Application of sulfonamide ionic liquid in cycloaddition reaction of CO2 and epoxy compound

Abstract

The invention discloses application of a sulfonamide ionic liquid catalyst system in preparation of cyclic carbonate, sulfonamide ionic liquid comprises cations and anions, and the cations are one or more of tetra-alkyl ammonium ions, tetra-alkyl phosphonium ions and trimethyl hydroxyethyl ammonium ions; the anion is one or more of sulfonamide ions or substituted sulfonamide ions; the sulfonamide ionic liquid is used as a catalyst and is used for catalyzing CO2 to react with an epoxy compound to prepare cyclic carbonate; the catalyst is easy to prepare and high in catalytic activity, under normal pressure, the dosage of the catalyst is 1-3 mol%, the reaction time is 1-48 hours, the reaction temperature is 25-100 DEG C, and a substituted epoxy compound can be converted into corresponding cyclic carbonate with high conversion rate and high selectivity. After the catalyst system is recycled for five times, the catalytic effect is not obviously reduced. Meanwhile, the catalyst system has good universality to substrates, and conversion of various epoxy compounds can be efficiently achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of green and clean organic catalysis, and specifically to an application of sulfonamide ionic liquids in the cycloaddition reaction of CO2 and epoxides. Background Art

[0002] Carbon dioxide is inexpensive, non-toxic, harmless, non-flammable, and at the same time is the main source of the greenhouse effect. As a special renewable resource, its resource utilization is of great significance. However, the thermodynamic and kinetic stability of carbon dioxide hinders its application in organic synthesis.

[0003] Cyclic carbonates synthesized from epoxides and carbon dioxide are high-boiling and high-polar organic solvents with excellent properties, and have extensive applications in the fields of organic synthesis, cosmetics, gas separation, battery media, and metal extraction. Moreover, cyclic carbonates are useful precursors for polymeric materials. Polycarbonates can be used to produce many products such as disposable packaging materials, disposable tableware, and sheets. Fortunately, the polycarbonates synthesized from epoxides and carbon dioxide are biodegradable polymer materials and do not cause pollution. To achieve the chemical conversion and utilization of carbon dioxide as a reactant, the key lies in its effective activation. Therefore, finding suitable catalysts has become a hot topic in this research field.

[0004] Currently, a variety of catalyst systems have been developed, such as alkali metal salts, organic bases, metal-organic frameworks (MOFs), covalent organic frameworks (COFs), coordination polymers, ionic liquids, etc. However, these catalyst systems often have relatively complex preparation methods, require relatively high reaction temperatures (>80°C), long reaction times (4 - 48 h), high CO2 pressures (0.1 - 5.0 Mpa), narrow substrate generality, complex product separation processes, and so on. Therefore, it is very necessary to develop a catalyst system with mild reaction conditions, green environmental protection, and high efficiency. Summary of the Invention

[0005] To solve the problems raised in the above background art, the object of the present invention is to develop a new type of ionic liquid catalyst system, which can effectively reduce the reaction conditions, and under relatively low CO2 pressure and in a short time, convert substituted epoxides into corresponding cyclic carbonates with high conversion rate and high selectivity. At the same time, this catalyst system has good generality for substrates and can efficiently realize the conversion of various epoxides.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a novel ionic liquid catalyst system. The sulfonamide-based ionic liquid catalyst system includes a cation and an anion. The cation is one or more of quaternary ammonium cations, quaternary phosphonium cations, trimethylethanolammonium ions, and protonated organic bases; the sulfonamide-based anion is one or more of benzenesulfonamide anions, para-substituted benzenesulfonamide anions, ortho-substituted benzenesulfonamide anions, and meta-substituted benzenesulfonamide anions.

[0008] The structure of the cation is:

[0009]

[0010] one or more of;

[0011] The structure of the anion is:

[0012] one or more of;

[0013] wherein n is 1, 2, 3, or 4;

[0014] The R groups are each one of -CH3, -C2H5, -C3H7, -C4H9, -OCH3, -NO2, -NH2, -Cl.

[0015] Preferably, the cation is one or more of tetraalkylammonium ions, tetraalkylphosphonium ions, and trimethylethanolammonium ions; the anion is one or more of sulfonamide ions and substituted sulfonamide ions.

[0016] The structure of the cation is

[0017] one or more of;

[0018] The structure of the anion is

[0019]

[0020] one or more of.

[0021] The preparation steps of the sulfonamide-based ionic liquid catalyst system are:

[0022] React the cationic compound with the sulfonamide-based anionic compound at 20 - 35 °C for 12 - 24 h to obtain the ionic liquid.

[0023] Further, specifically, the preparation steps of the sulfonamide ionic liquid catalyst system are as follows: Dissolve the cationic compound in a certain amount of ethanol (10 mmol cationic compound / 10 - 20 mL EtOH), add the sulfonamide anionic compound to the above reaction system, stir at 20 - 35 °C for 12 - 24 hours, carry out vacuum distillation on the obtained reaction product to remove the solvent (ethanol), and vacuum dry the residue to obtain the corresponding ionic liquid. The conditions for vacuum drying include: the vacuum pressure is -0.01 Mpa to -0.05 Mpa, the temperature is 60 - 100 °C, and the time is 24 hours; preferably, after removing the solvent, vacuum dry at 60 - 80 °C for 24 hours to obtain the ionic liquid.

[0024] Further, the molar ratio of the cationic compound to the substituted sulfonamide anionic compound is 1:1.

[0025] The cationic compound is one or more of a P- or N-containing compound and an organic base. The P- or N-containing compound is tetraalkylphosphonium hydroxide, tetraalkylammonium hydroxide, trimethylhydroxyethylammonium hydroxide, or trihexyltetradecylphosphonium hydroxide. Among them, the alkyl groups contained in the tetraalkylphosphonium hydroxide and tetraalkylammonium hydroxide are one or more of methyl, ethyl, propyl, butyl, hexyl, and tetradecyl; the organic base is one or more of tetramethylguanidine, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5-diazabicyclo[4.3.0]-5-nonene, triethylenediamine, and 4-dimethylaminopyridine;

[0026] The sulfonamide anionic compound is one or more of benzenesulfonamide, p-toluenesulfonamide, p-ethylbenzenesulfonamide, p-propylbenzenesulfonamide, p-butylbenzenesulfonamide, 4-chlorobenzenesulfonamide, 4-methoxybenzenesulfonamide, 4-nitrobenzenesulfonamide, sulfanilamide, o-methylbenzenesulfonamide, o-ethylbenzenesulfonamide, o-propylbenzenesulfonamide, o-butylbenzenesulfonamide, 2-chlorobenzenesulfonamide, 2-methoxybenzenesulfonamide, 2-nitrobenzenesulfonamide, 2-aminobenzenesulfonamide, m-methylbenzenesulfonamide, m-ethylbenzenesulfonamide, m-propylbenzenesulfonamide, m-butylbenzenesulfonamide, 3-chlorobenzenesulfonamide, 3-methoxybenzenesulfonamide, 3-nitrobenzenesulfonamide, and 3-aminobenzenesulfonamide.

[0027] The present invention provides the application of the above-mentioned sulfonamide ionic liquid in the coupling reaction of CO2 and epoxide, specifically: using the above sulfonamide ionic liquid as a catalyst, without any solvent and cocatalyst, catalytically preparing cyclic carbonate by the cycloaddition reaction of CO2 and epoxide under mild conditions.

[0028] The epoxide is

[0029] one of;

[0030] Among them,

[0031] R 1 = H, CH3, CH2Cl or CH2Br;

[0032] R 2 = H;

[0033] R 3 = Bu, PhCH2, Ph or C8H 17 .

[0034] A specific method for catalytic conversion of epoxides to cyclic carbonates using a sulfonamide-based ionic liquid includes the following steps: adding the above-mentioned sulfonamide-based ionic liquid to the above epoxide, introducing CO2, and reacting to obtain cyclic carbonate.

[0035] Furthermore, the CO2 pressure is 0.1 - 0.5 Mpa, the reaction temperature is 25 - 100 °C (preferably, the reaction temperature is 60 - 100 °C), and the reaction time is 1 - 48 hours.

[0036] Furthermore, as a catalyst, the dosage of the sulfonamide-based ionic liquid is 1 - 3 mol% of the epoxide.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] In the present invention, the sulfonamide-based ionic liquid is used as a catalyst, and the reaction conditions for catalytic conversion are mild. Even with a small amount of catalyst, it still has high activity; high catalytic efficiency, high product selectivity, and good substrate universality; no additional solvents or co-catalysts are required during the reaction; the catalyst is easily recovered and has good recycling performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 1H NMR of the reaction mixture for catalytic conversion of epichlorohydrin to cyclic carbonate by the ionic liquid in Example 4 1 1H NMR;

[0040] Figure 2 For the recycling test of the ionic liquid in Test Example 4. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0042] The equations involved in this embodiment are as follows:

[0043]

[0044] Example 1

[0045] The sulfonamide ionic liquid is prepared by the following method:

[0046] Dissolve tetrabutylphosphonium chloride (0.75 mmol) in 25 mL of absolute ethanol. The resulting solution is subjected to 2 - 3 anion exchanges with three - fold molar amount of Amberlite IRN78 hydroxide - form ion - exchange resin, and the completeness of the exchange is detected using an aqueous silver nitrate solution. If the anions are not completely exchanged, this solution is again subjected to ion - exchange with fresh hydroxide - form ion - exchange resin until the exchange is complete. The content of the obtained tetrabutylphosphonium hydroxide is determined by 1 H NMR.

[0047] Add an equimolar amount of p - toluenesulfonamide to the above - mentioned solution, stir at 20 - 35 °C for 12 - 24 hours. After removing the solvent by distillation, the resulting residue is dried at 60 °C under vacuum of - 0.01 Mpa for 24 h to obtain tetrabutylphosphonium p - toluenesulfonamide ionic liquid.

[0048] In some embodiments of the present invention, the preparation methods of other ionic liquids are the same as that of tetrabutylphosphonium p - toluenesulfonamide ionic liquid, except that the tetrabutylphosphonium is replaced with tetrabutylammonium, trimethylhydroxyethylammonium or trihexyltetradecylphosphonium cations; and the p - toluenesulfonamide is replaced with anions such as p - methoxybenzenesulfonamide, p - chlorobenzenesulfonamide, p - aminobenzenesulfonamide or o - nitrobenzenesulfonamide.

[0049] Example 2

[0050] Preparation of cyclic carbonate: autoclave method

[0051] Add 0.25 mmol of trihexyltetradecylphosphonium p - toluenesulfonamide ionic liquid to a 50 mL autoclave, then add 10.0 mmol of epichlorohydrin. After sealing, carbon dioxide is introduced into the autoclave. After displacing the gas 3 times, the pressure of carbon dioxide is charged to 0.5 Mpa, and the reaction is carried out at 80 °C for 3 hours. After the reaction is completed, the autoclave is cooled to room temperature, the excess gas is released, and the reaction mixture system is transferred to a vacuum distillation device. The cyclic carbonate is prepared by vacuum distillation, and at the same time, the ionic liquid is separated and recovered.

[0052] By 1 HNMR measurement of the reaction mixture, it is calculated that the selectivity of the prepared cyclic carbonate is greater than 99.0%, and the conversion rate of epichlorohydrin is 99.0%.

[0053] Selectivity refers to the ratio of the yield of the target product to the conversion rate of the substrate, that is, the proportion of the target product in the sum of the main product and by-products. The higher the selectivity, the fewer the by-products.

[0054] The conversion rate is calculated according to 1 the ratio of the target product to the raw material and the target product in the 1H NMR spectrum. The higher the ratio, the higher the conversion rate.

[0055] Example 3

[0056] Preparation of cyclic carbonate: atmospheric pressure method

[0057] Add 0.25 mmol of trihexyltetradecylphosphonium p-toluenesulfonamide ionic liquid to a 50 mL two-necked round-bottom flask equipped with a reflux condenser. Subsequently, add 10.0 mmol of epichlorohydrin. Place a three-way valve with a CO2 gas-filled balloon on the mouth of the round-bottom flask. After displacing the gas 3 times, react at 80 °C for 3 hours. After the reaction is completed, cool to room temperature, release the excess gas, transfer the reaction mixture system to a vacuum distillation device, and obtain cyclic carbonate by vacuum distillation while separating and recovering the ionic liquid.

[0058] By 1 1H NMR determination, it is calculated that the selectivity of the prepared cyclic carbonate is greater than 99.0%, and the conversion rate of epichlorohydrin is 93.5%.

[0059] Examples 1 and 2 can compare the autoclave method (0.5 Mpa) with the atmospheric pressure balloon method (0.1 Mpa). Both methods can obtain similar conversion rates of epichlorohydrin and selectivities of cyclic carbonate. In subsequent experiments, the atmospheric pressure method with milder reaction conditions was selected.

[0060] Example 4

[0061] Add 0.25 mmol of tetrabutylphosphonium p-toluenesulfonamide ionic liquid to a 50 mL two-necked round-bottom flask equipped with a reflux condenser. Subsequently, add 10.0 mmol of epichlorohydrin. Place a three-way valve with a CO2 gas-filled balloon on the mouth of the round-bottom flask. After displacing the gas 3 times, react at 80 °C for 3 hours. After the reaction is completed, cool to room temperature, release the excess gas, transfer the reaction mixture system to a vacuum distillation device, and obtain cyclic carbonate by vacuum distillation while separating and recovering the ionic liquid.

[0062] By 1 1H NMR determination, it is calculated that the selectivity of the prepared cyclic carbonate is greater than 99.0%, and the conversion rate of epichlorohydrin is 97.9% ( Figure 1 ).

[0063] Example 5

[0064] In a 50 mL two-necked round-bottom flask equipped with a reflux condenser, 0.25 mmol of tetrabutylammonium p-toluenesulfonamide ionic liquid was added. Subsequently, 10.0 mmol of epichlorohydrin was added. A three-way valve with a balloon filled with CO2 gas was placed at the mouth of the round-bottom flask. After displacing the gas three times, the reaction was carried out at 80 °C for 3 hours. After the reaction was completed, it was cooled to room temperature, and the excess gas was released. The reaction mixture was transferred to a vacuum distillation apparatus, and the cyclic carbonate was prepared by vacuum distillation while the ionic liquid was separated and recovered.

[0065] By 1 1H NMR measurement, the selectivity of the prepared cyclic carbonate was calculated to be greater than 99.0%, and the conversion rate of epichlorohydrin was 96.2%.

[0066] Example 6

[0067] In a 50 mL two-necked round-bottom flask equipped with a reflux condenser, 0.25 mmol of trimethylethanolammonium p-toluenesulfonamide ionic liquid was added. Subsequently, 10.0 mmol of epichlorohydrin was added. A three-way valve with a balloon filled with CO2 gas was placed at the mouth of the round-bottom flask. After displacing the gas three times, the reaction was carried out at 80 °C for 3 hours. After the reaction was completed, it was cooled to room temperature, and the excess gas was released. The reaction mixture was transferred to a vacuum distillation apparatus, and the cyclic carbonate was prepared by vacuum distillation while the ionic liquid was separated and recovered.

[0068] By 1 1H NMR measurement, the selectivity of the prepared cyclic carbonate was calculated to be greater than 99.0%, and the conversion rate of epichlorohydrin was 92.6%.

[0069] Example 7

[0070] In a 50 mL two-necked round-bottom flask equipped with a reflux condenser, 0.25 mmol of tetrabutylphosphonium p-chlorobenzenesulfonamide ionic liquid was added. Subsequently, 10.0 mmol of epichlorohydrin was added. A three-way valve with a balloon filled with CO2 gas was placed at the mouth of the round-bottom flask. After displacing the gas three times, the reaction was carried out at 80 °C for 3 hours. After the reaction was completed, it was cooled to room temperature, and the excess gas was released. The reaction mixture was transferred to a vacuum distillation apparatus, and the cyclic carbonate was prepared by vacuum distillation while the ionic liquid was separated and recovered.

[0071] By 1 1H NMR measurement, the selectivity of the prepared cyclic carbonate was calculated to be greater than 99.0%, and the conversion rate of epichlorohydrin was 93.3%.

[0072] Example 8

[0073] In a 50 mL two-necked round-bottom flask equipped with a reflux condenser, 0.25 mmol of tetrabutylphosphonium p-methoxybenzenesulfonamide ionic liquid was added. Subsequently, 10.0 mmol of epichlorohydrin was added. A three-way valve with a balloon filled with CO2 gas was placed at the mouth of the round-bottom flask. After displacing the gas three times, the reaction was carried out at 80 °C for 3 hours. After the reaction was completed, it was cooled to room temperature, and the excess gas was released. The reaction mixture was transferred to a vacuum distillation apparatus, and the cyclic carbonate was obtained by vacuum distillation while the ionic liquid was separated and recovered.

[0074] By 1 1H NMR determination, the selectivity of the prepared cyclic carbonate was calculated to be greater than 99.0%, and the conversion rate of epichlorohydrin was 95.6%.

[0075] Example 9

[0076] In a 50 mL two-necked round-bottom flask equipped with a reflux condenser, 0.25 mmol of tetrabutylphosphonium benzenesulfonamide ionic liquid was added. Subsequently, 10.0 mmol of epichlorohydrin was added. A three-way valve with a balloon filled with CO2 gas was placed at the mouth of the round-bottom flask. After displacing the gas three times, the reaction was carried out at 80 °C for 3 hours. After the reaction was completed, it was cooled to room temperature, and the excess gas was released. The reaction mixture was transferred to a vacuum distillation apparatus, and the cyclic carbonate was obtained by vacuum distillation while the ionic liquid was separated and recovered.

[0077] By 1 1H NMR determination, the selectivity of the prepared cyclic carbonate was calculated to be greater than 99.0%, and the conversion rate of epichlorohydrin was 96.2%.

[0078] Example 10

[0079] In a 50 mL two-necked round-bottom flask equipped with a reflux condenser, 0.25 mmol of tetrabutylphosphonium o-nitrobenzenesulfonamide ionic liquid was added. Subsequently, 10.0 mmol of epichlorohydrin was added. A three-way valve with a balloon filled with CO2 gas was placed at the mouth of the round-bottom flask. After displacing the gas three times, the reaction was carried out at 80 °C for 3 hours. After the reaction was completed, it was cooled to room temperature, and the excess gas was released. The reaction mixture was transferred to a vacuum distillation apparatus, and the cyclic carbonate was obtained by vacuum distillation while the ionic liquid was separated and recovered.

[0080] By 1 1H NMR determination, the selectivity of the prepared cyclic carbonate was greater than 99.0%, and the conversion rate of epichlorohydrin was 85.5%.

[0081] Based on the above experimental data, it is found that benzenesulfonamide ionic liquids have good selectivity and conversion rate for the cycloaddition reaction of CO2 and epichlorohydrin. The attachment of electron-donating groups or electron-withdrawing groups to the benzene ring of benzenesulfonamide has a slight influence on the reaction. This is because electron-donating groups can increase the basicity of benzenesulfonamide ionic liquids, so they have relatively better conversion rates for the formation of cyclic carbonates. The cation part has little influence on the reaction.

[0082] Test Example 1

[0083] Based on the above test results, according to the same experimental method as in Example 4, the amount of tetrabutylphosphonium p-toluenesulfonamide ionic liquid was adjusted to 1.0 - 3.0 mol% for the reaction, and the effect of the catalyst amount on the cycloaddition reaction was investigated. The specific results are shown in Table 1:

[0084] Table 1

[0085]

[0086] a TON: Moles of chloropropylene carbonate produced per mole of IL; TOF: Moles of chloropropylene carbonate produced per mole of IL per hour.

[0087] Based on the above experimental data, when the amount of the ionic liquid catalyst selected in the present invention is 1.0 - 3.0 mol%, good catalytic effects are achieved.

[0088] Test Example 2

[0089] Based on the above test results, according to the same experimental method as in Example 4, the reaction was carried out with the amount of tetrabutylphosphonium p-toluenesulfonamide ionic liquid being 2.5 mol%, and the effect of the reaction temperature on the cycloaddition reaction was investigated. The specific results are shown in Table 2:

[0090] Table 2

[0091]

[0092]

[0093] a TON: Moles of chloropropylene carbonate produced per mole of IL; TOF: Moles of chloropropylene carbonate produced per mole of IL per hour.

[0094] Based on the above experimental data, when the reaction temperature selected by the present invention is above 60°C, a better conversion rate can be obtained.

[0095] Test Example 3

[0096] The sulfonamide ionic liquid prepared by the present invention has good universality for different epoxide substrates. According to the same experimental method as in Example 4, different substrates were replaced for the reaction. The specific results are shown in Table 3:

[0097] Table 3

[0098]

[0099] Test Example 4

[0100] Based on the above test results, according to the same method as in Example 4, the recycling effect test of the ionic liquid was carried out. The specific test data are as Figure 2 shown. It can be seen from Figure 2 the data that the sulfonamide ionic liquid prepared by the present invention has good recycling performance.

[0101] Comparative Example

[0102] According to the method of Example 4, the difference is that the catalyst used is a catalyst of the prior art. The results are shown in Table 4.

[0103] Table 4

[0104]

[0105]

[0106] [1] S.Yue, H.L.Qu, X.X.Song, X.N.Feng, Novel hyfroxyl-functionalized ionic liquids as efficient catalysts for the conversion of CO2 into cyclic carbonates under metal / halogen / cocatalyst / solvent-free conditions. New J.Chem. 46(2022), 5881-5888.

[0107] https: / / doi.org / 10.1039 / D2NJ00257D

[0108] [2]C. Li, F. Liu, T. X. Zhao, J. R. Gu, P. Chen, T. Chen, Highly efficient CO2 fixation into cyclic carbonate by hydroxyl-functionalized protic ionic liquids at atmospheric pressure, Mol. Catal. 511 (2021), 111756. https: / / doi.org / 10.1016 / j.mcat.2021.111756。

[0109] As can be seen from the results in Table 4, when the ionic liquid provided by the present invention is used as a catalyst for catalytic conversion of CO2 into cyclic carbonate, it has significantly better effects such as short reaction time, low reaction temperature, small pressure, low catalyst dosage, and high conversion rate of epoxide.

[0110] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0111] It should be noted that the above content only illustrates the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements all fall within the protection scope of the claims of the present invention.

Claims

1. Use of a sulfonamide-based ionic liquid in the cycloaddition reaction of CO2 and epoxides, characterized in that, Sulfonamide ionic liquids are used as catalysts to catalyze the cycloaddition reaction of CO2 and epoxides to prepare cyclic carbonates under the conditions of 25 - 100 °C.

2. Use of a sulfonamide-based ionic liquid in the cycloaddition reaction of CO2 and epoxides according to claim 1, characterized in that, The sulfonamide ionic liquids include cations and anions, and the structure of the cations is: one or more of; The structure of the anions is: one or more of; wherein n is 1, 2, 3 or 4; The R groups are each one of -CH3, -C2H5, -C3H7, -C4H9, -OCH3, -NO2, -NH2, -Cl.

3. Use of a sulfonamide-based ionic liquid according to claim 2 in the coupling reaction of CO2 and epoxide, characterized in that, The structure of the cations is one or more of; The structure of the anions is one or more of 4. Use of a sulfonamide ionic liquid according to claim 1 in the cycloaddition reaction of CO2 and an epoxide, characterized in that The epoxide is one of; Wherein, R 1 = H, CH3, CH2Cl or CH2Br; R 2 = H; R 3 = Bu, PhCH2, Ph or C8H 17 .

5. Use of a sulfonamide ionic liquid according to claim 2 or 3 in the cycloaddition reaction of CO2 and an epoxide, characterized in that, The preparation method of the sulfonamide ionic liquids includes the following steps: reacting a cationic compound with a sulfonamide anionic compound at 20 - 35 °C for 12 - 24 h to obtain the ionic liquids.

6. Use of a sulfonamide-based ionic liquid in the cycloaddition reaction of CO2 and epoxides according to claim 5, characterized in that, The molar ratio of the cationic compound to the sulfonamide anionic compound is 1:

1.

7. A method for catalytic conversion of epoxides to cyclic carbonates by a sulfonamide-based ionic liquid, characterized in that, Including the following steps: Adding a catalyst sulfonamide ionic liquid to the epoxide, introducing CO2, and reacting to obtain cyclic carbonate; The sulfonamide ionic liquid is the sulfonamide ionic liquid in any one of claims 1 - 3, 5, 6, and the epoxide is the epoxide in claim 4.

8. A method for catalytic conversion of epoxides to cyclic carbonates using a sulfonamide-based ionic liquid according to claim 7, characterized in that, The CO2 pressure is 0.1 - 0.5 MPa, the reaction temperature is 25 - 100 °C, and the reaction time is 1 - 48 hours.

9. A method for catalytic conversion of epoxides to cyclic carbonates using a sulfonamide-based ionic liquid according to claim 7, characterized in that, The dosage of the sulfonamide ionic liquid is 1 - 3 mol% of the epoxide.

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