A method for preparing cyclic carbonate compounds

Abstract

This patent belongs to the field of organic catalysis technology, specifically disclosing a method for catalytically fixing carbon dioxide. Under conditions of 60–140°C, epoxides and carbon dioxide are used to generate cyclic carbonate compounds under the catalysis of this catalyst. This method for carbon dioxide fixation exhibits high conversion efficiency, no metal residue, mild reaction conditions, and easy catalyst preparation, showing great potential for commercial application in fields such as biomedicine and polymer preparation.

Description

Technical Field

[0001] This invention belongs to the field of organic catalysis technology, and specifically relates to a method for preparing cyclic carbonate compounds by fixing carbon dioxide. Background Technology

[0002] Over the past few decades, anthropogenic emissions of carbon dioxide have garnered widespread global attention due to their dramatic increase in atmospheric concentration. This surge in atmospheric carbon dioxide levels has led to rising sea levels, melting glaciers and ice shelves, desertification, and increasingly frequent extreme weather events. Therefore, developing efficient chemical processes for fixing and utilizing carbon dioxide has become a current research hotspot. The chemical fixation of carbon dioxide into high-value-added chemicals has received considerable attention within the context of sustainable chemistry. The synthesis of cyclic carbonates from carbon dioxide and epoxides has been extensively studied because cyclic carbonates can be used as monomers for polycarbonates, electrolytes for lithium-ion batteries, polar aprotic solvents, and intermediates for many chemicals and pharmaceuticals.

[0003] The kinetic and thermodynamic stability of carbon dioxide is a major limitation to its use as a chemical feedstock, thus requiring catalysts capable of simultaneously activating both carbon dioxide and epoxides. Much effort in synthesizing cyclic carbonates from carbon dioxide and epoxides has focused on metal-based homogeneous catalysts, which exhibit high catalytic activity and selectivity. Organic catalysts are also beginning to attract researchers' interest in the synthesis of cyclic carbonates because they are generally more cost-effective, sustainable, and less toxic than metal-based catalysts. Many organic catalysts have been studied, including ammonium salts, phosphonates, imidazole salts, and imidazole-based ionic liquids, and two-component systems composed of polyols and quaternary ammonium salts have been developed. These systems are characterized by low energy consumption, environmental friendliness, and 100% atom utilization, aligning with the principles of green chemistry.

[0004] Most organic catalysts that catalyze the synthesis of cyclic carbonates from carbon dioxide and epoxides are salts composed of anions and cations. The cations form hydrogen bonds with the epoxy substrate, the anions attack the epoxy to open the ring, and then the carbon dioxide inserts into the ring, closing the ring to form a cyclic carbonate. For example, Zhang et al. (ACS Sustainable Chem. Eng. 2017, 5, 2841-2846) used [DMAPH]Br to convert diluted carbon dioxide into carbonates at atmospheric pressure with a yield of up to 96% and a selectivity of 99%. Other pyridine salts (Green Chem. 2009, 11, 1876), imidazole salts (GreenChem. 2013, 15, 1584), ammonium salts (Catal. Sci. Technol. 2014, 4, 1585), phosphate salts (ChemSusChem. 2015, 8, 2655), and nitrogen heterocyclic carbenes (ChemSusChem. 2014, 7, 962) have also yielded carbonate products with high yields and high selectivity.

[0005] However, these catalysts are expensive, have complex purification methods, and involve too many synthesis steps, which leads to a decrease in yield and thus limits their application. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for the catalytic fixation of carbon dioxide to synthesize cyclic carbonate compounds. This invention employs a novel organic ion-pair catalyst to achieve a [3+2] cycloaddition reaction between epoxides and carbon dioxide, yielding cyclic carbonate compounds with high selectivity. This catalyst-based synthesis method is simple, the catalytic reaction conditions are mild, and it has a wide range of applicable substrates. The resulting cyclic carbonate compounds are free of metal residues, demonstrating significant commercial potential in fields such as microelectronics and polymer fabrication where strict control over metal residue content is crucial.

[0007] This invention proposes a novel bifunctional catalyst—an organic catalyst in which the hydroxyl group on the second or third carbon of ascorbic acid is alkylated with different substituents and used as a hydrogen bond donor, while the tetrabutylammonium hydroxide cation acts as a nucleophilic co-catalyst. This catalyst catalyzes the highly selective formation of cyclic carbonates from epoxides and carbon dioxide. Ascorbic acid, as a hydrogen bond donor, activates the epoxide and stabilizes the ionic intermediate. The tetrabutylammonium hydroxide cation, due to its mutual repulsion with the cyclopropenyl cation, exhibits enhanced nucleophilicity, attacking the epoxide and causing ring-opening. The target catalyst is obtained by dropwise addition of alkylated ascorbic acid to a methanol solution of tetrabutylammonium hydroxide at 0°C; the post-processing is simple and easy to operate.

[0008] This invention identifies and solves problems arising from practical needs by utilizing a bifunctional ascorbic acid ion pair, acting as both a hydrogen bond donor and a nucleophilic anion, to catalyze the synthesis of epoxides with different substituents. This organic molecular catalytic system is the first to be applied to the cycloaddition reaction of epoxides with carbon dioxide, exhibiting mild conditions, high conversion rates, and high selectivity.

[0009] The technical solutions to achieve the above objectives are as follows:

[0010] A method for synthesizing cyclic carbonates, using a catalyst shown in Formula I or Formula II to catalyze the reaction of an epoxide shown in Formula III with carbon dioxide to generate cyclic carbonate compounds:

[0011]

[0012] in,

[0013] Bu4N + It is a tetrabutylammonium hydroxide cation;

[0014] R 1 It is independently selected from methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, isopentyl, hexyl, isohexyl, heptyl, isohexyl, octyl, isooctyl, alkenylmethyl, alkenylethyl, allyl, benzyl;

[0015] R 2 R 3 Independently selected from hydrogen, C1-C4 straight-chain or branched alkyl groups, halogenated C1-C4 straight-chain or branched alkyl groups, phenyl groups, substituted phenyl groups, or R-type alkyl groups. 4 -O-CH2-; the substituent in the "substituted phenyl" is selected from halogens or C1-C5 straight-chain or branched alkyl groups; the "R" 4 R in "-O-CH2-" 4 It is selected from phenyl, phenyl substituted with C1-C3 straight-chain or branched alkyl, allyl or C1-C4 straight-chain or branched alkyl.

[0016] Preferably, the catalyst shown in Formula I is selected from the following structures:

[0017]

[0018]

[0019] Preferably, the preparation method of catalysts numbered 1 to 8 is as follows:

[0020] (1) Weigh out ascorbic acid (1.98 mmol), alkylating reagent (2.49 mmol), triphenylphosphine (2.25 mmol), and diethyl azodicarbonate (2.22 mmol) and mix them in tetrahydrofuran solution (10-40 ml) at -78 °C. After reacting for 15-28 h, column chromatography (dichloromethane / methanol 15-25:1) is used to obtain alkylated ascorbic acid.

[0021] (2) Dissolve the alkylated ascorbic acid obtained in (1) in 50 ml of methanol solution;

[0022] (3) At 0℃, the alkylated ascorbic acid methanol solution and the tetrabutylammonium hydroxide methanol solution are mixed evenly at a molar ratio of (2-1.5:1) and stirred at room temperature for 15-28h.

[0023] (4) After the reaction is complete, the reaction solution is evaporated under reduced pressure, 100 ml of acetonitrile is added and filtered to remove unreacted alkylated ascorbic acid. The filtered solution is collected and evaporated under reduced pressure, and then dried in a vacuum oven at 70°C overnight to obtain the catalyst.

[0024] Preferably, the preparation method of catalyst 9-16 is as follows:

[0025] (1) Weigh ascorbic acid (2 mol) into acetone, add acetyl chloride (0.1 mol) to the rapidly stirred suspension, stir the mixture at room temperature for 15-20 h, filter to collect the precipitate, wash the precipitate three times with ethyl acetate, and dry the precipitate overnight in a vacuum drying oven;

[0026] (2) Weigh the product (4.63 mmol) obtained in step 1 into a mixed solution of dimethyl sulfoxide / tetrahydrofuran (3:2);

[0027] (3) Weigh 9.26 mmol of organic bases such as potassium tert-butoxide into a mixed solution of dimethyl sulfoxide / tetrahydrofuran (3:2);

[0028] (4) Under conditions of -15 to -10℃, slowly add the mixed solution from step 3 to the mixed solution from step 2, and react for 7 to 10 minutes;

[0029] (5) Weigh the alkylating agent (5.09 mmol) and add it dropwise to the mixed solution in step 4 within 3 min. Stir the mixed solution at room temperature for 3 to 5 h.

[0030] (6) Quench the reaction with 0.25M hydrochloric acid (20ml) and extract the product three times with ethyl acetate;

[0031] (7) The organic layer was dried with anhydrous sodium sulfate, the solvent was removed under reduced pressure, and the product was purified by column chromatography (n-hexane / ethyl acetate 3:1).

[0032] The alkylating agents used to prepare the catalyst include iodomethane, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol, isohexanol, heptanol, isoheptanol, octanol, isooctanol, ethmethanol, vinyl alcohol, allyl alcohol and benzyl alcohol, iodomethane, iodoethane, iodopropane, iodobutane, iodooctane, allyl bromide, and benzyl bromide.

[0033] Preferably, the epoxide represented by Formula III is selected from styrene oxide, epichlorohydrin, epibromopropane, allyl glycidyl ether, butyl ethylene oxide, 2-toluene glycidyl ether, phenyl glycidyl ether, methyl glycidyl ether, tert-butyl glycidyl ether, and methyl acrylate glycidyl ether.

[0034] The structure of epoxides is shown in the table below:

[0035]

[0036] Preferably, the specific method for fixing carbon dioxide is as follows: under anhydrous and oxygen-free conditions, in an inert gas or nitrogen atmosphere, a catalyst represented by Formula I or Formula II and an epoxide represented by Formula III are added to a reaction vessel, carbon dioxide is introduced, the reaction vessel is heated, and the product is separated after the reaction is completed.

[0037] The molar ratio of the epoxy compound represented by Formula III to the catalyst represented by Formula I or Formula II is 200–1000:1; the reaction temperature is 60–140°C; the reaction time is 6–24 h; and the initial reaction pressure is 0.1–1.5 MPa.

[0038] The post-processing involves cooling the reaction solution, performing column chromatography (petroleum ether: ethyl acetate = 5:1), and then evaporating to obtain the product.

[0039] The structure of cyclic carbonates is shown in the figure below.

[0040]

[0041] Beneficial effects

[0042] The technical solution of this invention can achieve the following effects:

[0043] (1) The catalyst provided by the present invention can efficiently synthesize cyclic carbonate compounds with high added value. Compared with the existing methods for synthesizing cyclic carbonates using metal catalysts, it has the characteristics of high selectivity (>99%), no metal residue, and mild conditions.

[0044] (2) This invention proposes a novel bifunctional catalyst for the first time: a bifunctional organic catalyst that uses the hydroxyl group on the 2nd or 3rd carbon of ascorbic acid as a hydrogen bond donor after alkylation with different substituents, and the tetrabutylammonium hydroxide cation as a nucleophilic co-catalyst, to catalyze the high-selectivity formation of cyclic carbonates from epoxides and carbon dioxide.

[0045] (3) This invention enables the catalytic synthesis of cyclic carbonate compounds under normal pressure and low catalytic loading conditions. The reaction time is short and the temperature is low, resulting in highly selective cyclic carbonates. Compared to other conditions involving high temperature, high pressure, long reaction time, and high catalyst loading, the reaction conditions of this invention are very mild.

[0046] (4) The catalyst raw materials of this invention are inexpensive, the purification method is complex, the synthesis steps are few and the yield is improved. At the same time, the substrate of this reaction has wide applicability and has great potential for commercial application in fields such as biomedicine and polymer preparation.

[0047] In summary, compared with other existing catalytic systems, the present invention has significant advantages such as being mild, efficient, easy to prepare, and free of metal residues. Attached Figure Description

[0048] Figure 1 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 1

[0049] Figure 2 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 2

[0050] Figure 3 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 3

[0051] Figure 4 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 4

[0052] Figure 5 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 5

[0053] Figure 6 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 6

[0054] Figure 7 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 7

[0055] Figure 8 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 8

[0056] Figure 9 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 9

[0057] Figure 10: 1H NMR spectrum of the cyclic carbonate product obtained in Example 10

[0058] Figure 11 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 11

[0059] Figure 12 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 12

[0060] Figure 13 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 13

[0061] Figure 14 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 14

[0062] Figure 15 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 15

[0063] Figure 16 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 16

[0064] Figure 17 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 17

[0065] Figure 18 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 18

[0066] Figure 19 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 19

[0067] Figure 20 : Proton NMR spectrum of catalyst No. 1

[0068] Figure 21 : Proton NMR spectrum of catalyst No. 2

[0069] Figure 22 : Proton NMR spectrum of catalyst No. 3

[0070] Figure 23 : Proton NMR spectrum of catalyst No. 5

[0071] Figure 24 : Proton NMR spectrum of catalyst No. 6

[0072] Figure 25 : Proton NMR spectrum of catalyst No. 8

[0073] Figure 26 : Proton NMR spectrum of catalyst No. 9 Detailed Implementation

[0074] The present invention can be further illustrated by the following embodiments, which are for illustrative purposes only and not for limiting the invention. Any person skilled in the art will understand that these embodiments do not limit the invention in any way, and that appropriate modifications and data transformations can be made thereto without departing from the spirit and scope of the invention.

[0075] The proton and carbon NMR spectra involved in the examples were measured using a Bruker Ascend TM-400 NMR analyzer, and the deuterated reagents used were deuterated chloroform (CDCl3) and deuterated methanol (CD3OD).

[0076] All raw materials used in the following examples were purchased from Alfa Aesar.

[0077] The structure of the catalytic system used in the examples is as follows:

[0078]

[0079]

[0080] The structure of the epoxide used in the examples is as follows:

[0081]

[0082]

[0083] I. Catalyst Preparation Examples

[0084] The preparation method of catalyst No. 1 is as follows:

[0085] Step 1: Preparation of alkylated ascorbic acid: Ascorbic acid (1.98 mmol) was mixed with methanol (2.49 mmol), triphenylphosphine (2.25 mmol), and diethyl azodicarbonate (2.22 mmol) in tetrahydrofuran solution (10-40 ml) at -78 °C. After reacting for 15-28 h, column chromatography (dichloromethane / methanol 15:1) was performed to obtain ascorbic acid with hydroxymethylation of hydroxyl group 3.

[0086] Step 2: Dissolve 25.0 mmol of the methylated ascorbic acid obtained in Step 1 in 50 ml of methanol solution;

[0087] Step 3: At 0℃, the methylated ascorbic acid methanol solution and 40% tetrabutylammonium hydroxide methanol solution are mixed evenly at a molar ratio of 1.5:1 and stirred at room temperature for 15 hours.

[0088] Step 4: After the reaction is complete, the reaction solution is evaporated under reduced pressure, 100 ml of acetonitrile is added, and the unreacted methylated ascorbic acid is removed by filtration. The filtered solution is collected and evaporated under reduced pressure, and then dried in a vacuum oven at 70°C overnight to obtain catalyst No. 1.

[0089] The preparation method of catalyst No. 2 is as follows:

[0090] Step 1: Preparation of alkylated ascorbic acid: Ascorbic acid (1.98 mmol) was mixed with ethanol (2.49 mmol), triphenylphosphine (2.25 mmol), and diethyl azodicarbonate (2.22 mmol) in tetrahydrofuran solution (10-40 ml) at -78 °C. After reacting for 15-28 h, column chromatography (dichloromethane / methanol 15:1) was performed to obtain hydroxyethylated ascorbic acid (3).

[0091] Step 2: Dissolve 25.0 mmol of the ethylated ascorbic acid obtained in Step 1 in 50 ml of methanol solution;

[0092] Step 3: At 0℃, the ethylated ascorbic acid methanol solution and 40% tetrabutylammonium hydroxide methanol solution are mixed evenly at a molar ratio of 1.5:1 and stirred at room temperature for 15 hours.

[0093] Step 4: After the reaction is complete, the reaction solution is evaporated under reduced pressure, 100 ml of acetonitrile is added, and the unreacted ethylated ascorbic acid is removed by filtration. The filtered solution is collected and evaporated under reduced pressure, and then dried in a vacuum oven at 70°C overnight to obtain catalyst No. 2.

[0094] The preparation method of catalyst No. 3 is as follows:

[0095] Step 1: Preparation of alkylated ascorbic acid: Ascorbic acid (1.98 mmol) was mixed with propanol (2.49 mmol), triphenylphosphine (2.25 mmol), and diethyl azodicarbonate (2.22 mmol) in tetrahydrofuran solution (10-40 ml) at -78 °C. After reacting for 15-28 h, column chromatography (dichloromethane / methanol 15:1) was performed to obtain hydroxypropylated ascorbic acid (3).

[0096] Step 2: Dissolve 25.0 mmol of the propylated ascorbic acid obtained in Step 1 in 50 ml of methanol solution;

[0097] Step 3: At 0℃, mix the propylated ascorbic acid methanol solution and 40% tetrabutylammonium hydroxide methanol solution at a molar ratio of 1.7:1, and stir at room temperature for 15 hours.

[0098] Step 4: After the reaction is complete, the reaction solution is evaporated under reduced pressure, 100 ml of acetonitrile is added and filtered to remove unreacted propylated ascorbic acid. The filtered solution is collected and evaporated under reduced pressure, then dried in a vacuum oven at 70°C overnight to obtain catalyst No. 3.

[0099] The preparation method of catalyst No. 4 is as follows:

[0100] Step 1: Preparation of alkylated ascorbic acid: Ascorbic acid (1.98 mmol) was mixed with pentanol (2.49 mmol), triphenylphosphine (2.25 mmol), and diethyl azodicarbonate (2.22 mmol) in tetrahydrofuran solution (10-40 ml) at -78 °C. After reacting for 15-28 h, column chromatography (dichloromethane / methanol 20:1) was performed to obtain hydroxypentylated ascorbic acid (number 3).

[0101] Step 2: Dissolve 25.0 mmol of the pentylated ascorbic acid obtained in Step 1 in 50 ml of methanol solution;

[0102] Step 3: At 0℃, mix the pentylated ascorbic acid methanol solution and 40% tetrabutylammonium hydroxide methanol solution at a molar ratio of 1.5:1, and stir at room temperature for 15 hours.

[0103] Step 4: After the reaction is complete, the reaction solution is evaporated under reduced pressure, 100 ml of acetonitrile is added, and the unreacted pentylated ascorbic acid is removed by filtration. The filtered solution is collected and evaporated under reduced pressure, and then dried in a vacuum oven at 70°C overnight to obtain catalyst No. 4.

[0104] The preparation method of catalyst No. 5 is as follows:

[0105] Step 1: Preparation of alkylated ascorbic acid: Ascorbic acid (1.98 mmol) was mixed with heptanol (2.49 mmol), triphenylphosphine (2.25 mmol), and diethyl azodicarbonate (2.22 mmol) in tetrahydrofuran solution (10-40 ml) at -78 °C. After reacting for 15-28 h, column chromatography (dichloromethane / methanol 20:1) was performed to obtain ascorbic acid with hydroxyl group 3 heptylated.

[0106] Step 2: Dissolve 25.0 mmol of the heptylated ascorbic acid obtained in Step 1 in 50 ml of methanol solution;

[0107] Step 3: At 0℃, the heptylated ascorbic acid methanol solution and 40% tetrabutylammonium hydroxide methanol solution are mixed evenly at a molar ratio of 1.5:1 and stirred at room temperature for 15 hours.

[0108] Step 4: After the reaction is complete, the reaction solution is evaporated under reduced pressure, 100 ml of acetonitrile is added and filtered to remove unreacted heptylated ascorbic acid. The filtered solution is collected and evaporated under reduced pressure, then dried in a vacuum oven at 70°C overnight to obtain catalyst No. 5.

[0109] The preparation method of catalyst No. 6 is as follows:

[0110] Step 1: Preparation of alkylated ascorbic acid: Ascorbic acid (1.98 mmol) was mixed with octanol (2.49 mmol), triphenylphosphine (2.25 mmol), and diethyl azodicarbonate (2.22 mmol) in tetrahydrofuran solution (10-40 ml) at -78 °C. After reacting for 15-28 h, column chromatography (dichloromethane / methanol 20:1) was performed to obtain octylated ascorbic acid with hydroxyl group 3.

[0111] Step 2: Dissolve 25.0 mmol of the octylated ascorbic acid obtained in Step 1 in 50 ml of methanol solution;

[0112] Step 3: At 0℃, mix the octylated ascorbic acid methanol solution and 40% tetrabutylammonium hydroxide methanol solution at a molar ratio of 2:1, and stir at room temperature for 15 hours.

[0113] Step 4: After the reaction is complete, the reaction solution is evaporated under reduced pressure, 100 ml of acetonitrile is added and filtered to remove unreacted octylated ascorbic acid. The filtered solution is collected and evaporated under reduced pressure, then dried in a vacuum oven at 70°C overnight to obtain catalyst No. 6.

[0114] The preparation method of catalyst No. 8 is as follows:

[0115] Step 1: Preparation of alkylated ascorbic acid: Ascorbic acid (1.98 mmol) was mixed with benzyl alcohol (2.49 mmol), triphenylphosphine (2.25 mmol), and diethyl azodicarbonate (2.22 mmol) in tetrahydrofuran solution (10-40 ml) at -78 °C. After reacting for 15-28 h, column chromatography (dichloromethane / methanol 20:1) was performed to obtain ascorbic acid with hydroxyphenylmethylation of hydroxyl group 3.

[0116] Step 2: Dissolve 25.0 mmol of the benzylated ascorbic acid obtained in Step 1 in 50 ml of methanol solution;

[0117] Step 3: At 0℃, the benzylated ascorbic acid methanol solution and 40% tetrabutylammonium hydroxide methanol solution are mixed evenly at a molar ratio of 1.8:1 and stirred at room temperature for 15 hours.

[0118] Step 4: After the reaction is complete, the reaction solution is evaporated to dryness under reduced pressure. 100 ml of acetonitrile is added, and the mixture is filtered to remove unreacted benzylated ascorbic acid. The filtered solution is collected, evaporated to dryness under reduced pressure, and dried overnight in a vacuum oven at 70°C to obtain catalyst No. 8. Preparation method of catalyst No. 9:

[0119] Step 1: Weigh 2 mol of ascorbic acid into acetone, add 0.1 mol of acetyl chloride to the rapidly stirred suspension, stir the mixture at room temperature for 15-20 h, filter to collect the precipitate, wash the precipitate three times with ethyl acetate, and dry the precipitate overnight in a vacuum drying oven.

[0120] Step 2: Weigh the product obtained in Step 1 (1 g, 4.63 mmol) into a mixed solution of dimethyl sulfoxide / tetrahydrofuran (3:2);

[0121] Step 3: Weigh 1.04 g (9.26 mmol) of organic base such as potassium tert-butoxide into a mixed solution of dimethyl sulfoxide / tetrahydrofuran (3:2);

[0122] Step 4: Under conditions of -15 to -10℃, slowly add the mixed solution from step 3 to the mixed solution from step 2 dropwise, and react for 7 to 10 minutes;

[0123] Step 5: Weigh 5.09 mmol of iodomethane and add it dropwise to the mixed solution from Step 4 over 3 minutes. Stir the mixed solution at room temperature for 3–5 hours.

[0124] Step 6: Quench the reaction with 0.25M hydrochloric acid (20ml) and extract the product three times with ethyl acetate;

[0125] Step 7: Dry the organic layer with anhydrous sodium sulfate, remove the solvent under reduced pressure, and purify the product by column chromatography (n-hexane / ethyl acetate 3:1) to obtain catalyst No. 9.

[0126] II. Examples of Preparation of Cyclic Carbonate Compounds

[0127] Example 1:

[0128] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 1 (10.7 mg, 0.025 mmol, 0.0025 equiv) was added under nitrogen purging, followed by epoxide A (1.12 ml, 10 mmol, 1.0 equiv), and carbon dioxide (1 MPa) was introduced. The reactor was placed in an oil bath at 120°C for 12 hours with a stirring rate of 400 rpm. After the reaction, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a yellow solid, which was dried to constant weight. NMR calculations showed a conversion of 92% and a selectivity >99%. The 1H NMR spectrum of the product is shown below. Figure 1 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 7.49–7.40 (m, 3H), 7.40–7.28 (m, 2H), 5.67 (t, J = 8.0 Hz, 1H), 4.79 (t, J = 8.4 Hz, 1H), 4.33 (dd, J = 8.7, 7.8 Hz, 1H).

[0129] Example 2:

[0130] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 2 (11.71 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide A (1.12 ml, 10 mmol, 1.0 equiv), and carbon dioxide (0.5 MPa) was introduced. The reactor was reacted at 120 °C for 12 hours in an oil bath with a stirring rate of 400 rpm. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a yellow solid, which was dried to constant weight. NMR calculations showed a conversion of 85% and a selectivity >99%. The 1H NMR spectrum of the product is shown below. Figure 2 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 7.49–7.40 (m, 3H), 7.40–7.28 (m, 2H), 5.67 (t, J = 8.0 Hz, 1H), 4.79 (t, J = 8.4 Hz, 1H), 4.33 (dd, J = 8.7, 7.8 Hz, 1H).

[0131] Example 3:

[0132] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 3 (11.50 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide A (10 mmol, 1.0 equiv) and carbon dioxide (1 MPa). The reactor was placed in an oil bath at 120°C with a stirring rate of 400 rpm for 24 hours. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a yellow solid. After drying to constant weight, the conversion was calculated to be 86% and the selectivity >99% by NMR. The proton NMR spectrum of the product is shown below. Figure 3 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 7.49–7.40 (m, 3H), 7.40–7.28 (m, 2H), 5.67 (t, J = 8.0 Hz, 1H), 4.79 (t, J = 8.4 Hz, 1H), 4.33 (dd, J = 8.7, 7.8 Hz, 1H).

[0133] Example 4:

[0134] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 5 (12.8 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide A (10 mmol, 1.0 equiv) and carbon dioxide (0.5 MPa). The reactor was reacted at 100°C for 18 hours in an oil bath with a stirring rate of 400 rpm. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a yellow solid. After drying to constant weight, NMR analysis showed a conversion of 66% and a selectivity >80%. The 1H NMR spectrum of the product is shown below. Figure 4 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 7.49–7.40 (m, 3H), 7.40–7.28 (m, 2H), 5.67 (t, J = 8.0 Hz, 1H), 4.79 (t, J = 8.4 Hz, 1H), 4.33 (dd, J = 8.7, 7.8 Hz, 1H).

[0135] Example 5:

[0136] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 6 (53.2 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide A (10 mmol, 1.0 equiv) and carbon dioxide (0.5 MPa). The reactor was reacted at 120°C for 8 hours in an oil bath with a stirring rate of 300 rpm. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a yellow solid. After drying to constant weight, the conversion was calculated to be 65% and the selectivity >60% by NMR. The proton NMR spectrum of the product is shown below. Figure 5 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 7.49–7.40 (m, 3H), 7.40–7.28 (m, 2H), 5.67 (t, J = 8.0 Hz, 1H), 4.79 (t, J = 8.4 Hz, 1H), 4.33 (dd, J = 8.7, 7.8 Hz, 1H).

[0137] Example 6

[0138] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 8 (12.7 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide A (10 mmol, 1.0 equiv) and carbon dioxide (1 MPa). The reactor was placed in an oil bath at 140 °C for 24 hours with a stirring rate of 500 rpm. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a yellow solid. After drying to constant weight, the conversion was calculated to be 52% and the selectivity >90% by NMR. The proton NMR spectrum of the product is shown below. Figure 6 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 7.49–7.40 (m, 3H), 7.40–7.28 (m, 2H), 5.67 (t, J = 8.0 Hz, 1H), 4.79 (t, J = 8.4 Hz, 1H), 4.33 (dd, J = 8.7, 7.8 Hz, 1H).

[0139] Example 7

[0140] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 4 (12.2 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide A (5 mmol, 1.0 equiv) and carbon dioxide (0.5 MPa). The reactor was placed in an oil bath at 120 °C for 18 hours with a stirring rate of 400 rpm. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a yellow solid. After drying to constant weight, NMR calculations showed a conversion of 85% and a selectivity >90%. The product's 1H NMR spectrum was also analyzed. Figure 7 As shown in the figure (H NMR spectrum, 400 Hz, CDCl3). The spectral data are: δ 7.49–7.40 (m, 3H), 7.40–7.28 (m, 2H), 5.67 (t, J = 8.0 Hz, 1H), 4.79 (t, J = 8.4 Hz, 1H), 4.33 (dd, J = 8.7, 7.8 Hz, 1H).

[0141] Example 8

[0142] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 9 (11.4 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide A (5 mmol, 1.0 equiv) and carbon dioxide (1 MPa). The reactor was then subjected to a stirring rate of 400 rpm in an oil bath at 120 °C for 12 hours. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a yellow solid. After drying to constant weight, the conversion was calculated to be 86% and the selectivity >90% by NMR. The proton NMR spectrum of the product is shown below. Figure 8 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 7.49–7.40 (m, 3H), 7.40–7.28 (m, 2H), 5.67 (t, J = 8.0 Hz, 1H), 4.79 (t, J = 8.4 Hz, 1H), 4.33 (dd, J = 8.7, 7.8 Hz, 1H).

[0143] Example 9

[0144] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 1 (10.7 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide B (10 mmol, 1.0 equiv) and carbon dioxide (0.5 MPa). The reactor was reacted at 120°C for 18 hours in an oil bath with a stirring rate of 400 rpm. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a colorless, transparent oily substance. This oil was dried to constant weight, with a conversion rate of 71%. The 1H NMR spectrum of the product is shown below. Figure 9 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 4.98 (dq, J = 9.3, 4.9, 4.5 Hz, 1H), 4.58 (td, J = 8.6, 1.4 Hz, 1H), 4.43–4.35 (m, 1H), 3.79 (ddd, J = 12.3, 5.3, 1.4 Hz, 1H), 3.71 (ddd, J = 12.2, 3.7, 1.2 Hz, 1H).

[0145] Example 10

[0146] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 1 (10.7 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide C (10 mmol, 1.0 equiv) and carbon dioxide (0.5 MPa). The reactor was reacted at 120°C for 16 hours in an oil bath with a stirring rate of 400 rpm. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a colorless, transparent oil. After drying to constant weight, the conversion was calculated to be 78% and the selectivity >90% by NMR. The proton NMR spectrum of the product is shown below. Figure 10 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 4.97 (dq, J = 8.2, 5.3 Hz, 1H), 4.62 (dd, J = 8.9, 8.2 Hz, 1H), 4.37 (dd, J = 8.9, 5.9 Hz, 1H), 3.60 (d, J = 5.2 Hz, 2H).

[0147] Example 11

[0148] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 1 (10.7 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide D (10 mmol, 1.0 equiv) and carbon dioxide (1.5 MPa). The reactor was reacted at 100°C for 12 hours in an oil bath with a stirring rate of 400 rpm. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a colorless, transparent oil. After drying to constant weight, the conversion was calculated to be 86% and the selectivity >99% by NMR. The proton NMR spectrum of the product is shown below. Figure 11 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 5.89–5.73 (m, 1H), 5.24–5.12 (m, 2H), 4.83–4.73 (m, 1H), 4.45 (t, J = 8.4 Hz, 1H), 4.36–4.28 (m, 1H), 4.05–3.92 (m, 2H), 3.64 (dd, J = 11.2, 3.4 Hz, 1H), 3.54 (dd, J = 11.2, 3.7 Hz, 1H).

[0149] Example 12

[0150] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 1 (10.7 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide E (10 mmol, 1.0 equiv) and carbon dioxide (0.5 MPa). The reactor was placed in an oil bath at 60°C with a stirring rate of 400 rpm for 18 hours. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a colorless oily liquid. After drying to constant weight, the conversion was calculated to be 75% and the selectivity >90% by NMR. The proton NMR spectrum of the product is shown below. Figure 12 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 4.69 (qd, J = 7.5, 5.4 Hz, 1H), 4.55–4.47 (m, 1H), 4.05 (dd, J = 8.4, 7.2 Hz, 1H), 1.78 (dddd, J = 14.0, 10.2, 7.5, 4.8 Hz, 1H), 1.72–1.62 (m, 1H), 1.47–1.27 (m, 4H), 0.99–0.81 (m, 3H).

[0151] Example 13

[0152] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 1 (4.28 mg, 0.01 mmol, 0.001 equiv) was added under inert gas conditions, followed by epoxide F (10 mmol, 1.0 equiv), and carbon dioxide (1 MPa) was introduced. The reactor was placed in an oil bath at 120°C with a stirring rate of 400 rpm for 12 hours. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a colorless oily liquid. After drying to constant weight, the conversion was calculated to be 86% and the selectivity >90% by NMR. The proton NMR spectrum of the product is shown below. Figure 13 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 7.16 (ddd, J = 7.3, 4.1, 2.7 Hz, 2H), 6.93 (td, J = 7.4, 1.0 Hz, 1H), 6.81–6.75 (m, 1H), 5.05 (ddt, J = 8.6, 5.5, 3.3 Hz, 1H), 4.67–4.54 (m, 2H), 4.26 (dd, J = 10.6, 3.6 Hz, 1H), 4.13 (dd, J = 10.6, 3.1 Hz, 1H), 2.22 (s, 3H).

[0153] Example 14

[0154] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 1 (10.7 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide G (10 mmol, 1.0 equiv) and carbon dioxide (0.5 MPa). The reactor was placed in an oil bath at 80°C with a stirring rate of 400 rpm for 12 hours. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a white solid. After drying to constant weight, the conversion was calculated to be 72% and the selectivity >90% by NMR. The proton NMR spectrum of the product is shown below. Figure 14 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 7.38–7.26 (m, 2H), 7.05–6.97 (m, 1H), 6.94–6.87 (m, 2H), 5.07–4.97 (m, 1H), 4.60 (t, J = 8.5 Hz, 1H), 4.52 (dd, J = 8.5, 5.9 Hz, 1H), 4.23 (dd, J = 10.6, 4.0 Hz, 1H), 4.13 (dd, J = 10.7, 3.6 Hz, 1H).

[0155] Example 15

[0156] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 1 (10.7 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide H (10 mmol, 1.0 equiv) and purging with carbon dioxide (0.5 MPa). The reactor was reacted at 120°C for 6 hours in an oil bath with a stirring rate of 400 rpm. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a colorless oily liquid. After drying to constant weight, the conversion was calculated to be 64% and the selectivity >90% by NMR. The proton NMR spectrum of the product is shown below. Figure 15 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 4.79 (ddt, J = 8.4, 6.0, 3.7 Hz, 1H), 4.47 (t, J = 8.4 Hz, 1H), 4.35 (dd, J = 8.3, 6.0 Hz, 1H), 3.62 (dd, J = 11.1, 3.6 Hz, 1H), 3.53 (dd, J = 11.1, 3.8 Hz, 1H), 3.39 (s, 3H).

[0157] Example 16

[0158] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 1 (10.7 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide I (10 mmol, 1.0 equiv) and purging with carbon dioxide (0.5 MPa). The reactor was reacted at 100°C for 6 hours in an oil bath with a stirring rate of 350 rpm. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a colorless oily liquid. After drying to constant weight, the conversion was calculated to be 56% and the selectivity >50% by NMR. The proton NMR spectrum of the product is shown below. Figure 16 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 4.81–4.71 (m, 1H), 4.47 (t, J = 8.2 Hz, 1H), 4.38 (dd, J = 8.3, 5.8 Hz, 1H), 3.61 (dd, J = 10.3, 4.6 Hz, 1H), 3.57–3.51 (m, 1H), 1.19 (s, 9H).

[0159] Example 17

[0160] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 1 (10.7 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide J (10 mmol, 1.0 equiv). The inert gas in the reaction flask was then removed, and carbon dioxide was introduced. This process was repeated three times. A carbon dioxide-filled balloon was inserted, and the reactor was placed in an oil bath at 100°C for 6 hours with a stirring rate of 400 rpm. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a colorless oily liquid. After drying to constant weight, the conversion was calculated to be 36% and the selectivity >40% by NMR. The proton NMR spectrum of the product is shown below. Figure 17 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 6.14 (t, J = 1.1 Hz, 1H), 5.64 (p, J = 1.5 Hz, 1H), 4.97 (ddt, J = 8.7, 5.6, 3.4 Hz, 1H), 4.58 (t, J = 8.6 Hz, 1H), 4.42 (dd, J = 12.6, 3.1 Hz, 1H), 4.36–4.28 (m, 1H), 1.94 (t, J = 1.2 Hz, 3H).

[0161] Example 18

[0162] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 1 (10.7 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide A (10 mmol, 1.0 equiv). The inert gas in the reaction flask was then removed, and carbon dioxide was introduced. This process was repeated three times. A carbon dioxide-filled balloon was inserted, and the reactor was placed in an oil bath at 100°C for 24 hours with a stirring rate of 400 rpm. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a yellow solid, which was dried to constant weight. The conversion was 61%, and the selectivity was >80%. The proton NMR spectrum of the product is shown below. Figure 18 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 7.49–7.40 (m, 3H), 7.40–7.28 (m, 2H), 5.67 (t, J = 8.0 Hz, 1H), 4.79 (t, J = 8.4 Hz, 1H), 4.33 (dd, J = 8.7, 7.8 Hz, 1H).

[0163] Example 19

[0164] The reaction flask was subjected to standard Schlenk procedures to remove water and oxygen from the reaction system. Catalyst No. 1 (10.7 mg, 0.025 mmol, 0.0025 equiv) was added under inert gas conditions, followed by epoxide A (10 mmol, 1.0 equiv). The inert gas in the reaction flask was then removed, and carbon dioxide was introduced. This process was repeated three times. A carbon dioxide-filled balloon was inserted, and the reactor was placed in an oil bath at 120°C for 24 hours with a stirring rate of 500 rpm. After the reaction was complete, the reaction tube was removed and allowed to cool naturally. Column chromatography (petroleum ether: ethyl acetate = 5:1) yielded a mixed solution containing the product. The solution was evaporated to dryness using a rotary evaporator to obtain a yellow solid. After drying to constant weight, the conversion was calculated to be 72% and the selectivity >80% by NMR. The proton NMR spectrum of the product is shown below. Figure 19 As shown (H NMR spectrum, 400 Hz, CDCl3). Spectral data are: δ 7.49–7.40 (m, 3H), 7.40–7.28 (m, 2H), 5.67 (t, J = 8.0 Hz, 1H), 4.79 (t, J = 8.4 Hz, 1H), 4.33 (dd, J = 8.7, 7.8 Hz, 1H).

Claims

1. A method for preparing a cyclic carbonate compound, characterized in that, Using a catalyst shown in Formula I or Formula II, the epoxide shown in Formula III undergoes a cycloaddition reaction with carbon dioxide to obtain cyclic carbonate compounds. R in the catalyst shown in Formula I or Formula II 1 It is independently selected from methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, isopentyl, hexyl, isohexyl, heptyl, isohexyl, octyl, isooctyl, alkenylmethyl, alkenylethyl, allyl or benzyl; R in the epoxide shown in Formula III 2 R 3 Independently selected from hydrogen, C1-C4 straight-chain or branched alkyl groups, halogenated C1-C4 straight-chain or branched alkyl groups, phenyl groups, substituted phenyl groups, or R-type alkyl groups. 4 -O-CH2-; The substituents in the "substituted phenyl" are selected from halogens or C1-C5 straight-chain or branched alkyl groups. The "R" 4 R in "-O-CH2-" 4 It is selected from phenyl, phenyl substituted with C1-C3 straight-chain or branched alkyl, allyl or C1-C4 straight-chain or branched alkyl.

2. The preparation method according to claim 1, characterized in that, The bifunctional catalyst represented by Formula I is selected from compounds numbered 1 to 8, and the bifunctional catalyst represented by Formula II is selected from compounds numbered 9 to 16.

3. The preparation method according to claim 1, characterized in that, The preparation method of the catalyst shown in Formula I is as follows: Step 1: Ascorbic acid, alkylating agent, triphenylphosphine and diethyl azodicarbonate are dissolved in tetrahydrofuran solution and reacted. After the reaction, the alkylated ascorbic acid is obtained by separation. Step 2: Dissolve the alkylated ascorbic acid in a methanol solution to obtain an alkylated ascorbic acid methanol solution; Step 3: Prepare a tetrabutylammonium hydroxide methanol solution and add it to the alkylated ascorbic acid methanol solution to carry out the reaction; Step four: After the reaction is complete, the catalyst is obtained by separation and drying.

4. The preparation method according to claim 1, characterized in that, The preparation method of the catalyst shown in Formula II is as follows: Step 1: Mix ascorbic acid, acetone and acetyl chloride. After the reaction, wash the precipitate with ethyl acetate and then vacuum dry it. Step 2: Mix the product obtained in Step 1, dimethyl sulfoxide, and tetrahydrofuran solution to obtain solution A; Step 3: Dissolve potassium tert-butoxide in a solution of dimethyl sulfoxide and tetrahydrofuran to obtain solution B; Step four: Add solution B to solution A to obtain solution C; Step 5: Add the alkylating agent to solution C to carry out the reaction; Step six: Add hydrochloric acid to solution C. After the reaction is complete, the catalyst is obtained by extraction and purification.

5. The preparation method according to claim 1, characterized in that, The R of the epoxide shown in Formula III 2 For hydrogen, R 3 Independently selected from hydrogen, C1-C4 straight-chain or branched alkyl groups, halogenated C1-C4 straight-chain or branched alkyl groups, phenyl groups, substituted phenyl groups, or R-type alkyl groups. 4 -O-CH2-; or R 3 For hydrogen, R 2 Independently selected from hydrogen, C1-C4 straight-chain or branched alkyl groups, halogenated C1-C4 straight-chain or branched alkyl groups, phenyl groups, substituted phenyl groups, or R-type alkyl groups. 4 -O-CH2-; The substituents in the "substituted phenyl" are selected from halogens or C1-C5 straight-chain or branched alkyl groups. The "R" 4 R in "-O-CH2-" 4 It is selected from phenyl, phenyl substituted with C1-C3 straight-chain or branched alkyl, allyl or C1-C4 straight-chain or branched alkyl.

6. The preparation method according to claim 1, characterized in that, The epoxides represented by Formula III are selected from compounds numbered A to J:

7. The preparation method according to claim 1, characterized in that, Using a catalyst shown in Formula I or Formula II, the epoxide shown in Formula III is reacted with carbon dioxide. The reaction vessel is heated, and after the reaction is completed, cyclic carbonate compounds are separated. Wherein, the catalyst of Formula I is the catalyst shown in number 1, and the epoxide of Formula III is any one of the epoxides numbered A to J; Alternatively, the catalyst of Formula I may be the catalyst shown in numbers 1 to 8, and the epoxide shown in Formula III may be the epoxide shown in number A; Alternatively, the catalyst of Formula II may be the catalyst shown in number 9, and the epoxide shown in Formula III may be the epoxide shown in number A; 8. The preparation method according to claim 7, characterized in that, The reaction is carried out under anhydrous and oxygen-free conditions in an inert gas or nitrogen atmosphere; the molar ratio of the epoxide to the catalyst is 200-1000:1; the reaction temperature is 60-140℃; the reaction time is 6-24h; and the initial reaction pressure is 0.1-1.5MPa.

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