Transition metal catalyst based on terpyridyl ligand as well as preparation method and application of transition metal catalyst
By using a transition metal catalyst based on terpyridine ligands, copolymerization of olefins and polar monomers was achieved, which solved the problem of the limitation of non-polar properties in polyolefin materials and improved the application range and performance of the materials.
Patent Information
- Application Number
- CN202511042610.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-28
- Publication Date
- 2025-11-18
AI Technical Summary
Existing polyolefin materials have limited applications due to their non-polar properties, making it difficult to introduce polar functional groups into the non-polar framework to improve dyeability and compatibility.
By using a transition metal catalyst based on terpyridine ligands, a stable octahedral coordination configuration is formed between the synthesized terpyridine ligands and cobalt. Different substituents are introduced to regulate electronic effects, thereby achieving copolymerization of olefins and polar monomers.
Under mild reaction conditions, the catalyst is simple to synthesize, low in cost, high in yield, and has stable catalytic activity. It can effectively introduce polar functional groups into the polyolefin skeleton and improve the material properties.
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Figure CN120965773A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application provides a transition metal catalyst based on terpyridine ligand, a preparation method and application thereof, and particularly relates to application in the field of catalyzing copolymerization of olefin and polar monomer. BACKGROUND
[0002] Polyolefin materials are ubiquitous in daily life, and are the largest annual output and the most widely used polymer materials, but one of the biggest shortcomings is its non-polar property, and the introduction of polar functional groups into the non-polar skeleton of polyolefin provides dyeability, adhesion and compatibility with other polymer matrices for non-polar polymers, so people expect to copolymerize olefin and polar monomer to obtain functionalized olefin with high performance. The application introduces polar functional groups into the non-polar skeleton of polyolefin by preparing a transition metal catalyst based on terpyridine ligand, so that the polyolefin material has a wider application. This is undoubtedly crucial for the development of polyolefin industry, and the development of a new generation of olefin polymerization catalyst undoubtedly promotes the progress of the polyolefin industry.
[0003] Cobalt-mediated radical polymerization (CMRP) is an effective and versatile method for controlling the polymerization of vinyl monomers based on the reversible deactivation of cobalt complex growth radical. Terpyridine is a classic multidentate nitrogen-containing ligand, and the complex formed by the terpyridine and cobalt has also become a research hotspot in the field of catalysis. The three pyridine rings of terpyridine form a stable octahedral coordination configuration with the cobalt center through a conjugated system, which inhibits the loss of the metal center, and different substituents are introduced into the para position of the central ring and the peripheral pyridine ring of terpyridine, so as to accurately regulate the catalytic performance of the cobalt complex, such as polymerization activity, polymer relative molecular mass and distribution, branching degree, copolymerization performance and the like. SUMMARY
[0004] In view of the current situation of the prior art, the application provides a transition metal catalyst based on terpyridine ligand, a preparation method and application thereof.
[0005] To achieve the above object, the application provides a transition metal complex based on terpyridine ligand, and the structural formula is as follows:
[0006]
[0007] wherein R1 is selected from any one of a hydrogen atom, an electron-donating group or a fluorine atom electron-withdrawing group; and R2 is selected from a hydrogen atom electron-donating group.
[0008] A preparation method of a transition metal catalyst based on terpyridine ligand, comprising the following steps:
[0009] (1) Synthesis of ligand: sequentially adding a first reagent, a second reagent, anhydrous ethanol and deionized water, heating and stirring, then adding NaOH for timed reaction, and then adding excess ammonia water until the reaction is completed to obtain a ligand product, wherein the first reagent is selected from 2-acetylpyridine or 2-acetyl-6-methylpyridine, and the second reagent is any one or several of benzaldehyde, p-methylbenzaldehyde, p-fluorobenzaldehyde or p-chlorobenzaldehyde;
[0010] (2) Synthesis of metal complex: under an inert gas atmosphere, dissolving the ligand product in step (1) with dichloromethane, and adding cobalt acetylacetonate for stirring at room temperature, and obtaining a metal complex after the reaction is completed;
[0011] (3) Copolymerization of ethylene and vinyl acetate: under an inert gas atmosphere, mixing a free radical initiator, anhydrous tetrahydrofuran and vinyl acetate to obtain a monomer-initiator solution, mixing the monomer-initiator solution with the metal complex under an ethylene gas atmosphere, stirring at a temperature of 70-90℃ and a gas pressure of 0.4-1.6 MPa to carry out a polymerization reaction, obtaining a white solution, and obtaining the transition metal catalyst after evaporating and removing the solvent.
[0012] Preferably, in step (1), the molar ratio of the first reagent to the second reagent is 2:1; the ratio of anhydrous ethanol to deionized water is 2:1; the molar ratio of NaOH to the second reagent is 1:1.5; and the molar ratio of ammonia water to the second reagent is 1:1.
[0013] Preferably, in step (1), the temperature of the heating and stirring is 70-90℃, and the stirring is carried out at 400-600 rpm for 10-12 h; and the timed reaction time is 10-12 h.
[0014] Preferably, in step (2), the molar ratio of cobalt acetylacetonate to the ligand is 1:1-1:1.1; and the stirring is carried out at 400-600 rpm at room temperature for 20-24 h.
[0015] Preferably, the molar ratio of vinyl acetate to the metal complex is 500:1-600:1, and the molar ratio of the initiator in the monomer-initiator solution to the metal complex is 3:1-4:1.
[0016] Preferably, the transition metal catalyst is a cobalt metal catalyst.
[0017] An application of a transition metal catalyst based on a terpyridine ligand in a copolymerization reaction of olefins and polar monomers.
[0018] Preferably, the method comprises the following steps: in a high-pressure reactor without water and oxygen, argon is introduced, the transition metal catalyst, the free radical initiator and the polar monomer are sequentially injected into the reactor, the polymerization reaction is started by introducing an olefin gas stream and stirring, and a copolymer of the olefin and the polar monomer is obtained.
[0019] Preferably, the polar monomer is vinyl acetate, the free radical initiator is azobisisobutyronitrile, the molar ratio of the transition metal catalyst to the polar monomer is 1:500-1:600, the molar ratio of the transition metal catalyst to the free radical initiator is 1:3-1:4, the polymerization reaction temperature is 70-90 DEG C, the stirring reaction time is 6-12 h, and the stirring speed is 250-350 rpm.
[0020] The present application has the following advantages:
[0021] (1) The catalyst synthesis steps in the present application are simple, the raw materials used are low in price and easy to obtain, the reaction conditions are relatively mild, there is no by-product in the reaction, and the yield of the product is relatively high;
[0022] (2) In the present application, the structure of the terpyridine ligand is regulated, and the electronic effect is regulated by introducing different substituents, so as to further improve the stability and catalytic activity of the catalyst;
[0023] (3) In the present application, the three pyridine rings of the terpyridine form a stable octahedral coordination configuration with the cobalt center through a conjugated system, which inhibits the loss of the metal center, and this can reduce the cost while maintaining the stability of the catalytic activity. BRIEF DESCRIPTION OF DRAWINGS
[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0025] Figure 1 It is the nuclear magnetic hydrogen spectrum of the first product in Example 1 of the present application;
[0026] Figure 2 It is the infrared spectrum of the metal complex one in Example 1 of the present application;
[0027] Figure 3 It is the nuclear magnetic hydrogen spectrum of the second product in Example 2 of the present application;
[0028] Figure 4 It is the infrared spectrum of the metal complex two in Example 2 of the present application;
[0029] Figure 5NMR hydrogen spectrum of the third product in Example 3 of the present application;
[0030] Figure 6 Infrared spectrum of the metal complex three in Example 3 of the present application;
[0031] Figure 7 NMR hydrogen spectrum of the fourth product in Example 4 of the present application;
[0032] Figure 8 Infrared spectrum of the metal complex four in Example 4 of the present application;
[0033] Figure 9 NMR hydrogen spectrum of the EVA copolymer in Example 5 of the present application. DETAILED DESCRIPTION
[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.
[0035] The present application provides a metal catalyst based on terpyridine ligand, and its structural formula is as follows:
[0036]
[0037] wherein R1 is selected from any one of electron-donating groups such as hydrogen atom, and electron-withdrawing groups such as fluorine atom; and R2 is selected from electron-donating groups such as hydrogen atom.
[0038] The present application also provides a metal catalyst based on terpyridine ligand and a preparation method thereof, comprising the following steps:
[0039] (1) Synthesis of ligand: a first reagent, a second reagent, anhydrous ethanol and deionized water are sequentially added into a 250 mL round-bottom flask, the above-mentioned 250 mL round-bottom flask is placed in an oil bath for heating and stirring, then 2 g of NaOH is weighed and added into the round-bottom flask, and the reaction is timed for 30 min, 3 mL of excess 37% volume fraction of ammonia water is added, and the reaction is continued for 12 h, deionized water is added to precipitate the solid, the excess raw material is removed by vacuum filtration and washed with anhydrous ethanol, and a white powder product is obtained;
[0040] (2) Synthesis of metal complex: under a nitrogen atmosphere, the ligand synthesized in step (1) is weighed, dichloromethane is added into a 250 mL round-bottom flask to dissolve, and a third reagent is added, and stirring is carried out at room temperature, after the reaction is completed, the reaction liquid is concentrated and the solid is precipitated with anhydrous ether, the supernatant is removed and washed for two to three times, and dried to obtain the metal complex;
[0041] (3) Copolymerization of ethylene and vinyl acetate: In a glove box under nitrogen protection, the free radical initiator AIBN was dissolved in 30-40 mL of anhydrous tetrahydrofuran (THF), transferred to a polymerization bottle and vinyl acetate was added. The cobalt complex catalyst was placed in a 100 mL high-pressure reactor that had been pre-treated with three vacuum-argon purgings. An inert gas protection environment was established through a double-row pipe system. Under continuous argon flow protection, the monomer-initiator solution was transferred to the reactor using a syringe. High-purity ethylene gas was introduced into the system to an initial pressure of 0.4-1.6 MPa (gauge pressure). After sealing the reaction system, the temperature was raised to 70-90 °C to initiate the polymerization reaction. Mechanical stirring (250-350 rpm) was maintained for 10-12 h to ensure that the reaction proceeded fully. After the reaction was terminated, a grayish-white solution was obtained. After removing the THF solvent by rotary evaporation, the crude product was placed in a vacuum drying oven at 45 °C for 6 h to finally obtain a grayish-white viscous polymer.
[0042] The first reagent is selected from any one of 2-acetylpyridine and 2-acetyl-6-methylpyridine; the second reagent is any one of benzaldehyde, p-methylbenzaldehyde, p-fluorobenzaldehyde and p-chlorobenzaldehyde; and the third reagent is cobalt acetylacetonate.
[0043] The molar ratio of the first reagent to the second reagent is 2:1; the ratio of anhydrous ethanol to deionized water is 2:1.
[0044] In step (1), the temperature of the heated stirring oil bath is 70-90℃, and the oil is stirred at 400-600 rpm for 10-12 hours.
[0045] The molar ratio of the third reagent to the ligand is 1:1 to 1:1.1. For example, the molar ratio of the third reagent to the ligand can be any value within the above range, such as 1:1 or 1:1.1.
[0046] In step (2), the mixture is stirred on a stirring table at 400-600 rpm for 20-24 hours at room temperature. For example, the stirring speed can be any value within the range of 400, 500 or 600 rpm; the stirring time can be any value within the range of 20, 22 or 24 hours.
[0047] In step (3), the anhydrous tetrahydrofuran is 30-40 mL, for example, the anhydrous tetrahydrofuran can be any value within the above range such as 30, 35 or 40.
[0048] In step (3), the reaction temperature is 70-90℃, for example, the reaction temperature can be any value within the range of 70, 80 or 90; the stirring reaction time is 10-12h, for example, the stirring time can be any value within the range of 10, 11 or 12; and the stirring speed is 250-350rpm, for example, the stirring speed can be any value within the range of 250, 300 or 350.
[0049] The present invention also provides a method for copolymerization of olefins and polar monomers catalyzed by a transition metal catalyst based on terpyridine ligands, comprising at least the following steps: argon gas is introduced into an anhydrous and oxygen-free high-pressure reactor, and a metal catalyst, a free radical initiator and a polar monomer are sequentially injected into it. An ethylene gas stream is introduced and stirring is started to carry out polymerization for 6-12 hours. The obtained product is washed with ethanol and then vacuum dried to constant weight to obtain a copolymer of ethylene and polar monomers.
[0050] The polar monomer is vinyl acetate, and the free radical initiator is azobisisobutyronitrile.
[0051] The molar ratio of the metal catalyst to the polar monomer is 1:500-1:600, for example, the molar ratio of the metal catalyst to the polar monomer can be any value within the above range such as 1:500, 1:550 or 1:600; the molar ratio of the metal catalyst to the free radical initiator is 1:3-1:4, for example, the molar ratio of the metal catalyst to the free radical initiator can be any value within the above range such as 1:3, 1:3.5 or 1:4.
[0052] The polymerization is carried out by stirring for 6-12 hours. For example, the stirring time can be any value within the above range, such as 6, 9 or 12.
[0053] The general formula for synthesizing the above catalyst is:
[0054]
[0055] The general formula for the above-mentioned olefin coordination polymerization is as follows:
[0056]
[0057]
[0058] R1 is selected from any one of electron-donating groups such as hydrogen atoms and electron-withdrawing groups such as fluorine atoms; R2 is selected from electron-donating groups such as hydrogen atoms.
[0059] The technical solution of the present invention will be described in detail below through several specific embodiments. Unless otherwise stated, the raw materials and reagents used in the following embodiments are all commercially available products, or can be prepared by conventional methods in the art, and the instruments used in the embodiments are all commercially available.
[0060] Example 1
[0061] (1) Weigh 2-acetylpyridine (2.42 g, 20 mmol) and benzaldehyde (1.06 g, 10 mmol) into a 250 mL round-bottom flask. Prepare a mixed solution of anhydrous ethanol and deionized water in a ratio of 2:1. Add 25 mL of the solution to the 250 mL round-bottom flask. Place the round-bottom flask in an oil bath and heat and stir at 80 °C. Then weigh 2 g of NaOH into the round-bottom flask and react for 30 min. Add 3 mL of excess 37% ammonia water and continue the reaction for 12 h. After the reaction is complete, add excess deionized water to precipitate the precipitate. Filter under reduced pressure and wash with anhydrous ethanol. Dry under vacuum to obtain 4.03 g of white powder 2-acetylpyridine benzaldehyde terpyridine ligand-1, with a yield of 65%.
[0062] (2) Weigh the synthesized ligand 1 (0.31 g, 1 mmol) into a 100 mL round-bottom flask, add 10 mL of dichloromethane to dissolve it, and add cobalt acetylacetonate (0.26 g, 1 mmol, dissolved in 10 mL of methanol solution). Replace the system with a nitrogen atmosphere, stir at room temperature for 24 h to ensure the reaction is complete, then transfer to a single-necked flask, concentrate the reaction solution to 3 mL, add anhydrous diethyl ether to precipitate the product and wash it 3 times. Remove the solvent under vacuum to obtain complex 1 (0.20 g of reddish-brown powder, yield 35%).
[0063] Figure 1 The product's 1H NMR spectrum showed peaks unique to the target ligand structure, and the proportion of the integrated area of each peak in the product spectrum was consistent with the proportion of different protons in the ligand molecular formula, indicating the successful preparation of the target product.
[0064] Figure 2 The skeletal stretching vibration peak of terpyridine's pyridine ring (1581 cm⁻¹) -1 After coordination, due to the formation of coordinate bonds between nitrogen atoms and cobalt ions, the electron cloud density changes, and the peak position may shift to a lower wavenumber (1520 cm⁻¹). -1 Offset.
[0065] Example 2
[0066] (1) Weigh 2-acetylpyridine (2.42 g, 20 mmol) and p-methylbenzaldehyde (1.20 g, 10 mmol) into a 250 mL round-bottom flask, add 25 mL of a mixed solution of anhydrous ethanol and deionized water = 2:1, place the round-bottom flask in an oil bath and heat and stir at 80 °C, then weigh 2 g of NaOH into a double-necked flask, time the reaction for 30 min, add 3 mL of excess 37% ammonia water, continue the reaction for 12 h, after the reaction is completed, add excess deionized water to precipitate the precipitate, filter under reduced pressure and wash with anhydrous ethanol, and dry under vacuum to obtain 1.35 g of white powder 2-acetylpyridine condensed p-methylbenzaldehyde terpyridine ligand II, with a yield of 42%;
[0067] (2) Weigh the synthesized ligand II (0.32 g, 1 mmol) into a 100 mL round-bottom flask, add 10 mL of dichloromethane to dissolve it, and add cobalt acetylacetonate (0.26 g, 1 mmol, dissolved in 10 mL of methanol solution). Replace the system with a nitrogen atmosphere, stir at room temperature for 24 h to ensure the reaction is complete, and then transfer it to a single-necked flask. Concentrate the reaction solution to 3 mL, add anhydrous diethyl ether to precipitate the product and wash it 3 times. Remove the solvent under vacuum to obtain complex II (0.24 g of dark brown powder, yield 38.8%).
[0068] Figure 3 The product's 1H NMR spectrum showed peaks unique to the target ligand structure, and the proportion of the integrated area of each peak in the product spectrum was consistent with the proportion of different protons in the ligand molecular formula, indicating the successful preparation of the target product.
[0069] Figure 4 The skeletal stretching vibration peak of terpyridine's pyridine ring (1581 cm⁻¹) -1 After coordination, due to the formation of coordinate bonds between nitrogen atoms and cobalt ions, the electron cloud density changes, and the peak position may shift to a lower wavenumber (1510 cm⁻¹). -1 Offset.
[0070] Example 3
[0071] (1) Weigh 2.71 g (20 mmol) of 2-acetyl-6-methylpyridine and 1.06 g (10 mmol) of benzaldehyde into a 250 mL round-bottom flask. Add 25 mL of a mixed solution of anhydrous ethanol and deionized water in a ratio of 2:1. Place the double-necked flask in an oil bath and heat and stir at 80 °C. Then weigh 2 g of NaOH into the round-bottom flask and react for 30 min. Add 3 mL of excess 37% ammonia water and continue the reaction for 12 h. After the reaction is complete, add excess deionized water to precipitate the precipitate. Filter under reduced pressure and wash with anhydrous ethanol. Dry under vacuum to obtain 1.32 g of white powder 2-acetyl-6-methylpyridine acetal terpyridine ligand tripyridine, with a yield of 39%.
[0072] (2) Weigh the synthesized ligand 3 (0.467 g, 1 mmol) into a 100 mL round-bottom flask, add 10 mL of dichloromethane to dissolve it, and add cobalt acetylacetonate (0.26 g, 1 mmol, dissolved in 10 mL of methanol solution). Replace the system with a nitrogen atmosphere, stir at room temperature for 24 h to ensure the reaction is complete, then transfer to a single-necked flask, concentrate the reaction solution to 3 mL, add anhydrous diethyl ether to precipitate the product and wash it 3 times. Remove the solvent under vacuum to obtain complex 3 (0.26 g of dark brown powder, yield 43.7%).
[0073] Figure 5 The product's 1H NMR spectrum showed peaks unique to the target ligand structure, and the proportion of the integrated area of each peak in the product spectrum was consistent with the proportion of different protons in the ligand molecular formula, indicating the successful preparation of the target product.
[0074] Figure 6 The skeletal stretching vibration peak of terpyridine's pyridine ring (1580 cm⁻¹) -1 After coordination, due to the formation of coordinate bonds between nitrogen atoms and cobalt ions, the electron cloud density changes, and the peak position may shift to a lower wavenumber (1510 cm⁻¹). -1 Offset.
[0075] Example 4
[0076] (1) Weigh 2-acetylpyridine (2.42 g, 20 mmol) and p-fluorobenzaldehyde (1.24 g, 10 mmol) into a 250 mL round-bottom flask, add 25 mL of a mixed solution of anhydrous ethanol and deionized water = 2:1, place the double-necked flask in an oil bath and heat and stir at 80 °C, then weigh 2 g of NaOH into the double-necked flask, time the reaction for 30 min, add 3 mL of excess 37% ammonia water, continue the reaction for 12 h, after the reaction is completed, add excess deionized water to precipitate the precipitate, filter under reduced pressure and wash with anhydrous ethanol, and dry under vacuum to obtain 1.42 g of white powder 2-acetylpyridine condensed p-fluorobenzaldehyde terpyridine ligand tetrakis, yield 43.4%;
[0077] (2) Weigh the synthesized ligand 4 (0.98 g, 3 mmol) into a 100 mL round-bottom flask, add 10 mL of dichloromethane to dissolve it, and add cobalt acetylacetonate (0.26 g, 1 mmol, dissolved in 10 mL of methanol solution). Replace the system with a nitrogen atmosphere, stir at room temperature for 24 h to ensure the reaction is complete, and then transfer it to a single-necked flask. Concentrate the reaction solution to 3 mL, add anhydrous diethyl ether to precipitate the product and wash it 3 times. Remove the solvent under vacuum to obtain complex 4 (0.59 g of brown powder, yield 33.7%).
[0078] Figure 7The product's 1H NMR spectrum showed peaks unique to the target ligand structure, and the proportion of the integrated area of each peak in the product spectrum was consistent with the proportion of different protons in the ligand molecular formula, indicating the successful preparation of the target product.
[0079] Figure 8 The skeletal stretching vibration peak of terpyridine's pyridine ring (1582 cm⁻¹) -1 After coordination, due to the formation of coordinate bonds between nitrogen atoms and cobalt ions, the electron cloud density changes, and the peak position may shift to a lower wavenumber (1511 cm⁻¹). -1 Offset.
[0080] Example 5
[0081] Copolymerization of ethylene and vinyl acetate: In a nitrogen-protected glove box, 0.9 mmol of free radical initiator AIBN was weighed and dissolved in 36 mL of anhydrous tetrahydrofuran (THF). The solution was transferred to a polymerization flask and 150 mmol of vinyl acetate was added. The cobalt complex catalysts I, II, and III prepared in Examples 1, 2, and 3 were placed in 100 mL high-pressure reactors that had been pre-treated with three vacuum-argon purgings. An inert gas protection environment was established through a double-row pipe system. Under continuous argon flow protection, the monomer-initiator solution was transferred to the reactor using a syringe. High-purity ethylene gas was introduced into the system to an initial pressure of 0.8 MPa. After sealing the reaction system, the temperature was raised to 80 °C to initiate the polymerization reaction. Mechanical stirring was maintained at 300 rpm for 12 h to ensure the reaction proceeded fully. After the reaction was terminated, a grayish-white solution was obtained. After removing the THF solvent by rotary evaporation, the crude product was placed in a vacuum drying oven at 45 °C for 6 h to finally obtain a grayish-white viscous polymer.
[0082] Figure 9 The peak at 4.88 ppm in the 1H NMR spectrum is the elution position of hydrogen on the carbon adjacent to oxygen in vinyl acetate, and the peaks at 1.20-2.30 ppm are the elution positions of the remaining protons in ethylene and vinyl acetate. By calculating the integral area of the 1H NMR spectrum, it can be inferred that the ethylene insertion rate in the copolymer chain is 53.5%.
[0083] In summary, the technical solution of this invention uses terpyridine, which has excellent coordination ability, as a ligand to prepare a transition metal catalyst. By introducing different substituents to regulate the electronic effect of the ligand, the catalytic performance of the catalyst is optimized, achieving favorable control over catalytic activity, polymer relative molecular mass and distribution, copolymerization performance, etc. The three pyridine rings of terpyridine form a stable octahedral coordination configuration with the cobalt center through a conjugated system, inhibiting the loss of the metal center. This can reduce costs while maintaining the stability of catalytic activity. The catalyst synthesis steps are relatively simple, the raw materials used are inexpensive and readily available, the reaction conditions are relatively mild, the reaction has no by-products, and the product yield is relatively high.
[0084] The above detailed embodiments provide a specific description of the analytical methods involved in this invention. It should be noted that the above description is only intended to help those skilled in the art better understand the methods and ideas of this invention, and is not intended to limit the scope of the invention. Without departing from the principles of this invention, those skilled in the art can make appropriate adjustments or modifications to this invention, and such adjustments and modifications should also fall within the protection scope of this invention.
Claims
1. A transition metal catalyst based on terpyridine ligands, characterized in that, Its structural formula is: R1 is selected from either a hydrogen atom electron-donating group or a fluorine atom electron-withdrawing group; R2 is selected from a hydrogen atom electron-donating group.
2. A method for preparing a transition metal catalyst based on a terpyridine ligand according to claim 1, characterized in that, Includes the following steps: (1) Synthesis of ligand: The first reagent, the second reagent, anhydrous ethanol and deionized water were added in sequence, heated and stirred, then NaOH was added and the reaction was timed, and then excess ammonia was added until the reaction was completed to obtain the ligand product. The first reagent was selected from 2-acetylpyridine or 2-acetyl-6-methylpyridine, and the second reagent was any one or more of benzaldehyde, p-methylbenzaldehyde, p-fluorobenzaldehyde or p-chlorobenzaldehyde. (2) Synthesis of metal complex: Under an inert gas atmosphere, the ligand product in step (1) was dissolved in dichloromethane, and cobalt acetylacetone was added and stirred at room temperature. After the reaction was completed, the metal complex was obtained. (3) Copolymerization of ethylene and vinyl acetate: Under an inert gas atmosphere, a monomer-initiator solution is obtained by mixing a free radical initiator, anhydrous tetrahydrofuran and vinyl acetate. The monomer-initiator solution and the metal complex are subjected to polymerization reaction under an ethylene gas atmosphere at a temperature of 70-90℃ and a pressure of 0.4-1.6MPa to obtain a white solution. The transition metal catalyst is obtained after evaporation to remove the solvent.
3. The preparation method according to claim 2, characterized in that, In step (1), the molar ratio of the first reagent to the second reagent is 2:1; the ratio of anhydrous ethanol to deionized water is 2:1; the molar ratio of NaOH to the second reagent is 1:1.5; and the molar ratio of ammonia to the second reagent is 1:
1.
4. The preparation method according to claim 2, characterized in that, In step (1), the heating and stirring temperature is 70-90℃, and the stirring is carried out at 400-600 rpm for 10-12 hours; the timing reaction time is 10-12 hours.
5. The preparation method according to claim 2, characterized in that: In step (2), the molar ratio of cobalt acetylacetone to the ligand is 1:1 to 1:1.1; and the mixture is stirred at 400-600 rpm for 20-24 hours at room temperature.
6. The preparation method according to any one of claims 2-5, characterized in that, The molar ratio of vinyl acetate to the metal complex is 500:1-600:1, and the molar ratio of initiator to metal complex in the monomer-initiator solution is 3:1-4:
1.
7. The preparation method according to claim 6, characterized in that, The transition metal catalyst is a cobalt metal catalyst.
8. The application of the transition metal catalyst based on terpyridine ligands as described in claim 1 in the copolymerization reaction of olefins and polar monomers.
9. The application according to claim 8, characterized in that, At least the following steps are included: Argon gas is introduced into an anhydrous and oxygen-free high-pressure reactor, and the transition metal catalyst, free radical initiator and polar monomer are injected into it in sequence. An olefin gas stream is introduced and stirring is started to carry out the polymerization reaction, and a copolymer of olefin and polar monomer is obtained.
10. The application according to claim 9, characterized in that, The polar monomer is vinyl acetate, the free radical initiator is azobisisobutyronitrile, the molar ratio of the transition metal catalyst to the polar monomer is 1:500-1:600, the molar ratio of the transition metal catalyst to the free radical initiator is 1:3-1:4, the polymerization reaction temperature is 70-90℃, the stirring reaction time is 6-12h, and the stirring speed is 250-350rpm.