A catalyst for preparing cyclic carbonates and a method for preparing cyclic carbonates using the same

Abstract

The present invention discloses a catalyst for preparing cyclic carbonates and a method for preparing cyclic carbonates therefrom, belonging to the technical field of organic catalytic synthesis. A series of urea-phosphonium salts are used as catalysts, and the urea-phosphonium salts catalyze the cycloaddition reaction of carbon dioxide and epoxides to obtain cyclic carbonates. This method has relatively mild reaction conditions, the reaction system does not contain metals, the synthesis method of the used catalyst is simple, it has good chemical stability and excellent catalytic effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic catalytic synthesis, and particularly relates to a catalyst for preparing cyclic carbonates and a method for preparing cyclic carbonates using the same. Background Art

[0002] Carbon dioxide (CO2) is generally regarded as an industrial waste, but CO2 is also a cheap, abundant and non-toxic C1 source. Therefore, the chemical conversion of CO2 into high-value-added products has become a hot topic in green and sustainable chemistry research. Among these conversions, the atom-economic cycloaddition reaction (CCE) of CO2 and epoxides is the most studied and can be used to produce cyclic organic carbonates. These cyclic organic carbonates can be used as intermediates for fine chemical synthesis, aprotic polar solvents, electrolytes for lithium-ion batteries, monomers for polymerization reactions, etc. However, CO2 is the final product of thermal combustion, and its thermodynamic limitations and kinetic barriers make cycloaddition infeasible without a catalyst. Many catalysts and catalytic systems have been developed for the CCE reaction, including homogeneous and heterogeneous catalysts with or without transition metals. Traditional catalysts usually require high temperature, high pressure and high-purity carbon dioxide, and the carbonate products catalyzed by metal catalysts are prone to metal residues, which limits their applications in the fields of biomedicine and microelectronics. Recently, organic catalysts have attracted increasing attention in this field due to their low energy consumption and environmental friendliness and are regarded as alternatives to metal-based catalysts. Summary of the Invention

[0003] To solve the above problems, the present invention discloses a catalyst for preparing cyclic carbonates, and also provides a method for synthesizing cyclic carbonates from carbon dioxide and epoxides under relatively mild conditions. The catalyst used in this method does not contain metals, is easy to prepare, has good chemical stability and higher catalytic efficiency.

[0004] A series of urea-phosphonium salts are synthesized and applied in the present invention. It contains a bidentate hydrogen bond donor structure and a halogen anion structure and can be used as a bifunctional catalyst for synthesizing cyclic carbonates from epoxides and CO2. The structure of the urea-phosphonium salt is shown in Formula I:

[0005]

[0006] Wherein

[0007] X is selected from Cl, Br or I;

[0008] Y is selected from O or S;

[0009] R 1Selected from straight-chain or branched-chain alkyl groups having 1 to 6 carbon atoms, cyclohexyl, phenyl, poly-substituted or mono-substituted phenyl, and the substituents in the mono-substituted or poly-substituted phenyl are selected from methyl, fluoro, or trifluoromethyl;

[0010] R 2 Selected from H, phenyl, benzyl, isopropyl, and tert-butyl;

[0011] R 3 Selected from straight-chain or branched-chain alkyl groups having 1 to 10 carbon atoms, cyclohexyl, phenyl, mono-substituted or poly-substituted phenyl, or benzyl, and the substituents in the mono-substituted or poly-substituted phenyl or benzyl are selected from methyl, methoxy, fluoro, or trifluoromethyl.

[0012] Preferably, the substituents in the poly-substituted or mono-substituted phenyl in R 1 can be selected from 3,5-bis(trifluoromethyl), 4-trifluoromethyl, or 4-methyl.

[0013] Preferably, R 1 is selected from 3,5-bis(trifluoromethyl)phenyl, 4-trifluoromethylphenyl, 4-methylphenyl, cyclohexyl, or tert-butyl.

[0014] The epoxide is selected from the structure of formula II:

[0015]

[0016] R 4 、R 5 are selected from hydrogen, straight-chain or branched-chain alkyl groups having 1 to 4 carbon atoms, allyl, phenyl, halogen or alkyl-substituted phenyl, chlorine or bromine-substituted alkyl, R 6 -O-CH2-, and the R 6 is selected from phenyl, phenyl substituted with alkyl groups having 1 to 3 carbon atoms, allyl, or straight-chain or branched-chain alkyl groups having 1 to 4 carbon atoms.

[0017] Preferably, R 4 and R 5 are selected from hydrogen, n-butyl, allyl, halomethyl, phenyl, halophenyl, or R 6 -O-CH3, and the R 6 is selected from phenyl, tolyl, allyl, tert-butyl, or methyl.

[0018] Preferably, Y is selected as O, R 1 is selected from 3,5-bis(trifluoromethyl)phenyl, 4-trifluoromethylphenyl, 4-methylphenyl, cyclohexyl, and tert-butyl, R 2 is selected from H, R 3 is selected as benzyl, that is, the urea-phosphonium salt described in formula I is preferably selected from the following structures:

[0019]

[0020] A method for preparing a cyclic carbonate, in the presence of an initiator, using a urea-phosphonium salt catalyst to catalyze the cycloaddition reaction of carbon dioxide and an epoxide, wherein the urea-phosphonium salt catalyst is the catalyst shown in Formula I as described above, and the epoxide is selected from the structure of Formula II:

[0021]

[0022] R 4 and R 5 are each independently selected from hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, an allyl group, a phenyl group, a halogen or an alkyl-substituted phenyl group, a chlorine- or bromine-substituted alkyl group, R 6 -O-CH2-, and the R 6 is selected from a phenyl group, a phenyl group substituted with an alkyl group having 1 to 3 carbon atoms, an allyl group or a straight-chain or branched alkyl group having 1 to 4 carbon atoms.

[0023] Preferably, the epoxide of Formula II is selected from 3-chloro-1,2-epoxypropane, 3-bromo-1,2-epoxypropane, 1,2-epoxyhexane, 1,2-epoxy-5-hexene, 4-chlorostyrene epoxide, 2-phenyloxirane, 2-(methoxymethyl)oxirane, 2-(tert-butoxymethyl)oxirane, 1-allyloxy-2,3-epoxypropane, 1,2-epoxy-3-phenoxypropane and 2-[(2-methylphenoxy)methyl]oxirane, that is, the structure of the epoxide of Formula II is as follows:

[0024]

[0025] Preferably, the reaction temperature of the preparation method is 20 to 140 °C, the initial pressure of carbon dioxide is 0.1 to 2 MPa, and the molar ratio of the catalyst to the epoxide is 1:1000 to 1:20.

[0026] Particularly preferably, the reaction temperature of the preparation method is 100 °C or 120 °C, the initial pressure of carbon dioxide is 0.1 MPa, and the molar ratio of the catalyst to the epoxide is 1:1000 to 1:50.

[0027] Preferably, the specific steps of the preparation method include:

[0028] (1) Adding the urea-phosphonium salt catalyst shown in Formula I and the epoxide shown in Formula II into a reaction vessel, and replacing the air in the reaction vessel with carbon dioxide. The molar ratio of the urea-phosphonium salt catalyst shown in Formula I to the epoxide shown in Formula II is 1:100;

[0029] (2) Charge the reaction vessel with CO2 to an initial pressure of 0.1 MPa and heat it to 100 °C or 120 °C;

[0030] (3) React for 1 - 12 h, cool, and obtain the cyclic carbonate by column chromatography of the reaction solution.

[0031] Preferably, the preparation method of the catalyst comprises the following steps:

[0032] A. Add 2 - bis(diphenylphosphino)ethylamine to a dichloromethane solution of isothiocyanate R1NCO, react at room temperature for 8 - 12 h, add an appropriate amount of n - hexane to the reaction solution, filter the reaction solution, wash the filter residue with n - hexane in small portions multiple times, and vacuum - dry the product for 48 h;

[0033] B. Under N2 protection, add an appropriate amount of toluene to the product obtained in step A, heat to dissolve, then add benzyl chloride / bromide / iodide, reflux at 110 °C for 8 h, and filter or column - purify the reaction solution to obtain the urea - phosphonium salt catalyst;

[0034] The urea - phosphonium salt catalyst described in the present invention can be used as a bifunctional catalyst. Among them, the bidentate hydrogen - bond donor of the urea structure can form a hydrogen bond with the oxygen on the epoxide, activating the epoxide. The halogen anion attacks the carbon - oxygen bond as a nucleophile, causing the epoxide to ring - open. The urea - phosphonium salt stabilizes / activates the terminal oxygen anion formed by the ring - opening of the epoxide. The oxygen anion attacks carbon dioxide as a nucleophile to form a carbonate anion intermediate. The carbonate anion intermediate undergoes an intramolecular nucleophilic attack to form a cyclic carbonate ring, and at the same time, the catalyst is released.

[0035] Beneficial effects

[0036] (1) The synthesis method of the catalyst used in the present invention is simple and the raw materials are easily available.

[0037] (2) The present invention provides a method for synthesizing cyclic carbonates from carbon dioxide and epoxides under relatively mild conditions.

[0038] (3) The catalyst used in the present invention does not contain metals, and the obtained product has no metal residue, showing great application prospects in fields such as biomedicine and microelectronics.

[0039] (4) The reaction process does not require the use of solvents, avoiding the toxicity of organic solvents; the catalyst loading used in the present invention is small, which is beneficial to cost savings.

[0040] (5) The catalyst used in the present invention is a bifunctional catalyst, and the catalyst structure has a wide range of tunability, making the system flexible and variable.

[0041] In summary, compared with the existing catalytic systems, the present invention has obvious advantages such as simplicity, mildness, high efficiency, metal-free, solvent-free, and system flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 : 1H NMR spectrum of catalyst 1 obtained in Example 1

[0043] Figure 2 : 1H NMR spectrum of catalyst 2 obtained in Example 2

[0044] Figure 3 : 1H NMR spectrum of catalyst 3 obtained in Example 3

[0045] Figure 4 : 1H NMR spectrum of catalyst 6 obtained in Example 4

[0046] Figure 5 : 1H NMR spectrum of catalyst 9 obtained in Example 5

[0047] Figure 6 : 1H NMR spectrum of catalyst 12 obtained in Example 6

[0048] Figure 7 : 1H NMR spectrum of catalyst 15 obtained in Example 7

[0049] Figure 8 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 15

[0050] Figure 9 : 13C NMR spectrum of the cyclic carbonate product obtained in Example 15

[0051] Figure 10 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 21

[0052] Figure 11 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 22

[0053] Figure 12 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 23

[0054] Figure 13 : 13C NMR spectrum of the cyclic carbonate product obtained in Example 23

[0055] Figure 14 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 24

[0056] Figure 15 : 13C NMR spectrum of the cyclic carbonate product obtained in Example 24

[0057] Figure 16 : 1H NMR spectrum of the cyclic carbonate product obtained in Example 25

[0058] Figure 17 : Carbon spectrum of the cyclic carbonate product obtained in Example 25

[0059] Figure 18 : Proton spectrum of the cyclic carbonate product obtained in Example 26

[0060] Figure 19 : Proton spectrum of the cyclic carbonate product obtained in Example 27

[0061] Figure 20 : Proton spectrum of the cyclic carbonate product obtained in Example 28

[0062] Figure 21 : Carbon spectrum of the cyclic carbonate product obtained in Example 28

[0063] Figure 22 : Proton spectrum of the cyclic carbonate product obtained in Example 29

[0064] Figure 23 : Proton spectrum of the cyclic carbonate product obtained in Example 30 Detailed implementation manners

[0065] The present invention can be further illustrated by the following examples, which are for illustration purposes only and not intended to limit the present invention. Any ordinary technician in the art can understand that these examples do not limit the present invention in any way, and appropriate modifications and data transformations can be made without departing from the essence and scope of the present invention.

[0066] The nuclear magnetic resonance proton spectrum involved in the examples was measured using a Bruker Ascend TM-400 nuclear magnetic resonance proton spectrometer from Bruker Corporation. The deuterated reagents used were deuterated chloroform (CDCl3) and deuterated dimethyl sulfoxide (DMSO-d6).

[0067] The structure of the catalyst used in the examples is as follows:

[0068]

[0069] The structure of the epoxide used in the examples is as follows:

[0070]

[0071] Example 1:

[0072] Preparation of Catalyst 1: In a reaction flask, 2.3 g (10 mmol) of 2-(diphenylphosphino)ethylamine was dissolved in 20 ml of dichloromethane, and then 1.8 ml (10 mmol) of 3,5-bis(trifluoromethyl)phenyl isocyanate was added dropwise thereto. The reaction was carried out at room temperature for 8 h. 40 ml of n-hexane was added to the reaction solution, and the mixture was filtered. The filter cake was washed with a small amount of n-hexane several times and then dried in a vacuum drying oven for 24 h to obtain a white solid. Under N2 purge, the filter cake was added to a water- and oxygen-free reaction flask. After dissolving it by heating with 10 ml of toluene, 1.2 ml of benzyl chloride (10 mmol) was added thereto, and the mixture was heated under reflux at 110 °C for 8 h. The solvent in the system was removed under reduced pressure, and the obtained mixture was subjected to column purification (dichloromethane / methanol = 80 / 1). The product was dried to obtain an off-white waxy solid with a yield of 81%. The 1H NMR spectrum of the product is as shown in Figure 1 shown below. 1 H NMR (400 MHz, Chloroform-d) δ 9.71 (s, 1H), 8.01 (t, J = 5.9 Hz, 1H), 7.89 (s, 2H), 7.74 (dd, J = 12.4, 7.7 Hz, 4H), 7.65 (dt, J = 7.9, 4.2 Hz, 2H), 7.55 (td, J = 7.7, 3.3 Hz, 4H), 7.35 (s, 1H), 7.15 (td, J = 7.4, 2.2 Hz, 1H), 7.05 (t, J = 7.6 Hz, 2H), 6.91 (dd, J = 7.6, 2.5 Hz, 2H), 4.74 (d, J = 14.6 Hz, 2H), 3.57 (dd, J = 15.8, 6.4 Hz, 2H), 3.21 (dt, J = 12.8, 6.5 Hz, 2H).

[0073] Example 2:

[0074] Preparation of Catalyst 2: In a reaction flask, 2.3 g (10 mmol) of 2-(diphenylphosphino)ethylamine was dissolved in 20 ml of dichloromethane, and then 1.8 ml (10 mmol) of 3,5-bis(trifluoromethyl)phenyl isocyanate was added dropwise thereto. The reaction was carried out at room temperature for 8 h. 40 ml of n-hexane was added to the reaction solution, and the mixture was filtered. The filter cake was washed with a small amount of n-hexane several times and then dried in a vacuum drying oven for 24 h to obtain a white solid. Under N2 purge, the filter cake was added to a water- and oxygen-free reaction flask. After dissolving it by heating with 10 ml of toluene, 1.2 ml of benzyl bromide (10 mmol) was added thereto, and the mixture was heated under reflux at 110 °C for 8 h. The solvent in the system was removed under reduced pressure, and the obtained mixture was subjected to column purification (dichloromethane / methanol = 60 / 1). The product was dried to obtain a light yellow waxy solid with a yield of 87%. The 1H NMR spectrum of the product is as shown in Figure 2 shown below. 11H NMR (400 MHz, Chloroform-d) δ 9.34 (s, 1H), 7.87 (s, 2H), 7.7–7.61 (m, 7H), 7.54 (td, J = 7.7, 3.3 Hz, 4H), 7.35 (s, 1H), 7.15 (td, J = 7.4, 2.2 Hz, 1H), 7.04 (t, J = 7.6 Hz, 2H), 6.91 (dd, J = 7.6, 2.5 Hz, 2H), 4.72 (d, J = 14.6 Hz, 2H), 3.57 (dt, J = 16.4, 6.2 Hz, 2H), 3.20 (dt, J = 12.7, 6.5 Hz, 2H).

[0075] Example 3:

[0076] Preparation of catalyst 3: In a reaction flask, 2.3 g (10 mmol) of 2-(diphenylphosphino)ethylamine was dissolved in 20 ml of dichloromethane, and then 1.8 ml (10 mmol) of 3,5-bis(trifluoromethyl)phenyl isocyanate was added dropwise thereto. The reaction was carried out at room temperature for 8 h. 40 ml of n-hexane was added to the reaction solution, and the mixture was filtered. The filter cake was washed with a small amount of n-hexane several times and dried in a vacuum drying oven for 24 h to obtain a white solid. Under N2 purge, the filter cake was added to a reaction flask that had been dehydrated and deoxygenated. After heating and dissolving in 10 ml of toluene, 1.3 ml of benzyl iodide (10 mmol) was added thereto, and the mixture was heated under reflux at 110 °C for 8 h. The solvent in the system was removed under reduced pressure, and the resulting mixture was column-purified (dichloromethane / methanol = 40 / 1). The product was dried to obtain a yellow waxy solid with a yield of 88%. The 1H NMR spectrum of the product is as Figure 3 shown. 1 1H NMR (400 MHz, Chloroform-d) δ 8.78 (s, 1H), 7.87 (s, 2H), 7.75–7.64 (m, 6H), 7.57 (td, J = 7.7, 3.4 Hz, 4H), 7.39 (s, 1H), 7.32 (t, J = 5.8 Hz, 1H), 7.20 (td, J = 7.4, 2.2 Hz, 1H), 7.10 (t, J = 7.6 Hz, 2H), 6.93 (dd, J = 7.6, 2.5 Hz, 2H), 4.65 (d, J = 14.4 Hz, 2H), 3.63 (dq, J = 18.0, 6.2 Hz, 2H), 3.20 (dt, J = 12.5, 6.4 Hz, 2H).

[0077] Example 4:

[0078] Preparation of Catalyst 6: In a reaction flask, 2.3 g (10 mmol) of 2-(diphenylphosphino)ethylamine was dissolved in 20 ml of dichloromethane, and then 1.5 ml (10 mmol) of 4-trifluoromethylphenyl isocyanate was added dropwise thereto. The reaction was carried out at room temperature for 8 h. 80 ml of n-hexane was added to the reaction system, and a solid precipitated. The mixture was filtered, and the filter cake was washed with a small amount of n-hexane several times. The filter cake was placed in a vacuum drying oven and dried for 24 h to obtain an off-white solid. Under N2 purge, the filter cake was added to a reaction flask that had been dehydrated and deoxygenated. After adding 10 ml of toluene and heating to dissolve, 1.3 ml (10 mmol) of benzyl iodide was added thereto, and the mixture was heated under reflux at 110 °C for 8 h. The reaction solution was filtered, and the filter cake was washed with a small amount of acetone several times. The filter cake was dried to obtain a yellow solid with a yield of 85%. The 1H NMR spectrum of the product is as shown in Figure 4 shown below. 1 H NMR(400MHz,Chloroform-d)δ8.58(s,1H),7.78–7.63(m,6H),7.54(ddd,J=19.8,9.9,6.0Hz,6H),7.39(d,J=8.5Hz,2H),7.24–7.14(m,2H),7.08(t,J=7.6Hz,2H),6.92(dd,J=7.7,2.5Hz,2H),4.65(d,J=14.5Hz,2H),3.57(dq,J=17.7,6.3Hz,2H),3.17(dt,J=12.4,6.3Hz,2H).

[0079] Example 5:

[0080] Preparation of Catalyst 9: In a reaction flask, 2.3 g (10 mmol) of 2-(diphenylphosphino)ethylamine was dissolved in 20 ml of dichloromethane, and then 1.3 ml (10 mmol) of 4-methylphenyl isocyanate was added dropwise thereto. The reaction was carried out at room temperature for 8 h. 80 ml of n-hexane was added to the reaction system, and a solid precipitated. The mixture was filtered, and the filter cake was washed with a small amount of n-hexane several times. The filter cake was placed in a vacuum drying oven and dried for 24 h to obtain a white solid. Under N2 purge, the filter cake was added to a reaction flask that had been dehydrated and deoxygenated. After adding 10 ml of toluene and heating to dissolve, 1.3 ml (10 mmol) of benzyl iodide was added thereto, and the mixture was heated under reflux at 110 °C for 8 h. The reaction solution was filtered, and the filter cake was washed with a small amount of acetone several times. The filter cake was dried to obtain a yellow solid with a yield of 91%. The 1H NMR spectrum of the product is as shown in Figure 5 shown below. 11H NMR (400 MHz, Chloroform-d) δ 7.94 (s, 1H), 7.80–7.66 (m, 6H), 7.59 (td, J = 7.8, 3.4 Hz, 4H), 7.28 (s, 1H), 7.26 (d, J = 2.0 Hz, 1H), 7.20 (td, J = 7.3, 2.1 Hz, 1H), 7.11 (t, J = 7.6 Hz, 3H), 7.00 (d, J = 8.2 Hz, 2H), 6.93 (dd, J = 7.7, 2.4 Hz, 2H), 4.65 (d, J = 14.4 Hz, 2H), 3.58 (dq, J = 18.3, 6.1 Hz, 2H), 3.18 (dt, J = 12.3, 6.2 Hz, 2H), 2.26 (s, 3H).

[0081] Example 6:

[0082] Preparation of Catalyst 12: In a reaction flask, 2.3 g (10 mmol) of 2-(diphenylphosphino)ethylamine was dissolved in 20 ml of dichloromethane, and then 1.3 ml (10 mmol) of cyclohexyl isocyanate was added dropwise thereto. The reaction was carried out at room temperature for 12 h. 80 ml of n-hexane was added to the reaction system, and a solid precipitated. The mixture was filtered, and the filter cake was washed with n-hexane in small portions several times. The filter cake was placed in a vacuum drying oven and dried for 24 h to obtain a pale yellow solid. Under N2 purge, the filter cake was added to a reaction flask that had been dehydrated and deoxygenated. After adding 10 ml of toluene and heating to dissolve it, 1.3 ml of benzyl iodide (10 mmol) was added thereto, and the mixture was heated under reflux at 110 °C for 8 h. The reaction solution was filtered, and the filter cake was washed with acetone in small portions several times. The filter cake was dried to obtain a yellow solid with a yield of 83%. The 1H NMR spectrum of the product is as Figure 6 shown. 1 1H NMR (400 MHz, DMSO-d6) δ 7.99–7.59 (m, 10H), 7.29–7.19 (m, 3H), 6.99 (dd, J = 7.2, 2.4 Hz, 2H), 6.21–5.91 (m, 2H), 4.70 (d, J = 15.9 Hz, 2H), 3.33–3.18 (m, 3H), 3.06 (dt, J = 13.8, 7.4 Hz, 2H), 1.64 (ddt, J = 24.4, 12.4, 3.8 Hz, 4H), 1.50 (dt, J = 12.4, 3.9 Hz, 1H), 1.30–0.97 (m, 5H).

[0083] Example 7:

[0084] Preparation of Catalyst 15: In a reaction flask, 2.3 g (10 mmol) of 2-(diphenylphosphino)ethylamine was dissolved in 20 ml of dichloromethane, and then 1.2 ml (10 mmol) of tert-butyl isocyanate was added dropwise thereto. The reaction was carried out at room temperature for 12 h. 80 ml of n-hexane was added to the reaction system, and a solid precipitated. The mixture was filtered, and the filter cake was washed with a small amount of n-hexane several times. The filter cake was placed in a vacuum drying oven and dried for 24 h to obtain a pale yellow solid. Under N2 purge, the filter cake was added to a reaction flask that had been dehydrated and deoxygenated. After heating and dissolving in 10 ml of toluene, 1.3 ml of benzyl iodide (10 mmol) was added thereto, and the mixture was heated under reflux at 110 °C for 8 h. The reaction solution was filtered, and the filter cake was washed with a small amount of acetone several times. The filter cake was dried to obtain a yellow solid with a yield of 84%. The 1H NMR spectrum of the product is as shown in Figure 7 shown below. 1 H NMR(400MHz,Chloroform-d)δ7.77–7.60(m,10H),7.21(td,J=7.8,7.3,4.4Hz,1H),7.14(q,J=7.5,6.2Hz,2H),6.97–6.88(m,2H),6.51(s,1H),5.62(s,1H),4.58(d,J=14.5Hz,2H),3.45(dd,J=19.5,6.0Hz,2H),3.09(dd,J=12.0,6.0Hz,2H),1.28(s,9H).

[0085] Example 8:

[0086] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 30.6 mg (0.05 mmol) of Catalyst 1 was added thereto, followed by 0.6 ml (5 mmol) of Compound 21. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. The reaction flask was placed in an oil bath at 120 °C and reacted for 6 h. After the reaction was completed, it was cooled, and column purification was carried out (petroleum ether:ethyl acetate = 10:1). The product was dried to obtain a pale yellow oily liquid with a conversion rate of 33%.

[0087] Example 9:

[0088] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 32.8 mg (0.05 mmol) of Catalyst 2 was added thereto, followed by 0.6 ml (5 mmol) of Compound 21. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. The reaction flask was placed in an oil bath at 120 °C and reacted for 6 h. After the reaction was completed, it was cooled, and column purification was carried out (petroleum ether:ethyl acetate = 10:1). The product was dried to obtain a pale yellow oily liquid with a conversion rate of 81%.

[0089] Example 10:

[0090] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 35.1 mg (0.05 mmol) of catalyst 3 was added thereto, then 0.6 ml (5 mmol) of compound 21 was added. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 120 °C and reacted for 6 h. After the reaction was completed, it was cooled, column purified (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid, conversion rate: 95%.

[0091] Example 11:

[0092] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 31.7 mg (0.05 mmol) of catalyst 6 was added thereto, then 0.6 ml (5 mmol) of compound 21 was added. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 120 °C and reacted for 6 h. After the reaction was completed, it was cooled, column purified (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid, conversion rate: 91%.

[0093] Example 12:

[0094] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 29.0 mg (0.05 mmol) of catalyst 9 was added thereto, then 0.6 ml (5 mmol) of compound 21 was added. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 120 °C and reacted for 6 h. After the reaction was completed, it was cooled, column purified (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid, conversion rate: 79%.

[0095] Example 13:

[0096] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 28.6 mg (0.05 mmol) of catalyst 12 was added thereto, then 0.6 ml (5 mmol) of compound 21 was added. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 120 °C and reacted for 6 h. After the reaction was completed, it was cooled, column purified (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid, conversion rate: 63%.

[0097] Example 14:

[0098] The reaction flask was dehydrated and deoxygenated. Under N2 purging, 27.3 mg (0.05 mmol) of catalyst 15 was added thereto, then 0.6 ml (5 mmol) of compound 21 was added. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 120 °C and reacted for 6 h. After the reaction was completed, it was cooled, column purified (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid. Conversion rate: 86%.

[0099] Example 15:

[0100] The reaction flask was dehydrated and deoxygenated. Under N2 purging, 35.1 mg (0.05 mmol) of catalyst 1 was added thereto, then 0.6 ml (5 mmol) of compound 21 was added. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 100 °C and reacted for 4 h. After the reaction was completed, it was cooled, column purified (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid. Conversion rate: 83%. The 1H NMR spectrum of the product is as Figure 8 shown, and the 13C NMR spectrum is as Figure 9 shown. 1 H NMR(400MHz,Chloroform-d)δ7.52–7.31(m,5H),5.67(t,J=8.0Hz,1H),4.80(t,J=8.4Hz,1H),4.33(dd,J=8.6,7.9Hz,1H). 13 CNMR(101MHz,Chloroform-d)δ154.97,135.87,129.78,129.28,125.97,78.08,71.2.

[0101] Example 16:

[0102] The reaction flask was dehydrated and deoxygenated. Under N2 purging, 35.1 mg (0.05 mmol) of catalyst 1 was added thereto, then 0.6 ml (5 mmol) of compound 21 was added. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 80 °C and reacted for 4 h. After the reaction was completed, it was cooled, column purified (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid. Conversion rate: 62%.

[0103] Example 17:

[0104] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 70.2 mg (0.1 mmol) of catalyst 1 was added thereto, followed by 0.6 ml (5 mmol) of compound 21. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 100 °C and reacted for 4 h. After the reaction was completed, it was cooled, purified by column (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid, conversion rate: 96%.

[0105] Example 18:

[0106] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 17.6 mg (0.025 mmol) of catalyst 1 was added thereto, followed by 0.6 ml (5 mmol) of compound 21. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 100 °C and reacted for 4 h. After the reaction was completed, it was cooled, purified by column (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid, conversion rate: 67%.

[0107] Example 19:

[0108] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 10.5 mg (0.015 mmol) of catalyst 1 was added thereto, followed by 0.6 ml (5 mmol) of compound 21. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 100 °C and reacted for 4 h. After the reaction was completed, it was cooled, purified by column (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid, conversion rate: 31%.

[0109] Example 20:

[0110] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 3.5 mg (0.005 mmol) of catalyst 1 was added thereto, followed by 0.6 ml (5 mmol) of compound 21. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 100 °C and reacted for 4 h. After the reaction was completed, it was cooled, purified by column (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid, conversion rate: 9%.

[0111] Example 21:

[0112] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 35.1 mg (0.05 mmol) of catalyst 1 was added thereto, then 0.4 ml (5 mmol) of compound 16 was added. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 100 °C and reacted for 4 h. After the reaction was completed, it was cooled, column purified (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid. Conversion rate: 90%. The 1H NMR spectrum of the product is as shown in Figure 10 shown. 1 1H NMR (400 MHz, Chloroform-d) δ 4.97 (s, 1H), 4.58 (s, 1H), 4.41 (d, J = 5.7 Hz, 1H), 3.75 (dd, J = 14.6, 4.6 Hz, 2H).

[0113] Example 22:

[0114] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 35.1 mg (0.05 mmol) of catalyst 1 was added thereto, then 0.42 ml (5 mmol) of compound 17 was added. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 100 °C and reacted for 4 h. After the reaction was completed, it was cooled, column purified (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid. Conversion rate: 93%. The 1H NMR spectrum of the product is as shown in Figure 11 shown. 1 1H NMR (400 MHz, Chloroform-d) δ 4.94 (d, J = 4.0 Hz, 1H), 4.58 (s, 1H), 4.34 (d, J = 5.9 Hz, 1H), 3.58 (d, J = 1.2 Hz, 2H).

[0115] Example 23:

[0116] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 35.1 mg (0.05 mmol) of catalyst 1 was added thereto, then 0.6 ml (5 mmol) of compound 18 was added. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 100 °C and reacted for 4 h. After the reaction was completed, it was cooled, column purified (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid. Conversion rate: 93%. The 1H NMR spectrum of the product is as shown in Figure 12 shown, and the 13C NMR spectrum is as shown in Figure 13 shown. 11H NMR (400 MHz, Chloroform-d) δ 4.68 (qd, J = 7.5, 5.4 Hz, 1H), 4.51 (t, J = 8.1 Hz, 1H), 4.04 (dd, J = 8.4, 7.2 Hz, 1H), 1.78 (dddd, J = 14.0, 10.2, 7.4, 4.8 Hz, 1H), 1.71–1.61 (m, 1H), 1.47–1.28 (m, 4H), 0.90 (t, J = 6.9 Hz, 3H). 13 13C NMR (101 MHz, Chloroform-d) δ 155.22, 77.16, 69.48, 33.56, 26.46, 22.27, 13.82.

[0117] Example 24:

[0118] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 35.1 mg (0.05 mmol) of Catalyst 1 was added thereto, and then 0.56 ml (5 mmol) of Compound 19 was added. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. The reaction flask was placed in an oil bath at 100 °C and reacted for 4 h. After the reaction was completed, it was cooled, purified by column chromatography (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid. Conversion rate: 96%. The 1H NMR spectrum of the product is as shown in Figure 14 shown, and the 13C NMR spectrum is as shown in Figure 15 shown. 1 1H NMR (400 MHz, Chloroform-d) δ 5.77 (ddt, J = 17.0, 10.2, 6.7 Hz, 1H), 5.11–4.99 (m, 2H), 4.71 (qd, J = 7.7, 5.1 Hz, 1H), 4.51 (t, J = 8.2 Hz, 1H), 4.07 (dd, J = 8.5, 7.2 Hz, 1H), 2.29–2.12 (m, 2H), 1.91 (dtd, J = 14.1, 8.1, 5.9 Hz, 1H), 1.76 (dddd, J = 14.0, 8.7, 7.0, 5.1 Hz, 1H). 13 13C NMR (101 MHz, Chloroform-d) δ 155.08, 136.18, 116.45, 76.43, 69.41, 33.08, 28.70.

[0119] Example 25:

[0120] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 35.1 mg (0.05 mmol) of catalyst 1 was added thereto, followed by 0.6 ml (5 mmol) of compound 20. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. The reaction flask was placed in an oil bath at 100 °C and reacted for 8 h. After the reaction was completed, it was cooled, purified by column chromatography (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid with a conversion rate of 93%. The 1H NMR spectrum of the product is as shown in Figure 16 shown, and the 13C NMR spectrum is as shown in Figure 17 shown. 1 1H NMR (400 MHz, Chloroform-d) δ 7.45–7.36 (m, 2H), 7.32–7.28 (m, 2H), 5.66 (t, J = 8.0 Hz, 1H), 4.80 (t, J = 8.4 Hz, 1H), 4.29 (dd, J = 8.7, 7.8 Hz, 1H). 13 13C NMR (101 MHz, Chloroform-d) δ 154.70, 135.76, 134.38, 129.53, 127.41, 77.34, 71.08.

[0121] Example 26:

[0122] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 35.1 mg (0.05 mmol) of catalyst 1 was added thereto, followed by 0.45 ml (5 mmol) of compound 22. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. The reaction flask was placed in an oil bath at 100 °C and reacted for 4 h. After the reaction was completed, it was cooled, purified by column chromatography (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid with a conversion rate of 94%. The 1H NMR spectrum of the product is as shown in Figure 18 shown. 1 1H NMR (400 MHz, Chloroform-d) δ 4.80 (d, J = 2.3 Hz, 1H), 4.49 (s, 1H), 4.38 (d, J = 6.1 Hz, 1H), 3.62 (d, J = 3.8 Hz, 1H), 3.57 (d, J = 3.8 Hz, 1H), 3.42 (s, 3H).

[0123] Example 27:

[0124] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 35.1 mg (0.05 mmol) of catalyst 1 was added thereto, then 0.71 ml (5 mmol) of compound 23 was added. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 100 °C and reacted for 4 h. After the reaction was completed, it was cooled, purified by column (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid. Conversion rate: 94%. The 1H NMR spectrum of the product is as shown in Figure 19 shown. 1 1H NMR (400 MHz, Chloroform-d) δ 4.74 (ddt, J = 7.9, 5.8, 3.8 Hz, 1H), 4.43 (t, J = 8.3 Hz, 1H), 4.32 (dd, J = 8.3, 5.8 Hz, 1H), 3.57 (dd, J = 10.5, 4.1 Hz, 1H), 3.46 (dd, J = 10.5, 3.5 Hz, 1H), 1.13 (s, 9H).

[0125] Example 28:

[0126] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 35.1 mg (0.05 mmol) of catalyst 1 was added thereto, then 0.6 ml (5 mmol) of compound 24 was added. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 100 °C and reacted for 10 h. After the reaction was completed, it was cooled, purified by column (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid. Conversion rate: 90%. The 1H NMR spectrum of the product is as shown in Figure 20 shown, and the 13C NMR spectrum is as shown in Figure 21 shown. 1 1H NMR (400 MHz, Chloroform-d) δ 5.88 (ddt, J = 17.4, 10.8, 5.6 Hz, 1H), 5.37–5.19 (m, 2H), 4.83 (ddt, J = 8.0, 6.0, 3.9 Hz, 1H), 4.51 (t, J = 8.4 Hz, 1H), 4.41 (dd, J = 8.4, 6.0 Hz, 1H), 4.12–4.02 (m, 2H), 3.70 (dd, J = 11.0, 4.0 Hz, 1H), 3.63 (dd, J = 11.0, 3.8 Hz, 1H). 13 13C NMR (101 MHz, Chloroform-d) δ 155.06, 133.77, 118.11, 75.12, 72.73, 68.95, 66.40.

[0127] Example 29:

[0128] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 35.1 mg (0.05 mmol) of catalyst 1 was added thereto, followed by 0.68 ml (5 mmol) of compound 25. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 100 °C and reacted for 6 h. After the reaction was completed, it was cooled, purified by column (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid. Conversion rate: 92%. The 1H NMR spectrum of the product is as Figure 22 shown. 1 H NMR (400 MHz, Chloroform-d) δ 7.31 (s, 2H), 7.01 (s, 1H), 6.98–6.87 (m, 2H), 5.03 (dd, J = 5.1, 3.3 Hz, 1H), 4.61 (s, 1H), 4.53 (dd, J = 8.5, 5.9 Hz, 1H), 4.23 (s, 1H), 4.15 (d, J = 3.5 Hz, 1H).

[0129] Example 30:

[0130] The reaction flask was dehydrated and deoxygenated. Under N2 purge, 35.1 mg (0.05 mmol) of catalyst 1 was added thereto, followed by 0.76 ml (5 mmol) of compound 26. The gas in the reaction flask was replaced with carbon dioxide three times, and then a balloon filled with carbon dioxide was inserted to provide the carbon dioxide required for the reaction. It was placed in an oil bath at 100 °C and reacted for 6 h. After the reaction was completed, it was cooled, purified by column (petroleum ether:ethyl acetate = 10:1), and the product was dried to obtain a pale yellow oily liquid. Conversion rate: 93%. The 1H NMR spectrum of the product is as Figure 23 shown. 1 H NMR (400 MHz, Chloroform-d) δ 7.16 (s, 2H), 6.93 (d, J = 1.1 Hz, 1H), 6.79 (s, 1H), 5.05 (d, J = 3.1 Hz, 1H), 4.62 (s, 2H), 4.24 (d, J = 3.5 Hz, 1H), 4.14 (d, J = 3.0 Hz, 1H), 2.22 (s, 3H).

Claims

1. A catalyst for preparing cyclic carbonates, characterized in that, The catalyst used is a urea-phosphonium salt catalyst, and the urea-phosphonium salt catalyst is selected from the following structures:

2. A method for preparing a cyclic carbonate, characterized in that, In the presence of an initiator, a urea-phosphonium salt catalyst is used to catalyze the cycloaddition reaction of carbon dioxide and an epoxide. The urea-phosphonium salt catalyst is the catalyst described in claim 1, and the epoxide is selected from the structure of formula II: R 4 , R 5 is selected from hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, allyl, phenyl, a phenyl group substituted by an alkyl group, an alkyl group substituted by chlorine or bromine, R 6 -O-CH2-, and the R 6 is selected from phenyl, a phenyl group substituted by an alkyl group having 1 to 3 carbon atoms, allyl, or a branched or linear alkyl group having 1 to 4 carbon atoms.

3. The method according to claim 2, characterized in that, The described R 4 and R 5 are selected from hydrogen, n-butyl, allyl, halomethyl, phenyl, halophenyl or R 6 -O-CH3, and the described R 6 is selected from phenyl, tolyl, allyl, tert-butyl or methyl.

4. The method according to claim 2, characterized in that, The structure of the epoxide of formula II is as follows:

5. The method according to claim 2, characterized in that The reaction temperature of the method is 20-140 °C, the initial pressure of carbon dioxide is 0.1-2 MPa, and the molar ratio of the catalyst to the epoxide is 1:1000-1:

20.

6. The method according to claim 5, characterized in that, The reaction temperature of the method is 100 °C or 120 °C, the initial pressure of carbon dioxide is 0.1 MPa, and the molar ratio of the catalyst to the epoxide is 1:1000-1:

50.

7. The method according to claim 2, wherein The specific steps of the method include: (1) Add the urea-phosphonium salt catalyst shown in formula I and the epoxide shown in formula II to a reaction vessel, and displace the air in the reaction vessel with carbon dioxide. The molar ratio of the urea-phosphonium salt catalyst shown in formula I to the epoxide shown in formula II is 1:100; (2) Charge CO2 into the reaction vessel to an initial pressure of 0.1 MPa and heat to 100 °C or 120 °C; (3) React for 1-12 h, cool, and obtain the cyclic carbonate from the reaction solution by column chromatography.

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