Preparation method of trifluoromethanesulfonate ionic liquid

Abstract

The invention provides a preparation method of trifluoromethanesulfonic acid ionic liquid. According to the preparation method, trifluoromethanesulfonic acid, pyrrole salt, pyridinium salt, pyrazine salt and the like are subjected to substitution reaction, static layering, organic phase water washing and organic phase drying to achieve the purpose of generating the trifluoromethanesulfonic acid ionic liquid. The prepared trifluoromethanesulfonic acid ionic liquid is high in purity, good in yield and suitable for large-scale industrial application. The method provided by the invention is green and environment-friendly, and does not use harsh reaction conditions and organic solutions; meanwhile, the cost is low, the yield is high, and the purity of a crude product can reach 99.95% or above after the crude product is purified; and the method has the advantages of less required equipment, small occupied area and low investment, and can realize industrial production.

Description

Technical Field

[0001] The invention belongs to the field of fine chemicals, and in particular relates to a method for preparing trifluoromethanesulfonate ionic liquid. Background Art

[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 that are liquid at temperatures below 100°C. Most ionic liquids are liquid at or near room temperature. There are various classifications of ionic liquids. Based on the cation, they can be categorized as imidazole, pyridinium, pyrrole, quaternary ammonium, and quaternary phosphonium. Based on the anion, they can be further divided into metallic and non-metallic types. Furthermore, based on the functionalities they possess, 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] As emerging green materials, ionic liquids are widely used. Currently, the global ionic liquid market is primarily focused on applications in electrochemistry, catalysis, synthesis and extraction, separation engineering, and green solvents. Trifluoromethanesulfonate ionic liquids, in particular, have attracted significant attention due to their excellent properties, including low volatility, non-flammability, and high thermal stability. The preparation of trifluoromethanesulfonate imine ionic liquids is of significant significance.

[0004] As an emerging green material, ionic liquids have a wide range of applications. Currently, the global ionic liquid market is primarily focused on applications in electrochemistry, catalysis, synthesis and extraction, separation engineering, and green solvents. They can be used as solvents in Friedel-Crafts reactions, Diels-Alder reactions, solutions in CC coupling reactions, and Michael reactions.

[0005] The method for preparing ionic liquids is reported in the following related literature and patents: CN201910718973.1 reports the preparation of ionic liquids containing side chains by reacting epichlorohydrin and alkyl imidazoles of different chain lengths. - The invention further synthesizes imidazole polyionic liquid 1 by combining polyionic liquid 1 with a metal salt to synthesize imidazole polyionic liquid 2 with different anions. The raw material epichlorohydrin used in this invention is listed as a Class 2A carcinogen and may pose a health risk to users. The overall yield is also low, affecting the subsequent use of the product.

[0006] CN202210294649.3 reports a method for preparing an ionic liquid: (1) dissolving a compound whose cation is a quaternary ammonium ion, a quaternary phosphonium ion, an imidazolium ion or an imidazolinium ion in an organic solvent to form an organic phase, and dissolving an anion such as [BF4] - PF6- , [CF3SO3] - or [Tf2N] - (1) dissolving the organic phase and the aqueous phase in water to form an aqueous phase; wherein the molar ratio of the anionic compound to the cationic compound is greater than or equal to 1; (2) mixing and stirring the organic phase and the aqueous phase so that the two phases are fully in contact and react; and (3) separating the ionic liquid through a modified polyimide nanofiltration membrane. The present invention requires the use of an organic solvent, which increases the difficulty of separating the product from the solvent and requires a large amount of energy to separate the two, resulting in energy waste and high costs.

[0007] Authorized invention patent CN02824172.X reports a method for preparing ionic liquids by conducting an ion exchange reaction between a quaternary phosphonium, imidazole, or pyridinium halide providing an appropriate cationic component and a salt providing an appropriate anionic component. This method requires the reaction to be carried out under ultrasonication. This invention has harsh reaction conditions, and ultrasound can cause significant harm to the human body. 1. Impact on the eyes and skin: It can cause eye congestion and edema, and even induce cataracts and conjunctivitis. 2. Impact on the nervous system: It can cause cell necrosis and vascular paralysis. 3. Impact on the circulatory system: It can cause nerve paralysis, slow blood flow, increase blood viscosity, and even induce thrombosis. 4. Impact on bone development: It can affect the bone development of young children. 5. Impact on the reproductive system: It can damage sperm and eggs, affect conception, and even cause fetal malformations.

[0008] The applicant believes that most of the existing technologies have the following problems: ① using harsh reaction conditions; ② the raw materials are highly hazardous; ③ the presence of organic solvents. Summary of the Invention

[0009] The present invention aims to provide a method for preparing trifluoromethanesulfonate ionic liquids under mild conditions and high purity.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] A method for preparing a trifluoromethanesulfonate ionic liquid is provided, wherein the trifluoromethanesulfonate ionic liquid is prepared by a one-step reaction, and the steps include:

[0012] Step 1: mixing AB with water and stirring to obtain a mixed solution; wherein AB is one of pyrazine salt, pyridinium salt and thiazole salt;

[0013] Step 2: adding trifluoromethanesulfonic acid dropwise to the mixed solution prepared in step 1, stirring to react to generate an ionic liquid aqueous solution, cooling, stopping stirring and allowing to stand, and separating the aqueous phase from the organic phase;

[0014] Step 3: washing the organic phase with water and dehydrating under vacuum.

[0015] Furthermore, the mass concentration of AB in the mixed solution in step 1 is 30-90%; and the temperature of the mixed solution in step 1 is 10-30°C.

[0016] Furthermore, the molar ratio of AB to trifluoromethanesulfonic acid is 1.02 to 1.05:1, the pyrazine salt is 5,8-dibromobenzopyrazine salt or 2-amino-3,5-dibromopyrazine salt, the pyridine salt is 4-dimethylaminopyridine or 3-amino-1-ethylpyridine salt, and the thiazole salt is 5-aminothiazole salt or 2-amino-4-methylthiazole salt.

[0017] Furthermore, in step 2, the trifluoromethanesulfonic acid is added dropwise for 1-6 hours, preferably 2-4 hours; and after the addition is complete, the reaction is continued for 1-4 hours, preferably 2-3 hours.

[0018] Furthermore, in step 2, the temperature of the dropwise addition and the reaction are both 10-30°C, preferably 10°C or 15°C; and the temperature is lowered to 0-10°C, preferably 0-5°C.

[0019] Furthermore, the organic phase after stratification in step 3 is washed with water for 2-7 times, and the amount of water added is 20-80% of the total mass of the organic phase, preferably 30-50%. The water used for washing is high-purity water with a purity of ≥8N.

[0020] Furthermore, in step 3, the organic phase is washed with water until the conductivity is ≤500 μS / cm.

[0021] Furthermore, in step 3, the dehydration temperature is 70-150° C., preferably 90-110° C., and the vacuum degree is ≤-0.075 MPa.

[0022] Furthermore, the mass concentration of AB in the mixed solution in step 1 is 60-80%.

[0023] Furthermore, the molar ratio of AB to trifluoromethanesulfonic acid is 1.03:1.

[0024] The present invention prepares trifluoromethanesulfonate ionic liquids through a one-step reaction, and the reaction equation is as follows:

[0025] AB+CF3SO3H→ACF3SO3+HB

[0026] Wherein AB is pyridinium salt, pyrazine salt, thiazole salt, and B is chlorine or bromine element.

[0027] The preparation method specifically comprises the following steps:

[0028] (1) Mixing raw materials AB and water: Add a certain amount of pyrazine salt, thiazole salt or pyridinium salt into a reactor, add a certain amount of water, stir to dissolve, and prepare the raw material AB aqueous solution.

[0029] (2) Cooling the mixed solution: Cool the mixed solution of raw materials AB to between 10-30°C while stirring.

[0030] (3) Trifluoromethanesulfonic acid addition: trifluoromethanesulfonic acid is delivered to a high-position dropping tank via a delivery pump. Trifluoromethanesulfonic acid is added dropwise under normal pressure, with the temperature controlled between (10 and 30)°C and stirred at 50 Hz. The trifluoromethanesulfonic acid is added dropwise within (1-6) hours. The reaction is continued with stirring at this reaction temperature for (1 to 4) hours.

[0031] (4) Cooling and stabilizing the reaction mixture: The reaction mixture is cooled to 0-10°C under stirring, and then gradually separated into layers and phases under static conditions. The organic matter is washed with water.

[0032] (5) Water washing: After stratification, the organic phase is washed with water (20-80% of the total mass of the organic phase), and water is added 2-7 times for washing, so that the metal ions in the organic matter are discharged with the water phase until all metal ions are qualified.

[0033] (6) The organic matter that meets the metal ion test standard is poured into a drying kettle and dehydrated and distilled at a negative pressure of (-0.075 to -0.098) MPa at (70 to 150) °C to reduce the moisture content of the organic matter to the required range.

[0034] (8) Packaging: The dried organic matter is filled into the required packaging.

[0035] Beneficial effects of the present invention:

[0036] The preparation method provided by the present invention involves only one-step reaction, shortens the reaction time, reduces process cost, and has a simple impurity removal process, thereby providing a reliable process guarantee for the industrial development of trifluoromethanesulfonate ionic liquids.

[0037] The method of the present invention is green and environmentally friendly, does not require harsh reaction conditions and the use of organic solvents; at the same time, it has low cost and high yield, and the crude product can reach a high purity of more than 99.95% after purification; and requires less equipment, occupies a small area, has low investment, and can realize industrial production. DETAILED DESCRIPTION

[0038] The present invention is further described below with reference to the following examples. The present invention includes but is not limited to the following examples, and any equivalent replacement or partial improvement made under the principle of the present invention shall be deemed to be within the scope of protection of the present invention.

[0039] The preparation method of 5,8-dibromobenzopyrazine trifluoromethanesulfonate, 5-aminothiazole trifluoromethanesulfonate, and 4-dimethylaminopyridine trifluoromethanesulfonate involved in this application comprises the following steps:

[0040] Trifluoromethanesulfonic acid is pumped to a high-level tank via a feed pump. AB is added to a reactor, and a certain amount of water is added for stirring and dissolution. Trifluoromethanesulfonic acid is then added dropwise at a controlled temperature of 10-30°C under normal pressure. The addition rate is controlled to ensure that the addition is complete within 1-6 hours. After the addition is complete, the temperature is controlled at 10-30°C for 1-4 hours. Stirring is then stopped, and the mixture is allowed to stand for stratification. The organic matter is separated and washed with water. After multiple washes, the metal ion content in the aqueous phase is controlled to be within the acceptable range. The organic matter is vacuum-dried in a drying kettle, and the aqueous phase is collected and sent to a waste treatment tank. After vacuum removal, the water is packaged for sale.

[0041] The synthesis kettle involved in the present application is a jacketed kettle with stirring, the jacket contains water, and the temperature is controlled by a heating rod; the drying kettle is a jacketed kettle with stirring.

[0042] The raw materials involved in this application are 5,8-dibromobenzopyrazine chloride, pyridinium salt, 4-dimethylaminopyridinium salt, trifluoromethanesulfonic acid and water. The raw materials used are shown in Table 1.

[0043] Table 1

[0044] raw material Mass purity / % factory Trifluoromethanesulfonic acid ≥99％ CSSC (Handan) Perri Special Gases Co., Ltd. High purity water ≥8N CSSC (Handan) Perri Special Gases Co., Ltd. 5,8-Dibromobenzopyrazine chloride ≥98％ Suzhou Haofan Biotechnology Co., Ltd. 5-aminothiazole salt ≥99％ Shandong Jinhe Chemical Co., Ltd. 4-Dimethylaminopyridinium salt ≥99％ Nanjing Baimuda Biotechnology Co., Ltd.

[0045] The test items and indicators of the ionic liquids 5,8-dibromobenzopyrazine trifluoromethanesulfonate, 5-aminothiazole trifluoromethanesulfonate, and 4-dimethylaminopyridine trifluoromethanesulfonate of the present application are shown in Table 2.

[0046] Table 2

[0047]

[0048]

[0049] After testing, the yield of the obtained 5,8-dibromobenzopyrazine trifluoromethanesulfonate, 5-aminothiazole trifluoromethanesulfonate, and 4-dimethylaminopyridine trifluoromethanesulfonate ionic liquid products reached 97%, the purity reached above 99.9%, and all metal ions were within the required range. The following is an example.

[0050] Example 1-1

[0051] Dissolve 151g of 5,8-dibromobenzopyrazine in 100g of water, stir, and add to a sealed reactor. Then, add 150g of trifluoromethanesulfonic acid to the addition tank. While stirring, maintain the reactor temperature at 10°C. After the trifluoromethanesulfonic acid is added dropwise over 3 hours, stir for 1 hour. Cool to 1°C, stop stirring, and allow to stand for 0.5 hours before separating the layers. Pour the organic matter into a reactor, wash the organic phase with 100g of high-purity water, and collect the aqueous phase. Stir for 1 hour, then stop stirring, allow to stand for 0.5 hours, and allow the layers to separate. Pour the organic phase back into the reactor and wash with 100g of high-purity water. Sample the aqueous phase for metal ion content, and if all are within acceptable limits, discontinue water washing. Dry the organic matter at 90-100°C under a vacuum of -0.0980 MPa. Collect all the aqueous phases and dispose of them in a wastewater tank. Specific test data are shown in Table 1-1.

[0052] Table 1-1 Product testing data table

[0053]

[0054]

[0055] Example 1-2

[0056] Dissolve 151g of 5,8-dibromobenzopyrazine in 100g of water, stir, and add to a sealed reactor. Then, add 150g of trifluoromethanesulfonic acid to the addition tank. While stirring, maintain the reactor temperature at 30°C. After the trifluoromethanesulfonic acid is added dropwise over 3 hours, stir and react for 4 hours. Cool to 5°C, stop stirring, and allow to stand for 0.5 hours before separating the layers. Pour the organic matter into a reactor, wash the organic phase with 100g of high-purity water, and collect the aqueous phase. Stir for 1 hour, then stop. Allow to stand for 0.5 hours before separating the layers. Pour the organic phase back into the reactor and wash with 100g of high-purity water. Sample the aqueous phase for metal ion content, and if all are within acceptable limits, discontinue water washing. Dry the organic matter at 90-100°C under a vacuum of -0.0980 MPa. Collect all aqueous phases and dispose of them in a wastewater tank. Specific test data are shown in Tables 1-2.

[0057] Table 1-2 Product testing data table

[0058]

[0059]

[0060] Example 2-1

[0061] Dissolve 103.2g of 5-aminothiazole salt in 50g of water, stir and mix, and add to a sealed reactor. Then, add 150g of trifluoromethanesulfonic acid to the addition tank. While stirring, maintain the reactor temperature at 10°C. After the trifluoromethanesulfonic acid is added dropwise over 1 hour, stir and react for 2 hours. Cool to 1°C, stop stirring, and allow to stand for 0.5 hour before separating. Pour the organic matter into a reactor, wash the organic phase with 75g of high-purity water, and collect the aqueous phase. Stir for 1 hour, then stop stirring, allow to stand for 0.5 hour, and allow the organic phase to separate. Pour the organic phase back into the reactor and wash with 75g of high-purity water. Sample the aqueous phase for metal ion content, and if all are within acceptable limits, discontinue water washing. Dry the organic matter at 90-100°C under a vacuum of -0.0980 MPa. Collect all aqueous phases and dispose of them in a wastewater tank. Specific test data are shown in Table 2-1.

[0062] Table 2-1 Product testing data table

[0063]

[0064]

[0065] Example 2-2

[0066] Dissolve 103.2g of 5-aminothiazole salt in 50g of water, stir and mix, and add to a sealed reactor. Then, add 150g of trifluoromethanesulfonic acid to the addition tank. While stirring, maintain the reactor temperature at 30°C. After the trifluoromethanesulfonic acid is added dropwise over 1 hour, stir and react for 2 hours. Cool to 5°C, stop stirring, and allow to stand for 0.5 hour before separating. Pour the organic matter into a reactor, wash the organic phase with 75g of high-purity water, and collect the aqueous phase. Stir for 1 hour, then stop. Allow to stand for 0.5 hour to separate. Pour the organic phase back into the reactor and wash with 75g of high-purity water. Sample the aqueous phase for metal ion content, and if all are within acceptable limits, discontinue water washing. Dry the organic matter at 90-100°C under a vacuum of -0.0980 MPa. Collect all aqueous phases and dispose of them in a wastewater tank. Specific test data are shown in Table 2-2.

[0067] Table 2-2 Product testing data table

[0068]

[0069]

[0070] Example 3-1

[0071] Dissolve 126g of 4-dimethylaminopyridine salt in 75g of water, stir and mix, and add to a sealed reactor. Then, add 150g of trifluoromethanesulfonic acid to the addition tank. While stirring, maintain the reactor temperature at 10°C. After the trifluoromethanesulfonic acid is added dropwise over 3 hours, stir and react for 1 hour. Cool to 1°C, stop stirring, and allow to stand for 0.5 hour before separating. Pour the organic matter into a reactor, wash the organic phase with 90g of high-purity water, and collect the aqueous phase. Stir for 1 hour, then stop stirring, allow to stand for 0.5 hour, and allow the organic phase to separate. Pour the organic phase back into the reactor and wash with 90g of high-purity water. Sample the aqueous phase for metal ion content, and if all are within acceptable limits, discontinue water washing. Dry the organic matter at 90-100°C under a vacuum of -0.0980 MPa. Collect all aqueous phases and dispose of them in a wastewater tank. Specific test data are shown in Table 3-1.

[0072] Table 3-1 Product testing data table

[0073]

[0074]

[0075] Example 3-2

[0076] Dissolve 126g of 4-dimethylaminopyridine salt in 75g of water, stir and mix, and add to a sealed reactor. Then, add 150g of trifluoromethanesulfonic acid to the addition tank. While stirring, maintain the reactor temperature at 30°C. After the trifluoromethanesulfonic acid is added dropwise over 3 hours, stir and react for 4 hours. Cool to 1°C, stop stirring, and allow to stand for 0.5 hours before separating. Pour the organic matter into a reactor, wash the organic phase with 90g of high-purity water, and collect the aqueous phase. Stir for 1 hour, then stop. Allow to stand for 0.5 hours to separate. Pour the organic phase back into the reactor and wash with 90g of high-purity water. Sample the aqueous phase for metal ion content, and if all are within acceptable limits, discontinue water washing. Dry the organic matter at 90-100°C under a vacuum of -0.0980 MPa. Collect all aqueous phases and dispose of them in a wastewater tank. Specific test data are shown in Table 3-2.

[0077] Table 3-2 Product testing data table

[0078]

[0079] According to the above examples, corresponding trifluoromethanesulfonate ionic liquid products can be obtained in Examples 1-1 to 3-2 of the present invention.

[0080] The yield of Example 1-1 is 98.5%, the purity is ≥99.9%, and the chromaticity and metal ion content of the product meet the product testing requirements.

[0081] The yield of Example 1-2 is 98.8%, the purity is ≥99.9%, and the chromaticity and metal ion content of the product meet the product testing requirements.

[0082] The yield of Example 2-1 is 98%, the purity is ≥99.9%, and the color and metal ion content of the product meet the product testing requirements.

[0083] The yield of Example 2-2 is 98.3%, the purity is ≥99.9%, and the color and metal ion content of the product meet the product testing requirements.

[0084] The yield of Example 3-1 is 97.5%, the purity is ≥99.9%, and the color and metal ion content of the product meet the product testing requirements.

[0085] The yield of Example 3-2 is 98%, the purity is ≥99.9%, and the color and metal ion content of the product meet the product testing requirements.

[0086] The above describes in detail the specific embodiments of the present invention. It should be understood that numerous modifications and variations based on the concepts of the present invention can be made by those skilled in the art without inventive effort. Therefore, any technical solution that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for preparing a trifluoromethanesulfonate ionic liquid, characterized in that the trifluoromethanesulfonate ionic liquid is prepared by a one-step reaction, the steps comprising the following: Step 1: mixing AB with water and stirring to obtain a mixed solution; wherein AB is one of pyrazine salt, pyridinium salt and thiazole salt; Step 2: adding trifluoromethanesulfonic acid dropwise to the mixed solution prepared in step 1, stirring to react to generate an ionic liquid aqueous solution, cooling, stopping stirring and allowing to stand, and separating the aqueous phase from the organic phase; Step 3: washing the organic phase with water and dehydrating under vacuum.

2. The method for preparing a trifluoromethanesulfonate ionic liquid according to claim 1, wherein the mass concentration of AB in the mixed solution in step 1 is 30-90%; and the temperature of the mixed solution in step 1 is 10-30°C.

3. A method for preparing a trifluoromethanesulfonate ionic liquid according to claim 1, wherein the molar ratio of AB to trifluoromethanesulfonic acid is 1.02 to 1.05:1, the pyrazine salt is 5,8-dibromobenzopyrazine salt or 2-amino-3,5-dibromopyrazine salt, the pyridinium salt is 4-dimethylaminopyridine or 3-amino-1-ethylpyridinium salt, and the thiazole salt is 5-aminothiazole salt or 2-amino-4-methylthiazole salt.

4. The method for preparing a trifluoromethanesulfonate ionic liquid according to claim 1, wherein the trifluoromethanesulfonic acid is added dropwise for 1-6 hours in step 2, and the reaction is continued for 1-4 hours after the addition is completed.

5. The method for preparing a trifluoromethanesulfonate ionic liquid according to claim 1, wherein the temperature of the dropwise addition and neutralization reaction in step 2 is 10-30°C and then cooled to 0-10°C.

6. The method for preparing a trifluoromethanesulfonate ionic liquid according to claim 1, wherein the organic phase after layering in step 3 is washed with water for 2-7 times, the amount of water added being 20-80% of the total mass of the organic phase, and the water used for washing is high-purity water with a purity of ≥8N. 7 . The method for preparing a trifluoromethanesulfonate ionic liquid according to claim 1 , wherein the step 3 is washing with water until the conductivity of the organic phase is ≤500 μS / cm.

8. The method for preparing a trifluoromethanesulfonate ionic liquid according to claim 1, wherein the dehydration temperature in step 3 is 70-150°C and the vacuum degree is ≤-0.075 MPa.

9. The method for preparing a trifluoromethanesulfonate ionic liquid according to claim 1, wherein the mass concentration of AB in the mixed solution in step 1 is 60-80%. 10 . The method for preparing a trifluoromethanesulfonate ionic liquid according to claim 1 , wherein the molar ratio of AB to trifluoromethanesulfonic acid is 1.03:1.

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