Aminophenol iron complex and preparation method and application thereof

Abstract

The application provides an amido phenolic iron complex, a preparation method and application thereof. The amido phenolic iron complex comprises a metal central atom Fe and a ligand coordinated with the metal central atom Fe, and the ligand has a structure shown in formula I: in formula I, R1, R1', R2 and R2' are the same or different, and each is independently selected from H, Me, t Bu; and R is selected from the amido phenolic iron complex. The preparation method is simple, as a catalyst, the amido phenolic iron complex has the characteristics of safety, non-toxicity, green environmental protection, low cost, mild catalytic condition, no additional solvent, high catalytic efficiency and high selectivity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic synthesis, and particularly relates to an amine-based phenolic iron complex as well as a preparation method and application thereof. BACKGROUND

[0002] Carbon dioxide is a non-toxic, inexhaustible green carbon (C1) resource, and is also the final product of carbon cycle. How to capture, store and utilize it has become an effective technology to cope with global climate change and reduce carbon dioxide emissions. So far, there are many ways to recycle and utilize carbon dioxide. The conversion of carbon dioxide into valuable chemical products through chemical reactions has attracted widespread attention. The reaction of carbon dioxide with epoxide has important research significance. The reaction has 100% atom economy, which meets the principles of green chemistry. Carbon dioxide and epoxide can not only be used to prepare carbon dioxide-based polycarbonates through polymerization for products such as degradable plastics, but also can be used to prepare cyclic carbonates through cycloaddition. As high-value-added chemicals, cyclic carbonates are not only the synthesis monomers of polycarbonates and polyurethanes, but also the components of important polar aprotic solvents and lithium ion battery electrolytes, which have the environmental friendly characteristics of low toxicity, high boiling point, low volatility and biodegradability.

[0003] The catalysts for synthesizing cyclic carbonates include metal oxides, metal complexes, alkali metal halides, metal organic frameworks, ionic liquids and supported catalysts, etc. The main metals used include alkali (alkaline earth) metals (magnesium, potassium, calcium, etc.), transition metals (chromium, manganese, cobalt, nickel, copper), rare earth metals (lanthanum, samarium, samarium, ytterbium) and other metals. ZL201810720223.3 discloses a preparation method of cyclic carbonate, which uses diethylene glycol amine bridged double aryl oxy rare earth-zinc hetero-bimetallic complex as catalyst to realize the effective utilization of carbon dioxide. ZL202110936786.8 discloses a method for synthesizing cyclic carbonates from carbon dioxide and cyclohexene oxide using a sulfonated metal (zinc, cobalt, manganese) Salen and polyether ionic liquid binary system as catalyst. Under the condition of 120℃ for 24h, the yield of cyclohexene oxide is 85.7% and the selectivity is 93%. ZL202210522712.4 discloses a phosphomolybdate-modified copper-porphyrin cobalt metal organic framework catalyst. The copper hydroxide solution added with phosphomolybdate solution is soaked in a cobalt tetra-carboxyphenyl porphyrin solution to obtain a phosphomolybdate-modified copper-porphyrin cobalt MOF material. By adding ionic liquid 1-vinyl-3-ethyl imidazole bromide, initiator and crosslinking agent, an integrated metal organic framework-based CO2 photo-thermal catalyst is polymerized, which can realize the photo-thermal catalytic conversion of CO2 to prepare cyclic carbonates.

[0004] The current synthesis process of cyclic carbonate still has many disadvantages, such as high pressure reaction (more than 10 atmospheres), addition of solvent (dichloromethane, etc.), and the like. Effective catalytic activity is also faced with the disadvantages of toxic metal residues, high cost of catalyst, complex synthesis process, low yield, and unsuitable for large-scale promotion, and the like. SUMMARY

[0005] In order to solve the above problems, the present application aims to provide an amine-based phenolic iron complex and a preparation method and application thereof, the amine-based phenolic iron complex preparation method is simple, as a catalyst, has the characteristics of safe and non-toxic, green and environmentally friendly, low cost, mild catalytic conditions, no additional solvent, high catalytic efficiency and high selectivity, and the like.

[0006] In order to achieve the above-mentioned purpose, the present application provides an amine-based phenolic iron complex, which comprises a metal central atom Fe and a ligand coordinated with the metal central atom Fe, the ligand has a structure shown in Formula I:

[0007]

[0008] In Formula I, R1, R1', R2, R2' are the same or different, and each is independently selected from H, Me, t Bu; R is selected from

[0009] According to a specific embodiment of the present application, preferably, the amine-based phenolic iron complex is selected from one or more than two combinations of , wherein R1, R2 are the same or different, and each is independently selected from H, Me, t Bu; X is selected from Cl, Br; more preferably, R1, R2 are the same or different, and each is independently selected from Me, t Bu; X is selected from Cl.

[0010] The present application also provides a preparation method of the above-mentioned amine-based phenolic iron complex, which comprises the following steps:

[0011] (1) Under the atmosphere of protective gas, formaldehyde aqueous solution is added to the solution containing the compound shown in Formula II, then a primary amine-containing aliphatic reagent is added, and heated to reflux for 24-48h (preferably 36h) to obtain the target ligand;

[0012]

[0013] In Formula II, R1, R2 are the same or different, and each is independently selected from H, Me, tBu; the primary amine-containing aliphatic reagent is selected from one or a combination of more than two of 1-(2-aminoethyl)piperidine, (S)-2-(aminomethyl)-1-ethylpyrrolidine, N-(2-aminoethyl)morpholine, cyclohexylmethylamine;

[0014] (2) under a protective gas atmosphere, a solution of an iron salt is added to the solution of the target ligand obtained in step (1), a triethylamine reagent is added, and the reaction is stirred for 10-20 h (preferably 15 h) to obtain the amine-based phenolic iron complex.

[0015] According to a specific embodiment of the present application, preferably, in steps (1) and (2), the protective gas comprises one or a combination of more than two of nitrogen, argon, and helium.

[0016] According to a specific embodiment of the present application, preferably, in step (1), the solvent of the solution of the compound of formula II is methanol and / or ethanol.

[0017] According to a specific embodiment of the present application, preferably, in step (1), the molar ratio of the primary amine-containing aliphatic reagent, formaldehyde, and the compound of formula II is 1:1.5-2.5:1.5-2.5, and more preferably 1:2:2.

[0018] According to a specific embodiment of the present application, preferably, in step (2), the solvent of the solution of the iron salt is methanol and / or ethanol.

[0019] According to a specific embodiment of the present application, preferably, in step (2), the solvent of the solution of the target ligand is methanol and / or ethanol.

[0020] According to a specific embodiment of the present application, preferably, in step (2), the iron salt is ferric chloride and / or ferric bromide.

[0021] According to a specific embodiment of the present application, preferably, in step (2), the molar ratio of the target ligand, the iron salt, and triethylamine is 1:1:2-3, and more preferably 1:1:2.

[0022] According to a specific embodiment of the present application, the above preparation method comprises the following specific steps:

[0023] (1) synthesis of the ligand: under the protection of a protective gas, a formaldehyde aqueous solution and a primary amine-containing aliphatic reagent are sequentially added to an alcohol solution of the compound of formula II, and the reaction is stirred, heated, and refluxed for 24-48 h (preferably 36 h), after which the reaction solution is cooled, filtered to obtain white precipitates, the precipitates are dissolved in dichloromethane and filtered through celite, and the target ligand is obtained after recrystallization in acetonitrile / dichloromethane;

[0024] (2) Synthesis of the complex: under the protection of protective gas, the target ligand and iron salt are respectively dissolved in alcohol solvent, the iron salt solution is added to the target ligand solution, and triethylamine reagent is added, and the reaction is stirred for 10-20h (preferably 15h), and after the reaction is completed, the amine-based phenolic iron complex is obtained after cooling and filtering, and the process is shown in Reaction Formula IV,

[0025]

[0026] The application also provides application of the amine-based phenolic iron complex as a catalyst in catalytic synthesis of cyclic carbonate.

[0027] The application also provides a method for catalytic synthesis of cyclic carbonate, which uses the amine-based phenolic iron complex as a catalyst, and the method comprises the following steps: mixing the amine-based phenolic iron complex and a cocatalyst, adding an epoxide compound shown in Formula III under the protection of protective gas, and passing carbon dioxide to perform a cycloaddition reaction,

[0028]

[0029] In Formula III, when R3 is H, R4 is CH3 or CH2Cl; and when R3 is not H, the epoxide compound is cyclohexene oxide.

[0030] The process of catalytic synthesis of cyclic carbonate is shown in Reaction Formula V,

[0031]

[0032] According to a specific embodiment of the application, preferably, in the method for catalytic synthesis of cyclic carbonate, the cocatalyst comprises one or a combination of two or more of tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride (TBAC), bis(triphenylphosphine)ammonium chloride (PPNCl), and 4-dimethylaminopyridine (DMAP).

[0033] According to a specific embodiment of the application, preferably, in the method for catalytic synthesis of cyclic carbonate, the epoxide compound comprises one or a combination of two or more of cyclohexene oxide, propylene oxide, and epichlorohydrin.

[0034] According to a specific embodiment of the application, preferably, in the method for catalytic synthesis of cyclic carbonate, the molar ratio of the amine-based phenolic iron complex, the cocatalyst, and the epoxide compound is 1:1-8:100-2000.

[0035] According to a specific embodiment of the application, preferably, in the method for catalytic synthesis of cyclic carbonate, the reaction temperature is 60-130°C, and more preferably 80-130°C.

[0036] According to a specific embodiment of the present application, preferably, in the method for catalytically synthesizing cyclic carbonates, the reaction time is 5-15 h.

[0037] According to a specific embodiment of the present application, preferably, in the method for catalytically synthesizing cyclic carbonates, the pressure of carbon dioxide is 0.1-5 MPa, more preferably 3 MPa.

[0038] According to a specific embodiment of the present application, the above-mentioned method for catalytically synthesizing cyclic carbonates comprises the following specific steps: the reaction kettle is preheated and dried in advance, after being cooled to room temperature, the amine-based phenolic iron complex and the cocatalyst are sequentially added into the reaction kettle and screwed tightly, the reaction kettle is vacuumized and replaced with inert gas, the anhydrous epoxide is added again under the protection of inert gas, the carbon dioxide is introduced to a certain pressure, and then the oil bath pot is put in, the cycloaddition reaction is carried out at a certain temperature. After the reaction is completed, the reaction kettle is cooled to room temperature by ice water mixture, the carbon dioxide gas is released to reduce the pressure, the kettle is opened to take samples for nuclear magnetic resonance hydrogen spectrum and infrared spectrum detection.

[0039] The present application provides an amine-based phenolic iron complex catalyst with good performance, which has simple preparation process, high catalytic efficiency, can catalyze CO2 and various epoxides to synthesize different types of cyclic carbonates, has mild synthesis conditions, does not need to add external solvent, and does not have the problem of heavy metal residue, and has wide industrial application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1A The H NMR spectrum of the ligand L1.1 is shown in the following figure: 1 The H NMR spectrum of the ligand L1.1 is shown in the following figure:

[0041] Figure 1B The H NMR spectrum of the ligand L1.1 is shown in the following figure: 13 The H NMR spectrum of the ligand L1.1 is shown in the following figure:

[0042] Figure 2 The H NMR spectrum of the ligand L1.2 is shown in the following figure: 1 The H NMR spectrum of the ligand L1.2 is shown in the following figure:

[0043] Figure 3 The H NMR spectrum of the ligand L1.3 is shown in the following figure: 1 The H NMR spectrum of the ligand L1.3 is shown in the following figure:

[0044] Figure 4A The H NMR spectrum of the ligand L2 is shown in the following figure: 1 The H NMR spectrum of the ligand L2 is shown in the following figure:

[0045] Figure 4B The H NMR spectrum of the ligand L2 is shown in the following figure: 13 The H NMR spectrum of the ligand L2 is shown in the following figure:

[0046] Figure 5A The H NMR spectrum of the ligand L3 is shown in the following figure: 1 The H NMR spectrum of the ligand L3 is shown in the following figure:

[0047] Figure 5B H NMR spectrum of the ligand L3 13 C NMR spectrum

[0048] Figure 6A H NMR spectrum of the ligand L4 1 H NMR spectrum

[0049] Figure 6B C NMR spectrum of the ligand L4 13 C NMR spectrum

[0050] Figure 7 UV-Vis spectrum of the ligands L1-L4 and complexes C1-C4

[0051] Figure 8 H NMR spectrum of the cycloaddition reaction product cyclohexene carbonate 1 H NMR spectrum

[0052] Figure 9 IR spectrum of the cycloaddition reaction product cyclohexene carbonate

[0053] Figure 10 H NMR spectrum of the cycloaddition reaction product propylene carbonate 1 H NMR spectrum

[0054] Figure 11 H NMR spectrum of the cycloaddition reaction product chloropropylene carbonate 1 H NMR spectrum. DETAILED DESCRIPTION

[0055] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present application, the technical solutions of the present application are described in detail as follows, but it should not be understood as a limitation to the implementable scope of the present application.

[0056] In the chemical formulae of the present application, the “-”, dotted bond or bold black bond only represents the connection between groups, and does not specifically refer to a single bond, for example, the connection between groups can be a single bond connection, a coordination connection, or a combination of single bond connection and coordination connection, etc.

[0057] Example 1

[0058] This example provides an aminophenol iron complex catalyst C1.1, the structure of which is shown below, which is prepared by the following steps:

[0059]

[0060] (1) Synthesis of ligand L1.1: 2,4-di-tert-butylphenol (2.06 g, 10 mmol) was added into a Schlenk flask under argon atmosphere, dissolved in methanol (20 mL), and then formaldehyde aqueous solution (0.75 mL, 10 mmol) and 1-(2-aminoethyl)piperidine (0.71 mL, 5 mmol) were added successively. The reaction was stopped after stirring and heating under reflux for 36 h, and the reaction solution was cooled to room temperature. The white precipitate was obtained by filtration, dissolved in dichloromethane, and filtered through celite. The white ligand L1.1 (2.00 g, 71%) was obtained by recrystallization from acetonitrile / dichloromethane. Its 1 H NMR spectrum is shown in Figure 1A , 13 C NMR spectrum is shown in Figure 1B , and its UV-Vis spectrum is shown in Figure 7 ;

[0061] 1 H NMR (500 MHz, CDC13) δ 9.61 (s, 2H), 7.19 (s, 2H), 6.87 (s, 2H), 3.58 (s, 4H), 2.59 (s, 4H), 2.45 (s, 4H), 1.79 (s, 4H), 1.52 (s, 2H), 1.40 (s, 18H), 1.27 (s, 18H); 13 C NMR (126 MHz, CDC13) δ 153.12 (s), 140.15 (s), 135.88 (s), 124.72 (s), 123.29 (s), 121.30 (s), 56.37 (s), 55.58 (s), 54.86 (s), 48.34 (s), 34.94 (s), 34.05 (s), 31.69 (s), 29.57 (s), 24.68 (s), 24.33 (s); The successful synthesis of the ligand was proved by UV-Vis spectrum and nuclear magnetic characterization of the ligand.

[0062] (2) Synthesis of complex C1.1: The ligand L1.1 (1.13 g, 2 mmol) was dissolved in methanol (20 mL) in a Schlenk flask under argon atmosphere, and a methanol (40 mL) solution of anhydrous FeCl3 (0.32 g, 2 mmol) was added to the ligand. Triethylamine (0.56 mL, 4 mmol) was added to the Schlenk flask, and the reaction was stirred for 15 h. After the reaction was completed, the amine-based phenolic iron complex C1.1 (1.06 g, 81%) was obtained by filtration after cooling. Its UV-Vis spectrum is shown in Figure 7 ;

[0063] HRMS (m / z): [M-Cl] + Calcd. for [C37 H 58 FeN2O2-Cl] + : 618.3842, found: 618.3845; the complex was characterized by UV-Vis spectrum and high resolution mass spectrum, which proved the successful synthesis of the complex.

[0064] Example 2

[0065] This example provides an aminophenol iron complex catalyst C1.2, the structure of which is shown below, which is prepared by the following steps:

[0066]

[0067] (1) Synthesis of ligand L1.2: under argon protection, 2-tert-butyl-4-methylphenol (1.64 g, 10 mmol) was added to a Schlenk flask, dissolved in methanol (20 mL), and then formaldehyde aqueous solution (0.75 mL, 10 mmol) and 1-(2-aminoethyl)piperidine (0.71 mL, 5 mmol) were added in sequence. After stirring and heating under reflux for 36 h, the reaction was stopped, the reaction solution was cooled to room temperature, and white precipitate was obtained by filtration. The precipitate was dissolved in dichloromethane and filtered through celite. After purification by recrystallization in acetonitrile / dichloromethane, white ligand L1.2 (1.61 g, 67%) was obtained. Its 1 H NMR spectrum is shown in Figure 2 , and its UV-Vis spectrum is shown in Figure 7 ;

[0068] 1 H NMR (500 MHz, CDCl3) δ 9.44 (s, 2H), 6.97 (s, 2H), 6.69 (s, 2H), 3.52 (s, 4H), 2.56 (s, 4H), 2.43 (s, 4H), 2.22 (s, 6H), 1.77 (s, 4H), 1.50 (s, 2H), 1.38 (s, 18H); the ligand was successfully synthesized by UV-Vis spectrum and nuclear magnetic resonance characterization of the ligand.

[0069] (2) Synthesis of complex C1.2: under argon atmosphere, ligand L1.2 (0.96 g, 2 mmol) was dissolved in methanol (20 mL) in a Schlenk flask, a methanol (40 mL) solution of anhydrous FeCl3 (0.32 g, 2 mmol) was added to the ligand, and then triethylamine (0.56 mL, 4 mmol) was added to the Schlenk flask. After stirring for 15 h, the reaction was stopped, and the aminophenol iron complex C1.2 (0.99 g, 87%) was obtained by filtration after cooling. Its UV-Vis spectrum is shown in Figure 7The UV-Vis spectrum of the ligand is shown in Figure 1.

[0070] Example 3

[0071] The present example provides an amino phenolic iron-based complex catalyst C1.3, the structure of which is shown below, which is prepared by the following steps:

[0072]

[0073] (1) Synthesis of ligand L1.3: Under argon protection, 2,4-dimethyl phenol (1.22 g, 10 mmol) was added to a Schlenk flask, dissolved in methanol (20 mL), and then formaldehyde aqueous solution (0.75 mL, 10 mmol) and 1-(2-aminoethyl)piperidine (0.71 mL, 5 mmol) were added in sequence. After stirring and heating under reflux for 36 h, the reaction was stopped, the reaction solution was cooled to room temperature, and white precipitate was obtained by filtration. The precipitate was dissolved in dichloromethane and filtered through celite. After recrystallization in acetonitrile / dichloromethane, white ligand L1.3 (1.03 g, 52%) was obtained. 1 The H NMR spectrum is shown in Figure 2. Figure 3 The UV-Vis spectrum is shown in Figure 3. Figure 7 ;

[0074] 1 H NMR (500 MHz, CDCl3) δ 9.21 (s, 2H), 6.85 (s, 2H), 6.66 (s, 2H), 3.57 (s, 4H), 2.56 (s, 4H), 2.38 (s, 4H), 2.19 (s, 12H), 1.77 (s, 4H), 1.49 (s, 2H); the successful synthesis of the ligand was proved by UV-Vis spectrum and nuclear magnetic resonance characterization of the ligand.

[0075] (2) Synthesis of complex C1.3: Under argon atmosphere, the ligand L1.3 (0.79 g, 2 mmol) was dissolved in methanol (20 mL) in a Schlenk flask, a methanol (40 mL) solution of anhydrous FeCl3 (0.32 g, 2 mmol) was added to the ligand, and then triethylamine (0.56 mL, 4 mmol) was added to the Schlenk flask. After stirring for 15 h, the reaction was completed, and the amino phenolic iron-based complex C1.3 (0.81 g, 83%) was obtained by filtration after cooling. Figure 7 The successful synthesis of the complex was proved by UV-Vis spectrum characterization of the complex.

[0076] Example 4

[0077] The present embodiment provides an amino phenolic iron complex catalyst C2, the structure is shown as follows, which is prepared by the following steps:

[0078]

[0079] (1) Synthesis of ligand L2: under the protection of argon, 2,4-di-tert-butyl phenol (2.06 g, 10 mmol) was added into a Schlenk flask, dissolved in methanol (20 mL), and then formaldehyde aqueous solution (0.75 mL, 10 mmol) and (s)-2-(aminomethyl)-1-ethylpyrrolidine (0.70 mL, 5 mmol) were added in sequence, the reaction was stopped after stirring and heating under reflux for 36 h, and white ligand L2 (1.64 g, 58%) was obtained after purification by recrystallization from acetonitrile / dichloromethane; the H NMR spectrum is shown in 1 HNMR spectrum is shown in Figure 4A , 13 C NMR spectrum is shown in Figure 4B , and the ultraviolet-visible spectrum is shown in Figure 7 ;

[0080] 1 H NMR (500 MHz, CDCl3) δ 9.68 (s, 2H), 7.20 (s, 2H), 6.87 (s, 2H), 3.86 (s, 2H), 3.42 (s, 2H), 3.35 (s, 1H), 3.04 (s, 1H), 2.67 (s, 2H), 2.48 (s, 1H), 2.24 (s, 2H), 1.90 (s, 1H), 1.67 (s, 2H), 1.51 (s, 1H), 1.39 (s, 18H), 1.27 (s, 18H), 1.20 (s, 3H); 13 C NMR (126 MHz, CDCl3) δ 153.57 (s), 140.10 (s), 135.97 (s), 124.86 (s), 123.34 (s), 121.77 (s), 64.39 (s), 58.46 (s), 53.95 (s), 53.54 (s), 50.01 (s), 34.94 (s), 34.07 (s), 31.71 (s), 29.56 (s), 28.52 (s), 22.75 (s), 13.00 (s); the successful synthesis of the ligand was proved by ultraviolet-visible spectrum and nuclear magnetic characterization of the ligand.

[0081] (2) Synthesis of complex C2: Ligand L2 (1.13 g, 2 mmol) was dissolved in methanol (20 mL) in a Schlenk flask under argon atmosphere, a solution of anhydrous FeCl3 (0.32 g, 2 mmol) in methanol (40 mL) was added to the ligand, and triethylamine (0.56 mL, 4 mmol) was added to the Schlenk flask, the reaction was stirred for 15 h, and the reaction was completed after cooling and filtration to obtain the amine-based phenolic iron complex C2 (1.14 g, 87%); its UV-Vis spectrum is shown in Figure 7 ; the successful synthesis of the complex was proved by UV-Vis spectrum characterization of the complex.

[0082] Example 5

[0083] This example provides an amine-based phenolic iron complex catalyst C3, the structure of which is shown below, which is prepared by the following steps:

[0084]

[0085] (1) Synthesis of ligand L3: 2,4-di-tert-butylphenol (2.06 g, 10 mmol) was added to a Schlenk flask under argon protection, dissolved in methanol (20 mL), and then formaldehyde aqueous solution (0.75 mL, 10 mmol) and 1-(2-aminoethyl)morpholine (0.65 mL, 5 mmol) were added in sequence, the reaction was stopped after stirring and heating under reflux for 36 h, the reaction liquid was cooled to room temperature, and white precipitate was obtained by filtration, which was dissolved in dichloromethane and filtered through celite, and then purified by recrystallization from acetonitrile / dichloromethane to obtain white ligand L3 (1.93 g, 68%); its UV-Vis spectrum is shown in 1 H NMR spectrum is shown in Figure 5A , 13 C NMR spectrum is shown in Figure 5B , and its UV-Vis spectrum is shown in Figure 7 ;

[0086] 1 H NMR (500 MHz, CDCI3) δ 9.25 (s, 2H), 7.20 (d, 2H), 6.87 (d, 2H), 3.90 (s, 4H), 3.59 (s, 4H), 2.66 (s, 4H), 2.53 (s, 4H), 1.38 (s, 18H), 1.26 (s, 18H); 13C NMR (126 MHz, CDCI3) δ 152.71 (s), 140.60 (s), 135.96 (s), 124.86 (s), 123.52 (s), 121.17 (s), 65.97 (s), 56.19 (s), 54.92 (s), 53.55 (s), 47.95 (s), 34.94 (s), 34.08 (s), 31.67 (s), 29.54 (s); the successful synthesis of the ligand was proved by UV-Vis spectrum and nuclear magnetic characterization of the ligand.

[0087] (2) Synthesis of complex C3: under the protection of argon, the ligand L3 (1.13 g, 2 mmol) was dissolved in a solution of methanol (20 mL) in a Schlenk flask, a solution of anhydrous FeCl3 (0.32 g, 2 mmol) dissolved in methanol (40 mL) was added to the ligand, and triethylamine (0.56 mL, 4 mmol) was added to the Schlenk flask, and the reaction was stirred for 15 h. After the reaction was completed, the amine-based phenolic iron complex C3 (1.17 g, 89%) was obtained after cooling and filtration; its UV-Vis spectrum is shown in Figure 7 ; the successful synthesis of the complex was proved by UV-Vis spectrum characterization of the complex.

[0088] Example 6

[0089] This example provides an amine-based phenolic iron complex catalyst C4, the structure of which is shown below, which is prepared by the following steps:

[0090]

[0091] (1) Synthesis of ligand L4: under the protection of argon, 2,4-di-tert-butylphenol (2.06 g, 10 mmol) was added to a Schlenk flask, dissolved in methanol (20 mL), and then formaldehyde aqueous solution (0.75 mL, 10 mmol) and cyclohexylmethylamine (0.65 mL, 5 mmol) were added in sequence. After stirring, heating and refluxing for 36 h, the reaction was stopped, the reaction liquid was cooled to room temperature, and white precipitate was obtained by filtration. The precipitate was dissolved in dichloromethane and filtered through celite, and then purified by recrystallization with acetonitrile / dichloromethane to obtain white ligand L4 (1.68 g, 61%); its UV-Vis spectrum is shown in 1 H NMR spectrum is shown in Figure 6A , 13 CNMR spectrum is shown in Figure 6B , and its UV-Vis spectrum is shown in Figure 7 ;

[0092] 1H NMR (500 MHz, CDCI3) δ 7.89 (s, 2H), 7.21 (s, 2H), 6.91 (s, 2H), 3.63 (s, 4H), 2.31 (d, 2H), 1.71 (d, 2H), 1.59 (s, 4H), 1.40 (s, 18H), 1.27 (s, 18H), 1.20 - 1.05 (m, 3H), 0.76 (q, 2H); 13 C NMR (126 MHz, CDCI3) δ 152.41 (s), 141.64 (s), 136.12 (s), 125.34 (s), 123.57 (s), 121.99 (s), 62.00 (s), 58.61 (s), 35.42 (s), 34.99 (s), 31.77 (d), 29.83 (s), 26.58 (s), 25.92 (s); The ligand was successfully synthesized by UV-visible spectrum and nuclear magnetic characterization of the ligand.

[0093] (2) Synthesis of complex C4: The ligand L4 (1.10 g, 2 mmol) was dissolved in methanol (20 mL) in a Schlenk flask under an argon atmosphere, a methanol (40 mL) solution of anhydrous FeCl3 (0.32 g, 2 mmol) was added to the ligand, and triethylamine (0.56 mL, 4 mmol) was added to the Schlenk flask, and the reaction was stirred for 15 h. After the reaction was completed, the amine-based phenolic iron complex C4 (1.04 g, 81%) was obtained after cooling and filtration. Its UV-visible spectrum is shown in Figure 7 ; The complex was successfully synthesized by UV-visible spectrum characterization of the complex.

[0094] Example 7

[0095] The present example provides a method for catalytically synthesizing cyclic carbonate, which comprises the following steps:

[0096] The catalyst C1.1 and the cocatalyst TBAB (molar ratio of catalyst, cocatalyst and epoxy cyclohexane is 1:4:1000) were sequentially added to a reaction kettle equipped with a magnet, the reaction kettle was sealed, and multiple vacuum and argon replacement cycles were performed through double-tube. Under argon protection, 2 mL of anhydrous epoxy cyclohexane was added, carbon dioxide was filled, and the pressure was controlled at 3 MPa. The reaction was carried out at 100°C for 9 h. After the reaction was completed, the reaction kettle was cooled to room temperature with an ice-water mixture, the gas was released and depressurized, and sampling was performed for 1 HNMR (see Figure 8 ) and infrared spectrum detection (see Figure 9 ), which proved that the product was cyclohexene carbonate, the yield was 55.6%, and the selectivity was 99%.

[0097] Example 8

[0098] This example provides a method for catalytic synthesis of cyclic carbonate, which is to change the co-catalyst in Example 7 to TBAC, and other conditions are the same. The product cyclohexene carbonate is obtained, the yield is 20.1%, and the selectivity is 53.8%.

[0099] Example 9

[0100] This example provides a method for catalytic synthesis of cyclic carbonate, which is to change the co-catalyst in Example 7 to PPNCl, and other conditions are the same. The product cyclohexene carbonate is obtained, the yield is 28.2%, and the selectivity is greater than 67.7%.

[0101] Example 10

[0102] This example provides a method for catalytic synthesis of cyclic carbonate, which is to change the co-catalyst in Example 7 to DMAP, and other conditions are the same. The product cyclohexene carbonate is obtained, the yield is 4.5%, and the selectivity is greater than 76.9%.

[0103] From the reactivity of Examples 7-10, it can be seen that the amine-based phenolic iron complex can catalyze the synthesis of cyclohexene carbonate from cyclohexene oxide and CO2, and when the co-catalyst is TBAB, the selectivity reaches 99%.

[0104] Example 11

[0105] This example provides a method for catalytic synthesis of cyclic carbonate, which is to change the reaction temperature in Example 7 to 85°C, and other conditions are the same. The product cyclohexene carbonate is obtained, the yield is 32.6%, and the selectivity is 98.1%.

[0106] Example 12

[0107] This example provides a method for catalytic synthesis of cyclic carbonate, which is to change the reaction temperature in Example 7 to 115°C, and other conditions are the same. The product cyclohexene carbonate is obtained, the yield is 67.6%, and the selectivity is greater than 99%.

[0108] Example 13

[0109] This example provides a method for catalytic synthesis of cyclic carbonate, which is to change the reaction temperature in Example 7 to 130°C, and other conditions are the same. The product cyclohexene carbonate is obtained, the yield is 83.6%, and the selectivity is greater than 99%.

[0110] From the reactivity of Examples 7, 11-13, it can be seen that as the reaction temperature increases, both the conversion rate and the selectivity gradually increase.

[0111] Example 14

[0112] The present example provides a method for catalytically synthesizing cyclic carbonate, which is to change the reaction pressure in Example 7 to 1 MPa, and other conditions are the same. The product cyclohexene carbonate is obtained, with a yield of 33.6%, and a selectivity of more than 99%.

[0113] Example 15

[0114] The present example provides a method for catalytically synthesizing cyclic carbonate, which is to change the reaction pressure in Example 7 to 5 MPa, and other conditions are the same. The product cyclohexene carbonate is obtained, with a yield of 53.3%, and a selectivity of more than 99%.

[0115] As can be seen from the reaction activities of Examples 7, 14 and 15, with the increase of carbon dioxide pressure, the conversion rate shows a trend of first increasing and then decreasing.

[0116] Example 16

[0117] The present example provides a method for catalytically synthesizing cyclic carbonate, which is to change the catalyst in Example 7 to C1.2, and other conditions are the same. The product cyclohexene carbonate is obtained, with a yield of 51.8%, and a selectivity of more than 99%.

[0118] Example 17

[0119] The present example provides a method for catalytically synthesizing cyclic carbonate, which is to change the catalyst in Example 7 to C1.3, and other conditions are the same. The product cyclohexene carbonate is obtained, with a yield of 51.8%, and a selectivity of more than 99%.

[0120] Example 18

[0121] The present example provides a method for catalytically synthesizing cyclic carbonate, which is to change the catalyst in Example 7 to C2, and other conditions are the same. The product cyclohexene carbonate is obtained, with a yield of 30.8%, and a selectivity of more than 99%.

[0122] Example 19

[0123] The present example provides a method for catalytically synthesizing cyclic carbonate, which is to change the catalyst in Example 7 to C3, and other conditions are the same. The product cyclohexene carbonate is obtained, with a yield of 60.9%, and a selectivity of 82.8%.

[0124] Example 20

[0125] The present example provides a method for catalytically synthesizing cyclic carbonate, which is to change the catalyst in Example 7 to C4, and other conditions are the same. The product cyclohexene carbonate is obtained, with a yield of 48.7%, and a selectivity of 67.3%.

[0126] Example 21

[0127] This example provides a method for catalytic synthesis of cyclic carbonate, which is to change the epoxycyclohexane in Example 7 to epoxpropane, the reaction temperature is 80℃, the reaction time is 5h, and other conditions are the same. Sampling is performed 1 H NMR (see Figure 10 ), the yield of propylene carbonate is 89.0%, and the selectivity is 99%.

[0128] Example 22

[0129] This example provides a method for catalytic synthesis of cyclic carbonate, which is to change the epoxpropane in Example 7 to epoxchloropropane, and other conditions are the same. Sampling is performed 1 H NMR (see Figure 11 ), the yield of chloropropylene carbonate is 96.2%, and the selectivity is greater than 99%.

[0130] The amine-based phenol iron complex provided in the present application has a simple preparation process, can efficiently catalyze carbon dioxide and epoxide (epoxycyclohexane, epoxpropane and epoxchloropropane) to synthesize cyclic carbonate through cycloaddition reaction, the selectivity can reach more than 99%, the conditions are mild, no additional solvent is needed, the synthesized cyclic carbonate does not have heavy metal residue problem, and has a wide industrial application prospect.

Claims

1. A method for catalytically synthesizing cyclic carbonate by using an amine-based phenolic iron complex as a catalyst, the method comprising the following steps: mixing the amine-based phenolic iron complex and a cocatalyst, adding an epoxide compound under a protective gas atmosphere, and introducing carbon dioxide to perform a cycloaddition reaction; wherein the epoxide compound is cyclohexene oxide, and the cocatalyst is tetrabutylammonium bromide; the cycloaddition reaction temperature is 100-130℃, and the pressure of carbon dioxide is 3-5 MPa; the amine-based phenolic iron complex comprises a metal central atom Fe and a ligand coordinated to the metal central atom Fe; the amine-based phenolic iron complex is prepared by the following steps: (1) adding a formaldehyde aqueous solution to a solution containing a compound shown in Formula II under a protective gas atmosphere, then adding an aliphatic reagent containing a primary amine, and heating to reflux for 24-48 h to obtain a target ligand; the aliphatic reagent containing a primary amine is selected from 1-(2-aminoethyl)piperidine or N-(2-aminoethyl)morpholine; (2) adding a solution containing an iron salt to the solution of the target ligand obtained in step (1) under a protective gas atmosphere, and adding a triethylamine reagent to react for 10-20 h to obtain the amine-based phenolic iron complex; in steps (1) and (2), the protective gas comprises one or a combination of two or more of nitrogen, argon, and helium; in step (1), the solvent of the solution containing the compound shown in Formula II is methanol and / or ethanol; in step (1), the molar ratio of the aliphatic reagent containing a primary amine, formaldehyde, and the compound shown in Formula II is 1:1.5-2.5:1.5-2.5; in step (1), the molar ratio of the aliphatic reagent containing a primary amine, formaldehyde, and the compound shown in Formula II is 1:2:2; in step (2), the solvent of the solution containing an iron salt is methanol and / or ethanol; in step (2), the solvent of the solution of the target ligand is methanol and / or ethanol; in step (2), the iron salt is ferric chloride and / or ferric bromide; in step (2), the molar ratio of the target ligand, the iron salt, and triethylamine is 1:1:2-3; in step (2), the molar ratio of the target ligand, the iron salt, and triethylamine is 1:1:2; the molar ratio of the amine-based phenolic iron complex, the cocatalyst, and the epoxide compound is 1:1-8:100-2000; and the cycloaddition reaction time is 5-15 h. ​ ​ ​ ​ The aminophenolic iron complex is selected from the group consisting of or ; wherein R1, R2are the same or different, each independently selected from H, Me, t Bu; X is selected from Cl, Br.

2. The process for the catalytic synthesis of cyclic carbonates according to claim 1, wherein, R1, R2are the same or different, each independently selected from Me, t Bu; X is selected from Cl.

3. The process for the catalytic synthesis of cyclic carbonates according to claim 1, wherein, ​ ​ Formula II, In formula II, R1, R2are the same or different, each independently selected from H, Me, t Bu; ​ ​ 4. The process for the catalytic synthesis of cyclic carbonates according to claim 3, wherein, ​ 5. The process for the catalytic synthesis of cyclic carbonates according to claim 3, wherein, ​ 6. The process for the catalytic synthesis of cyclic carbonates according to claim 3, wherein, ​ 7. The process for the catalytic synthesis of cyclic carbonates according to claim 3, wherein, ​ 8. The process for the catalytic synthesis of cyclic carbonates according to claim 3, wherein, ​ 9. The process for the catalytic synthesis of cyclic carbonates according to claim 3, wherein, ​ 10. The process for the catalytic synthesis of cyclic carbonates according to claim 3, wherein, ​ 11. The process for the catalytic synthesis of cyclic carbonates according to claim 3, wherein, ​ 12. The process for the catalytic synthesis of cyclic carbonates according to claim 3, wherein, ​ 13. The process for the catalytic synthesis of cyclic carbonates according to claim 1, wherein, ​ 14. The process for the catalytic synthesis of cyclic carbonates according to claim 1, wherein, ​

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