Preparation method of difluoromethanesulfonimide and its alkali metal salt

Abstract

The present invention provides a preparation method of difluoromethanesulfonimide and its alkali metal salts. The preparation method comprises the following steps: (1) reacting fluorosulfonylimidazolium salt with a primary amide under the action of an acid-binding agent to generate N,N-difluoromethanesulfonamide; (2) reacting an alcohol or an alkali metal salt of an alcohol with the N,N-difluoromethanesulfonamide under the action of a catalyst to generate the difluoromethanesulfonimide or its alkali metal salt. The preparation method uses fluorosulfonylimidazolium salt, amide, and alcohol substances as raw materials. The raw materials are common industrial products or can be synthesized from common industrial products. Most of the by-products can be recycled, greatly reducing the cost. It has the advantages of fast reaction rate, mild reaction conditions, low requirements for equipment, low reaction energy consumption, easy separation of products, environmental friendliness, and low cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of fine chemical engineering, and particularly relates to a preparation method of difluoromethanesulfonimide and its alkali metal salts. Background Art

[0002] Lithium salts and sodium salts with difluoromethanesulfonimide anions have been reported to have good thermodynamic stability, high conductivity and hydrolysis resistance. As electrolyte additives, they can improve the battery cycle life and safety issues, and enhance the battery performance. Among them, lithium difluoromethanesulfonimide (LiFSI) has been successfully commercialized by several companies in recent years.

[0003] At present, the production process routes of lithium difluoromethanesulfonimide mainly have two categories: one is to first synthesize difluoromethanesulfonimide, and then react difluoromethanesulfonimide with the corresponding metal salt to obtain the product. The other is to directly fluorinate dichloromethanesulfonimide with a fluoride salt to obtain lithium difluoromethanesulfonimide or other difluoromethanesulfonimide salts, and then obtain lithium difluoromethanesulfonimide through ion exchange technology. For the first type of process route, most companies choose to fluorinate dichloromethanesulfonimide with hydrogen fluoride (CN106044728A, CN104925765B, CN110436424A, WO2015143866A1, CN110467163B, CN107055493B), but this process requires the use of highly dangerous hydrogen fluoride, and the synthesis process of dichloromethanesulfonimide often requires chlorosulfonic acid or thionyl chloride as reactants, which also belong to dangerous chemicals. In addition, a large amount of hydrogen chloride and sulfur dioxide gases will be generated during the reaction process, which not only has high requirements for equipment, but also has high tail gas treatment costs. In patents such as CN113697784A, CN104918913B and CN114044497A, sulfinyl fluoride or sulfonyl fluoride is used as a fluorinating agent to directly synthesize difluoromethanesulfonimide in one step. However, whether it is sulfinyl fluoride or sulfonyl fluoride, it is gaseous at normal temperature and pressure, and the reaction rate at normal pressure is slow, and the yield is low. If high-pressure production is to be carried out industrially, it has high requirements for equipment and high danger. Martin Beran et al. used fluorosulfonic acid and urea to synthesize difluoromethanesulfonimide in one step (ZAAC.2005, 631, 55 - 59), but fluorosulfonic acid is expensive and the reaction yield is low, which is not suitable for industrial production. For the second type of process route, it is also difficult to avoid the above-mentioned drawbacks of the dichloromethanesulfonimide synthesis process. In addition, these fluoride salts often use heavy metal fluoride salts, which are highly toxic and have great harm to the environment (Inorg.Synth.1968, 11, 138 - 141, Inorg.Chem.1998, 37, 6295 - 6303).

[0004] Therefore, it is necessary to develop a synthesis process of difluoromethanesulfonimide or alkali metal difluoromethanesulfonimide salts with mild reaction conditions, fast reaction rate, less or no generation of three wastes. Summary of the Invention

[0005] Based on this, the object of the present invention is to provide a preparation method of bis(fluorosulfonyl)imide and its alkali metal salts; the reaction conditions of the preparation method are mild, the reaction rate is fast, and it is green and safe.

[0006] To achieve the above object, the present invention adopts the following technical solutions.

[0007] A preparation method of bis(fluorosulfonyl)imide or its alkali metal salts, comprising the following steps: (1) reacting a fluorosulfonylimidazolium salt with a primary amide under the action of an acid-binding agent to generate N,N-bis(fluorosulfonyl)amide; (2) reacting an alcohol or an alkali metal salt of an alcohol with the N,N-bis(fluorosulfonyl)amide under the action of a catalyst to generate the bis(fluorosulfonyl)imide or its alkali metal salts;

[0008] The fluorosulfonylimidazolium salt is selected from the compounds represented by the following general structural formula:

[0009]

[0010] Wherein, R1, R2 and R3 are each independently selected from H and alkyl groups having 1 to 5 carbon atoms; is selected from trifluoromethylsulfonate anion, fluorosulfonate anion, and tetrafluoroborate anion.

[0011] In some embodiments, the fluorosulfonylimidazolium salt is selected from at least one of 1-(fluorosulfonyl)-2,3-dimethylimidazolium-3-trifluoromethylsulfonate, 1-(fluorosulfonyl)-3-methylimidazolium-3-trifluoromethylsulfonate, 1-(fluorosulfonyl)-3,4-dimethyl-2-ethylimidazolium-3-trifluoromethylsulfonate, 1-(fluorosulfonyl)-3-methyl-2-isopropylimidazolium-3-trifluoromethylsulfonate, 1-(fluorosulfonyl)-3,5-dimethylimidazolium-3-trifluoromethylsulfonate, 1-(fluorosulfonyl)-2,3-dimethylimidazolium-3-fluorosulfonate, 1-(fluorosulfonyl)-3-methylimidazolium-3-fluorosulfonate, 1-(fluorosulfonyl)-3,4-dimethyl-2-ethylimidazolium-3-fluorosulfonate, 1-(fluorosulfonyl)-3-methyl-2-isopropylimidazolium-3-fluorosulfonate, 1-(fluorosulfonyl)-3,5-dimethylimidazolium-3-fluorosulfonate, 1-(fluorosulfonyl)-2,3-dimethylimidazolium-3-tetrafluoroborate, 1-(fluorosulfonyl)-3-methylimidazolium-3-tetrafluoroborate, 1-(fluorosulfonyl)-3,4-dimethyl-2-ethylimidazolium-3-tetrafluoroborate, 1-(fluorosulfonyl)-3-methyl-2-isopropylimidazolium-3-tetrafluoroborate, and 1-(fluorosulfonyl)-3,5-dimethylimidazolium-3-tetrafluoroborate.

[0012] In a preferred embodiment, the fluorosulfonyl imidazolium salt is 1-(fluorosulfonyl)-2,3-dimethylimidazolium-3-trifluoromethylsulfonate.

[0013] In some embodiments, the primary amide is selected from at least one of formamide, acetamide, propionamide, and butyramide.

[0014] In some embodiments, the acid-binding agent is selected from at least one of triethylamine, N,N-diisopropylethylamine, pyridine, and 4-dimethylaminopyridine.

[0015] In some embodiments, the alcohol is selected from at least one of methanol, ethanol, propanol, and butanol; and the alkali metal salt of the alcohol is selected from at least one of the sodium salt, potassium salt, and lithium salt of the alcohol.

[0016] In some embodiments, the solvent for the reaction in step (1) is selected from at least one of acetonitrile, dichloromethane, ethyl acetate, and dimethyl carbonate.

[0017] In some embodiments, the catalyst in step (2) comprises cobalt dichlorobipyridine and manganese; and the molar ratio of cobalt dichlorobipyridine, manganese, and primary amide is (4-10):1.

[0018] In some embodiments, the molar ratio of cobalt dichlorobipyridine, manganese, and primary amide is (4-10):1:(40-200).

[0019] In some embodiments, the molar ratio of the fluorosulfonyl imidazolium salt, primary amide, and alcohol or alkali metal salt of the alcohol is (2-3):1:(1-1.5).

[0020] In a preferred embodiment, the molar ratio of the fluorosulfonyl imidazolium salt and primary amide is (2.5-3):1.

[0021] In some embodiments, the temperature of the reaction in step (1) is 10-40 °C.

[0022] In some embodiments, the temperature of the reaction in step (2) is 50-90 °C.

[0023] In some embodiments, the method for preparing the bis(fluorosulfonyl)imide or its alkali metal salt comprises the following steps: (1) reacting a fluorosulfonyl imidazolium salt and a primary amide under the action of an acid-binding agent, then adding ethyl acetate to the product, performing acid washing, water washing, and concentrating the organic phase under negative pressure to obtain N,N-bis(fluorosulfonyl)amide; (2) reacting an alcohol or an alkali metal salt of the alcohol with the N,N-bis(fluorosulfonyl)amide under the action of a catalyst, filtering the product by suction, washing the filtrate with water, and distilling the organic phase under negative pressure to obtain the bis(fluorosulfonyl)imide or its alkali metal salt.

[0024] In some embodiments, the temperature of the vacuum concentration is 30 to 50 °C.

[0025] In some embodiments, the temperature of the vacuum distillation is 40 to 60 °C.

[0026] In some embodiments, the pickling is hydrochloric acid pickling.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention provides a method for preparing difluoromethanesulfonimide and its alkali metal salts. The preparation method uses fluorosulfonylimidazolium salts to fluorosulfonylate primary amides, overcomes the defect of slow fluorosulfonylation of secondary amines by sulfonyl fluoride gas, effectively improves the reaction rate, and the reactions can all be carried out under relatively mild temperature conditions. The present invention uses amides as amine sources, avoiding the by-product of fluorosulfonylmethylimine formed by sulfonyl fluoride and the R-CH2-NH2 structure in an alkaline environment; uses alcohols as hydrogen sources, with economical raw materials and can generate ester economic compounds; improves the product yield by optimizing the reaction raw materials. Most of the raw materials used in the preparation method of the present invention are common industrial products, and most of the by-products can be recycled, greatly reducing the cost. Therefore, the present invention has the advantages of fast reaction rate, mild reaction conditions, low equipment requirements, low reaction energy consumption, easy product separation, environmental friendliness and low cost. Detailed Embodiments

[0029] In the following examples of the present invention, the experimental methods without specific conditions are usually carried out under conventional conditions or according to the conditions recommended by the manufacturers. All kinds of commonly used chemical reagents used in the examples are commercially available products.

[0030] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0031] The terms "comprising" and "having" and any variations thereof in the present invention are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product or equipment comprising a series of steps is not limited to the listed steps or modules, but optionally further includes steps not listed, or optionally further includes other steps inherent to these processes, methods, products or equipment.

[0032] In the present invention, "a plurality of" means two or more. "And / or" describes the relationship between associated objects and indicates that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0033] The present invention provides a method for preparing a bis(fluorosulfonyl)imide represented by Structural Formula 1 and an alkali metal salt of bis(fluorosulfonyl)imide represented by Structural Formula 2; wherein, M is selected from Na, K, Li:

[0034]

[0035] The preparation method includes the following steps: (1) reacting a fluorosulfonylimidazolium salt with a primary amide under the action of an acid-binding agent to form an N,N-bis(fluorosulfonyl)amide; (2) reacting an alcohol or an alkali metal salt of an alcohol with the N,N-bis(fluorosulfonyl)amide under the action of a catalyst to form the bis(fluorosulfonyl)imide or its alkali metal salt;

[0036] The fluorosulfonylimidazolium salt is selected from compounds represented by the following general structural formula:

[0037]

[0038] wherein, R1, R2 and R3 are each independently selected from H and an alkyl group having 1 to 5 carbon atoms; is selected from a trifluoromethylsulfonate anion, a fluorosulfonate anion, and a tetrafluoroborate anion.

[0039] In some embodiments, the fluorosulfonyl imidazolium salt is selected from at least one of 1-(fluorosulfonyl)-2,3-dimethylimidazole-3-trifluoromethanesulfonate, 1-(fluorosulfonyl)-3-methylimidazole-3-trifluoromethanesulfonate, 1-(fluorosulfonyl)-3,4-dimethyl-2-ethylimidazole-3-trifluoromethanesulfonate, 1-(fluorosulfonyl)-3-methyl-2-isopropylimidazole-3-trifluoromethanesulfonate, 1-(fluorosulfonyl)-3,5-dimethylimidazole-3-trifluoromethanesulfonate, 1-(fluorosulfonyl)-2,3-dimethylimidazole-3-fluorosulfonate, 1-(fluorosulfonyl)-3-methylimidazole-3-fluorosulfonate, 1-(fluorosulfonyl)-3,4-dimethyl-2-ethylimidazole-3-fluorosulfonate, 1-(fluorosulfonyl)-3-methyl-2-isopropylimidazole-3-fluorosulfonate, 1-(fluorosulfonyl)-3,5-dimethylimidazole-3-fluorosulfonate, 1-(fluorosulfonyl)-2,3-dimethylimidazole-3-tetrafluoroborate, 1-(fluorosulfonyl)-3-methylimidazole-3-tetrafluoroborate, 1-(fluorosulfonyl)-3,4-dimethyl-2-ethylimidazole-3-tetrafluoroborate, 1-(fluorosulfonyl)-3-methyl-2-isopropylimidazole-3-tetrafluoroborate, and 1-(fluorosulfonyl)-3,5-dimethylimidazole-3-tetrafluoroborate.

[0040] In some embodiments, the primary amide is selected from at least one of formamide, acetamide, propionamide, and butyramide.

[0041] In some embodiments, the alcohol is selected from at least one of methanol, ethanol, propanol, and butanol; the alkali metal salt of the alcohol is selected from at least one of the sodium salt, potassium salt, and lithium salt of the alcohol.

[0042] In some embodiments, the acid-binding agent is selected from at least one of triethylamine, N,N-diisopropylethylamine, pyridine, and 4-dimethylaminopyridine.

[0043] In a preferred embodiment, the acid-binding agent is selected from triethylamine.

[0044] In some embodiments, the solvent for the reaction in step (1) is selected from at least one of acetonitrile, dichloromethane, ethyl acetate, and dimethyl carbonate.

[0045] In a preferred embodiment, the solvent for the reaction in step (1) is acetonitrile.

[0046] In a preferred embodiment, the fluorosulfonyl imidazolium salt is 1-(fluorosulfonyl)-2,3-dimethylimidazole-3-trifluoromethanesulfonate, and its structural formula and structural simplified formula are shown as structural formula 3 and structural formula 4 respectively:

[0047]

[0048] Taking the fluorosulfonyl imidazolium salt as 1-(fluorosulfonyl)-2,3-dimethylimidazol-3-trifluoromethanesulfonate, the acid-binding agent as triethylamine, and the solvent as acetonitrile as examples, the synthetic routes of the bis(fluorosulfonyl)imide and the alkali metal salt of bis(fluorosulfonyl)imide in the present invention are as follows respectively:

[0049] Bis(fluorosulfonyl)imide:

[0050]

[0051]

[0052] Alkali metal salt of bis(fluorosulfonyl)imide:

[0053]

[0054] The following is an illustration in combination with specific examples.

[0055] N,N-Bis(fluorosulfonyl)acetamide was determined by fluorine nuclear magnetic resonance and mass spectrometry: 19F NMR (282 MHz, CD3CN) δ 58.2 (s); ESI-MS (m / z): 222 [M-H]-. The bis(fluorosulfonyl)imide and its metal salts were characterized by anion and cation chromatography.

[0056] Example 1

[0057] At 0 °C, 5.9 g of acetamide, 82 g of 1-(fluorosulfonyl)-2,3-dimethylimidazol-3-trifluoromethanesulfonate and 157 g of acetonitrile were added to a 500 ml flask. After stirring for 10 min, 5.1 g of triethylamine was added dropwise. Then the reaction was terminated after reacting at 25 °C for 4 hours. After adding 180 g of ethyl acetate, it was washed successively with 200 g of 1% hydrochloric acid and (200 g × 3) water. The organic phase was concentrated under negative pressure (40 °C) to about 100 ml to obtain a concentrated solution of the product N,N-bis(fluorosulfonyl)acetamide. 9.2 g of ethanol, a mixture of 3.5 g of dichlorodipyridylcobalt (II) and 0.05 g of manganese were added to a 250 ml flask as a catalyst, and the concentrated product from the previous step was added. The reaction was carried out at 60 °C for 12 hours, cooled to room temperature and filtered. The filtrate was washed with water (100 ml × 3). The organic phase was distilled under negative pressure (50 °C) until no bubbles emerged to obtain the product bis(fluorosulfonyl)imide (16.53 g, yield 91.3%).

[0058] Example 2

[0059] At 0 °C, 1.18 g of acetamide, 16.4 g of 1-(fluorosulfonyl)-2,3-dimethylimidazolium-3-trifluoromethanesulfonate, and 31.4 g of acetonitrile were added to a 100 ml flask. After stirring for 6 min, 1.02 g of triethylamine was added dropwise. Then, the reaction was terminated after reacting at 25 °C for 2 h. After adding 45 g of ethyl acetate, it was successively washed with 60 g of 1% hydrochloric acid and (60 g × 3) of water, filtered, and concentrated under reduced pressure (40 °C) to obtain about 30 ml of a concentrated solution of N,N-bis(fluorosulfonyl)acetamide. 17.3 g of a 6% lithium ethoxide ethanol solution and a mixture of 0.7 g of dichlorobipyridine cobalt(II) and 0.01 g of manganese were added to a 100 ml flask. The concentrated product from the previous step was added, and the reaction was carried out at 60 °C for 5 h. After cooling to room temperature, it was filtered, washed with water (30 g × 3), and the solvent was removed by distillation under reduced pressure (50 °C) after suction filtration to obtain the product lithium bis(fluorosulfonyl)imide (3.37 g, yield 90.2%).

[0060] Example 3

[0061] At 0 °C, 2.4 g of acetamide, 32.8 g of 1-(fluorosulfonyl)-2,3-dimethylimidazolium-3-trifluoromethanesulfonate, and 62.8 g of acetonitrile were added to a 150 ml flask. After stirring for 6 min, 2.04 g of triethylamine was added dropwise. Then, the reaction was terminated after reacting at 25 °C for 2 h. After adding 90 g of ethyl acetate, it was successively washed with 100 g of 1% hydrochloric acid and (100 g × 3) of water, filtered, and concentrated under reduced pressure (40 °C) to obtain about 50 ml of a concentrated solution of N,N-bis(fluorosulfonyl)acetamide. 13.6 g of a 20% sodium ethoxide ethanol solution and a mixture of 1.4 g of dichlorobipyridine cobalt(II) and 0.02 g of manganese were added to a 150 ml flask. The concentrated product from the previous step was added, and the reaction was carried out at 60 °C for 6 h. After cooling to room temperature, it was filtered, washed with water (50 g × 3), and the solvent was removed by distillation under reduced pressure (50 °C) for the organic phase to obtain the product sodium bis(fluorosulfonyl)imide (7.06 g, yield 87.0%).

[0062] Example 4

[0063] At 0 °C, 2.4 g of acetamide, 32.8 g of 1-(fluorosulfonyl)-2,3-dimethylimidazolium-3-trifluoromethanesulfonate and 62.8 g of acetonitrile were added to a 150 ml flask. After stirring for 6 min, 2.04 g of triethylamine was added dropwise. Then the reaction was terminated after reacting at 25 °C for 2 h. After adding 90 g of ethyl acetate, it was successively washed with 100 g of 1% hydrochloric acid and (100 g × 3) of water, filtered, and concentrated under reduced pressure (40 °C) to obtain about 50 ml of a concentrated solution of N,N-bis(fluorosulfonyl)acetamide. 22.5 g of a 15% potassium ethoxide ethanol solution and a mixture of 1.4 g of dichlorobipyridine cobalt(II) and 0.04 g of manganese were added to a 150 ml flask. The concentrated product from the previous step was added, and the reaction was carried out at 60 °C for 6 h. After cooling to room temperature, it was filtered and washed with water (50 g × 3). The organic phase was then distilled under reduced pressure (50 °C) to remove the solvent, and potassium bis(fluorosulfonyl)imide was obtained (8.19 g, yield 93.5%).

[0064] Example 5

[0065] At 0 °C, 5.9 g of acetamide, 82 g of 1-(fluorosulfonyl)-2,3-dimethylimidazolium-3-trifluoromethanesulfonate and 157 g of acetonitrile were added to a 500 ml flask. After stirring for 10 min, 5.1 g of triethylamine was added dropwise. Then the reaction was terminated after reacting at 25 °C for 4 h. After adding 180 g of ethyl acetate, it was successively washed with 200 g of 1% hydrochloric acid and (200 g × 3) of water. The organic phase was concentrated under reduced pressure (40 °C) to about 100 ml to obtain a concentrated solution of the product N,N-bis(fluorosulfonyl)acetamide. 9.2 g of ethanol and 0.59 g of cobalt powder as a catalyst were added to a 250 ml flask. The concentrated product from the previous step was added, and the reaction was carried out at 60 °C for 24 h. After cooling to room temperature, it was filtered, and the filtrate was washed with water (100 ml × 3). The organic phase was distilled under reduced pressure (50 °C) until no bubbles emerged, and bis(fluorosulfonyl)imide was obtained (6.8 g, yield 37.8%).

[0066] Example 6

[0067] At 0 °C, 1.18 g of acetamide, 16.4 g of 1-(fluorosulfonyl)-2,3-dimethylimidazolium trifluoromethanesulfonate, and 50 g of ethyl methyl carbonate were added to a 100 ml flask. After stirring for 6 min, 1.02 g of triethylamine was added dropwise. Then, the reaction was terminated after reacting at 25 °C for 2 h. It was washed successively with 60 g of 1% hydrochloric acid and (60 g × 3) of water, filtered, and concentrated under reduced pressure (60 °C) to obtain about 30 ml of a concentrated solution of N,N-bis(fluorosulfonyl)acetamide. 17.3 g of a 6% lithium ethoxide ethanol solution and a mixture of 0.7 g of dichlorobipyridine cobalt(II) and 0.01 g of manganese were added to a 100 ml flask. The concentrated product from the previous step was added, and the reaction was carried out at 60 °C for 5 h. After cooling to room temperature, it was filtered, washed with water (30 g × 3), and the solvent was removed by distillation under reduced pressure (50 °C) to obtain the product lithium bis(fluorosulfonyl)imide (2.7 g, yield 72.1%).

[0068] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0069] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent for the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention shall be subject to the appended claims.

Claims

1. A method for preparing difluoromethanesulfonimide or its alkali metal salt, characterized in that, It includes the following steps: (1) Under the action of an acid-binding agent, a fluorosulfonyl imidazolium salt and a primary amide are reacted at a temperature of 10 to 40 °C to generate N,N-bis(fluorosulfonyl)amide; (2) An alcohol or an alkali metal salt of an alcohol and the N,N-bis(fluorosulfonyl)amide are reacted at a temperature of 50 to 90 °C under the action of a catalyst to generate the bis(fluorosulfonyl)imide or its alkali metal salt. The fluorosulfonyl imidazolium salt is selected from the compounds represented by the following general structural formula: ； Formula (I); Among them, R1, R2 and R3 are each independently selected from H and alkyl groups having 1 to 5 carbon atoms; selected from trifluoromethylsulfonate anion, fluorosulfonate anion, tetrafluoroborate anion; The primary amide is selected from at least one of formamide, acetamide, propionamide, and butyramide; The catalyst contains dichlorobipyridine cobalt and manganese; the molar ratio of dichlorobipyridine cobalt to manganese is (4 to 10):1; The molar ratio of the fluorosulfonyl imidazolium salt, the primary amide, and the alcohol or the alkali metal salt of the alcohol is (2 to 3):1:(1 to 1.5).

2. The preparation method of the difluoromethanesulfonimide or its alkali metal salt according to claim 1, wherein, The fluorosulfonyl imidazolium salt is selected from at least one of 1-(fluorosulfonyl)-2,3-dimethylimidazolium-3-trifluoromethanesulfonate, 1-(fluorosulfonyl)-3-methylimidazolium-3-trifluoromethanesulfonate, 1-(fluorosulfonyl)-3,4-dimethyl-2-ethylimidazolium-3-trifluoromethanesulfonate, 1-(fluorosulfonyl)-3-methyl-2-isopropylimidazolium-3-trifluoromethanesulfonate, 1-(fluorosulfonyl)-3,5-dimethylimidazolium-3-trifluoromethanesulfonate, 1-(fluorosulfonyl)-2,3-dimethylimidazolium-3-fluorosulfonate, 1-(fluorosulfonyl)-3-methylimidazolium-3-fluorosulfonate, 1-(fluorosulfonyl)-3,4-dimethyl-2-ethylimidazolium-3-fluorosulfonate, 1-(fluorosulfonyl)-3-methyl-2-isopropylimidazolium-3-fluorosulfonate, 1-(fluorosulfonyl)-3,5-dimethylimidazolium-3-fluorosulfonate, 1-(fluorosulfonyl)-2,3-dimethylimidazolium-3-tetrafluoroborate, 1-(fluorosulfonyl)-3-methylimidazolium-3-tetrafluoroborate, 1-(fluorosulfonyl)-3,4-dimethyl-2-ethylimidazolium-3-tetrafluoroborate, 1-(fluorosulfonyl)-3-methyl-2-isopropylimidazolium-3-tetrafluoroborate, and 1-(fluorosulfonyl)-3,5-dimethylimidazolium-3-tetrafluoroborate.

3. The preparation method of difluoromethanesulfonimide or its alkali metal salt according to claim 1, characterized in that, The acid-binding agent is selected from at least one of triethylamine, N,N-diisopropylethylamine, pyridine, and 4-dimethylaminopyridine.

4. The preparation method of the difluoromethanesulfonimide or its alkali metal salt according to claim 1, characterized in that, The alcohol is selected from at least one of methanol, ethanol, propanol, and butanol; the alkali metal salt of the alcohol is selected from at least one of the sodium salt, potassium salt, and lithium salt of the alcohol.

5. The preparation method of difluoromethanesulfonimide or its alkali metal salt according to any one of claims 1 to 4, characterized in that, It includes the following steps: (1) React a fluorosulfonyl imidazolium salt with a primary amide under the action of an acid-binding agent, then add ethyl acetate to the product, wash with acid, wash with water, and concentrate the organic phase under negative pressure to obtain an N,N-bis(fluorosulfonyl)amide; (2) React an alcohol or an alkali metal salt of an alcohol with the N,N-bis(fluorosulfonyl)amide under the action of a catalyst, filter the product by suction, wash the filtrate with water, and distill the organic phase under negative pressure to obtain the bis(fluorosulfonyl)imide or its alkali metal salt.

Images