Metal organic ligand complex, preparation method and application thereof, and preparation method of carbon dioxide-based polycarbonate

Abstract

The invention provides a metal organic ligand complex, a preparation method and application thereof, and a preparation method of carbon dioxide-based polycarbonate, and belongs to the technical field of polycarbonate synthesis. The preparation method comprises the following steps: combining 5-(hydroxymethyl)-1H-pyrrole-2-formaldehyde with a nitrogen-containing ligand to generate an organic ligand, then carrying out a coordination complexation reaction on the organic ligand and metal to prepare the metal organic ligand complex, and blending metal potential through the organic ligand to obtain the metal organic ligand complex. Further, the metal active potential on the metal organic ligand complex enables the epoxide to be subjected to ring opening and carbon dioxide to be inserted to complete the whole reaction, so that the carbon dioxide-based polycarbonate is prepared. The carbon dioxide-based polycarbonate obtained by the invention has the advantages of high content of carbonate groups, high molecular weight, narrow molecular weight distribution, high selectivity and few byproducts (cyclic carbonate).

Description

Technical Field

[0001] This invention belongs to the field of polycarbonate synthesis technology, specifically relating to a metal-organic ligand complex and its preparation method and application, and a method for preparing carbon dioxide-based polycarbonate. Background Technology

[0002] Carbon dioxide is primarily produced by the combustion of various fossil fuels (such as coal, oil, and natural gas), and the increase in atmospheric carbon dioxide levels is a major cause of global warming. Therefore, reusing carbon dioxide and converting it into high-value-added materials has significant practical implications.

[0003] The production of polycarbonate consumes a significant amount of carbon dioxide. Therefore, as a biodegradable and recyclable plastic, polycarbonate can effectively reduce dependence on traditional fossil fuels, thereby reducing carbon dioxide emissions. Furthermore, due to its excellent properties and processing characteristics, polycarbonate has wide applications in medical devices, electronics, and other fields.

[0004] The reported methods for preparing polycarbonate can be categorized into the following types based on the type of catalyst used in the reaction system:

[0005] Zinc glutarate catalyst. The zinc glutarate catalyst is composed of zinc and glutaric acid. Its advantages are simple preparation and low by-products. However, the activity of this catalyst is poor and the molecular weight of the polycarbonate prepared is low (see existing technology: Liu Zhen, Wu Yulong, Nie Yingfang et al. Research progress on the synthesis of carbon dioxide-based polycarbonate by zinc glutarate system [J]. Molecular Catalysis, 2023, 37(05):498-511).

[0006] Bimetallic salt cyanide catalysts. Bimetallic salt cyanide catalysts are composed of two metal salt cyanides. Bimetallic salt cyanide catalysts have the advantages of high catalytic activity, high relative molecular weight of polycarbonate prepared, low degree of unsaturation and narrow distribution, but the content of carbonate groups in the polymer is low, resulting in poor mechanical properties of polycarbonate products (see existing technology: Zhao Jingwen, Xu Jie. Preparation progress and catalytic mechanism of bimetallic cyanide complex catalysts [J]. Polyurethane Industry, 2022, 37(05):9-11+23).

[0007] Metal salt porphyrin catalysts. Metal salt porphyrin catalysts are composed of porphyrin and metal salts, and a phase transfer catalyst is added to the reaction system to prepare polycarbonate. Polycarbonate synthesized using this catalyst has high molecular weight and narrow distribution. However, the catalyst synthesis is complex, resulting in high price, and the separation of the catalyst from the product is difficult (see existing technology: Guo Hongchen, Qin Yusheng, Wang Xianhong, et al. Copolymerization of carbon dioxide and propylene oxide catalyzed by aluminum porphyrin complexes [J]. Applied Chemistry, 2019, 36(10): 1118-1127).

[0008] Rare earth complex catalysts. Rare earth complex catalysts are complexes composed of rare earth metal salts, alkyl zinc, and polyols. By changing the types of each component, the activity and selectivity of the catalyst can be controlled. Rare earth complex catalysts have the advantages of high carbonate group content and good selectivity in synthesized polycarbonates, but the catalysts have low efficiency and high cost (see existing technology: Cheng Ruihua, Zhou Yujie, Hou Qiaoli, et al. Rare earth ternary catalytic system ZnO / SiO2 supported and quaternary ammonium salt catalyzed CO2 and propylene oxide synthesis of high molecular weight polycarbonate[J]. Chinese Journal of Catalysis, 2018, 39(08):1303-1310.).

[0009] Salen catalysts are metal complexes prepared from metal salts, primary diamine compounds, and salicylaldehyde compounds. The advantages of Salen catalysts are that the synthesized polycarbonates have high molecular weight and narrow distribution, but the catalyst preparation method is complicated, the amount used is large, and it cannot be recycled, resulting in high cost (see existing technology: Xia Li, Wang Wenzhen, Li Leilei, et al. Research progress of Salen-type catalysts for copolymerization of carbon dioxide and epoxides [J]. Journal of Xi'an Petroleum University (Natural Science Edition), 2019, 34(04):109-118.).

[0010] Therefore, it is crucial to develop a low-cost, highly active, and highly stable catalyst for the preparation of high-value-added polycarbonate products. Summary of the Invention

[0011] In view of this, the purpose of this invention is to provide a metal-organic ligand complex, its preparation method and application, and a method for preparing carbon dioxide-based polycarbonate. The metal-organic ligand complex provided by this invention has the advantages of low cost, high activity and high stability; using the metal-organic ligand complex provided by this invention as a catalyst for the preparation of carbon dioxide-based polycarbonate has the advantages of high carbonate group content, high molecular weight, narrow molecular weight distribution, high selectivity and few by-products (cyclic carbonates).

[0012] To achieve the above objectives, the present invention provides the following technical solution:

[0013] This invention provides a metal-organic ligand complex having the structure shown in Formula I, Formula II, or Formula III:

[0014]

[0015] In Formulas I to III, L1 is 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde; L2 is the compound shown in Formula a; L3 is the compound shown in Formula b; L4 is the compound shown in Formula c; and M is one or more of zinc, cobalt, iron, nickel, copper, titanium, and aluminum.

[0016]

[0017] In L2, R1, R2, R3, R4, and R5 are independently hydrogen, methyl, or ethyl;

[0018] In L3, R6 and R7 are independently hydrogen, methyl, ethyl, or phenyl;

[0019] In L4, R8, R9, R 10 R 11 R 12 R 13 R 14 and R 15 It can be hydrogen or methyl on its own.

[0020] Preferably, it has the structure shown in any one of Equations 1 to 7:

[0021]

[0022] This invention provides a method for preparing the organometallic ligand complex described above, comprising the following steps:

[0023] A nitrogen-containing ligand, 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde, an organic amine, a metal salt, and a polar organic solvent are mixed and subjected to a solvothermal reaction to obtain the organometallic ligand complex.

[0024] The nitrogen-containing ligand includes any one of the compounds with structures shown in formulas a to c;

[0025]

[0026] Among them, R1, R2, R3, R4 and R5 are independently hydrogen, methyl or ethyl;

[0027] R6 and R7 are independently hydrogen, methyl, ethyl, or phenyl;

[0028] R8, R9, R 10 R 11 R 12 R 13 R 14 and R 15 Independently hydrogen or methyl;

[0029] The metal salt contains one or more of the following metals: zinc, cobalt, iron, nickel, copper, titanium, and aluminum.

[0030] Preferably, the molar ratio of the nitrogen-containing ligand to 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde is (1-2):(1-6); the molar ratio of the nitrogen-containing ligand to the organic amine is (1-2):(0.001-10); and the molar ratio of the nitrogen-containing ligand to the metal salt is (1-2):(1-3).

[0031] Preferably, the temperature of the solvothermal reaction is 50–150°C, and the time is 1–24 h.

[0032] This invention provides the application of the metal-organic ligand complexes described in the above-described scheme or the metal-organic ligand complexes prepared by the above-described preparation method as catalysts in the preparation of carbon dioxide-based polycarbonates.

[0033] This invention provides a method for preparing carbon dioxide-based polycarbonate, comprising the following steps:

[0034] Provide raw materials; the raw materials include at least organometallic ligand complexes, epoxides, and carbon dioxide;

[0035] Under vacuum conditions, the raw materials are mixed and subjected to a polymerization reaction to obtain the carbon dioxide-based polycarbonate; the organometallic ligand complex is the organometallic ligand complex according to claim 1 or 2 or the organometallic ligand complex prepared by the preparation method according to any one of claims 3 to 5.

[0036] Preferably, the molar ratio of the organometallic ligand complex to the epoxide is (0.00001 to 0.01):1; and the pressure of the carbon dioxide is 0.1 to 5 MPa.

[0037] Preferably, the raw materials further include acid anhydrides and / or organic solvents; the molar ratio of the acid anhydride to the epoxide is (0.01 to 100): 1.

[0038] Preferably, the polymerization reaction is carried out at a temperature of 50–120°C for a time of 6–48 hours.

[0039] This invention provides a metal-organic ligand complex having the structure shown in Formula I, Formula II, or Formula III:

[0040]

[0041] In Formulas I to III, L1 is 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde; L2 is the compound shown in Formula a; L3 is the compound shown in Formula b; L4 is the compound shown in Formula c; and M is one or more of zinc, cobalt, iron, nickel, copper, titanium, and aluminum.

[0042]

[0043] In L2, R1, R2, R3, R4, and R5 are independently hydrogen, methyl, or ethyl;

[0044] In L3, R6 and R7 are independently hydrogen, methyl, ethyl, or phenyl;

[0045] In L4, R8, R9, R10 R 11 R 12 R 13 R 14 and R 15 It can be hydrogen or methyl on its own.

[0046] The organometallic ligand complexes provided by this invention have the advantages of low cost, high activity, and high stability.

[0047] This invention provides a method for preparing a metal-organic ligand complex. The method involves combining 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde with a nitrogen-containing ligand to generate an organic ligand, which then undergoes a coordination complexation reaction with a metal to prepare the metal-organic ligand complex. By adjusting the metal potential through the organic ligand, the active potential of the metal on the metal-organic ligand complex is adjusted to induce ring-opening of the epoxide and insertion of carbon dioxide, thus completing the entire reaction and preparing carbon dioxide-based polycarbonate.

[0048] The metal-organic ligand complex provided by this invention is used as a catalyst to prepare carbon dioxide-based polycarbonate. The resulting carbon dioxide-based polycarbonate has a high content of carbonate groups, a high molecular weight, and a narrow molecular weight distribution. It also has the advantages of high selectivity and few by-products (cyclic carbonates).

[0049] The preparation method provided by this invention is simple, and the organometallic ligand complex can be separated and recycled by centrifugation after the reaction. The obtained polycarbonate can be used alone or added as an additive to other synthetic products. Therefore, the polycarbonate product provided by this invention has good social and economic benefits. Detailed Implementation

[0050] This invention provides a metal-organic ligand complex having the structure shown in Formula I, Formula II, or Formula III:

[0051]

[0052] In Formulas I to III, L1 is 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde; L2 is the compound shown in Formula a; L3 is the compound shown in Formula b; L4 is the compound shown in Formula c; and M is one or more of zinc, cobalt, iron, nickel, copper, titanium, and aluminum.

[0053]

[0054] In L2, R1, R2, R3, R4, and R5 are independently hydrogen, methyl, or ethyl;

[0055] In L3, R6 and R7 are independently hydrogen, methyl, ethyl, or phenyl;

[0056] In L4, R8, R9, R 10 R 11 R 12 R 13 R 14 and R 15 It can be hydrogen or methyl on its own.

[0057] In this invention, the organometallic ligand complex preferably has the structure described in any one of Formulas 1 to 7:

[0058]

[0059]

[0060] In this invention, organic ligands and metals form metal-organic ligand complexes through NM coordination bonds.

[0061] This invention provides a method for preparing the organometallic ligand complex described above, comprising the following steps:

[0062] A nitrogen-containing ligand, 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde, an organic amine, a metal salt, and a polar organic solvent are mixed and subjected to a solvothermal reaction to obtain the organometallic ligand complex.

[0063] Unless otherwise specified, all raw materials and equipment used in this invention are commercially available.

[0064] In this invention, the nitrogen-containing ligand preferably includes any one of the compounds with structures shown in formulas a to c;

[0065]

[0066] Wherein, R1, R2, R3, R4, and R5 are independently hydrogen, methyl, or ethyl; R6 and R7 are independently hydrogen, methyl, ethyl, or phenyl; R8, R9, and R 10 R 11 R 12 R 13 R 14 and R 15 It can be hydrogen or methyl on its own.

[0067] In this invention, the structural formula of 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde is shown in formula d:

[0068]

[0069] In this invention, the molar ratio of the nitrogen-containing ligand to 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde is preferably (1-2):(1-6), and more preferably 1:4.

[0070] In this invention, the organic amine preferably includes one or more of diethylamine, triethylamine, aniline, and p-phenylenediamine. In this invention, the molar ratio of the nitrogen-containing ligand to the organic amine is preferably (1-2):(0.001-10), more preferably 1:(0.001-1), and even more preferably 1:0.001. The organic amine of this invention can adjust the pH of the reaction solution during the reaction of the metal and the ligand, thus playing a regulatory role.

[0071] In this invention, the metal salt preferably includes one of the following: metal formate, acetate, propionate, nitrate, and oxalate; the metal in the metal salt preferably includes one or more of zinc, cobalt, iron, nickel, copper, titanium, and aluminum. In this invention, the molar ratio of the nitrogen-containing ligand to the metal salt is preferably (1-2):(1-3), and more preferably 1:1.

[0072] In this invention, the polar organic solvent preferably includes one or more of methanol, ethanol, isopropanol, tert-butanol, N,N-dimethylformamide, and N,N-dimethylacetamide. This invention does not have particular requirements on the amount of the polar organic solvent used; amounts well known in the art can be used.

[0073] In this invention, the temperature of the solvothermal reaction is preferably 50-150°C, and the time is preferably 1-24 hours.

[0074] In this invention, the solvothermal reaction is preferably carried out under stirring conditions. This invention does not have particular requirements for the stirring speed; any speed well-known in the art can be used.

[0075] To complete the solvothermal reaction, the present invention preferably removes the solvent, washes, and dries the resulting reaction solution.

[0076] The present invention does not have any special requirements for the solvent removal method, as long as the solvent in the obtained reaction solution can be removed to obtain the metal-organic ligand complex.

[0077] In this invention, the detergent for washing preferably includes one or more of methanol, ethanol, isopropanol, tert-butanol, N,N-dimethylformamide and N,N-dimethylacetamide.

[0078] In this invention, the drying temperature is preferably 80-150°C, more preferably 90-130°C, and even more preferably 100-120°C.

[0079] This invention involves combining 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde with a nitrogen-containing ligand to generate an organic ligand, which then undergoes a coordination complexation reaction with a metal to prepare the metal-organic ligand complex. By adjusting the metal potential through the organic ligand, the active metal potential on the metal-organic ligand complex is increased to open the epoxide ring and allow carbon dioxide to be inserted to complete the entire reaction, thereby preparing carbon dioxide-based polycarbonate.

[0080] This invention provides the application of the organometallic ligand complexes described in the above-described scheme or the organometallic ligand complexes prepared by the preparation method described in the above-described scheme in the preparation of carbon dioxide-based polycarbonates.

[0081] Carbon dioxide-based polycarbonate can be prepared using the metal-organic ligand complex provided by this invention. The resulting carbon dioxide-based polycarbonate has a high content of carbonate groups, a high molecular weight, and a narrow molecular weight distribution. It also has the advantages of high selectivity and few by-products (cyclic carbonates).

[0082] This invention provides a method for preparing carbon dioxide-based polycarbonate, comprising the following steps:

[0083] Provide raw materials; the raw materials include at least organometallic ligand complexes, epoxides, and carbon dioxide;

[0084] Under vacuum conditions, the raw materials are mixed and subjected to a polymerization reaction to obtain the carbon dioxide-based polycarbonate; the organometallic ligand complex is the organometallic ligand complex described in the above scheme or the organometallic ligand complex prepared by the preparation method described in the above scheme.

[0085] In this invention, the raw materials include at least organometallic ligand complexes, epoxides, and carbon dioxide, and preferably also include acid anhydrides and / or organic solvents. Specifically, the raw materials can be organometallic ligand complexes, epoxides, and carbon dioxide; or organometallic ligand complexes, epoxides, carbon dioxide, and organic solvents; or organometallic ligand complexes, epoxides, acid anhydrides, and carbon dioxide; or organometallic ligand complexes, epoxides, acid anhydrides, carbon dioxide, and organic solvents.

[0086] When the raw materials do not include organic solvents, the present invention preferably includes mixing the raw materials under vacuum conditions as follows: mixing the raw materials other than epoxide and carbon dioxide, then evacuating and purging with nitrogen, repeating this operation until a vacuum state is reached, then adding epoxide and purging with carbon dioxide.

[0087] When the raw materials include organic solvents, the present invention preferably includes mixing the raw materials under vacuum conditions as follows: mixing the raw materials other than epoxides and carbon dioxide, then evacuating and purging with nitrogen, repeating this operation until a vacuum state is reached, then adding epoxides and organic solvents, and purging with carbon dioxide.

[0088] In this invention, the vacuum level of the vacuum condition is preferably <10 kPa.

[0089] In this invention, the epoxide preferably includes one or more of ethylene oxide, propylene oxide, cyclohexane oxide, epichlorohydrin, and styrene oxide. In this invention, the molar ratio of the organometallic ligand complex to the epoxide is preferably (0.00001–0.01):1, more preferably (0.0001–0.001):1.

[0090] In this invention, the addition of carbon dioxide is preferably the introduction of carbon dioxide gas; the pressure of the carbon dioxide is preferably 0.1 to 5 MPa, more preferably 1 to 4 MPa.

[0091] In this invention, the acid anhydride preferably has the structure shown in formula e;

[0092]

[0093] In formula e, R' and R” are independently hydrogen, methyl, ethyl or phenyl.

[0094] In this invention, the molar ratio of the acid anhydride to the epoxide is preferably (0.01–100):1, more preferably (0.02–10):1, and even more preferably (0.02–0.5):1. In this invention, the acid anhydride is ring-opened and then connected to the epoxide.

[0095] In this invention, the organic solvent preferably includes one of dichloromethane, tetrahydrofuran, toluene, and ethylbenzene, and the volume ratio of the organic solvent to the epoxide is preferably (0.1-100):1, more preferably (10-80):1, and even more preferably (20-50):1.

[0096] In this invention, the temperature of the polymerization reaction is preferably 50-120°C, more preferably 70-100°C, and even more preferably 80-90°C; the time is preferably 6-48h, more preferably 10-35h, and even more preferably 15-25h.

[0097] To complete the polymerization reaction, the present invention preferably adds a hydrochloric acid-methanol solution to the obtained reaction solution to precipitate crude carbon dioxide-based polycarbonate, which is then washed, filtered, and dried in sequence.

[0098] In this invention, the concentration of hydrochloric acid in the hydrochloric acid-methanol solution is preferably 1 mol / L. This invention enables the end-capping of carbon dioxide-based polycarbonate by adding the hydrochloric acid-methanol solution, and also facilitates the precipitation of carbon dioxide-based polycarbonate.

[0099] The present invention does not have any special requirements for the washing, filtering and drying steps, and any method known in the art can be used to obtain pure carbon dioxide-based polycarbonate.

[0100] The preparation method provided by this invention is simple, and the organometallic ligand complex can be separated and recycled by centrifugation after the reaction. The obtained polycarbonate can be used alone or added as an additive to other synthetic products. Therefore, the polycarbonate product provided by this invention has good social and economic benefits.

[0101] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, provides a method for preparing and applying a metal-organic ligand complex and a method for preparing carbon dioxide-based polycarbonate, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0102] Example 1

[0103] A method for preparing organometallic ligand complexes:

[0104] Pyridine (10 mmol), 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde, triethylamine, and cobalt nitrate were added to a hydrothermal reactor in a molar ratio of 2:4:0.001:1. Methanol (50 mL) was added, and the mixture was heated to 50 °C and reacted for 1 h. After the reaction was completed, the organometallic ligand complex was centrifuged to separate the solid. The solid was then washed with ethanol, centrifuged three times, and dried at 80 °C for 12 h to obtain the pure organometallic ligand complex, the structure of which is shown in Formula 1.

[0105]

[0106] Example 2

[0107] A method for preparing organometallic ligand complexes:

[0108] Urea (10 mmol), 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde, diethylamine, and zinc formate were added to a hydrothermal reactor in a molar ratio of 1:4:0.001:1. Ethanol (50 mL) was added, and the mixture was heated to 80 °C and reacted for 4 h. After the reaction was completed, the organometallic ligand complex was centrifuged to separate the solid. The solid was then washed with ethanol, centrifuged three times, and dried at 100 °C for 12 h to obtain the pure organometallic ligand complex, the structure of which is shown in Formula 2.

[0109]

[0110] Example 3

[0111] A method for preparing organometallic ligand complexes:

[0112] 1,3-Dimethylurea (10 mmol), 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde, aniline, and ferric propionate were added to a hydrothermal reactor in a molar ratio of 1:4:0.001:1. N,N-Dimethylformamide (50 mL) was added, and the mixture was heated to 120 °C and reacted for 8 h. After the reaction was completed, the organometallic ligand complex was centrifuged to separate the solid. The solid was then washed with isopropanol, centrifuged three times, and dried at 120 °C for 12 h to obtain the pure organometallic ligand complex, the structure of which is shown in Formula 3.

[0113]

[0114] Example 4

[0115] A method for preparing organometallic ligand complexes:

[0116] 1-Ethyl-3-methylurea (10 mmol), 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde, p-phenylenediamine, and nickel oxalate were added to a hydrothermal reactor in a molar ratio of 1:4:0.001:1. N,N-dimethylacetamide (50 mL) was added, and the mixture was heated to 150 °C and reacted for 12 h. After the reaction was completed, the organometallic ligand complex was centrifuged to separate the solid. The solid was then washed with tert-butanol, centrifuged three times, and dried at 150 °C for 12 h to obtain the pure organometallic ligand complex, the structure of which is shown in Formula 4.

[0117]

[0118] Example 5

[0119] A method for preparing organometallic ligand complexes:

[0120] 2,2'-Bipyridine (10 mmol), 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde, p-phenylenediamine, and copper nitrate were added to a hydrothermal reactor in a molar ratio of 1:4:0.001:1. Isopropanol (50 mL) was added, and the mixture was heated to 120 °C and reacted for 16 h. After the reaction was completed, the organometallic ligand complex was centrifuged to separate the solid. The solid was then washed with N,N-dimethylformamide, centrifuged three times, and dried at 150 °C for 12 h to obtain the pure organometallic ligand complex, the structure of which is shown in Formula 5.

[0121]

[0122] Example 6

[0123] A method for preparing organometallic ligand complexes:

[0124] 6,6'-dimethyl-2,2'-bipyridine (10 mmol), 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde, p-phenylenediamine, and titanium nitrate were added to a hydrothermal reactor in a molar ratio of 1:4:0.001:1. Isopropanol (50 mL) was added, and the mixture was heated to 120 °C and reacted for 20 h. After the reaction was completed, the organometallic ligand complex was centrifuged to separate the solid. The solid was then washed with N,N-dimethylacetamide, centrifuged three times, and dried at 150 °C for 12 h to obtain the pure organometallic ligand complex, the structure of which is shown in Formula 6.

[0125]

[0126] Example 7

[0127] A method for preparing organometallic ligand complexes:

[0128] 4,4'-dimethyl-2,2'-bipyridine (10 mmol), 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde, p-phenylenediamine, and aluminum nitrate were added to a hydrothermal reactor in a molar ratio of 1:4:0.001:1. Isopropanol (50 mL) was added, and the mixture was heated to 150 °C and reacted for 24 h. After the reaction was completed, the organometallic ligand complex was centrifuged to separate the solid. The solid was then washed with N,N-dimethylacetamide, centrifuged three times, and dried at 150 °C for 12 h to obtain the pure organometallic ligand complex, the structure of which is shown in Formula 7.

[0129]

[0130] Example 8

[0131] A method for preparing carbon dioxide-based polycarbonate:

[0132] The organometallic ligand complex prepared in Example 1 (with a molar ratio of 0.00001:1 to the reactant ethylene oxide) was added to a 500 mL reactor. The reactor was evacuated and then filled with nitrogen. This process was repeated three times until the reactor was completely under vacuum (vacuum degree less than 10 kPa). Ethylene oxide (500 mmol) was added, and carbon dioxide was introduced at a pressure of 0.1 MPa. The mixture was heated to 50 °C and stirred to carry out the reaction. After 6 h of reaction, a methanol solution of 1 mol / L hydrochloric acid was added, and the mixture was washed, filtered, and dried sequentially to obtain polycarbonate polyol, i.e., the carbon dioxide-based polycarbonate, with the structure shown in formula g.

[0133]

[0134] Example 9

[0135] A method for preparing carbon dioxide-based polycarbonate:

[0136] The organometallic ligand complex prepared in Example 2 (with a molar ratio of organometallic ligand complex to reactant propylene oxide of 0.0001:1) was added to the reactor as a catalyst. The reactor was evacuated and then filled with nitrogen. This process was repeated three times until the reactor was completely under vacuum (vacuum degree less than 10 kPa). Propylene oxide (500 mmol) was added, and carbon dioxide was introduced at a pressure of 1 MPa. The mixture was heated to 70°C and stirred to carry out the reaction. After the reaction was completed for 12 h, a methanol solution of 1 mol / L hydrochloric acid was added, and the mixture was washed, filtered, and dried sequentially to obtain polycarbonate polyol, namely the carbon dioxide-based polycarbonate.

[0137] Example 10

[0138] A method for preparing a carbon dioxide-based polycarbonate product:

[0139] The organometallic ligand complex prepared in Example 3 (with a molar ratio of 0.001:1 to the total molar ratio of the organometallic ligand complex to the reactants cyclohexane oxide and propylene oxide) was added to the reactor as a catalyst. The reactor was evacuated and then filled with nitrogen. After repeating this process three times, the reactor was completely under vacuum (vacuum degree less than 10 kPa). Cyclohexane oxide (500 mmol) and propylene oxide (100 mmol) were added, and carbon dioxide was introduced at a pressure of 2 MPa. The mixture was heated to 100 °C and stirred to carry out the reaction. After the reaction was completed for 16 h, a methanol solution of 1 mol / L hydrochloric acid was added, and the mixture was washed, filtered, and dried sequentially to obtain polycarbonate polyol, namely the carbon dioxide-based polycarbonate.

[0140] Example 11

[0141] A method for preparing a carbon dioxide-based polycarbonate product:

[0142] The organometallic ligand complex prepared in Example 4 (with a molar ratio of organometallic ligand complex to epichlorohydrin of 0.01:1) was added to the reactor as a catalyst. The reactor was evacuated and then filled with nitrogen. This process was repeated three times until the reactor was completely under vacuum (vacuum degree less than 10 kPa). Epichlorohydrin (500 mmol) was added, and carbon dioxide was introduced at a pressure of 3 MPa. The mixture was heated to 120 °C and stirred to carry out the reaction. After 24 h of reaction, a methanol solution of 1 mol / L hydrochloric acid was added, and the mixture was washed, filtered, and dried sequentially to obtain polycarbonate polyol, i.e., the carbon dioxide-based polycarbonate.

[0143] Example 12

[0144] A method for preparing a carbon dioxide-based polycarbonate product:

[0145] Using the organometallic ligand complex prepared in Example 5 as a catalyst, the catalyst and succinic anhydride (molar ratio of succinic anhydride to propylene oxide is 10:1) (molar ratio of organometallic ligand complex to reactant propylene oxide is 0.0001:1) were added to a reaction vessel. The reaction vessel was evacuated and purged with nitrogen. After repeating this process three times, the reaction vessel was completely evacuated (vacuum degree less than 10 kPa). Propylene oxide (500 mmol) and dichloromethane (20 mL) were added, and carbon dioxide was introduced at a pressure of 4 MPa. The mixture was heated to 120 °C and stirred to carry out the reaction. After the reaction was completed for 36 h, a methanol solution of 1 mol / L hydrochloric acid was added, and the mixture was washed, filtered, and dried sequentially to obtain polycarbonate polyol, i.e., the carbon dioxide-based polycarbonate, with the structure shown in formula h.

[0146]

[0147] Example 13

[0148] A method for preparing a carbon dioxide-based polycarbonate product:

[0149] Using the organometallic ligand complex prepared in Example 6 as a catalyst, the catalyst and phthalic anhydride (the molar ratio of phthalic anhydride to ethylene oxide was 1:10) (the molar ratio of the organometallic ligand complex to the reactant ethylene oxide was 0.001:1) were added to a reaction vessel. The reaction vessel was evacuated and then filled with nitrogen. After repeating this process three times, the reaction vessel was completely under vacuum (vacuum degree less than 10 kPa). Ethylene oxide (500 mmol) and toluene (30 mL) were added, and carbon dioxide was introduced at a pressure of 5 MPa. The mixture was heated to 80 °C and stirred to carry out the reaction. After the reaction was completed for 36 h, a methanol solution of 1 mol / L hydrochloric acid was added, and the mixture was washed, filtered, and dried sequentially to obtain polycarbonate polyol, namely the carbon dioxide-based polycarbonate, with the structure shown in Formula i.

[0150]

[0151] Example 14

[0152] A method for preparing a carbon dioxide-based polycarbonate product:

[0153] Using the organometallic ligand complex prepared in Example 7 as a catalyst, the catalyst and benzoic anhydride (the molar ratio of benzoic anhydride to cyclohexane oxide was 1:50) (the molar ratio of the organometallic ligand complex to the reactant cyclohexane oxide was 0.001:1) were added to a reaction vessel. The reaction vessel was evacuated and then filled with nitrogen. After repeating this process three times, the reaction vessel was completely under vacuum (vacuum degree less than 10 kPa). Cyclohexane oxide (500 mmol) and tetrahydrofuran (50 mL) were added, and carbon dioxide was introduced at a pressure of 5 MPa. The mixture was heated to 120 °C and stirred to carry out the reaction. After the reaction was completed for 36 h, a methanol solution of 1 mol / L hydrochloric acid was added, and the mixture was washed, filtered, and dried sequentially to obtain polycarbonate polyol, namely the carbon dioxide-based polycarbonate.

[0154] Example 15

[0155] A method for preparing a carbon dioxide polycarbonate product:

[0156] Using the organometallic ligand complex prepared in Example 2 as a catalyst, the catalyst and succinic anhydride (succinic anhydride to epichlorohydrin molar ratio of 1:20) (the organometallic ligand complex to reactant epichlorohydrin molar ratio of 0.001:1) were added to a reaction vessel. The reaction vessel was evacuated and filled with nitrogen. After repeating this process three times, the reaction vessel was completely under vacuum (vacuum degree less than 10 kPa). Epichlorohydrin (500 mmol) was added, and carbon dioxide was introduced at a pressure of 5 MPa. The mixture was heated to 120 °C and stirred to carry out the reaction. After the reaction was completed for 36 h, a methanol solution of 1 mol / L hydrochloric acid was added, and the mixture was washed, filtered, and dried sequentially to obtain polycarbonate polyol, namely the carbon dioxide-based polycarbonate.

[0157] Example 16

[0158] A method for preparing a carbon dioxide-based polycarbonate product:

[0159] Using the organometallic ligand complex prepared in Example 3 as a catalyst, the catalyst and benzoic anhydride (the total molar ratio of benzoic anhydride to propylene oxide and ethylene oxide was 1:20) (the molar ratio of the organometallic ligand complex to the total molar ratio of the reactants propylene oxide and ethylene oxide was 0.001:1) were added to a reaction vessel. The reaction vessel was evacuated and then filled with nitrogen. After repeating this process three times, the reaction vessel was completely under vacuum (vacuum degree less than 10 kPa). Propylene oxide (500 mmol) and ethylene oxide (500 mmol) were added, and carbon dioxide was introduced at a pressure of 5 MPa. The mixture was heated to 120 °C and stirred to carry out the reaction. After the reaction was completed for 36 h, a methanol solution of 1 mol / L hydrochloric acid was added, and the mixture was washed, filtered, and dried sequentially to obtain polycarbonate polyol, namely the carbon dioxide-based polycarbonate.

[0160] The properties of the carbon dioxide-based polycarbonates obtained in Examples 8-16 are shown in Table 1.

[0161] Table 1. Properties of the carbon dioxide-based polycarbonates obtained in Examples 8-16

[0162]

[0163] Note a: The yield corresponds to the number of moles of epoxide added; CO2 content refers to the carbonate group content.

[0164] As can be seen from Table 1, the carbon dioxide-based polycarbonate prepared using the metal-organic ligand complex provided by the present invention has a high content of carbonate groups, a high molecular weight, a narrow molecular weight distribution, high selectivity, and few byproducts (cyclic carbonates).

[0165] Comparative Example 1

[0166] Carbon dioxide-based polycarbonates were prepared using zinc glutarate as a catalyst. See prior art: Moonhor Ree, Yongtaek Hwang, Jong-Seong Kim, Hyunchul Kim, Gahee Kim, Heesoo Kim, New findings in the catalytic activity of zinc glutarate and its application in the chemical fixation of CO2 into polycarbonates and their derivatives, Catalysis Today, Volume 115, Issues 1-4, 2006, Pages 134-145.

[0167] Comparative Example 2

[0168] Carbon dioxide-based polycarbonate was prepared using a bimetallic cyanide catalyst. See prior art: Zhang Rongzhao, Zhang Yong. Catalytic copolymerization of CO2 / propylene oxide using bimetallic cyanide complexes [J]. Plastics, 2023, 52(01):73-77.

[0169] Comparative Example 3

[0170] Carbon dioxide-based polycarbonate was prepared using an aluminum porphyrin catalyst. See existing technology: Wu Wei, Qin Yusheng, Wang Xianhong, Wang Fusong. Copolymerization of carbon dioxide and epoxides catalyzed by bifunctional aluminum porphyrin complexes [J]. Acta Polymerica Sinica, 2014, (07): 1017-1022.

[0171] Comparative Example 4

[0172] Carbon dioxide-based polycarbonate was prepared using a rare earth ternary catalyst. See existing technology: Cheng Ruihua, Zhou Yujie, Hou Qiaoli, et al. ZnO / SiO2 supported rare earth ternary catalytic system and quaternary ammonium salt catalysis for the synthesis of high molecular weight polycarbonate from CO2 and propylene oxide [J]. Chinese Journal of Catalysis, 2018, 39(08):1303-1310.

[0173] Comparative Example 5

[0174] Carbon dioxide-based polycarbonate was prepared using Salen catalyst. See existing technology: Li Jiajia, Zhou Yujie, Cheng Ruihua, Liu Baiping. Synthesis of SalenCo-(III)CN and its catalytic copolymerization of carbon dioxide and epoxides [J]. Acta Polymerica Sinica, 2017, (12): 1915-1922.

[0175] The properties of carbon dioxide-based polycarbonates obtained from Comparative Examples 1 to 5 are shown in Table 2, and are all the best data among the existing technologies.

[0176] Table 2. Properties of carbon dioxide-based polycarbonates obtained from Comparative Examples 1–5

[0177]

[0178] As shown in Table 2, the carbon dioxide-based polycarbonate prepared using the metal-organic ligand complex provided by this invention as a catalyst has a higher polycarbonate chain length, a smaller polymer dispersibility index, and fewer byproducts compared to the catalysts in the table above. In addition, the catalyst of this invention is a heterogeneous catalyst, which can be obtained by dissolution and centrifugation, and the obtained catalyst can be repeatedly recycled.

[0179] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A metal-organic ligand complex, characterized in that, It has the structure shown in Equation I, Equation II, or Equation III: In Formulas I to III, L1 is 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde; L2 is the compound shown in Formula a; L3 is the compound shown in Formula b; L4 is the compound shown in Formula c; and M is one or more of zinc, cobalt, iron, nickel, copper, titanium, and aluminum. In L2, R1, R2, R3, R4, and R5 are independently hydrogen, methyl, or ethyl; In L3, R6 and R7 are independently hydrogen, methyl, ethyl, or phenyl; In L4, R8, R9, R 10 R 11 R 12 R 13 R 14 and R 15 It can be hydrogen or methyl on its own.

2. The organometallic ligand complex according to claim 1, characterized in that, It has the structure shown in any one of Equations 1 to 7:

3. The method for preparing the organometallic ligand complex according to claim 1 or 2, characterized in that, Includes the following steps: A nitrogen-containing ligand, 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde, an organic amine, a metal salt, and a polar organic solvent are mixed and subjected to a solvothermal reaction to obtain the organometallic ligand complex. The nitrogen-containing ligand includes any one of the compounds with structures shown in formulas a to c; Among them, R1, R2, R3, R4 and R5 are independently hydrogen, methyl or ethyl; R6 and R7 are independently hydrogen, methyl, ethyl, or phenyl; R8, R9, R 10 R 11 R 12 R 13 R 14 and R 15 Independently hydrogen or methyl; The metal salt contains one or more of the following metals: zinc, cobalt, iron, nickel, copper, titanium, and aluminum.

4. The preparation method according to claim 3, characterized in that, The molar ratio of the nitrogen-containing ligand to 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde is (1-2):(1-6); the molar ratio of the nitrogen-containing ligand to the organic amine is (1-2):(0.001-10); and the molar ratio of the nitrogen-containing ligand to the metal salt is (1-2):(1-3).

5. The preparation method according to claim 3, characterized in that, The solvothermal reaction is carried out at a temperature of 50–150°C for a duration of 1–24 h.

6. The application of the organometallic ligand complex according to claim 1 or 2, or the organometallic ligand complex prepared by any one of claims 3 to 5, as a catalyst in the preparation of carbon dioxide-based polycarbonate.

7. A method for preparing carbon dioxide-based polycarbonate, characterized in that, Includes the following steps: Provide raw materials; the raw materials include at least organometallic ligand complexes, epoxides, and carbon dioxide; Under vacuum conditions, the raw materials are mixed and subjected to a polymerization reaction to obtain the carbon dioxide-based polycarbonate; the organometallic ligand complex is the organometallic ligand complex according to claim 1 or 2 or the organometallic ligand 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 molar ratio of the organometallic ligand complex to the epoxide is (0.00001 to 0.01):1; the pressure of the carbon dioxide is 0.1 to 5 MPa.

9. The preparation method according to claim 7 or 8, characterized in that, The raw materials also include acid anhydrides and / or organic solvents; the molar ratio of the acid anhydride to the epoxide is (0.01 to 100):

1.

10. The preparation method according to claim 7 or 8, characterized in that, The polymerization reaction is carried out at a temperature of 50–120°C for a duration of 6–48 hours.

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