[0017] Any known phase transfer catalyst can be selected in the embodiment of the present application, and the above-mentioned phase transfer catalyst is more suitable for the reaction system of the embodiment of the present application, which is beneficial to promote the progress of the first reaction and the second reaction, and improve the reaction efficiency between the raw materials dissolved in water and the organic solvent respectively.

[0018] In any embodiment, the first reaction is carried out at 10°C to 70°C; or

[0019] The first reaction is carried out at room temperature.

[0020] The first reaction has relatively loose requirements on temperature conditions and can be carried out at temperatures below room temperature, room temperature, or above room temperature. If convenience is taken into consideration, it can be carried out at room temperature.

[0021] In any embodiment, the second reaction is carried out under heating reflux conditions; and / or,

[0022] The temperature condition of the second reaction is 50°C to 80°C.

[0023] The energy required for the second reaction is higher than that for the first reaction. Therefore, when the second reaction is carried out under heating conditions, it is more conducive to promoting the reaction and improving the reaction efficiency.

[0024] In any embodiment, the alkali metal hydroxide aqueous solution used in the first reaction system has a concentration of alkali metal hydroxide of ω1; the alkali metal hydroxide aqueous solution used in the second reaction system has a concentration of alkali metal hydroxide of ω2; wherein,

[0025] ω1 is 5%-50%; and / or,

[0026] ω2 is 20%-60%; and / or,

[0027] ω1<ω2。

[0028] Selecting an appropriate alkali metal concentration is more conducive to the reaction. In the first reaction, the alkali metal hydroxide is mainly used to provide an alkaline environment; in the second reaction, the alkali metal hydroxide reacts with the fluorinated alcohol to form a fluorinated alcohol organic base. The second reaction is more difficult, so the concentration of the base used in the second reaction is higher than that in the first reaction, which is more conducive to the reaction.

[0029] In any embodiment, the molar ratio of p-toluenesulfonyl chloride to fluorinated alcohol in the first reaction system is 1-1.5:1; the molar ratio of fluorinated alcohol added to the second reaction system to the fluorinated alcohol in the first reaction system is 0.9-1.1:1.

[0030] The above molar ratio is adopted to make the usage ratio of each raw material reasonable, which is conducive to promoting the reaction.

[0031] In any embodiment, after the second reaction, the following steps are further included: standing for stratification, taking the organic phase, and then washing, drying, and distilling in sequence to obtain a refined fluoroether.

[0032] The prepared fluoroether can be purified or refined according to the intended use. For example, to achieve battery-grade purity, washing can be performed with water (e.g., deionized water); drying can be performed with anhydrous sodium sulfate; and rectification can be performed at atmospheric pressure.

[0033] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Various other advantages and benefits will become apparent to those skilled in the art by reading the detailed description of the preferred embodiment below. The accompanying drawings are only for the purpose of illustrating the preferred embodiment and are not to be considered as limiting the present application. In the accompanying drawings:

[0035] Figure 1 : Schematic diagram of the steps for preparing fluoroether according to some embodiments of the present application;

[0036] Figure 2 : According to Example 1 of the present application, the mass spectrum of the product bis(2,2-difluoroethyl) ether was prepared;

[0037] Figure 3 : According to Example 1 of the present application, the product bis(2,2-difluoroethyl) ether was prepared and obtained.

[0038] Figure 4 : According to Example 1 of the present application, the product bis(2,2-difluoroethyl) ether was prepared and obtained.

[0039] Figure 5 : According to Example 1 of the present application, the NMR fluorine spectrum of the product bis(2,2-difluoroethyl) ether was prepared;

[0040] Figure 6 : According to Example 2 of the present application, the mass spectrum of the product 1-fluoro-2-(2-fluoroethoxy)ethane was prepared;

[0041] Figure 7 : According to Example 2 of the present application, the NMR carbon spectrum of the product 1-fluoro-2-(2-fluoroethoxy)ethane was prepared;

[0042] Figure 8 : According to Example 2 of the present application, the product 1-fluoro-2-(2-fluoroethoxy)ethane was prepared and obtained:

[0043] Figure 9 : According to Example 2 of the present application, the NMR fluorine spectrum of the product 1-fluoro-2-(2-fluoroethoxy)ethane was prepared. DETAILED DESCRIPTION

[0044] The exemplary embodiments of the present disclosure will be described in more detail below. It should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Instead, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0045] The "ranges" disclosed in this application are defined in the form of lower limits and upper limits, where a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive of the end values ​​and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. In addition, if minimum range values ​​of 1 and 2 are listed, and maximum range values ​​of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise specified, the numerical range "a to b" is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0046] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0047] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0048] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, it is mentioned that the method may also include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0049] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0050] Fluoroethers, also known as hydrofluoroethers, are a new type of chlorofluorocarbon alternative and are widely used in foaming agents, cleaning agents, solvents, battery electrolytes, and liquid coolants. The preparation of fluoroethers typically involves multiple extraction and separation steps, resulting in complex, time-consuming, and high solvent costs.

[0051] The present invention utilizes a water-insoluble organic solvent and a phase transfer catalyst in the above steps, thereby achieving both a relatively fast reaction and a simple separation (standing and stratifying) to obtain the p-toluenesulfonate for subsequent reactions. This significantly simplifies the preparation process and reduces solvent costs while maintaining or shortening the total preparation time for the fluoroether.

[0052] The technical solutions described in the embodiments of the present application are applicable to the preparation of fluoroethers. The prepared fluoroethers can be used as final products in technical fields including foaming agents, cleaning agents, solvents, battery electrolytes, liquid coolants, etc.; alternatively, the prepared fluoroethers can be used as intermediates or raw materials to prepare downstream products.

[0053] In some embodiments, a method for preparing a fluoroether is provided, comprising:

[0054] Providing a first reaction system comprising p-toluenesulfonyl chloride, a fluorinated alcohol, an aqueous alkali metal hydroxide solution, a phase transfer catalyst, and an organic solvent that is insoluble in water; subjecting the first reaction system to a first reaction to generate p-toluenesulfonate, then allowing the system to stand for separation, discarding the aqueous phase, and obtaining an organic phase;

[0055] A second reaction system is provided, comprising the organic phase, a fluorine-containing alcohol and an alkali metal hydroxide aqueous solution; and the second reaction system is subjected to a second reaction to generate a fluoroether.

[0056] Fluoroether is prepared from p-toluenesulfonyl chloride and fluorine-containing alcohol, usually need to prepare intermediate p-toluenesulfonate first, and need alkali metal hydroxide to participate in the reaction. Because alkali metal hydroxide is present in aqueous phase, and other raw materials are dissolved in organic phase, therefore usually adopt the organic phase mutually soluble with water, so that all raw materials fully contact and react. However, like this, it will cause to need to introduce other solvents and extract and just can separate intermediate product p-toluenesulfonate. In the embodiment of the application, water-immiscible organic solvent is applied, and phase-transfer catalyst is applied simultaneously, thus can promote the alkali metal hydroxide in aqueous phase and other raw materials in organic phase to react at a faster speed. And, the p-toluenesulfonate prepared is dissolved in organic solvent, and impurity (alkali by-product etc.) is dissolved in aqueous phase, and after the first reaction finishes, without the need to extract, the organic phase that stratification obtains can be directly used in the second reaction system. And, in the second reaction system, without the need to add or replace other organic solvents, be conducive to simplifying operation step, be convenient to subsequent separation and purification.

[0057] Furthermore, the present examples utilize a water-insoluble organic solvent and a phase transfer catalyst to achieve a chemical reaction speed that meets practical application requirements. Furthermore, the present examples avoid the extraction step, significantly reducing the time required for separation and purification. Consequently, the total time required to prepare the fluoroether is shortened or at least comparable to that of existing technologies.

[0058] First reaction system

[0059] In an embodiment of the present application, the first reaction system includes p-toluenesulfonyl chloride, a fluorine-containing alcohol, an aqueous solution of an alkali metal hydroxide, a phase transfer catalyst, and an organic solvent, and the organic solvent is insoluble in water.

[0060] In some embodiments, the first reaction system consists of p-toluenesulfonyl chloride, a fluorine-containing alcohol, an aqueous alkali metal hydroxide solution, a phase transfer catalyst, and the organic solvent.

[0061] In some embodiments, the organic solvent includes at least one of toluene, benzene, carbon tetrachloride, ethyl acetate, cyclohexane, n-hexane, and 1,2-dichloroethane.

[0062] The above-mentioned organic solvent is insoluble in water and can be used in the embodiments of the present application. In addition, the second reaction is an exothermic reaction, and in some embodiments, it is carried out under the condition of heating reflux, and the system temperature is at least 50°C, at least 60°C, at least 70°C, or at least 80°C. The application of a solvent with a higher boiling point can better meet the temperature conditions of the second reaction without adding new other organic solvents. For example, under normal pressure conditions, the boiling point of toluene is 110.6°C, the boiling point of benzene is 80.1°C, the boiling point of carbon tetrachloride is 76.8°C, the boiling point of ethyl acetate is 77.2°C, the boiling point of cyclohexane is 80.7°C, the boiling point of n-hexane is 68.7°C, and the boiling point of 1,2-dichloroethane is 83.5°C. According to the actual temperature conditions of the second reaction, a suitable solvent can be selected from the above-mentioned organic solvents to ensure that the organic solvent remains liquid under the temperature conditions of the second reaction.

[0063] In the embodiments of the present application, fluorine-containing alcohol, or fluorine alcohol, refers to an alcohol having fluorine substitution, which participates in a chemical reaction according to the following reaction formula:

[0064]

[0065] Among them, R F A fluorinated alkyl group selected from C1 to C8.

[0066] In some embodiments, the number of fluorine substitutions in the fluorine-containing alcohol can be 1, 2 or more. For example, the fluorine-containing alcohol can be selected from at least one of the following groups: 2-fluoroethanol, 2,2-difluoroethanol, 2,2,2-trifluoroethanol, 3,3,3-trifluoropropan-1-ol, 2,2,3,3,3-pentafluoro-1-propanol, hexafluoroisopropanol, hexafluorobutanol, perfluorobutanol, octafluoropentanol, 4,4,5,5,5-pentafluoropentanol, 2-fluorocyclohexanol, trifluoromethylcyclohexanol, 1H,1H,7H-dodecafluoro-1-heptanol or perfluoro-1-octanol.

[0067] In embodiments of the present application, an aqueous alkali metal hydroxide solution refers to a hydroxide formed by an alkali metal, which is dissolved in water. Alkali metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). In some embodiments, the alkali metal hydroxide can be selected from at least one of the following groups: sodium hydroxide and potassium hydroxide.

[0068] In an embodiment of the present application, a phase transfer catalyst is a type of catalyst that can help reactants transfer from one phase (aqueous phase or organic phase) to another phase (organic phase or aqueous phase) where the reaction can occur, thereby accelerating the reaction rate of a heterogeneous system. In some embodiments, the phase transfer catalyst is selected from at least one of the following groups: polyethers, such as linear polyethylene glycol, linear polyethylene glycol dialkyl ether, etc.; cyclic crown ethers, such as 18-crown ether-6, 15-crown ether-5, cyclodextrin, etc.; quaternary ammonium salts, such as benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, etc.; tertiary amines, such as pyridine, tributylamine, etc.; quaternary ammonium bases; quaternary phosphonium salts, etc.

[0069] In some embodiments, the phase transfer catalyst includes at least one of tetrabutylammonium bromide, trioctylmethylammonium chloride, tetrabutylammonium chloride, and 18-crown-6. Such phase transfer catalysts are more suitable for the reaction system of the embodiments of the present application, are conducive to promoting the first reaction and the second reaction, and improve the reaction efficiency between the raw materials dissolved in water and the organic solvent, respectively.

[0070] In some embodiments, the concentration of the phase transfer catalyst in the first reaction system is 0.1% to 5% (mass percentage); for example, it can be 2% to 5%, specifically about 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.; it can be 0.1% to 2%, specifically about 0.1%, 0.3%, 0.5%, 1.5%, 2%, etc.

[0071] In the embodiments of the present application, the ratio of p-toluenesulfonyl chloride to the fluorinated alcohol is such that the reaction proceeds smoothly. In some embodiments, the molar ratio of p-toluenesulfonyl chloride to the fluorinated alcohol is 1 to 1.5:1, for example, about 1:1, 1.1:1, 1.2:1, 1.3:1, 1.35:1, 1.4:1, 1.5:1, etc.

[0072] In an embodiment of the present application, the alkali metal hydroxide aqueous solution used in the first reaction system, wherein the concentration of the alkali metal hydroxide is ω1; ω1 is 5%-50% (mass percentage), for example, it can be about 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc.

[0073] In some embodiments, the first reaction system can be prepared by: dissolving the fluorinated alcohol and p-toluenesulfonyl chloride in the organic solvent respectively to obtain a fluorinated alcohol solution and a p-toluenesulfonyl chloride solution; uniformly mixing the phase transfer catalyst and the fluorinated alcohol solution, adding an alkali metal hydroxide aqueous solution dropwise, and then adding the p-toluenesulfonyl chloride solution dropwise.

[0074] First reaction and organic phase separation

[0075] In the embodiment of the present application, the first reaction system is subjected to a first reaction to generate p-toluenesulfonate. The p-toluenesulfonate has a fluorine substitution, specifically:

[0076]

[0077] Among them, R F A fluorinated alkyl group selected from C1 to C8; R F From the group in the fluorine-containing alcohol, for example, R F It can be selected from -CH2-CH2F, -CH2-CHF2, -CH2-CF3, -CH2-CH2-CF3, -CH2-CF2-CF3, -CF(-CHF2)2, -CH2-CF2-CHF-CF3, -CH2-(CF2)2-CF3, -CH2-(CF2)3-CF3, -CH2-CH2-CH2-CF2-CF3, -C6H 10 F, -C6H 10 -CF3, -CH2-(CF2)4-CHF2, -CH2-(CF2)6-CF3, etc.

[0078] In some embodiments, the temperature condition of the first reaction is 10 to 70°C. The first reaction has a relatively loose requirement on the temperature condition and can be carried out under conditions below room temperature, room temperature, or above room temperature. For example, the temperature condition of the first reaction can be selected from about 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, etc. If convenience is considered, it can be carried out at room temperature. Room temperature is generally defined as 25°C ± 5°C.

[0079] In some embodiments, the first reaction is carried out according to the following steps: dissolving a fluorinated alcohol and p-toluenesulfonyl chloride in the organic solvent to obtain a fluorinated alcohol solution and a p-toluenesulfonyl chloride solution; uniformly mixing a phase transfer catalyst with the fluorinated alcohol solution, adding an alkali metal hydroxide aqueous solution dropwise, and stirring to react; then adding the p-toluenesulfonyl chloride solution dropwise, and stirring to react until the reaction is complete. The completion of the reaction can be detected by gas chromatography (GC).

[0080] In an embodiment of the present application, after the first reaction is completed, gas chromatography detection can be performed according to the following method: equipment model: Agilent 8860GC System, injection volume: 0.8 μl, split ratio: 10 to 1; injection port temperature: 280°C, detector temperature: 280°C; chromatographic column model: HP-5, size: 30m×320μm×0.25μm; programmed temperature method: 50°C for 5 min, increase to 210°C at a rate of 15°C / min, and maintain for 1 min.

[0081] In an embodiment of the present application, after the first reaction is completed, the mixture is allowed to stand for stratification, and the aqueous phase is discarded to obtain an organic phase. The prepared p-toluenesulfonic acid ester is dissolved in the organic solvent, and impurities (such as alkali byproducts) are dissolved in the aqueous phase. Therefore, by standing for stratification, the organic phase can be easily separated to obtain the organic phase that can be used in the subsequent steps. The organic phase can be obtained using a separatory funnel or other suitable device.

[0082] The second reaction system

[0083] In an embodiment of the present application, a fluorine-containing alcohol and an alkali metal hydroxide aqueous solution are added to the organic phase obtained after the first reaction to obtain a second reaction system. The fluorine-containing alcohol has the same meaning as the fluorine-containing alcohol in the first reaction system and can be arbitrarily selected from the fluorine-containing alcohol in the first reaction system; the specific type of the fluorine-containing alcohol added to the second reaction system can be the same as or different from the fluorine-containing alcohol in the first reaction system. The alkali metal hydroxide aqueous solution has the same meaning as the alkali metal hydroxide aqueous solution in the first reaction system and can be arbitrarily selected from the alkali metal hydroxide aqueous solution in the first reaction system; the specific type of the alkali metal hydroxide aqueous solution added to the second reaction system can be the same as or different from the alkali metal hydroxide aqueous solution in the first reaction system.

[0084] In some embodiments, no additional organic solvent is required to be added to the second reaction system. In the embodiments of the present application, the organic phase obtained from the first reaction can be directly used for subsequent reactions, thereby eliminating the need to add any additional organic solvent to the second reaction system, which not only saves solvent costs but also facilitates the recovery of subsequent products.

[0085] In some embodiments, a phase transfer catalyst is added to the second reaction system. The phase transfer catalyst has the same meaning as the phase transfer catalyst in the first reaction system and can be arbitrarily selected from the phase transfer catalyst in the first reaction system. The specific type of the phase transfer catalyst added to the second reaction system can be the same as or different from the phase transfer catalyst in the first reaction system.

[0086] After the first reaction is complete, some phase transfer catalyst may remain in the aqueous phase, making the content of phase transfer catalyst in the organic phase insufficient for the second reaction. Therefore, adding additional phase transfer catalyst to the second reaction system can help increase the reaction rate of the second reaction.

[0087] In some embodiments, the concentration of the phase transfer catalyst in the first reaction system is 2% to 5% (mass percentage), for example, it can be about 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.; in this case, the phase transfer catalyst retained in the organic phase can better meet the needs of the second reaction, and additional phase transfer catalyst may not be added to the second reaction system, or additional phase transfer catalyst may be added to the second reaction system.

[0088] In some embodiments, the concentration of the phase transfer catalyst in the first reaction system is less than 2%, and a certain amount of phase transfer catalyst is added to the second reaction system. In some embodiments, the concentration of the phase transfer catalyst in the first reaction system can be greater than or equal to 0.1% and less than 2% (mass percentage), for example, it can be selected from about 0.1%, 0.5%, 1.5%, 1.9%, etc.; in this case, the amount of phase transfer catalyst retained in the organic phase may not be easy to meet the needs of the second reaction, so adding a certain amount of phase transfer catalyst to the second reaction system is beneficial to improving the efficiency of the second reaction. The concentration of the additional phase transfer catalyst added to the second reaction system can be 0.1% to 2%, for example, it can be selected from about 0.1%, 0.5%, 1.5%, 2%, etc.

[0089] In some embodiments, the alkali metal hydroxide aqueous solution used in the second reaction system, wherein the concentration of the alkali metal hydroxide is ω2; ω2 is 20%-60% (mass percentage), for example, it can be about 20%, 25%, 30%, 35%, 40%, 45%, 50%, 50.5%, 55%, 60%, etc.

[0090] In some embodiments, ω1<ω2.

[0091] Since in the first reaction, the alkali metal hydroxide is mainly used to provide an alkaline environment, a too high concentration is not required; while in the second reaction, the alkali metal hydroxide reacts with the fluorine-containing alcohol to form a fluorine-containing alcohol organic base, and the second reaction is more difficult, the concentration of the base required for the second reaction is higher than that for the first reaction.

[0092] In some embodiments, the amount of the fluorinated alcohol added to the second reaction system is approximately or equal to the amount of the fluorinated alcohol in the first reaction system, for example, 0.9 to 1.1 times the amount of the fluorinated alcohol in the first reaction system.

[0093] In some embodiments, the second reaction system can be prepared by uniformly mixing a fluorine-containing alcohol, an optional phase transfer catalyst, and the organic phase, and then dropwise adding an alkali metal hydroxide aqueous solution.

[0094] Second reaction

[0095] In the embodiment of the present application, the second reaction system is subjected to a second reaction to generate a fluoroether. Specifically, the second reaction comprises:

[0096]

[0097] Among them, R F The fluorinated alkyl group selected from C1 to C8 has the same meaning as in the first reaction; R is selected from a C1 to C8 alkyl group, and sodium alcoholate RONa is obtained by reacting a fluorinated alcohol with an alkali metal hydroxide.

[0098] In some embodiments, the second reaction is carried out under heating conditions, specifically under heating and reflux conditions. In some embodiments, the temperature of the second reaction is 50-80°C, for example, selected from about 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, etc. In some embodiments, the reaction is stirred at 50-60°C for a certain time, and then the reaction is carried out under reflux conditions at 70-80°C for a certain time.

[0099] In some embodiments, the second reaction is carried out according to the following steps: uniformly mixing the fluorine-containing alcohol, an optional phase transfer catalyst and the organic phase, and then dropwise adding an aqueous solution of an alkali metal hydroxide; after the dropwise addition is complete, heating the mixture to carry out the second reaction.

[0100] Product purification

[0101] The prepared fluoroether can be purified or refined depending on its intended use. In some embodiments, after the second reaction, the process further includes the following steps: allowing the organic phase to stand for stratification, collecting the organic phase, and then sequentially washing, drying, and rectifying the organic phase to obtain a refined fluoroether. The refined fluoroether can achieve battery-grade purity and can be used in the preparation of battery electrolytes.

[0102] The purity of the fluoroether can be detected by gas chromatography (GC). In the embodiment of the present application, gas chromatography detection can be performed according to the following method: equipment model: Agilent 8860GC System, injection volume: 0.8 μl, split ratio: 10 to 1; injection port temperature: 280°C, detector temperature: 280°C; chromatographic column model: HP-5, size: 30m×320μm×0.25μm; programmed temperature method: 50°C for 5 min, increase to 210°C at a rate of 15°C / min, and maintain for 1 min.

[0103] In the embodiments of the present application, appropriate specific washing, drying, and distillation methods may be selected based on the intended use. For example, to achieve battery-grade purity, washing may be performed with water (e.g., deionized water); drying may be performed with anhydrous sodium sulfate; and distillation may be performed at atmospheric pressure.

[0104] Some examples are described in detail below, wherein the concentration of the alkali metal hydroxide aqueous solution is expressed in mass percentage (w / w).

[0105] Example 1

[0106] (1) 1 mol of 2,2-difluoroethanol was dissolved in 300 mL of carbon tetrachloride and added to a 2 L three-necked flask as a reactor. 3 g of tetrabutylammonium bromide was added and stirred at room temperature. 360 mL of a 20% aqueous sodium hydroxide solution was added dropwise and stirred for about 1 hour. 1.35 mol of p-toluenesulfonyl chloride was dissolved in 250 mL of carbon tetrachloride and added dropwise to the reactor solution. The mixture was stirred for 5 hours at room temperature to prepare p-toluenesulfonic acid-2,2-difluoroethanol ester. After the reaction was complete as detected by GC, the reaction was stopped and allowed to stand for separation. The lower organic phase was removed and directly used for the next step.

[0107] (2) 0.9 mol of 2,2-difluoroethanol was added to the organic phase obtained in step (1), and 3 g of tetrabutylammonium bromide was added at the same time; 260 mL of 40% potassium hydroxide aqueous solution was added dropwise to the above solution at room temperature, and after the addition was completed, the temperature was raised to 60° C. and the reaction was carried out for 3 h; the temperature was raised to 80° C. and refluxed, and the reaction was continued for 5 h. After the reaction was completed, water was added to dilute, the layers were separated, the water layer was removed, and the organic layer was washed twice with deionized water and then dried over anhydrous sodium sulfate. After atmospheric distillation, the product bis(2,2-difluoroethyl) ether was obtained, about 123 g, and the content was ≥99.6% by GC detection.

[0108] Example 2

[0109] The same operation as in Example 1 is performed except for the following differences:

[0110] In step (1), carbon tetrachloride is replaced by toluene; 2,2-difluoroethanol is replaced by 2-fluoroethanol; p-toluenesulfonyl chloride is added dropwise and the mixture is stirred at room temperature for 2 hours to prepare 2-fluoroethanol toluenesulfonate;

[0111] In step (2), 2,2-difluoroethanol was replaced with 2-fluoroethanol; after adding potassium hydroxide aqueous solution dropwise, the temperature was raised to 50°C for reaction for 5 hours, and then the temperature was raised to 70°C for reflux. The final product obtained in step (2) was 1-fluoro-2-(2-fluoroethoxy)ethane, approximately 90.1 g, with a GC content of ≥99.4%.

[0112] Example 3

[0113] The same operation as in Example 1 is performed except for the following differences:

[0114] In step (2), carbon tetrachloride was replaced with ethyl acetate; 2,2-difluoroethanol was replaced with 2-fluoroethanol; potassium hydroxide aqueous solution was added dropwise, the temperature was raised to 50°C, the reaction was continued for 6 hours, and then the temperature was raised to 80°C and refluxed, and the reaction was continued for 6 hours. The final product obtained in step (2) was 1,1-difluoro-2-(2-fluoroethoxy)-ethane, approximately 105.2 g, with a GC content of ≥99.6%.

[0115] Example 4

[0116] The same operation as in Example 1 is performed except for the following differences:

[0117] In step (2), no additional tetrabutylammonium bromide was added, resulting in the complete reaction of step (2) at 80° C. reflux for 5 hours, which was not complete, but took 12 hours to complete. The final product of step (2) was approximately 112.2 g of bis(2,2-difluoroethyl) ether, with a GC assay content of ≥99.3%.

[0118] Example 5

[0119] The same operation as in Example 1 is performed except for the following differences:

[0120] The amount of tetrabutylammonium bromide used in step (1) was 18.5 g. In step (2), no additional phase transfer catalyst was required, and the reaction was complete by reflux at 80° C. for 5 h. The product obtained in step (2) was approximately 121.7 g of bis(2,2-difluoroethyl) ether, with a GC content of ≥99.5%.

[0121] Examples 6 to 8

[0122] Except for the differences recorded in Table 1, the same operation as in Example 1 was carried out:

[0123] Table 1

[0124]

[0125] Example 9

[0126] The same operation as in Example 1 is performed except for the following differences:

[0127] In step (2), the concentration of the potassium hydroxide aqueous solution is 20%. Accordingly, to achieve complete reaction, after the potassium hydroxide aqueous solution is added dropwise, the temperature is raised to 60°C and the reaction is carried out for 12 hours. The temperature is then raised to 80°C and refluxed, and the reaction is continued for 15 hours. The product bis(2,2-difluoroethyl) ether obtained in step (2) is approximately 107.1 g, and the content determined by GC is ≥99.4%.

[0128] The above description is merely a preferred embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for preparing a fluoroether, characterized in that: include: Providing a first reaction system comprising p-toluenesulfonyl chloride, a fluorinated alcohol, an aqueous alkali metal hydroxide solution, a phase transfer catalyst, and an organic solvent that is insoluble in water; subjecting the first reaction system to a first reaction to generate p-toluenesulfonate, then allowing the system to stand for separation and collecting an organic phase; A second reaction system is provided, comprising the organic phase, a fluorine-containing alcohol and an alkali metal hydroxide aqueous solution; and the second reaction system is subjected to a second reaction to generate a fluoroether.

2. The method for preparing a fluoroether according to claim 1, wherein The organic solvent includes at least one of toluene, benzene, carbon tetrachloride, ethyl acetate, cyclohexane, n-hexane, and 1,2-dichloroethane.

3. The method for preparing a fluoroether according to claim 1 or 2, wherein: Before the second reaction, a phase transfer catalyst is added to the second reaction system.

4. The method for preparing a fluoroether according to claim 1 or 2, wherein: The concentration of the phase transfer catalyst in the first reaction system is 2% to 5%; or, The concentration of the phase transfer catalyst in the first reaction system is less than 2%, and a certain amount of phase transfer catalyst is added to the second reaction system before the second reaction.

5. The method for preparing a fluoroether according to any one of claims 1 to 4, wherein: The phase transfer catalyst includes at least one of tetrabutylammonium bromide, trioctylmethylammonium chloride, tetrabutylammonium chloride, and 18-crown ether-6.

6. The method for preparing a fluoroether according to any one of claims 1 to 5, wherein: The first reaction is carried out at 10°C to 70°C; or The first reaction is carried out at room temperature.

7. The method for preparing a fluoroether according to any one of claims 1 to 6, wherein: The second reaction is carried out under heating reflux conditions; and / or, The temperature condition of the second reaction is 50°C to 80°C.

8. The method for preparing a fluoroether according to any one of claims 1 to 7, wherein: The alkali metal hydroxide aqueous solution used in the first reaction system has a concentration of ω1; the alkali metal hydroxide aqueous solution used in the second reaction system has a concentration of ω2; wherein, ω1 is 5%-50%; and / or, ω2 is 20%-60%; and / or, ω1<ω2。 9. The method for preparing a fluoroether according to any one of claims 1 to 8, wherein: The molar ratio of p-toluenesulfonyl chloride to the fluorinated alcohol in the first reaction system is 1-1.5:1; the molar ratio of the fluorinated alcohol added to the second reaction system to the fluorinated alcohol in the first reaction system is 0.9-1.1:

1.

10. The method for preparing a fluoroether according to any one of claims 1 to 9, wherein: After the second reaction, the method further comprises the following steps: standing for stratification, taking the organic phase, and then washing, drying, and distilling the organic phase in sequence to obtain refined fluoroether.

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