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CN-122010843-A - Water-soluble ionic liquid and preparation method thereof

CN122010843ACN 122010843 ACN122010843 ACN 122010843ACN-122010843-A

Abstract

The invention discloses a water-soluble ionic liquid and a preparation method thereof, wherein the ionic liquid is 1, 3-bis (2-hydroxyethyl) imidazole lactate, and consists of cationic 1, 3-bis (2-hydroxyethyl) imidazole cation ([ DHEIM ] ﹢ ) and anionic lactate (2-hydroxypropyl, [ Lactate ] ‑ ), the purity of the ionic liquid is more than or equal to 99 percent, the thermal decomposition temperature of the ionic liquid in a nitrogen atmosphere is more than or equal to 200 ℃, the invention relates to the technical field of ionic liquid preparation, the ionic liquid is mutually soluble with water in any proportion at 25 ℃, the solubility is more than 500g/100mL of water, the water-soluble ionic liquid is matched with a reaction or separation system with high water content, the application range is wider, the preparation method has the advantages of simple process, mild reaction conditions, no need of harsh equipment, complete reaction ensured by optimizing the raw material molar ratio, no toxic and harmful waste is generated in the whole process, the invention accords with the green chemical engineering development concept, and is easy for industrial large-scale production.

Inventors

  • LIU JIN

Assignees

  • 辽宁石化职业技术学院

Dates

Publication Date
20260512
Application Date
20251225

Claims (10)

  1. 1. The water-soluble ionic liquid is characterized in that the ionic liquid is 1, 3-bis (2-hydroxyethyl) imidazole lactate, and consists of cationic 1, 3-bis (2-hydroxyethyl) imidazole cation ([ DHEIM ] ﹢ ) and anionic lactate (2-hydroxypropyl, [ Lactate ] - ).
  2. 2. The water-soluble ionic liquid of claim 1, wherein the ionic liquid has a purity of 99% or more.
  3. 3. The water-soluble ionic liquid according to claim 1, wherein the ionic liquid has a thermal decomposition temperature of 200 ℃ or more in a nitrogen atmosphere.
  4. 4. A water-soluble ionic liquid according to claim 1, wherein the ionic liquid is miscible with water in any proportion at 25 ℃ and has a solubility >500g/100mL water.
  5. 5. A method for preparing the water-soluble ionic liquid according to any one of claims 1 to 4, comprising the steps of: s1, mixing imidazole, 2-chloroethanol and acetonitrile, carrying out reflux reaction for 12-16 hours at 80-85 ℃ under the protection of nitrogen, removing acetonitrile by reduced pressure distillation after the reaction is finished, recrystallizing by absolute ethanol, and carrying out vacuum drying to obtain [ DHEIM ] Cl; S2, dissolving [ DHEIM ] Cl in deionized water, adding sodium lactate, stirring at room temperature for reaction for 24 hours, filtering to remove generated NaCl precipitate, concentrating the filtrate under reduced pressure, dissolving and filtering with absolute ethyl alcohol, concentrating under reduced pressure again, and drying in vacuum to obtain the 1, 3-bis (2-hydroxyethyl) imidazole lactate.
  6. 6. The method according to claim 5, wherein in the step S1, the molar ratio of the 2-chloroethanol to the imidazole is 2.2:1.
  7. 7. The method according to claim 5, wherein in the step S1, the vacuum drying condition is 60 ℃ and 0.09MPa, and the drying time is 8h.
  8. 8. The method according to claim 5, wherein in the step S2, the molar ratio of sodium lactate to [ DHEIM ] Cl is 1.1:1.
  9. 9. The method for preparing water-soluble ionic liquid according to claim 5, wherein in the step S2, the stirring speed is 300-500rpm, and the vacuum drying condition is 70 ℃ and 0.09MPa, and the drying time is 12 hours.
  10. 10. The method according to claim 5, wherein in step S2, after the NaCl precipitate is removed by filtration, the precipitate is washed 2 times with a small amount of deionized water, and an absolute ethanol dissolution filtration step is used to remove a trace amount of unreacted NaCl.

Description

Water-soluble ionic liquid and preparation method thereof Technical Field The invention relates to the technical field of ionic liquid preparation, in particular to a water-soluble ionic liquid and a preparation method thereof. Background The ionic liquid is a salt compound which consists of organic cations and inorganic/organic anions and is liquid at room temperature, has the outstanding characteristics of low vapor pressure, high chemical stability, strong designability and the like, and has wide application prospect in a plurality of fields such as catalytic reaction, gas absorption, biological separation, electrolyte materials and the like. The water-soluble ionic liquid has both inherent advantages and excellent water compatibility of the ionic liquid, and is widely used in the scenes of reaction medium, separation extractant, bioactive substance solvent and the like in an aqueous solution system. However, the thermal stability of the existing water-soluble ionic liquid is insufficient, the thermal decomposition temperature is lower than 200 ℃, the application of the ionic liquid in a medium-high temperature reaction system is limited, the partial preparation process is complex, the reaction condition is severe, the purity of the product is difficult to reach more than 99%, impurities (such as chloride ions and unreacted raw materials) remain to influence the application performance, the intersolubility of the partial ionic liquid and water is limited, the solubility of the partial ionic liquid and the water is lower than 500g/100mL, the use requirement of a high-concentration aqueous solution system cannot be met, and meanwhile, the impurity removal process in the existing preparation method is complex, particularly inorganic impurities such as chloride ions are difficult to thoroughly remove, and the industrial application of the product is restricted. Disclosure of Invention The invention aims to provide a water-soluble ionic liquid and a preparation method thereof, and aims to solve the problems in the prior art. In order to achieve the aim, the main technical scheme adopted by the invention comprises that the embodiment of the invention provides a water-soluble ionic liquid, wherein the ionic liquid is 1, 3-bis (2-hydroxyethyl) imidazole lactate, and consists of cation 1, 3-bis (2-hydroxyethyl) imidazole cation ([ DHEIM ] +) and anion lactate (2-hydroxypropyl, [ Lactate ] -). Further, the purity of the ionic liquid is more than or equal to 99 percent. Through recrystallization, multistage filtration and vacuum drying treatment in the subsequent preparation process, unreacted raw materials, byproducts and solvent residues are effectively removed, and the products are ensured to meet the scene requirements of strict requirements on impurity content, such as precision chemical engineering, biomedicine and the like. Further, the thermal decomposition temperature of the ionic liquid in the nitrogen atmosphere is more than or equal to 200 ℃. The stable combination of hydroxyethyl and imidazole rings in the molecular structure improves the thermal stability, and can be suitable for medium-high temperature reaction systems and application scenes needing long-term storage. Further, the ionic liquid is miscible with water at 25 ℃ in any proportion, and the solubility is >500g/100mL water. The hydroxyethyl group in the cation has strong hydrophilicity, and cooperates with lactate anions to endow the product with excellent water solubility, and can adapt to a reaction or separation system with high water content. The embodiment of the invention also provides a preparation method of the water-soluble ionic liquid, which comprises the following steps: s1, preparing an intermediate [ DHEIM ] Cl: Mixing imidazole, 2-chloroethanol and acetonitrile, reflux reacting for 12-16h at 80-85 ℃ under the protection of nitrogen, distilling under reduced pressure after the reaction is finished to remove acetonitrile, recrystallizing by absolute ethanol, and drying in vacuum to obtain [ DHEIM ] Cl. Further, in the step S1, the molar ratio of the 2-chloroethanol to the imidazole is 2.2:1. The 2-chloroethanol with the excessive 20 percent can ensure that two N atoms in imidazole molecules completely generate alkylation reaction, avoid the generation of monosubstituted byproducts and improve the yield and purity of the intermediate [ DHEIM ] Cl. Further, in step S1, the vacuum drying condition was 60℃and 0.09MPa, and the drying time was 8 hours. The condition can thoroughly remove the absolute ethyl alcohol remained in the recrystallization process on the premise of avoiding the decomposition of the intermediate, and prevents the interference of the solvent on the subsequent ion exchange reaction. S2, preparing a target product through ion exchange reaction: dissolving [ DHEIM ] Cl in deionized water, adding sodium lactate, stirring at room temperature for reaction for 24 hours, filtering to remove generated NaCl precipitate, c