Polyhydroxy acid ionic liquid, preparation method and application thereof, and method for catalytically converting CO2 into cyclic carbonate

Abstract

The invention relates to the field of catalytic conversion of CO2 into cyclic carbonate, and discloses a polyhydroxy acid ionic liquid, a preparation method and application thereof, and a method for catalytic conversion of CO2 into cyclic carbonate. Cations of the ionic liquid comprise quaternary ammonium cations and / or quaternary phosphonium cations, and anions are at least one of D or L-gluconate, D or L-tartaric acid monocarboxylate, D or L-tartaric acid dicarboxylate and D or L-lactate. The ionic liquid provided by the invention is used as a catalyst for catalytic conversion of CO2 and an epoxy compound into cyclic carbonate, and high conversion rate of the epoxy compound and high selectivity of a product can be obtained. According to the preparation method, pollution of metal or halogen can be avoided, good recyclability can be provided, and most of epoxy compounds can be converted into corresponding carbonic ester at high yield and conversion rate within a short time.

Description

Technical Field

[0001] The present invention relates to the field of catalytic conversion of CO 2 into cyclic carbonates, and particularly relates to a polyhydroxy acid ionic liquid, a preparation method and application thereof, and a method for catalytically converting CO 2 into cyclic carbonates. Background Art

[0002] Emissions of greenhouse gases mainly composed of CO 2 are considered to be the main reasons for global warming, frequent extreme weather, retreat of the earth's glaciers, rising sea levels, increasing incidence of cardiovascular and respiratory diseases, and accelerated spread of epidemic diseases. At the same time, CO 2 as a stable, non-toxic, inexhaustible and renewable C1 resource, has been widely studied by researchers in industry through physical and chemical methods for capture, storage and chemical conversion in order to reduce the concentration of CO 2 in the atmosphere. The cycloaddition reaction of CO 2 with epoxides to form cyclic carbonates is a reaction with 100% atom economy, and is also one of the most commonly used methods for converting CO 2 into high-value-added chemical products at present. And cyclic carbonates have wide applications in organic synthesis, electrochemistry and other aspects.

[0003] Although a variety of catalytic systems have been developed to complete this conversion, such as alkali metal salts, organic bases, metal-organic frameworks (MOF), covalent organic frameworks (COF), transition metal complexes, etc., most of these methods require high temperature, high pressure, long reaction time, complex product separation process, etc. Moreover, these catalysts all have the problem of subsequent reagent pollution (such as metal pollution, halogen pollution, etc.), and at the same time, the recycling effect is poor.

[0004] Therefore, there is still a need to develop a catalyst system with mild, economic and efficient reaction conditions. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems existing in the use of metal-containing or halogen-containing catalysts in the prior art, as well as the problems of low selectivity, conversion rate and recyclability of preparing cyclic carbonates, and to provide a polyhydroxy acid ionic liquid, a preparation method and application thereof, and a method for catalytically converting CO 2 into cyclic carbonates.

[0006] To achieve the above object, in the first aspect of the present invention, a polyhydroxy acid ionic liquid is provided, wherein the cation of the ionic liquid includes a quaternary ammonium cation and / or a quaternary phosphonium cation, and the anion is at least one of D or L-gluconate, D or L-tartrate monocarboxylate, D or L-tartrate dicarboxylate, D or L-lactate.

[0007] The second aspect of the present invention provides a method for preparing an ionic liquid, wherein the preparation method includes:

[0008] Reacting a P- or N-containing compound with a polyhydroxy acid to obtain the ionic liquid;

[0009] Wherein, the polyhydroxy acid is selected from at least one of D- or L-gluconic acid, D- or L-tartaric acid, and D- or L-lactic acid;

[0010] The P- or N-containing compound is selected from tetraalkylphosphonium hydroxide, tetraalkylammonium hydroxide, or trihexyltetradecylphosphonium hydroxide, wherein the alkyl groups contained in the tetraalkylphosphonium hydroxide and tetraalkylammonium hydroxide are selected from at least one of methyl, ethyl, propyl, butyl, hexyl, and tetradecyl.

[0011] The third aspect of the present invention provides an ionic liquid prepared by the preparation method of the present invention.

[0012] The fourth aspect of the present invention provides an application of the ionic liquid of the present invention in the preparation of 2 cyclic carbonates.

[0013] The fifth aspect of the present invention provides a method for preparing 2 cyclic carbonates, wherein the method includes: performing a synthesis reaction of carbon dioxide and an epoxide in the presence of a catalyst to obtain a cyclic carbonate; wherein, the catalyst is the ionic liquid of the present invention.

[0014] Through the above technical solutions, the present invention can achieve the following beneficial effects:

[0015] The ionic liquid provided by the present invention is used as a catalyst for 2 the catalytic conversion of an epoxide into a cyclic carbonate, and high conversion of the epoxide and high selectivity of the product can be obtained. For example, under the conditions of a CO 2 pressure of 0.1 MPa, a temperature of 80 °C, and a catalyst dosage of 1-7 mol%, 2 when reacting with epichlorohydrin, the conversion rate of epichlorohydrin can reach 98.0%, and the product selectivity is 99.0%.

[0016] In addition, the ionic liquid provided by the present invention can avoid metal or halogen pollution and can provide good recyclability. For example, when using trihexyltetradecylphosphonium L-lactate ionic liquid, after recycling 7 times, the catalytic conversion efficiency of 2 CO hardly decreases.

[0017] The catalyst system designed by the present invention has good universality for reaction substrates, and the vast majority of epoxides can be converted into corresponding carbonates in a relatively short time with high yields and conversion rates. Brief Description of the Drawings

[0018] Figure 1 shows the conversion rate and selectivity of the trihexyltetradecylphosphonium L-lactic acid ionic liquid of the present invention when recycled for use in the reaction of CO 2 with epichlorohydrin. Detailed Embodiments

[0019] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0020] The first aspect of the present invention provides a polyhydroxy acid ionic liquid, wherein the cation of the ionic liquid includes a quaternary ammonium cation and / or a quaternary phosphonium cation, and the anion is at least one of D- or L-gluconate, D- or L-tartrate monocarboxylate, D- or L-tartrate dicarboxylate, D- or L-lactate.

[0021] In some embodiments of the present invention, preferably, the quaternary ammonium cation has the structure shown in formula (1), and the quaternary phosphonium cation has the structure shown in formula (2) or formula (3), wherein, n is a positive integer from 1 to 4.

[0022] By selecting the above cations for the polyhydroxy acid ionic liquid of the present invention, the thermal stability, chemical stability of the ionic liquid can be improved and the hydrophobicity can be enhanced, and the source is easily available. Further, by selecting the following anions for the polyhydroxy acid ionic liquid of the present invention, the hydroxyl group and the carboxylate group therein act synergistically, and can have the effect of activating epoxides and CO 2 and promoting the reaction of preparing cyclic carbonates with CO 2 to occur under mild conditions.

[0023] Among them, the anion can be represented by the following structure: D-gluconate L-gluconate D-tartrate dicarboxylate L-tartrate dicarboxylate D-tartrate monocarboxylate L-tartrate monocarboxylate D-lactate L-lactate

[0024] In some embodiments of the present invention, preferably, the ionic liquid is selected from at least one of the compounds having the following structures:

[0025] Ionic liquid - 1: The cation is The anion is

[0026] Ionic liquid - 2: The cation is The anion is

[0027] Ionic liquid - 3: The cation is The anion is

[0028] Ionic liquid - 4: The cation is The anion is

[0029] Ionic liquid - 5: The cation is The anion is

[0030] Ionic liquid - 6: The cation is The anion is

[0031] Ionic liquid - 7: The cation is The anion is

[0032] Ionic liquid - 8: The cation is The anion is

[0033] Ionic liquid - 9: The cation is n is 1, 2, 3, or 4. Here, n represents the number of carbon atoms in the alkyl group of the cation. The cation can include compounds having an alkyl group with the above - mentioned number of carbon atoms, that is, the cation can be at least one of the compounds having tetramethyl, tetraethyl, tetrapropyl, and tetrabutyl that satisfy the chemical formula. Preferably, it is tetrabutyl (the same applies to the following cations). The anion is

[0034] Ionic liquid - 10: The cation is n is 1, 2, 3, or 4. The anion is

[0035] Ionic liquid - 11: The cation is n is 1, 2, 3, or 4. The anion is

[0036] Ionic liquid - 12: The cation is n is 1, 2, 3, or 4. The anion is

[0037] Ionic liquid - 13: The cation is n is 1, 2, 3, 4, and the anion is

[0038] Ionic liquid - 14: The cation is n is 1, 2, 3, 4, and the anion is

[0039] Ionic liquid - 15: The cation is n is 1, 2, 3, 4, and the anion is

[0040] Ionic liquid - 16: The cation is n is 1, 2, 3, 4, and the anion is

[0041] Ionic liquid - 17: The cation is n is 1, 2, 3, 4, and the anion is

[0042] Ionic liquid - 18: The cation is n is 1, 2, 3, 4, and the anion is

[0043] Ionic liquid - 19: The cation is n is 1, 2, 3, 4, and the anion is

[0044] Ionic liquid - 20: The cation is n is 1, 2, 3, 4, and the anion is

[0045] Ionic liquid - 21: The cation is n is 1, 2, 3, 4, and the anion is

[0046] Ionic liquid - 22: The cation is n is 1, 2, 3, 4, and the anion is

[0047] Ionic liquid - 23: The cation is n is 1, 2, 3, 4, and the anion is

[0048] Ionic liquid - 24: The cation is n is 1, 2, 3, 4, and the anion is

[0049] In the present invention, the above ionic liquids can be characterized by 1 H NMR, 13The obtained structure was determined by 13C NMR, IR, and MS analyses.

[0050] The second aspect of the present invention provides a method for preparing an ionic liquid, wherein the preparation method includes:

[0051] Reacting a P- or N-containing compound with a polyhydroxy acid to obtain the ionic liquid;

[0052] wherein the polyhydroxy acid is selected from at least one of D- or L-gluconic acid, D- or L-tartaric acid, and D- or L-lactic acid;

[0053] The P- or N-containing compound is selected from tetraalkylphosphonium hydroxide, tetraalkylammonium hydroxide, or trihexyltetradecylphosphonium hydroxide, wherein the alkyl groups contained in the tetraalkylphosphonium hydroxide and tetraalkylammonium hydroxide are selected from at least one of methyl, ethyl, propyl, butyl, hexyl, and tetradecyl.

[0054] In the present invention, the alkyl groups contained in the tetraalkylphosphonium hydroxide and tetraalkylammonium hydroxide may be the same, such as tetramethyl, tetraethyl, tetrapropyl, tetrabutyl, or different, such as trihexyltetradecyl. Preferably, the P- or N-containing compound is selected from tetrabutylammonium hydroxide, tetrabutylphosphonium hydroxide, or trihexyltetradecylphosphonium hydroxide.

[0055] In some embodiments of the present invention, preferably, the molar ratio of the polyhydroxy acid to the P- or N-containing compound is 1:1 - 2.

[0056] In the present invention, the tetraalkylphosphonium hydroxide can be prepared by ion exchange of tetraalkylphosphonium chloride with a hydroxide-form anion exchange resin. The specific steps may be as follows:

[0057] Dissolve tetraalkylphosphonium chloride in absolute ethanol (concentration 0.027 mol / L), and pass the resulting solution through Amberlitel IRN78 hydroxide-form ion exchange resin. Then, before use, determine that the anion exchange of the prepared tetraalkylphosphonium hydroxide is complete with an aqueous silver nitrate solution. The content of tetraalkylphosphonium hydroxide is determined by 1 1H NMR.

[0058] Correspondingly, for the preparation of the ionic liquid, react the obtained ethanol solution containing tetraalkylphosphonium hydroxide with the polyhydroxy acid. The preparation method further includes distilling off the solvent (ethanol) from the obtained reaction product under reduced pressure, and drying the residue under vacuum to obtain the corresponding ionic liquid. The conditions for vacuum drying include: the vacuum pressure is -0.01 MPa to -0.05 MPa, and the temperature is 60 - 100 °C.

[0059] Preferably, the conditions for the reaction include: the temperature is 20 - 30 °C, the pressure is 0.1 - 0.15 MPa, and the time is 2 - 24 h.

[0060] The third aspect of the present invention provides an ionic liquid prepared by the preparation method of the present invention. Preferably, the chemical composition of the ionic liquid can be as described above and will not be elaborated here.

[0061] The fourth aspect of the present invention provides an application of the ionic liquid of the present invention in the 2 preparation of cyclic carbonates.

[0062] The fifth aspect of the present invention provides a method for 2 preparing cyclic carbonates, wherein the method includes: performing a synthesis reaction on carbon dioxide and an epoxide in the presence of a catalyst to obtain a cyclic carbonate; wherein the catalyst is the ionic liquid of the present invention.

[0063] In some embodiments of the present invention, preferably, the dosage of the catalyst is 1-7 mol% of the epoxide.

[0064] In some embodiments of the present invention, preferably, the conditions of the synthesis reaction include: the reaction pressure is 0.1-0.5 MPa, the reaction temperature is 25-90 °C, preferably 40-80 °C, more preferably 60-80 °C, and further preferably 70-80 °C; the reaction time is 2-24 h.

[0065] In some embodiments of the present invention, preferably, the epoxide is selected from at least one of ethylene oxide, epichlorohydrin, epibromohydrin, benzyl glycidyl ether, allyl glycidyl ether, n-butyl glycidyl ether, 1,2-epoxy-2-methylpropane, octyl glycidyl ether, and phenyl glycidyl ether.

[0066] The present invention will be described in detail below through examples. In the following examples, the prepared ionic liquid can be 1 characterized by 13 1H NMR,

[0067] 13C NMR, IR, and MS analysis to determine the obtained structure. 2 CO

[0068] (99.99%) The raw material is a commercially available product from Nanjing Special Gas Company;

[0069] The raw material of D- or L-tartaric acid is a commercially available product from Shanghai Aladdin Reagent Co., Ltd.;

[0070] The solution of D- or L-gluconic acid is a commercially available product from Shanghai Aladdin Reagent Co., Ltd.;

[0071] D- or L-lactic acid is a commercially available product from Shanghai Aladdin Reagent Co., Ltd.;

[0072] Tetrabutylphosphonium chloride is a commercially available product from Shanghai Aladdin Reagent Co., Ltd.;

[0073] Trihexyltetradecylphosphonium chloride is a commercially available product from Shanghai Aladdin Reagent Co., Ltd.;

[0074] Propylene oxide, epichlorohydrin, epibromohydrin, benzyl glycidyl ether, butyl glycidyl ether, and 1,2-epoxy-2-methylpropane are all commercially available products from Shanghai Aladdin Reagent Co., Ltd.;

[0075] Phenyl glycidyl ether and octyl glycidyl ether are commercially available products from Anhui Anengji Chemical Reagent Co., Ltd.

[0076] Example 1

[0077] Dissolve trihexyltetradecylphosphonium chloride (0.67 mmol) in 25 mL of absolute ethanol, and slowly pass the solution through a column packed with three times the molar amount of Amberlite IRN78 hydroxide-form ion exchange resin (the hydroxide-form ion exchange resin was previously washed thoroughly with absolute ethanol and the air was removed). Control the flow rate. After two ion exchanges, replace the fresh hydroxide-form ion exchange resin and perform the exchange again. Before using the prepared trihexyltetradecylphosphonium hydroxide, take a small amount and add dilute nitric acid to neutralize it, and then use an aqueous silver nitrate solution to determine whether the anion exchange is complete. If not, the ion exchange experiment needs to be carried out again. The content of trihexyltetradecylphosphonium hydroxide is determined by 1 1H NMR.

[0078] Weigh the stoichiometric amount of polyhydroxy acid (the specific polyhydroxy acid and the feeding molar ratio are shown in Table 1), add it to the above ethanol solution containing trihexyltetradecylphosphonium hydroxide, stir at room temperature for 24 hours, remove the solvent by vacuum distillation, and dry the residue at 60 °C under vacuum of -0.01 MPa for 24 h to obtain the ionic liquid with the corresponding structure.

[0079] Table 1

[0080] Number Polyhydroxy acid Polyhydroxy acid: molar ratio of trihexyltetradecylphosphonium hydroxide Ionic liquid-1 D-Gluconic acid 1:1 Ionic liquid-2 D-Tartaric acid <![CDATA[1:2 c > Ionic liquid-3 D-Tartaric acid <![CDATA[1:1 a > Ionic liquid-4 L-Lactic acid 1:1 Ionic liquid-5 L-Gluconic acid 1:1 Ionic liquid-6 L-Tartaric acid <![CDATA[1:2 d > Ionic liquid-7 L-Tartaric acid <![CDATA[1:1 b > Ionic liquid-8 D-Lactic acid 1:1

[0081] Note: a - In the obtained ionic liquid, the anion is D-tartrate monocarboxylate;

[0082] b - In the obtained ionic liquid, the anion is L-tartrate monocarboxylate;

[0083] c - In the obtained ionic liquid, the anion is D-tartrate dicarboxylate;

[0084] d - In the obtained ionic liquid, the anion is L-tartrate dicarboxylate.

[0085] Example 2

[0086] Preparation of polyhydroxy acid quaternary ammonium ionic liquid

[0087] Add 25 mL (25 mmol) of tetrabutylammonium hydroxide (1 M, methanol) to a 100 mL conical flask, then add polyhydroxy acid (25 mmol) (the specific polyhydroxy acid and feed molar ratio are shown in Table 2). Stir at room temperature for 24 h, then distill off the solvent under reduced pressure. The obtained ionic liquid is dried at 60 °C under vacuum of -0.01 MPa for 24 h to obtain a white solid.

[0088] Table 2

[0089] Number Polyhydroxy acid Polyhydroxy acid: molar ratio of tetrabutylammonium hydroxide Ionic liquid-9 D-Gluconic acid 1:1 Ionic liquid-10 L-Gluconic acid 1:1 Ionic liquid-11 D-Tartaric acid <![CDATA[1:2 c > Ionic liquid-12 D-Tartaric acid <![CDATA[1:1 a > Ionic liquid-13 L-Lactic acid 1:1 Ionic liquid-14 L-Tartaric acid <![CDATA[1:2 d > Ionic liquid-15 L-Tartaric acid <![CDATA[1:1 b > Ionic liquid-16 D-Lactic acid 1:1

[0090] Note: a - In the obtained ionic liquid, the anion is D-tartaric acid monocarboxylate;

[0091] b - In the obtained ionic liquid, the anion is L-tartaric acid monocarboxylate;

[0092] c - In the obtained ionic liquid, the anion is D-tartaric acid dicarboxylate;

[0093] d - In the obtained ionic liquid, the anion is L-tartaric acid dicarboxylate.

[0094] Example 3

[0095] Preparation of polyhydroxy acid quaternary phosphonium ionic liquid

[0096] Dissolve tetrabutylphosphonium chloride (0.67 mmol) in 25 mL of absolute ethanol, and slowly pass the solution through a column packed with three times the molar amount of Amberlitel IRN78 hydroxide form ion exchange resin (the hydroxide form ion exchange resin is pre-washed thoroughly with absolute ethanol and air is removed). Control the flow rate. After two ion exchanges, replace the fresh hydroxide form ion exchange resin and perform the exchange again. Before use, take a small amount of the prepared tetrabutylphosphonium hydroxide, neutralize it with dilute nitric acid, and determine whether the anion exchange is complete with an aqueous silver nitrate solution. If not complete, the ion exchange experiment needs to be carried out again. The content of tetrabutylphosphonium hydroxide is determined by 1 H NMR.

[0097] Weigh the stoichiometric amount of polyhydroxy acid (the specific polyhydroxy acid and feed molar ratio are shown in Table 3), add it to the above ethanol solution containing tetrabutylphosphonium hydroxide, stir at room temperature for 24 hours, distill off the solvent under reduced pressure, and dry the residue at 60 °C under vacuum of -0.01 MPa for 24 h to obtain the ionic liquid with the corresponding structure.

[0098] Table 3

[0099] Number Polyhydroxy acid Polyhydroxy acid: molar ratio of tetrabutylphosphonium hydroxide Ionic liquid-17 D-Gluconic acid 1:1 Ionic liquid-18 L-Gluconic acid 1:1 Ionic liquid-19 D-Tartaric acid <![CDATA[1:2 c > Ionic liquid-20 D-Tartaric acid <![CDATA[1:1 a > Ionic liquid-21 L-Lactic acid 1:1 Ionic liquid-22 L-Tartaric acid <![CDATA[1:2 d > Ionic liquid-23 L-Tartaric acid <![CDATA[1:1 b > Ionic liquid-24 D-Lactic acid 1:1

[0100] Note: In the obtained ionic liquid, the anion is D-tartrate monocarboxylate;

[0101] b - In the obtained ionic liquid, the anion is L-tartrate monocarboxylate;

[0102] c - In the obtained ionic liquid, the anion is D-tartrate dicarboxylate;

[0103] d - In the obtained ionic liquid, the anion is L-tartrate dicarboxylate.

[0104] Example 4

[0105] Preparation of cyclic carbonate: autoclave method

[0106] Add 0.05 mmol of trihexyltetradecylphosphonium D-lactate ionic liquid into a 50 mL autoclave, then add 10.0 mmol of epichlorohydrin. After sealing, introduce carbon dioxide into the autoclave. After displacing the gas three times, charge the pressure of carbon dioxide to 0.5 MPa and react at 80 °C for 3 hours; after the reaction is completed, cool the autoclave 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.

[0107] Through 1 1H NMR determination, the selectivity of the obtained cyclic carbonate is greater than 99.0%, and the conversion rate of epichlorohydrin is 96.1%.

[0108] Example 5

[0109] Preparation of cyclic carbonate: atmospheric pressure method

[0110] Add 0.05 mmol of trihexyltetradecylphosphonium L-lactate ionic liquid into a 50 mL round-bottom flask, then add 10.0 mmol of epichlorohydrin. Place the three-way valve of the gas balloon filled with CO 2 gas at the mouth of the round-bottom flask. After displacing the gas three times, react at 80 °C for 3 h. 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.

[0111] Through 1 1H NMR determination, the selectivity of the obtained cyclic carbonate is greater than 99.0%, and the conversion rate of epichlorohydrin is 98.0%.

[0112] 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.

[0113] The conversion rate is calculated according to 1The 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.

[0114] The chemical reaction equations involved are as follows:

[0115] Examples 4 and 5 can be used to compare the autoclave method with the atmospheric pressure balloon method. Similar conversion rates of epichlorohydrin and selectivities of cyclic carbonates can be obtained by both methods. The atmospheric pressure method with milder reaction conditions was selected for subsequent experiments.

[0116] Example 6

[0117] 0.05 mmol of trihexyltetradecylphosphonium L-lactate ionic liquid was added to a 50 mL round-bottom flask, and then 10.0 mmol of epichlorohydrin was added. The three-way valve of the balloon filled with CO 2 gas was placed at the mouth of the round-bottom flask. After displacing the gas three times, the reaction was carried out at 40 °C for 3 hours. After the reaction, it was cooled to room temperature, the excess gas was released, and the reaction mixture was transferred to a vacuum distillation device to obtain cyclic carbonate by vacuum distillation.

[0118] By 1 ¹H NMR determination, the selectivity of the obtained cyclic carbonate was greater than 99.0%, and the conversion rate of epichlorohydrin was 35.9%.

[0119] Example 7

[0120] 0.05 mmol of trihexyltetradecylphosphonium L-lactate ionic liquid was added to a 50 mL round-bottom flask, and then 10.0 mmol of epichlorohydrin was added. The three-way valve of the balloon filled with CO 2 gas was placed at the mouth of the round-bottom flask. After displacing the gas three times, the reaction was carried out at 50 °C for 3 hours. After the reaction, it was cooled to room temperature, the excess gas was released, and the reaction mixture was transferred to a vacuum distillation device to obtain cyclic carbonate by vacuum distillation.

[0121] By 1 ¹H NMR determination, the selectivity of the obtained cyclic carbonate was greater than 99.0%, and the conversion rate of epichlorohydrin was 65.6%.

[0122] Example 8

[0123] 0.05 mmol of trihexyltetradecylphosphonium L-lactate ionic liquid was added to a 50 mL round-bottom flask, and then 10.0 mmol of epichlorohydrin was added. The three-way valve of the balloon filled with CO 2 gas was placed at the mouth of the round-bottom flask. After displacing the gas three times, the reaction was carried out at 60 °C for 3 hours. After the reaction, it was cooled to room temperature, the excess gas was released, and the reaction mixture was transferred to a vacuum distillation device to obtain cyclic carbonate by vacuum distillation.

[0124] By 1 1H NMR measurement, the selectivity of the obtained cyclic carbonate was greater than 99.0%, and the conversion rate of epichlorohydrin was 85.0%.

[0125] Example 9

[0126] 0.05 mmol of trihexyltetradecylphosphonium L-lactate ionic liquid was added to a 50 mL round-bottom flask, and then 10.0 mmol of epichlorohydrin was added. A three-way valve with a CO 2 gas balloon was placed at the mouth of the round-bottom flask. After displacing the gas 3 times, the reaction was carried out at 70 °C for 3 hours. After the reaction, it was cooled to room temperature, and the excess gas was released. The reaction mixture was transferred to a vacuum distillation device, and the cyclic carbonate was obtained by vacuum distillation.

[0127] By 1 1H NMR measurement, the selectivity of the obtained cyclic carbonate was greater than 99.0%, and the conversion rate of epichlorohydrin was 92.8%.

[0128] The specific test data are shown in Table 4:

[0129] Table 4

[0130] Number Temperature Chloropropylene carbonate selectivity, % Epichlorohydrin conversion rate, % Example 5 80℃ 99％ 98.0％ Example 6 40℃ 99％ 35.9％ Example 7 50℃ 99％ 65.6％ Example 8 60℃ 99％ 85.0％ Example 9 70℃ 99％ 92.8％

[0131] It can be seen from the data in Table 4 that by using the method provided by the present invention to prepare cyclic carbonate, the catalyst does not contain metal or halogen, and still can obtain good selectivity of allyl chloride cyclic carbonate, and the conversion rate of epichlorohydrin can also reach more than 85% at 60-80 °C and more than 92.5% at 70-80 °C, indicating that the ionic liquid catalyst system of the present invention has the advantages of good selectivity and high catalytic efficiency.

[0132] Test Example 1

[0133] Based on the above test results, according to the same method as in Example 5, the dosage of trihexyltetradecylphosphonium L-lactate ionic liquid was adjusted to 1.0-7.0 mol%. The reaction was carried out, and the conversion rate of epichlorohydrin and the selectivity of the product cyclic carbonate were measured. The specific test data are shown in Table 5.

[0134] Table 5

[0135]

[0136] It can be seen from the data in Table 5 that when the dosage of the polyhydroxy acid ionic liquid prepared by the present invention is 1.0-7.0 mol%, it has good catalytic effect.

[0137] Test Example 2

[0138] Based on the above test results, the usage effect test of ionic liquid recycling was carried out according to the same method as in Example 5, and the specific test data are as Figure 1 shown. From Figure 1 the data, it can be seen that the polyhydroxy acid ionic liquid prepared by the present invention has good recycling effect and economy.

[0139] Test Example 3

[0140] The polyhydroxy acid ionic liquid prepared by the present invention has good universality for different substrate epoxides. According to the same method as in Example 5, different substrate epoxides were replaced for the reaction, and the specific test data are shown in Table 6.

[0141] Table 6

[0142]

[0143]

[0144] Comparative Examples 1-2

[0145] According to the method of Example 5, the difference is that the catalyst used is a catalyst of the prior art (the literature marked below Table 7), and the reaction conditions are shown in Table 7. The results are shown in Table 7.

[0146] Table 7

[0147]

[0148] Note: a The number of moles of chloropropylene carbonate produced per mole of catalyst per hour;

[0149] [1]S.Yue,H.L.Qu,X.X.Song,X.N.Feng,Novel hyfroxyl-functionalized ionicliquids as efficient catalysts for the conversion of CO 2 into cycliccarbonates under metal / halogen / cocatalyst / solvent-free conditions.NewJ.Chem.46(2022),5881-5888.https: / / doi.org / 10.1039 / D2NJ00257D;

[0150] [2]C.Li,F.Liu,T.X.Zhao,J.R.Gu,P.Chen,T.Chen,Highly efficient CO 2Fixation 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。

[0151] As can be seen from the results in Table 7, when the ionic liquid provided by the present invention is used as a catalyst for catalytic conversion of CO 2 to cyclic carbonate, it has significantly better effects such as short reaction time, low reaction temperature, low pressure, small catalyst dosage, and high conversion rate of epoxide.

[0152] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A polyhydroxy acid ionic liquid, characterized in that: The cation of the ionic liquid includes a quaternary ammonium cation and / or a quaternary phosphonium cation, and the anion is at least one of D or L-gluconate, D or L-tartaric acid monocarboxylate, D or L-tartaric acid dicarboxylate, and D or L-lactate.

2. The ionic liquid according to claim 1, characterized in that The quaternary ammonium cation has a structure shown in formula (1), and the quaternary phosphonium cation has a structure shown in formula (2) or formula (3), Wherein, n is a positive integer from 1 to 4.

3. The ionic liquid according to claim 1 or 2, characterized in that The ionic liquid is selected from at least one of the compounds having the following structures: Ionic liquid-1: cation is The anion is D-gluconate; Ionic liquid-2: cation is The anion is D-tartrate dicarboxylate; Ionic liquid-3: cation is The anion is D-tartaric acid monocarboxylate; Ionic liquid-4: cation is The anion is L-lactate; Ionic liquid-5: cation is The anion is L-gluconate; Ionic liquid-6: cation is The anion is L-tartrate dicarboxylate; Ionic liquid-7: cation is The anion is L-tartaric acid monocarboxylate; Ionic liquid-8: cation is The anion is D-lactate; Ionic liquid-9: cation is n is 1, 2, 3, or 4, and the anion is D-gluconate; Ionic liquid-10: cation is n is 1, 2, 3, or 4, and the anion is L-gluconate; Ionic liquid-11: cation is n is 1, 2, 3, or 4, and the anion is D-tartaric acid dicarboxylate; Ionic liquid-12: cation is n is 1, 2, 3, or 4, and the anion is D-tartaric acid monocarboxylate; Ionic liquid-13: cation is n is 1, 2, 3, or 4, and the anion is L-lactate; Ionic liquid-14: cation is n is 1, 2, 3, or 4, and the anion is L-tartaric acid dicarboxylate; Ionic liquid-15: cation is n is 1, 2, 3, or 4, and the anion is L-tartaric acid monocarboxylate; Ionic liquid-16: cation is n is 1, 2, 3, or 4, and the anion is D-lactate; Ionic liquid-17: cation is n is 1, 2, 3, or 4, and the anion is D-gluconate; Ionic liquid-18: cation is n is 1, 2, 3, or 4, and the anion is L-gluconate; Ionic liquid-19: cation is n is 1, 2, 3, or 4, and the anion is D-tartaric acid dicarboxylate; Ionic liquid-20: cation is n is 1, 2, 3, or 4, and the anion is D-tartaric acid monocarboxylate; Ionic liquid-21: cation is n is 1, 2, 3, or 4, and the anion is L-lactate; Ionic liquid-22: cation is n is 1, 2, 3, or 4, and the anion is L-tartaric acid dicarboxylate; Ionic liquid-23: cation is n is 1, 2, 3, or 4, and the anion is L-tartaric acid monocarboxylate; Ionic liquid-24: cation is n is 1, 2, 3, or 4, and the anion is D-lactate.

4. A method for preparing an ionic liquid, characterized in that: The preparation method comprises: reacting a P- or N-containing compound with a polyhydroxy acid to obtain the ionic liquid; wherein the polyhydroxy acid is selected from at least one of D or L-gluconic acid, D or L-tartaric acid and D or L-lactic acid; The P or N-containing compound is selected from tetraalkylphosphine hydroxide, tetraalkylammonium hydroxide or trihexyltetradecylphosphine hydroxide, wherein the alkyl contained in the tetraalkylphosphine hydroxide and tetraalkylammonium hydroxide is selected from at least one of methyl, ethyl, propyl, butyl, hexyl and tetradecyl.

5. The preparation method according to claim 4, wherein: The molar ratio of the polyhydroxy acid to the P or N containing compound is 1:1-2; Preferably, the reaction conditions include: temperature of 20-30° C., pressure of 0.1-0.15 MPa, and time of 2-24 h.

6. An ionic liquid prepared by the preparation method according to claim 4 or 5.

7. Use of the ionic liquid according to any one of claims 1 to 3 and 6 in the preparation of cyclic carbonates from CO2.

8. A method for preparing cyclic carbonates from CO2, characterized in that: The method comprises: in the presence of a catalyst, subjecting carbon dioxide and an epoxy compound to a synthesis reaction to obtain a cyclic carbonate; wherein the catalyst is the ionic liquid according to any one of claims 1 to 3 and 6.

9. The method according to claim 8, wherein: The amount of the catalyst is 1-7 mol% of the epoxy compound; Preferably, the conditions of the synthesis reaction include: reaction pressure of 0.1-0.5 MPa, reaction temperature of 25-90° C., and reaction time of 2-24 h.

10. The method according to claim 8 or 9, wherein: The epoxy compound is selected from at least one of ethylene oxide, epichlorohydrin, epibromohydrin, benzyl glycidyl ether, allyl glycidyl ether, n-butyl glycidyl ether, 1,2-epoxy-2-methylpropane, octyl glycidyl ether, and phenyl glycidyl ether.

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