A tetradentate nitrogen ligand zinc complex, a preparation method and application thereof, and a preparation method of cyclic carbonate

Abstract

The application provides a tetradentate nitrogen ligand zinc complex and a preparation method and application thereof, and a preparation method of a cyclic carbonate, and relates to the technical field of organic catalytic synthesis.The tetradentate nitrogen ligand zinc complex provided by the application has the structure shown in formula I.The tetradentate nitrogen ligand zinc complex provided by the application is inexpensive, can be used as a catalyst to catalyze the efficient synthesis of a cyclic carbonate from an epoxide compound and carbon dioxide, and can overcome the defects of the prior art, such as high cost and large amount of catalysts, use of toxic organic solvents, difficulty in separation of products and catalysts, harsh reaction conditions and the like.

Description

Technical Field

[0001] This invention relates to the field of organic catalytic synthesis technology, specifically to a tetradentate nitrogen ligand zinc complex, its preparation method and application, and a method for preparing cyclic carbonates. Background Technology

[0002] Since the Industrial Revolution, the overexploitation of fossil fuels has caused global energy and environmental problems. The massive emission of carbon dioxide directly threatens the ecological environment upon which humanity depends for survival. Converting carbon dioxide into useful chemicals and materials is considered one of the most important ways to reduce carbon emissions and control environmental pollution. Currently, there are two main measures to address CO2 emission-related issues: CO2 reservoirs and CO2 resource utilization. In the past few decades, converting CO2 into high-value-added chemicals or fuel products has attracted increasing attention from researchers. However, the kinetic and thermodynamic stability of CO2 greatly limits its application in the chemical industry. Therefore, highly active substrates and catalysts are needed to activate CO2. To date, various methods have been successfully developed to convert CO2 into different high-value-added products. Among these methods, the route of synthesizing epoxy carbonates from CO2 and epoxy compounds is one of the most effective strategies, with 100% atom economy, and the resulting epoxy carbonate derivatives have wide applications in aprotic solvents, fine chemicals, petroleum additives, and electrolytes in lithium-ion batteries. Traditional catalytic systems typically require high temperature, high pressure, and co-catalysts such as halogenated quaternary ammonium salts. For example, Klein et al. reported that the salen-Zn(II) complex in the presence of tetrabutylammonium iodide (NBu4I, TBAI) can catalyze the cycloaddition reaction of epoxides with carbon dioxide to obtain cyclic carbonates (Chem. Commun. 2010, 46, 4580-4582). In my country, He Liangnian et al. studied zinc complexes of 1-hydroxy-2-pyridone, where Zn(OPO)2 and TBAI can efficiently catalyze the cycloaddition reaction of epoxides with carbon dioxide (Green Chem., 2016, 18, 226-231). The addition of co-catalysts increases the cost of the entire process to some extent. Besides these two-component catalytic systems, some bifunctional catalytic systems have also been developed, namely, those that introduce quaternary ammonium salts onto organic ligands. Ema et al. introduced quaternary ammonium salt functional units onto porphyrin ligands, achieving extremely high catalytic activity; however, the synthesis of these ligands is complex (Angew. Chem., Int. Ed. 2015, 54, 134-138). Therefore, the development of simple and practical catalysts has attracted widespread attention. Recently, single-component bifunctional zinc complex catalysts have gained significant attention in this field due to their low cost, lack of additives, and mild reaction conditions, representing an important direction for developing simple catalytic systems for this type of cycloaddition reaction. For example, Cho, Kim et al. recently studied the C3-symmetric nitrogen ligand, [Zn(Me3Tren)I]I complex, which catalyzes the cycloaddition reaction of epoxides with carbon dioxide without a co-catalyst (App. Catal. B: Environ. 2021, 280, 119395); however, this synthesis process is complex and costly. Summary of the Invention

[0003] The purpose of this invention is to provide a tetradentate nitrogen ligand zinc complex, its preparation method and application, and a method for preparing cyclic carbonates. The tetradentate nitrogen ligand zinc complex provided by this invention is inexpensive and can be used as a catalyst to efficiently synthesize cyclic carbonates from epoxides and carbon dioxide, thus overcoming the shortcomings of existing technologies such as expensive and large quantities of catalysts, use of highly toxic organic solvents, difficulty in separating products from catalysts, and harsh reaction conditions.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides a tetradentate nitrogen-ligand zinc complex having the structure shown in Formula I:

[0006]

[0007] In Formula I, It includes a diamino group, and X includes Br or I.

[0008] Preferably, the Including piperazinyl, piperazinyl, N,N'-dimethylethylenediamine or N,N'-dimethylcyclohexanediamine.

[0009] Preferably, the tetradentate nitrogen-ligand zinc complex comprises

[0010] This invention provides a method for preparing the tetradentate nitrogen-ligand zinc complex described in the above technical solution, comprising the following steps:

[0011] Mix the tetradentate nitrogen ligand shown in Formula II, the zinc salt, and the organic solvent, and heat under reflux to obtain the tetradentate nitrogen ligand zinc complex.

[0012]

[0013] Preferably, the molar ratio of the tetradentate nitrogen ligand to the zinc salt is 1:0.99 to 1.1.

[0014] Preferably, the heating reflux time is 10 to 30 hours.

[0015] This invention provides the application of the tetradentate nitrogen ligand zinc complex described in the above technical solution or the tetradentate nitrogen ligand zinc complex prepared by the above technical solution as a catalyst for cycloaddition reaction.

[0016] This invention provides a method for preparing cyclic carbonates, comprising the following steps: mixing an epoxide compound, carbon dioxide, and a tetradentate nitrogen ligand zinc complex, and performing a cycloaddition reaction to obtain a cyclic carbonate; wherein the tetradentate nitrogen ligand zinc complex is the tetradentate nitrogen ligand zinc complex described in the above technical solution or the tetradentate nitrogen ligand zinc complex prepared by the preparation method described in the above technical solution.

[0017] Preferably, the epoxy compound has the structure shown in Formula III or Formula IV:

[0018]

[0019] In Formula III, R 1 Including methyl, ethyl, halogenated, phenyl, phenolic, tert-butanol, hydrogen, allyl, or tert-butoxymethyl;

[0020] In formula IV, R 2 This includes phenyl, phenyl substituted with 1 to 2 carbon atoms, tert-butyl or allyl.

[0021] Preferably, the molar amount of the tetradentate nitrogen-ligand zinc complex is 0.1% to 2.5% of the molar amount of the epoxy compound.

[0022] This invention provides a tetradentate nitrogen-ligand zinc complex having the structure shown in Formula I. The tetradentate nitrogen-ligand zinc complex provided by this invention contains both metallic zinc ions as Lewis acid sites and anionic halogen moieties that can introduce Lewis bases, and can be used as a bifunctional catalyst for the synthesis of cyclic carbonates from epoxides and carbon dioxide.

[0023] This invention provides a method for preparing the tetradentate nitrogen ligand zinc complex described in the above technical solution. The preparation method provided by this invention is simple and has a short preparation step.

[0024] This invention provides a method for preparing cyclic carbonates. The method utilizes a tetradentate nitrogen-ligand zinc complex as a catalyst to catalyze the cycloaddition reaction of epoxides and carbon dioxide, synthesizing the important intermediate cyclic carbonate in one step. Example results show that using the tetradentate nitrogen-ligand zinc complex provided by this invention as a catalyst results in high selectivity, high conversion rate, and mild reaction conditions for the cycloaddition reaction of epoxides and carbon dioxide.

[0025] Using the tetradentate nitrogen-ligand zinc complex provided by this invention as a catalyst to catalyze the cycloaddition reaction of epoxides and carbon dioxide to prepare cyclic carbonates has the following advantages: 1) The tetradentate nitrogen-ligand zinc complex of this invention has the advantages of simple preparation method, small catalyst dosage, high catalytic efficiency, no solvent, and no additives. 2) The reaction conditions of this invention are mild, the process is simple, easy to operate, and the equipment requirements and reaction conditions are easy to achieve, making it suitable for large-scale production. 3) This method has a wide range of applicable substrates (suitable for different types of epoxides), and high-purity cyclic carbonates can be obtained in high yield after simple extraction and separation of the reaction mixture. Attached Figure Description

[0026] Figure 1 The proton NMR spectrum of the tetradentate nitrogen-ligand zinc complex 1 prepared in Example 1;

[0027] Figure 2 The carbon NMR spectrum of the tetradentate nitrogen-ligand zinc complex 1 prepared in Example 1;

[0028] Figure 3 The hydrogen nuclear magnetic resonance spectrum of the tetradentate nitrogen-ligand zinc complex 3 prepared in Example 3 is shown. Detailed Implementation

[0029] This invention provides a tetradentate nitrogen-ligand zinc complex having the structure shown in Formula I:

[0030]

[0031] In Formula I, It includes a diamino group, and X includes Br or I.

[0032] In this invention, the Preferably, it includes piperazine, piperazine, N,N'-dimethylethylenediamine, or N,N'-dimethylcyclohexanediamine. In a specific embodiment of the present invention, the tetradentate nitrogen ligand zinc complex uses piperazine, N,N'-dimethylethylenediamine, or N,N'-dimethylcyclohexanediamine as the diamine backbone and pyridine as the axial ligand.

[0033] In a specific embodiment of the present invention, the tetradentate nitrogen-ligand zinc complex includes

[0034]

[0035] This invention provides a method for preparing the tetradentate nitrogen-ligand zinc complex described in the above technical solution, comprising the following steps:

[0036] Mix the tetradentate nitrogen ligand shown in Formula II, the zinc salt, and the organic solvent, and heat under reflux to obtain the tetradentate nitrogen ligand zinc complex.

[0037]

[0038] In a specific embodiment of the present invention, the tetradentate nitrogen ligand includes (L1 tetradentate nitrogen ligand) (L2 tetradentate nitrogen ligand) or (L3 tetradentate nitrogen ligand).

[0039] In this invention, the preparation method of the L1 tetradentate nitrogen ligand preferably includes the following steps: using dichloromethane (CH2Cl2) and water as solvents, piperazine, 2-chloromethylpyridine hydrochloride, and sodium hydroxide are mixed to carry out a first substitution reaction to obtain the L1 tetradentate nitrogen ligand. In this invention, the molar ratio of piperazine, 2-chloromethylpyridine hydrochloride, and sodium hydroxide is preferably 1:2 to 6:2 to 10, more preferably 1:2:6. In this invention, the volume ratio of dichloromethane to water is preferably 1 to 5:5 to 1, more preferably 1:1; the volume ratio of piperazine to solvent is preferably 1 mmol: 20 mL. In this invention, the temperature of the first substitution reaction is preferably room temperature; the time of the first substitution reaction is preferably 10 to 24 hours, more preferably 12 hours. Preferably, the product is separated and purified after the first substitution reaction to obtain the L1 tetradentate nitrogen ligand. In this invention, the separation and purification of the product preferably includes: filtering the obtained reaction system, washing the filter cake with CH2Cl2, and collecting the filtrate; distilling the filtrate under reduced pressure to obtain an oily residue; adding NaOH solution to the oily residue and extracting the mixture with CH2Cl2; washing successively with a saturated aqueous solution of NaHCO3 and a saturated aqueous solution of NaCl, and combining the organic liquids; adding anhydrous Na2SO4 to the organic liquid for drying, then filtering to obtain an organic liquid, adding silica gel, and removing the solvent by rotary evaporation to obtain a solid powder; purifying the solid powder by silica gel column chromatography to obtain L1 tetradentate nitrogen ligand. In this invention, the concentration of the NaOH solution is preferably 1 mol / L.

[0040] In this invention, the preparation method of the L2 tetradentate nitrogen ligand preferably includes the following steps: using dichloromethane and water as solvents, N,N'-dimethylethylenediamine, 2-chloromethylpyridine hydrochloride, and sodium hydroxide are mixed and subjected to a second substitution reaction to obtain the L2 tetradentate nitrogen ligand. In this invention, the molar ratio of N,N'-dimethylethylenediamine, chloromethylpyridine hydrochloride, and sodium hydroxide is preferably 1:2 to 6:2 to 10. In this invention, the mass ratio of dichloromethane to water is preferably 1 to 5:5 to 1, more preferably 1:1; the volume ratio of N,N'-dimethylethylenediamine to solvent is preferably 1 mmol: 20 mL. In this invention, the temperature of the second substitution reaction is preferably room temperature; the time of the second substitution reaction is preferably 10 to 24 hours. Preferably, the product is separated and purified after the second substitution reaction to obtain the L2 tetradentate nitrogen ligand. In this invention, the separation and purification of the product preferably includes: filtering the obtained reaction system, washing the filter cake with CH2Cl2, and collecting the filtrate; distilling the filtrate under reduced pressure to obtain an oily residue; adding NaOH solution to the oily residue and extracting the mixture with CH2Cl2; washing successively with a saturated aqueous solution of NaHCO3 and a saturated aqueous solution of NaCl, and combining the organic liquids; adding anhydrous Na2SO4 to the organic liquid for drying, then filtering to obtain an organic liquid, adding silica gel, and removing the solvent by rotary evaporation to obtain a solid powder; purifying the solid powder by silica gel column chromatography to obtain L2 tetradentate nitrogen ligands. In this invention, the concentration of the NaOH solution is preferably 1 mol / L.

[0041] In this invention, the preparation method of the L3 tetradentate nitrogen ligand preferably includes the following steps: using dichloromethane and water as solvents, N,N'-dimethylcyclohexanediamine, 2-chloromethylpyridine hydrochloride, and sodium hydroxide are mixed and subjected to a third substitution reaction to obtain the L3 tetradentate nitrogen ligand. In this invention, the molar ratio of N,N'-dimethylcyclohexanediamine, chloromethylpyridine hydrochloride, and sodium hydroxide is preferably 1:2 to 6:2 to 10. In this invention, the mass ratio of dichloromethane to water is preferably 1 to 5:5 to 1, more preferably 1:1; the volume ratio of N,N'-dimethylcyclohexanediamine to solvent is preferably 1 mmol: 20 mL. In this invention, the temperature of the third substitution reaction is preferably room temperature; the time of the third substitution reaction is preferably 10 to 24 hours. Preferably, the product is separated and purified after the third substitution reaction to obtain the L3 tetradentate nitrogen ligand. In this invention, the separation and purification of the product preferably includes: filtering the obtained reaction system, washing the filter cake with CH2Cl2, and collecting the filtrate; distilling the filtrate under reduced pressure to obtain an oily residue; adding NaOH solution to the oily residue and extracting the mixture with CH2Cl2; washing successively with a saturated aqueous solution of NaHCO3 and a saturated aqueous solution of NaCl, and combining the organic liquids; adding anhydrous Na2SO4 to the organic liquid for drying, then filtering to obtain an organic liquid, adding silica gel, and removing the solvent by rotary evaporation to obtain a solid powder; purifying the solid powder by silica gel column chromatography to obtain L3 tetradentate nitrogen ligand. In this invention, the eluent used for silica gel column purification is preferably a mixture of petroleum ether and ethyl acetate; the volume ratio of petroleum ether to ethyl acetate in the mixture is preferably 100:1 to 1000. In this invention, the concentration of the NaOH solution is preferably 1 mol / L.

[0042] This invention involves mixing the tetradentate nitrogen ligand, a zinc salt, and an organic solvent, followed by heating under reflux to obtain a tetradentate nitrogen ligand-zinc complex. In this invention, the zinc salt preferably comprises zinc bromide or zinc iodide; the organic solvent preferably comprises ethanol, acetonitrile, or tetrahydrofuran. In this invention, the molar ratio of the tetradentate nitrogen ligand to the zinc salt is preferably 1:0.99–1.1, more preferably 1:1. In this invention, the mixing of the tetradentate nitrogen ligand, zinc salt, and organic solvent preferably comprises: dissolving the tetradentate nitrogen ligand in a portion of the organic solvent to obtain a tetradentate nitrogen ligand solution; dissolving the zinc salt in the remaining organic solvent to obtain a zinc salt solution; and adding the zinc salt solution dropwise to the tetradentate nitrogen ligand solution. In this invention, the concentration of the tetradentate nitrogen ligand solution is preferably 0.01–1.0 mol / L, more preferably 0.2 mol / L; the concentration of the zinc salt solution is preferably 0.01–1.0 mol / L, more preferably 0.2 mol / L. The present invention uses a dropwise addition method to add the zinc salt solution to the tetradentate nitrogen ligand solution, which is beneficial to the full coordination of zinc salt and ligand.

[0043] In this invention, the reflux heating time is preferably 10–30 hours, more preferably 15–20 hours. Preferably, after the reflux heating is completed, separation and purification are performed to obtain a tetradentate nitrogen-ligand zinc complex. In this invention, the separation and purification preferably includes: subjecting the obtained reflux product system to vacuum distillation to remove some ethanol, adding diethyl ether, filtering to obtain a solid, and washing the solid with anhydrous diethyl ether to obtain the tetradentate nitrogen-ligand zinc complex.

[0044] This invention provides the application of the tetradentate nitrogen ligand zinc complex described in the above technical solution or the tetradentate nitrogen ligand zinc complex prepared by the above technical solution as a catalyst for cycloaddition reaction.

[0045] This invention provides a method for preparing cyclic carbonates, comprising the following steps: mixing an epoxide compound, carbon dioxide, and a tetradentate nitrogen ligand zinc complex, and performing a cycloaddition reaction to obtain a cyclic carbonate; wherein the tetradentate nitrogen ligand zinc complex is the tetradentate nitrogen ligand zinc complex described in the above technical solution or the tetradentate nitrogen ligand zinc complex prepared by the preparation method described in the above technical solution.

[0046] In this invention, the epoxy compound preferably has the structure shown in Formula III or Formula IV:

[0047]

[0048] In Formula III, R 1 Preferred compounds include methyl, ethyl, halogenated, phenyl, phenolic, tert-butanol, hydrogen, allyl, or tert-butoxymethyl.

[0049] In formula IV, R 2 Preferred components include phenyl, phenyl substituted with 1 to 2 carbon atoms, tert-butyl, or allyl.

[0050] In specific embodiments of the present invention, the epoxy compound preferably includes: 3-chloro-1,2-epoxypropane, 3-bromo-1,2-dioxane, propylene oxide, 1,2-epoxybutane, 1,2-epoxy-5-hexene, 2-phenyl-epoxyethylene, 1-allyloxy-2,3-epoxypropane, 2-(tert-butoxymethyl)epoxyethylene, phenyl glycidyl ether, benzyl glycidyl ether, 2-toluene glycidyl ether, 1,4-butanediol diglycidyl ether, or neopentyl glycol glycidyl ether.

[0051] In this invention, the halogen group preferably includes a bromine group or a chlorine group.

[0052] In a specific embodiment of the present invention, the epoxy compound includes:

[0053]

[0054] In this invention, the molar amount of the tetradentate nitrogen ligand zinc complex is preferably 0.1 to 2.5% of the molar amount of the epoxy compound, more preferably 1 to 2%.

[0055] In this invention, a co-catalyst is preferably added during the preparation of the cyclic carbonate. The co-catalyst preferably comprises one or more of tetrabutylammonium bromide and tetrabutylammonium iodide. The molar amount of the co-catalyst is preferably 0.5-10% of the molar amount of the epoxide compound, more preferably 1-8%.

[0056] In this invention, no solvent is added during the cycloaddition reaction. During the cycloaddition reaction, the pressure of carbon dioxide is preferably 0.1–4 MPa, more preferably 0.5–2.0 MPa; the temperature of the cycloaddition reaction is preferably 30–100°C, more preferably 80–100°C; and the reaction time is preferably 6–24 hours.

[0057] In this invention, the reaction formula for the cycloaddition reaction is:

[0058]

[0059] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0060] The structures of the tetradentate nitrogen ligand and the tetradentate nitrogen ligand zinc complex used in the examples are as follows:

[0061] The structure of the epoxy compound used in the application example is as follows:

[0062] The structure of the cyclic carbonate generated in the application example is as follows:

[0063]

[0064] Example 1

[0065] Preparation of the tetradentate nitrogen-ligand zinc complex 1 catalyst: Piperazine (1 mmol), 2-chloromethylpyridine hydrochloride (2 mmol), NaOH aqueous solution (6.0 mmol dissolved in 10 mL distilled water), and CH2Cl2 (10 mL) were added to a glass round-bottom flask equipped with a stir bar, and the mixture was stirred vigorously at room temperature for 12 hours. After the reaction, the mixture was filtered, the filter cake was thoroughly washed with CH2Cl2, and the filtrate was collected. This filtrate was distilled under reduced pressure to obtain an oily residue. A 1 mol / L NaOH aqueous solution was added to the obtained residue. 10 mL) and extract the mixture with CH2Cl2; wash successively with saturated aqueous solution of NaHCO3 and NaCl, and combine the organic liquids; add an appropriate amount of anhydrous Na2SO4 to this liquid to dry and remove a small amount of water, then filter to obtain organic liquid, add silica gel, and remove the solvent by rotary evaporation to obtain solid powder; finally use analytical grade EtOAc-PE mixture as eluent to purify the solid powder by rapid silica gel column chromatography to obtain tetradentate nitrogen ligand L1 (yellow oily liquid, yield 56%, purity 99%).

[0066] Next, in a round-bottom flask, 1.0 mmol of the tetradentate nitrogen ligand L1, 5 mL of anhydrous ethanol, and a magnetic stir bar were added; 1.0 mmol of ZnBr2 was dissolved in 5 mL of ethanol to obtain a zinc bromide solution; the zinc bromide solution was added dropwise to the round-bottom flask; then, the temperature was raised to 55 °C and stirred for 10 hours; after the reaction was completed, the mixture was distilled under reduced pressure to remove most of the ethanol, and then diethyl ether was added. The mixture was filtered to obtain a white solid, washed three times with anhydrous diethyl ether, and dried to obtain tetradentate nitrogen ligand zinc complex 1 (white solid powder, yield 84%, purity 99%).

[0067] Figure 1 The proton NMR spectrum of the tetradentate nitrogen-ligand zinc complex 1 prepared in Example 1; 1 HNMR (400MHz, DMSO) δ = 8.84 (d, J = 5.2Hz, 2H), 8.18 (m, 2H), 7.75-7.63 (m, 4H), 4.20 (s, 4H), 3.38 (s, 2H), 2.97 (s, 6H), 8.84 (d, J = 121.2Hz, 2H).

[0068] Figure 2 The carbon NMR spectrum of the tetradentate nitrogen-ligand zinc complex 1 prepared in Example 1; 13 C NMR (101MHz, DMSO) δ = 155.41, 148.92, 141.34, 125.34, 125.22, 59.39, 55.40, 48.72, 23.26.

[0069] Example 2

[0070] Preparation of the tetradentate nitrogen-ligand zinc complex 2 catalyst: N,N'-dimethylethylenediamine (1 mmol), 2-chloromethylpyridine hydrochloride (2 mmol), sodium hydroxide aqueous solution (6.0 mmol dissolved in 10 mL distilled water), and CH2Cl2 (10 mL) were added to a glass round-bottom flask equipped with a stir bar, and the mixture was stirred vigorously at room temperature for 12 hours. After the reaction was completed, the mixture was filtered, the filter cake was thoroughly washed with dichloromethane, and the filtrate was collected. The filtrate was distilled under reduced pressure to obtain an oily residue. 1 mol / L of sodium hydroxide was added to the obtained residue. Sodium aqueous solution (10 mL) was used, and the mixture was extracted with dichloromethane. The mixture was washed sequentially with saturated aqueous solutions of NaHCO3 and NaCl, and the organic liquids were combined. An appropriate amount of anhydrous sodium sulfate was added to the liquid to dry it and remove a small amount of water. The mixture was then filtered to obtain an organic liquid. Silica gel was added, and the solvent was removed by rotary evaporation to obtain a solid powder. Finally, the solid powder was purified by rapid silica gel column chromatography using an analytical grade petroleum ether / ethyl acetate mixture as the eluent to obtain tetradentate nitrogen ligand L2 (a light yellow oily liquid with a yield of 62% and a purity of 99%).

[0071] Next, in a round-bottom flask, 1.0 mmol of the tetradentate nitrogen ligand L2, 5 mL of anhydrous ethanol, and a magnetic stir bar were added; 1.0 mmol of zinc bromide was dissolved in 5 mL of ethanol to obtain a zinc bromide solution; the zinc bromide solution was added dropwise to the round-bottom flask; then, the temperature was raised to 55 °C and stirred for 10 hours; after the reaction was completed, the mixture was distilled under reduced pressure to remove most of the ethanol, and then diethyl ether was added. The mixture was filtered to obtain a white solid, washed three times with anhydrous diethyl ether, and dried to obtain tetradentate nitrogen ligand zinc complex 2 (white solid powder, yield 79%, purity 99%).

[0072] 1 H NMR (400MHz, DMSO) δ = 9.02 (d, J = 4.4Hz, 2H), 8.08-8.13 (m, 2H), 7.67-7.58 (m, 4H), 4 .25(d,J=15.2Hz,2H),3.84(d,J=15.6Hz,2H),2.51-2.43(m,2H),2.25-2.20(m,8H).

[0073] 13 C NMR (101MHz, DMSO) δ = 155.12, 148.68, 140.50, 125.06, 124.38, 60.26, 51.94, 42.28

[0074] Example 3

[0075] Preparation of the tetradentate nitrogen-ligand zinc complex 3 catalyst: N,N'-dimethylcyclohexanediamine (1 mmol), 2-chloromethylpyridine hydrochloride (2 mmol), sodium hydroxide aqueous solution (6.0 mmol dissolved in 10 mL distilled water), and CH2Cl2 (10 mL) were added to a glass round-bottom flask equipped with a stir bar, and the mixture was stirred vigorously at room temperature for 12 hours. After the reaction was completed, the mixture was filtered, the filter cake was thoroughly washed with dichloromethane, and the filtrate was collected. The filtrate was distilled under reduced pressure to obtain an oily residue. 1 mol / L hydroxide was added to the obtained residue. The mixture was extracted with 10 mL of sodium chloride aqueous solution and dichloromethane. It was then washed sequentially with saturated aqueous solutions of NaHCO3 and NaCl, and the organic liquids were combined. An appropriate amount of anhydrous sodium sulfate was added to this liquid for drying to remove a small amount of water. The mixture was then filtered to obtain the organic liquid. Silica gel was added, and the solvent was removed by rotary evaporation to obtain a solid powder. Finally, using an analytical grade petroleum ether / ethyl acetate mixture as eluent, the solid powder was purified by rapid silica gel column chromatography to obtain tetradentate nitrogen ligand L3 (a light yellow oily liquid, yield 65%, purity 99%).

[0076] Next, in a round-bottom flask, 1.0 mmol of the tetradentate nitrogen ligand L3, 5 mL of anhydrous ethanol, and a magnetic stir bar were added; 1.0 mmol of ZnBr2 was dissolved in 5 mL of ethanol to obtain a zinc bromide solution; the zinc bromide solution was added dropwise to the round-bottom flask; then, the temperature was raised to 55 °C and stirred for 10 hours; after the reaction was completed, the anhydrous ethanol was removed by vacuum distillation, followed by the addition of diethyl ether, and the mixture was filtered to obtain a white solid. The solid was washed three times with diethyl ether and dried to obtain tetradentate nitrogen ligand zinc complex 3 (white solid powder, yield 92%, purity 99%).

[0077] The tetradentate nitrogen-ligand zinc complex 3 was characterized by NMR, such as... Figure 3 As shown, the results indicate that the tetradentate nitrogen-ligand zinc complex 3 is a mixture of two configurations.

[0078] Application Example 1

[0079] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst and 10 mmol of epoxide 4 were added to a 10 mL reaction flask. The air in the reaction flask was then replaced three times with carbon dioxide. A balloon filled with carbon dioxide was then placed on the reaction flask and placed in an oil bath at 30 °C for 24 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR. The target product was cyclic carbonate 17, with a yield of 60%.

[0080] Application Example 2

[0081] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 2 catalyst and 10 mmol of epoxide 4 were added to a 10 mL reaction flask. The air in the reaction flask was then replaced three times with carbon dioxide. A balloon filled with carbon dioxide was then placed on the reaction flask and placed in an oil bath at 30 °C for 24 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR spectroscopy. The target product was cyclic carbonate 17, with a yield of 26%.

[0082] Application Example 3

[0083] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 3 catalyst and 10 mmol of epoxide 4 were added to a 10 mL reaction flask. The air in the reaction flask was then replaced three times with carbon dioxide. A balloon filled with carbon dioxide was then placed on the reaction flask and placed in an oil bath at 30 °C for 24 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR spectroscopy. The target product was cyclic carbonate 17, with a yield of 40%.

[0084] Application Example 4

[0085] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst and 0.1 mmol of tetrabutylammonium bromide were added to a 10 mL reaction flask, along with 10 mmol of epoxide 4. The air in the reaction flask was then replaced three times with carbon dioxide. A balloon filled with carbon dioxide was then placed on top of the reaction flask, which was then placed in an oil bath at 30 °C for 24 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR spectroscopy. The target product was cyclic carbonate 17, with a yield of 84%.

[0086] Application Example 5

[0087] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst and 10 mmol of epoxide 4 were added to a 10 mL reaction flask. The air in the reaction flask was then replaced three times with carbon dioxide. A balloon filled with carbon dioxide was then placed on the reaction flask and placed in an oil bath at 40 °C for 24 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR. The target product was cyclic carbonate 17, with a yield of 68%.

[0088] Application Example 6

[0089] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst and 10 mmol of epoxide 4 were added to a 10 mL reaction flask. The air in the reaction flask was then replaced three times with carbon dioxide. A carbon dioxide-filled balloon was then placed on the reaction flask and placed in a 60 °C oil bath for 24 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR spectroscopy. The target product was cyclic carbonate 17, with a yield of 80%.

[0090] Application Example 7

[0091] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 10 mL autoclave, followed by 10 mmol of epoxide 4. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 1 MPa of carbon dioxide. The autoclave was placed in a 60 °C oil bath and reacted for 6 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR spectroscopy. The target product was cyclic carbonate 17, with a yield of 87%.

[0092] Application Example 8

[0093] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 10 mL autoclave, followed by 10 mmol of epoxide 4. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 1 MPa of carbon dioxide. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR spectroscopy. The target product was cyclic carbonate 17, with a yield of 98%.

[0094] Application Example 9

[0095] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 10 mL autoclave, followed by 10 mmol of epoxide 4. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 1 MPa of carbon dioxide. The autoclave was placed in an 80 °C oil bath and reacted for 4 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR spectroscopy. The target product was cyclic carbonate 17, with a yield of 94%.

[0096] Application Example 10

[0097] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 10 mL autoclave, followed by 10 mmol of epoxide 4. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 1 MPa of carbon dioxide. The autoclave was placed in an 80 °C oil bath and reacted for 2 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR spectroscopy. The target product was cyclic carbonate 17, with a yield of 84%.

[0098] Application Example 11

[0099] 0.01 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 10 mL autoclave, followed by 10 mmol of epoxide 4. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 1 MPa of carbon dioxide. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR spectroscopy. The target product was cyclic carbonate 17, with a yield of 15%.

[0100] Application Example 12

[0101] 0.05 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 10 mL autoclave, followed by 10 mmol of epoxide 4. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 1 MPa of carbon dioxide. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR spectroscopy. The target product was cyclic carbonate 17, with a yield of 67%.

[0102] Application Example 13

[0103] 0.07 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 10 mL autoclave, followed by 10 mmol of epoxide 4. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 1 MPa of carbon dioxide. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR spectroscopy. The target product was cyclic carbonate 17, with a yield of 82%.

[0104] Application Example 14

[0105] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 10 mL autoclave, followed by 10 mmol of epoxide 4. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 0.6 MPa carbon dioxide. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR spectroscopy. The target product was cyclic carbonate 17, with a yield of 80%.

[0106] Application Example 15

[0107] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 10 mL autoclave, followed by 10 mmol of epoxide 4. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 0.8 MPa carbon dioxide. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, tetrachloroethane was added as an internal standard, and the yield was analyzed by 1H NMR spectroscopy. The target product was cyclic carbonate 17, with a yield of 94%.

[0108] Application Example 16

[0109] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 25 mL autoclave, followed by 10 mmol of epoxide 4. The air in the autoclave was then replaced three times with carbon dioxide, and then 1.0 MPa of carbon dioxide was introduced. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and separated by silica gel column chromatography to obtain the target product cyclic carbonate 17 with a yield of 98%.

[0110] Product NMR data: 1 H NMR (400MHz, CDCl3) δ = 4.85 (d, J = 6.3, 1H), 4.61–4.49 (m, 1H), 4.02 (dd, J = 8.4, 7.3, 1H), 1.49 (d, J = 6.3, 3H). 13 C NMR (101MHz, CDCl3) δ = 155.00, 73.50, 70.64, 19.47.

[0111] Application Example 17

[0112] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 25 mL autoclave, followed by 10 mmol of epoxide 5. The air in the autoclave was then replaced three times with carbon dioxide, and then 1.0 MPa of carbon dioxide was introduced. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and purified by silica gel column chromatography to obtain the target product cyclic carbonate 18 with a yield of 98%.

[0113] Product NMR data: 1 H NMR (400MHz, CDCl3) δ = 4.95 (m, 1H), 4.59 (t, J = 8.5, 1H), 4.34 (dd, J = 8.5, 6.3, 1H), 3.58 (d, J = 5.1, 2H). 13 C NMR (101MHz, CDCl3) δ = 154.24, 74.07, 68.17, 31.52.

[0114] Application Example 18

[0115] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 25 mL autoclave, followed by 10 mmol of epoxide 6. The air in the autoclave was then replaced three times with carbon dioxide, and then 1.0 MPa of carbon dioxide was introduced. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and purified by silica gel column chromatography to obtain the target product cyclic carbonate 19 with a yield of 95%.

[0116] Product NMR data:1 H NMR (400MHz, CDCl3) δ = 4.85 (d, J = 6.3, 1H), 4.61–4.49 (m, 1H), 4.02 (dd, J = 8.4, 7.3, 1H), 1.49 (d, J = 6.3, 3H). 13 C NMR (101MHz, CDCl3) δ = 155.00, 73.50, 70.64, 19.47.

[0117] Application Example 19

[0118] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 25 mL autoclave, followed by 10 mmol of epoxide 7. The air in the autoclave was then replaced three times with carbon dioxide, and then 1.0 MPa of carbon dioxide was introduced. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and purified by silica gel column chromatography to obtain the target product cyclic carbonate 20 with a yield of 95%.

[0119] Product NMR data: 1 H NMR (400MHz, CDCl3) δ=4.76–4.60(m,1H),4.56–4.43(m,1H),4.07(dd,J=8.4,7.0,1H),1.88–1.67(m,2H),1.01(t,J=7.5,3H). 13 C NMR (101MHz, CDCl3) δ = 155.16, 78.05, 69.04, 26.93, 8.48.

[0120] Application Example 20

[0121] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 25 mL autoclave, followed by 10 mmol of epoxide 8. The air in the autoclave was then replaced three times with carbon dioxide, and then 1.0 MPa of carbon dioxide was introduced. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and separated by silica gel column chromatography to obtain the target product cyclic carbonate 21 with a yield of 86%.

[0122] Product NMR data: 1 H NMR(400MHz, CDCl3)δ=5.84–7.74(m,1H),5.09(dd,J=23.0,5.8,2H),4.88–4.68(m,1H),4 .54(t,J=8.1,1H),4.09(t,J=7.8,1H),2.39–2.10(m,2H),2.03–1.89(m,1H),1.78(m,1H). 13C NMR (101MHz, CDCl3) δ = 154.95, 136.07, 116.48, 76.31, 69.33, 33.10, 28.67.

[0123] Application Example 21

[0124] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 25 mL autoclave, followed by 10 mmol of epoxide 9. The air in the autoclave was then replaced three times with carbon dioxide, and then 1.0 MPa of carbon dioxide was introduced. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and separated by silica gel column chromatography to obtain the target product cyclic carbonate 22 with a yield of 98%.

[0125] Product NMR data: 1 H NMR (400MHz, CDCl3) δ=7.50–7.39(m,3H),7.38–7.33(m,2H),5.68(t,J=8.0,1H),4.80(t,J=8.4,1H),4.38–4.29(m,1H). 13 CNMR(101MHz, CDCl3)δ=154.93,135.87,129.73,129.24,125.93,78.04,71.23.

[0126] Application Example 22

[0127] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 25 mL autoclave, followed by 10 mmol of epoxide 10. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 1.0 MPa of carbon dioxide. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and purified by silica gel column chromatography to obtain the target product cyclic carbonate 23 with a yield of 96%.

[0128] Product NMR data: 1 H NMR(400MHz, CDCl3)δ=5.95–5.75(m,1H),5.35–5.18(m,2H),4.91–4.76(m,1H),4.50(t,J=8.4,1H), 4.39(dd,J=8.3,6.1,1H), 4.11–3.96(m,2H), 3.69(dd,J=11.0,4.0,1H), 3.61(dd,J=11.0,3.7,1H). 13 CNMR(101MHz, CDCl3)δ=154.93,133.67,117.98,75.02,72.64,68.86,66.30.

[0129] Application Example 23

[0130] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 25 mL autoclave, followed by 10 mmol of epoxide 11. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 1.0 MPa of carbon dioxide. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and separated by silica gel column chromatography to obtain the target product cyclic carbonate 24 with a yield of 93%.

[0131] Product NMR data: 1 H NMR (400MHz, CDCl3) δ=4.78–4.68(m,1H),4.42(t,J=8.3,1H),4.31(dd,J=8.2 ,5.8,1H),3.56(dd,J=10.5,4.0,1H),3.45(dd,J=10.6,3.5,1H),1.12(s,9H). 13 C NMR (101MHz, CDCl3) δ = 155.30, 75.36, 73.75, 66.48, 61.25, 27.24.

[0132] Application Example 24

[0133] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst and 10 mmol of epoxide 12 were added to a 25 mL autoclave. The air in the autoclave was then replaced three times with carbon dioxide. The autoclave was then purged with 1.0 MPa of carbon dioxide and placed in an 80 °C oil bath for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and separated by silica gel column chromatography to obtain the target product cyclic carbonate 25 with a yield of 96%.

[0134] Product NMR data: 1 H NMR(400MHz, CDCl3)δ=7.36–7.27(m,2H),7.02(t,J=7.4,1H),6.91(d,J=7.9,2H),5.09–5.03(m,1H), 4.61(t,J=8.4,1H), 4.53(dd,J=8.5,5.9,1H), 4.24(dd,J=10.6,4.2,1H), 4.14(dd,J=10.6,3.6,1H). 13 C NMR (101MHz, CDCl3) δ = 157.78, 154.68, 129.72, 122.02, 114.63, 74.13, 66.90, 66.26.

[0135] Application Example 25

[0136] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 25 mL autoclave, followed by 10 mmol of epoxide 13. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 1.0 MPa of carbon dioxide. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and separated by silica gel column chromatography to obtain the target product cyclic carbonate 26 with a yield of 91%.

[0137] Product NMR data: 1 H NMR(400MHz, CDCl3)δ=7.40–7.34(m,2H),7.34–7.28(m,3H),4.86–4.78(m,1H),4.59(q,J=12.0,2H), 4.47(t,J=8.4,1H), 4.38(dd,J=8.3,6.0,1H), 3.71(dd,J=11.0,3.7,1H), 3.60(dd,J=11.0,3.7,1H). 13 CNMR(101MHz, CDCl3)δ=155.02,137.15,128.60,128.10,127.50,75.09,73.70,68.89,66.32.

[0138] Application Example 26

[0139] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 25 mL autoclave, followed by 10 mmol of epoxide 14. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 1.0 MPa of carbon dioxide. The autoclave was placed in an 80 °C oil bath and reacted for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and separated by silica gel column chromatography to obtain the target product cyclic carbonate 27 with a yield of 93%.

[0140] Product NMR data: 1 H NMR (400MHz, CDCl3) δ=7.21–7.12(m,2H),6.92(dd,J=13.9,7.1,1H),6.78(d,J=8.6,1H),5.11–5.00( m,1H),4.68–4.54(m,2H),4.26(dd,J=10.6,3.6,1H),4.14(dd,J=10.6,3.1,1H),2.23(d,J=7.3,3H). 13 C NMR (101MHz, CDCl3) δ = 155.77, 154.76, 131.12, 127.13, 126.89, 121.70, 110.85, 74.19, 67.03, 66.25, 15.97.

[0141] Application Example 27

[0142] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 25 mL autoclave, followed by 10 mmol of epoxide 15. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 1.0 MPa of carbon dioxide. The autoclave was placed in an oil bath at 100 °C and reacted for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and purified by silica gel column chromatography to obtain the target product, cyclic carbonate 28, with a yield of 85%.

[0143] Product NMR data: 1 H NMR(400MHz,CDCl3,mixture ofstereoisomers)δ=4.85–4.76(m,1H),4.49(t,J=8.3,1H),4.43–4.34(m,1H),3.68(dd,J=11.1,3.3,1H),3.62–3.49(m,3H),1.63(s,4H). 13 C NMR (101MHz, CDCl3) δ=155.10,75.21,71.66,71.61,69.66,69.64,66.23,26.07,26.05.

[0144] Application Example 28

[0145] 0.1 mmol of tetradentate nitrogen-ligand zinc complex 1 catalyst was added to a 25 mL autoclave, followed by 10 mmol of epoxide 16. The air in the autoclave was then replaced three times with carbon dioxide, and the autoclave was then purged with 1.0 MPa of carbon dioxide. The autoclave was placed in an oil bath at 100 °C and reacted for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature and purified by silica gel column chromatography to obtain the target product cyclic carbonate 29 with a yield of 88%.

[0146] Product NMR data: 1 H NMR (400MHz, CDCl3, mixture of stereoisomers)δ=4.87–4.74(m,1H),4.53–4.31(m,2H),3.70–3.50(m,2H),3.39–3.07(m,2H),0.92-0.75(m,3H). 13 C NMR (101MHz, CDCl3) δ = 155.42, 155.31, 155.09, 78.82, 76.91, 76.83, 76.75, 75.40, 70.43, 70.2 9,70.14,69.31,66.27,66.22,36.68,36.37,36.30,36.21,22.09,22.00,21.93,21.58,21.53.

[0147] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A tetradentate nitrogen-ligand zinc complex having the structure shown in Formula I: Formula I; In Formula I, It is a high piperazine group, piperazine group, N,N'-dimethylethylenediamine group or N,N'-dimethylcyclohexanediamine group, and X is Br or I.

2. The tetradentate nitrogen-ligand zinc complex according to claim 1, characterized in that, The tetradentate nitrogen-ligand zinc complex includes , or .

3. A method for preparing the tetradentate nitrogen-ligand zinc complex according to any one of claims 1 to 2, comprising the following steps: Mix the tetradentate nitrogen ligand shown in Formula II, the zinc salt, and the organic solvent, and heat under reflux to obtain the tetradentate nitrogen ligand zinc complex. Formula II.

4. The preparation method according to claim 3, characterized in that, The molar ratio of the tetradentate nitrogen ligand to the zinc salt is 1:0.99~1.

1.

5. The preparation method according to claim 3, characterized in that, The heating and reflux time is 10 to 30 hours.

6. The application of the tetradentate nitrogen ligand zinc complex according to any one of claims 1 to 2 or the tetradentate nitrogen ligand zinc complex prepared by the preparation method according to any one of claims 3 to 5 as a catalyst for cycloaddition reactions.

7. A method for preparing a cyclic carbonate, characterized in that, The process includes the following steps: mixing an epoxy compound, carbon dioxide, and a tetradentate nitrogen ligand zinc complex, and performing a cycloaddition reaction to obtain a cyclic carbonate; wherein the tetradentate nitrogen ligand zinc complex is the tetradentate nitrogen ligand zinc complex according to any one of claims 1 to 2 or the tetradentate nitrogen ligand zinc complex prepared by the preparation method according to any one of claims 3 to 5.

8. The preparation method according to claim 7, characterized in that, The epoxy compound has the structure shown in Formula III or Formula IV: Formula III; Formula IV; In Formula III, R 1 Including methyl, ethyl, halogenated, phenyl, phenolic, tert-butanol, hydrogen, allyl, or tert-butoxymethyl; In formula IV, R 2 This includes phenyl, phenyl substituted with 1 to 2 carbon atoms, tert-butyl or allyl.

9. The preparation method according to claim 7, characterized in that, The molar amount of the tetradentate nitrogen-ligand zinc complex is 0.1 to 2.5% of the molar amount of the epoxy compound.

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