A method for preparing a bis(trifluoromethylsulfonyl)imide ionic liquid

Abstract

The application relates to a method for preparing a bis(trifluoromethylsulfonyl)imide ionic liquid. The method comprises the following steps: S1, weighing bis(trifluoromethylsulfonyl)imide and a first portion of an organic solvent, stirring and uniformly mixing the bis(trifluoromethylsulfonyl)imide and the first portion of the organic solvent; S2, weighing a second portion of the organic solvent, adding the second portion of the organic solvent into a reaction kettle; adding an organic salt into the reaction kettle; adding the material obtained in S1 into the reaction kettle dropwise to carry out reaction; S3, after the reaction is completed, carrying out distillation treatment on the ionic liquid, the bis(trifluoromethylsulfonyl)imide and the organic solvent mixture in the reaction kettle, recycling the organic solvent and the bis(trifluoromethylsulfonyl)imide, and the reaction kettle is the bis(trifluoromethylsulfonyl)imide ionic liquid. The bis(trifluoromethylsulfonyl)imide ionic liquid is prepared by using bis(trifluoromethylsulfonyl)imide and an organic salt as raw materials through a one-step method, the yield is high, separation is simple, and the method is beneficial to industrial production.

Description

Technical Field

[0001] This application belongs to the field of ionic liquid preparation, and relates to a method for preparing an imine-based ionic liquid, specifically a method for preparing a bis(trifluoromethanesulfonyl)imine-based ionic liquid. Background Technology

[0002] Ionic liquids, also known as room-temperature ionic liquids, room-temperature molten salts, or organic ionic liquids, are salts composed of organic cations and inorganic anions, which are liquid below 100°C. Most ionic liquids are liquid at or near room temperature. Ionic liquids can be classified in several ways. Based on the cation, they can be mainly divided into imidazole, pyridine, pyrrole, quaternary ammonium, and quaternary phosphine types. Based on the anion, they can be divided into metallic and non-metallic categories. Furthermore, according to the different functions of the product, ionic liquids can be further subdivided into polymeric ionic liquids, acid-functionalized ionic liquids, base-functionalized ionic liquids, chiral functionalized ionic liquids, and metal-functionalized ionic liquids.

[0003] Ionic liquids can be used as solvents in chemical reactions and as catalysts in heterogeneous catalysis. Among them, ionic liquids containing bis(trifluoromethanesulfonyl)imide groups are widely used in electrochemistry, reaction catalysis, antistatic agents, green solvents and other fields due to their excellent properties. Therefore, the preparation of bis(trifluoromethanesulfonyl)imide ionic liquids is of great significance.

[0004] The following are known literature and patent reports regarding methods for preparing bis(trifluoromethanesulfonyl)imide ionic liquids:

[0005] Chinese patent 201910718973.1 reports the preparation of an imidazole polyionic liquid 1 with Cl- side chains by reacting epichlorohydrin with alkyl imidazoles of different chain lengths; then, using polyionic liquid 1 as a raw material, imidazole polyionic liquid 2 with different anions is synthesized. Epichlorohydrin, the raw material, is listed in Group 2A of carcinogens, posing a certain degree of harm to users' health. Furthermore, the overall yield is low, affecting the subsequent effectiveness of the product.

[0006] Chinese Patent 202210294649.3 reports a method for preparing an ionic liquid: (1) a compound whose cations are quaternary ammonium ions, quaternary phosphorus ions, imidazole ions, or imidazole ions is dissolved in an organic solvent to form an organic phase, and a compound whose anions are [BF4]-, [PF6]-, [CF3SO3]-, or [Tf2N]- is dissolved in water to form an aqueous phase; wherein the molar ratio of the anionic compound to the cation compound is greater than or equal to 1; (2) the organic phase and the aqueous phase are mixed and stirred to allow the two phases to come into full contact and react; (3) the ionic liquid is obtained by separation through a nanofiltration membrane made of modified polyimide material. This preparation method requires the use of organic solvents, which increases the difficulty of separating the product from the solvent. A large amount of energy is required to separate the two, which is wasteful of energy and has a high cost.

[0007] Invention CN02824172.X discloses a method for preparing ionic liquids by carrying out an ion exchange reaction between a quaternary phosphonium, imidazole, or pyridine halide providing a suitable ionic component and a salt providing a suitable anionic component, wherein the method involves carrying out the reaction under sonication. This invention requires ultrasonic conditions, which are demanding; furthermore, ultrasound may pose a health hazard, making this method unsuitable for large-scale industrial production.

[0008] Therefore, there is an urgent need to propose a simple method for preparing bis(trifluoromethanesulfonyl)imide ionic liquids that is conducive to industrial production. Summary of the Invention

[0009] To address the technical problems of low yield, difficult separation, and unfavorable conditions for industrial production in the preparation of ionic liquids in existing technologies, this application proposes a method for preparing bis(trifluoromethanesulfonyl)imide ionic liquids. Using bis(trifluoromethanesulfonyl)imide and organic salts as raw materials, and in conjunction with an organic solvent, bis(trifluoromethanesulfonyl)imide ionic liquids are prepared in one step with high yield, simple separation, and favorable conditions for industrial production, thus optimizing the technical problems in existing technologies.

[0010] This application provides a method for preparing bis(trifluoromethanesulfonyl)imide ionic liquids using the following technical solution:

[0011] A method for preparing bis(trifluoromethanesulfonyl)imine ionic liquids includes the following steps:

[0012] S1. Mixing treatment: Weigh bis(trifluoromethanesulfonyl)imide and the first part of organic solvent separately, and stir and mix bis(trifluoromethanesulfonyl)imide and the first part of organic solvent in a weight ratio of (3~8):1 until uniform.

[0013] S2, Reaction: Weigh the second part of organic solvent and add it to the reactor at a weight ratio of (1-4):1; add the organic salt to the reactor at a weight ratio of 1:(2-5); add the material obtained in S1 dropwise to the reactor for reaction, controlling the temperature at (20-60)℃, the reaction pressure at (0-0.10)MPa, and the reaction time at (2-5)h;

[0014] S3. Distillation treatment: After the reaction is completed, the mixture of ionic liquid, bis(trifluoromethanesulfonyl)imide and organic solvent in the reaction vessel is distilled. The distillation temperature is controlled at (90~150)℃ and the pressure is (-0.1~-0.03)MPa. The organic solvent and bis(trifluoromethanesulfonyl)imide are recovered and reused. What remains in the reaction vessel is the bis(trifluoromethanesulfonyl)imide ionic liquid.

[0015] In one specific implementation of this application, the first organic solvent in S1 and the second organic solvent in S2 are the same substance.

[0016] In one specific embodiment of this application, the first or second organic solvent comprises any one of dichloromethane, ethyl acetate, acetonitrile, or acetone; the organic solvent has a purity of 99% and a color intensity of ≤5 Hazen.

[0017] In one specific embodiment of this application, the organic salt in S2 includes one of a quaternary ammonium salt, an imidazole salt, or a pyridine salt.

[0018] In one specific embodiment of this application, the bis(trifluoromethanesulfonyl)imide ionic liquid product has a mass fraction ≥99%, wherein the moisture content is ≤0.1%, the color is ≤100 Hazen, and the Fe content is ≤5×10⁻⁶. -6 K≤10×10 -6 Ba≤5×10 -6 Si≤10×10 -6 Na≤10×10 -6 Ca≤10×10 -6 B≤5×10 -6 .

[0019] The beneficial effects of this application are as follows: This application utilizes the reaction of bis(trifluoromethanesulfonyl)imide and organic salt, followed by distillation under controlled distillation conditions. It involves only one step of reaction, with short reaction time, few side reactions, reduced production costs, no waste generation, simple impurity removal process, high reaction efficiency, avoidance of multiple water washing to generate large amounts of wastewater, and requires less equipment, small footprint, and low investment, making it suitable for industrial production. Detailed Implementation

[0020] All raw materials used in the embodiments of this application are commercially available, as shown in Table 1; the detection methods and instruments involved in this application are shown in Table 2.

[0021] Table 1

[0022]

[0023] Table 2

[0024]

[0025] The solution of this application will be further described in detail below with reference to specific embodiments.

[0026] It should be noted that in the proposed scheme, the organic solvent can be any one of dichloromethane, ethyl acetate, acetonitrile, or acetone. The use of ethyl acetate, acetonitrile, and dichloromethane in the following examples is merely an example. Correspondingly, the organic salt in this application can be a quaternary ammonium salt, an imidazole salt, or a pyridine salt. The use of tributylmethylammonium chloride, 1-ethyl-3-methylimidazolium chloride, and 1-butylpyridine chloride in the following examples is merely an example.

[0027] Example 1

[0028] This application requests disclosure of a method for preparing bis(trifluoromethanesulfonyl)imine ionic liquids, specifically a method for preparing tri-n-butylammonium bis(trifluoromethanesulfonyl)imine ionic liquids, comprising the following steps:

[0029] Bis(trifluoromethanesulfonyl)imide and ethyl acetate solvent were added to a mixing reactor in a 3:1 ratio, with a total weight of 80 kg. The mixture was stirred until homogeneous and set aside. 50 kg of tributylmethylammonium chloride was added to the reactor, followed by 10 kg of ethyl acetate solvent. The mixture of bis(trifluoromethanesulfonyl)imide and ethyl acetate was then added dropwise to initiate the reaction. The reaction temperature was controlled at 20°C, and the reaction pressure at (0.03~0.10) MPa. After the reaction was completed, the mixture was stirred for another 2 hours. The hydrogen chloride produced during the reaction was absorbed by water and became hydrochloric acid as a byproduct. After the reaction was completed, ethyl acetate and bis(trifluoromethanesulfonyl)imide were recovered by distillation. The distillation was completed at a temperature of 100°C and a pressure of (-0.1~-0.095) MPa. The purity of the tri-n-butylmethylammonium bis(trifluoromethanesulfonyl)imide product is shown in Table 3. The weight was approximately 96.8 kg, and the yield was approximately 95.1%.

[0030] Table 3. Indices of Tri-n-Butylmethylammonium Bis(trifluoromethanesulfonyl)imide

[0031]

[0032]

[0033] Example 2

[0034] This application requests disclosure of a method for preparing bis(trifluoromethanesulfonyl)imide ionic liquids, specifically a method for preparing 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquids, comprising the following steps:

[0035] Bis(trifluoromethanesulfonyl)imide and acetonitrile solvent were added to a mixing reactor at a ratio of 8:1, with a total weight of 45 kg. The mixture was stirred until homogeneous and set aside. 20 kg of 1-ethyl-3-methylimidazolium chloride was added to the reactor, followed by 10 kg of acetonitrile solvent. The mixture of bis(trifluoromethanesulfonyl)imide and acetonitrile was then added dropwise to initiate the reaction. The reaction temperature was controlled at 60℃, and the reaction pressure at (0~0.005) MPa. After the reaction was completed, the mixture was stirred for another 5 hours. The hydrogen chloride produced during the reaction was absorbed by water and used as a hydrochloric acid byproduct. After the reaction was completed, acetonitrile and bis(trifluoromethanesulfonyl)imide were recovered by distillation. The distillation was completed at a temperature of 120℃ and a pressure of (-0.085~-0.080) MPa. The purity of the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide product is shown in Table 4. The weight was approximately 52.3 kg, and the yield was approximately 98.0%.

[0036] Table 4. 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide index

[0037]

[0038]

[0039] Example 3

[0040] This application requests disclosure of a method for preparing bis(trifluoromethanesulfonyl)imine ionic liquids, specifically a method for preparing 1-butylpyridine chloride bis(trifluoromethanesulfonyl)imine ionic liquids, comprising the following steps:

[0041] Bis(trifluoromethanesulfonyl)imide and dichloromethane solvent were added to a mixing reactor at a ratio of 6:1, with a total weight of 63 kg. The mixture was stirred until homogeneous and set aside. 30 kg of 1-butylpyridine chloride was added to the reactor, followed by 10 kg of dichloromethane solvent. The bis(trifluoromethanesulfonyl)imide and dichloromethane mixture was then added dropwise to initiate the reaction. The reaction temperature was controlled at 35°C, and the reaction pressure at (0.03~0.008) MPa. After the reaction was completed, the mixture was stirred for another 4 hours. The hydrogen chloride produced during the reaction was absorbed by water and used as a hydrochloric acid byproduct. After the reaction was completed, dichloromethane and bis(trifluoromethanesulfonyl)imide were recovered by distillation. The distillation was completed at a temperature of 112°C and a pressure of (-0.095~-0.090) MPa. The purity of the 1-butylpyridine chloride bis(trifluoromethanesulfonyl)imide product is shown in Table 5. The weight was approximately 71.2 kg, and the yield was approximately 97.9%.

[0042] Table 5. 1-Butylpyridine chloride bis(trifluoromethanesulfonyl)imine index

[0043]

[0044] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto; any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solution and improved concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing bis(trifluoromethanesulfonyl)imide ionic liquids, characterized in that, Includes the following steps: S1. Mixing treatment: Weigh bis(trifluoromethanesulfonyl)imide and the first part of organic solvent separately, and stir and mix bis(trifluoromethanesulfonyl)imide and the first part of organic solvent in a weight ratio of (3~8):1 until uniform. S2, Reaction: Weigh the second part of organic solvent and add it to the reactor at a weight ratio of (1~4):1; add the organic salt to the reactor at a weight ratio of 1:(2~5); add the material obtained in S1 dropwise to the reactor for reaction, controlling the temperature at 20~60℃, the reaction pressure at 0~0.10MPa, and the reaction time at 2~5h; S3. Distillation treatment: After the reaction is completed, the mixture of ionic liquid, bis(trifluoromethanesulfonyl)imide and organic solvent in the reaction vessel is distilled. The distillation temperature is controlled at 100~120℃ and the pressure is -0.1~-0.08MPa. The organic solvent and bis(trifluoromethanesulfonyl)imide are recovered and reused. What remains in the reaction vessel is the bis(trifluoromethanesulfonyl)imide ionic liquid. The first organic solvent in S1 and the second organic solvent in S2 are the same substance; The first or second organic solvent is selected from any one of dichloromethane, ethyl acetate, acetonitrile, or acetone; the organic solvent has a purity of 99% and a color intensity of ≤5 Hazen. The organic salt in S2 is selected from one of quaternary ammonium salts, imidazole salts, or pyridine salts.

2. The method for preparing bis(trifluoromethanesulfonyl)imide ionic liquids according to claim 1, characterized in that: The bis(trifluoromethanesulfonyl)imide ionic liquid product has a mass fraction ≥99%, with a moisture content ≤0.1%, a color ≤100 Hazen, and an Fe content ≤5×10⁻⁶. -6 K≤10×10 -6 Ba≤5×10 -6 Si≤10×10 -6 Na≤10×10 -6 Ca≤10×10 -6 B≤5×10 -6 .

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