Metal compounds containing tetradentate ligands, methods for their preparation and use

Abstract

The application relates to the technical field of polyolefin catalysts, and discloses a metal compound containing a tetradentate ligand and a preparation method and application thereof. The structural formula of the compound is shown as formula (I), wherein R is methyl, ethyl, propyl, butyl or benzyl; R 1 is selected from hydrogen or C1-C6 alkane; G is a tert-butyl group, an adamantyl group, a cyclopentyl group or a cyclohexyl group; X is halogen, Me or -NMe2; M is Ti or Zr; and n is 0, 1 or 2. The metal compound containing the tetradentate ligand introduces multi-site large steric substituents such as adamantyl groups and tert-butyl groups, has a single catalytic active center, can realize effective control of the molecular weight of a polymer through ligand structure design and polymerization condition regulation, has the advantages of high catalytic activity and stable performance, can not only maintain high catalytic activity, but also is more sensitive to water and oxygen, and is more easily stored and used compared with a metallocene catalyst. Formula (I)

Description

Technical Field

[0001] This invention relates to the field of polyolefin catalyst technology, specifically to a metal compound containing a tetradentate ligand, its preparation method, and its application. Background Technology

[0002] In recent years, metal catalysts containing heteroatom ligands have been extensively and deeply studied and developed due to their excellent thermal stability. In 2022, Mu et al. [Li F, He J, Mu Y, et al. Zirconium Complexes with Bulkier Amine Bis (phenolate) Ligands and Their Catalytic Properties for Ethylene (Co) polymerization [J]. Inorganic Chemistry, 2022, 61 (17): 6469-6479] reported the synthesis of a class of zirconium complexes based on NNOO tetradentate ligands, and used MAO, dry-MAO, MAO / BHT and AliBu3 / Ph3CB (C6F5)4 as activators to study olefin polymerization. The results showed that this type of catalyst exhibited excellent catalytic activity in the homopolymerization of ethylene; its activity was even higher in the copolymerization of ethylene and 1-hexene, and it could produce polymers with medium to high molecular weights.

[0003] In the same year, You et al. [Sun Y, Xu S, You F, et al. Synthesis and characterization of the titanium catalysts supported by pyrrolide-benzoxazole ligands and their application in ethylene polymerization [J]. Polyhedron, 2022, 219: 115791] prepared a novel NNNN tetradentate titanium-based olefin polymerization catalyst by coordinating pyrrolide-benzoxazole as a ligand with titanium tetrachloride. Using MAO as a co-catalyst, under optimized conditions (polymerization temperature 50℃, Al / Ti molar ratio 2000), the catalyst achieved a maximum activity of 3.08 × 10⁻⁶. 5 g PE mol -1 Ti h -1 .

[0004] However, the ligands reported in the aforementioned literature generally suffer from problems such as lengthy synthetic routes and high preparation costs. Furthermore, the resulting catalysts still fall short of industrial requirements in terms of thermal stability, catalytic lifetime, and catalytic activity, significantly limiting their practical applications. Therefore, there is an urgent need to develop a novel olefin polymerization catalyst that combines high temperature resistance and high activity, along with its applications, to effectively overcome the aforementioned shortcomings of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of existing heteroatom-containing ligands, such as lengthy synthetic routes, high preparation costs, and insufficient thermal stability, catalytic lifetime, and catalytic activity to meet industrial requirements. This invention provides a metal compound containing a tetradentate ligand, its preparation method, and its applications. This compound exhibits low sensitivity to water and oxygen, and its catalytic active center is not easily deactivated. By introducing nitrogen- and oxygen-containing coordinating heteroatoms at the ortho positions of the hydroxyl group on the benzene ring in the molecule, a stable tetracoordinate structure can be formed with the central metal, giving it excellent heat resistance in ethylene homopolymerization and copolymerization reactions, while also possessing the outstanding advantages of high catalytic activity and good stability.

[0006] To achieve the above objectives, the present invention provides a metal compound containing a tetradentate ligand, the structural formula of which is shown in formula (I);

[0007] Equation (I) Wherein, R is methyl, ethyl, propyl, butyl, or benzyl; R 1 Selected from hydrogen or C1-C6 alkanes; G is tert-butyl, adamantyl, cyclopentyl, or cyclohexyl; X is a halogen, Me, or -NMe2; M is Ti or Zr; n is 0, 1, or 2.

[0008] Preferably, the metal compound containing the tetradentate ligand is at least one of the following compounds: Compound C1: The compound shown in formula (I), wherein R is methyl, R 1 H is H, G is tert-butyl, M is Ti, X is Cl, and n is 1; Compound C2: The compound shown in formula (I), wherein R is methyl, R 1 H is H, G is tert-butyl, M is Zr, X is Cl, and n is 1; Compound C3: The compound shown in formula (I), wherein R is a methyl group, R 1 H is H, G is tert-butyl, M is Ti, X is Me, and n is 1; Compound C4: The compound shown in formula (I), wherein R is a methyl group, R 1 H is H, G is tert-butyl, M is Zr, X is Me, and n is 1; Compound C5: The compound shown in formula (I), wherein R is methyl, R 1 H is H, G is tert-butyl, M is Ti, X is Cl, and n is 0; Compound C6: The compound shown in formula (I), wherein R is methyl, R 1 H is H, G is tert-butyl, M is Ti, X is Cl, and n is 2; Compound C7: The compound shown in formula (I), wherein R is methyl, R 1 G is tert-butyl, M is adamantyl, X is Cl, and n is 1.

[0009] A second aspect of the present invention provides a method for preparing the above-mentioned metal compound containing a tetradentate ligand, the method comprising the following steps: (1) Under an inert atmosphere, the substituted salicylaldehyde shown in formula (II) is mixed with a diamine compound and reacted to obtain a diimine compound; (2) The diimine compound was reduced with a reducing agent under an inert atmosphere to obtain a reduction product; (3) Under an inert atmosphere, the reduction product, formaldehyde or haloalkanes, acetic acid, sodium borohydride and organic solvent are mixed and reacted to obtain the ligand; (4) The ligand is mixed with M(X)4 and reacted under an inert atmosphere;

[0010] Formula (II) Among them, R 1 Selected from hydrogen or C1-C6 alkanes; G is tert-butyl, adamantyl, cyclopentyl, or cyclohexyl; The diamine compound is selected from one of ethylenediamine, 1,3-propanediamine, and 1,4-butanediamine; The halohydrocarbon is selected from one of haloethane, halopropane, halobutane and benzyl halide; X is a halogen or -NMe2; M is either Ti or Zr.

[0011] Preferably, in step (1), the molar ratio of the substituted salicylaldehyde represented by formula (II) to the diamine compound is 1:0.1~1.

[0012] Preferably, in step (1), the conditions for the mixing reaction include: a temperature of 10~120℃ and a time of 1~20h.

[0013] Preferably, in step (2), the specific process of reducing the diimine compound with the reducing agent includes: mixing the diimine compound with an organic alcohol solvent, then adding the reducing agent under an ice-water bath, and then heating to 30~90℃ and reacting for 1~5h.

[0014] Preferably, the molar ratio of the diimine compound to the reducing agent is 1:1 to 10.

[0015] Preferably, the reducing agent is selected from at least one of lithium aluminum hydride, sodium borohydride, NaH and CaH2.

[0016] Preferably, in step (3), the molar ratio of the reduction product to the alkyl aldehyde is 1:2~20.

[0017] Preferably, the molar ratio of the reduction product to the acetic acid is 1:2 to 20.

[0018] Preferably, the molar ratio of the reduction product to the sodium borohydride is 1:0.5~10.

[0019] Preferably, the specific process of mixing and reacting the reduction product, the formaldehyde or haloalkanes, acetic acid, sodium borohydride and the organic solvent includes: mixing the reduction product, the formaldehyde or haloalkanes, acetic acid and the organic solvent, then adding the sodium borohydride under an ice-water bath, and then heating to 25°C~80°C and reacting for 5~20 hours.

[0020] Preferably, the organic solvent is selected from at least one of acetonitrile, ethanol, propanol, benzyl alcohol, and butanol.

[0021] Preferably, the molar ratio of the ligand to the M(X)4 is 1~2:1.

[0022] Preferably, the specific process of the ligand and the M(X)4 mixing reaction includes: mixing the ligand and the M(X)4 at -100℃ to -10℃, and then heating to 40~80℃ for 1~20h.

[0023] Preferably, in step (4), when X is a halogen, the ligand needs to be pre-activated first.

[0024] Preferably, the pre-activation process is as follows: under an inert atmosphere, the ligand is mixed with alkyl lithium and reacted to obtain a ligand lithium salt.

[0025] Preferably, in step (4), the molar ratio of the ligand to the alkyl lithium is 1:2~3.

[0026] Preferably, the alkyl lithium is methyl lithium and / or butyl lithium.

[0027] A third aspect of the present invention provides an olefin polymerization catalyst, which includes a main catalyst and a co-catalyst, wherein the main catalyst is the aforementioned metal compound containing a tetradentate ligand; Preferably, the co-catalyst is alkylaluminum and / or alkoxyaluminum; Preferably, the molar ratio of the main catalyst (calculated as M) to the co-catalyst (calculated as Al) is 1:50~2000.

[0028] A fourth aspect of the present invention provides an olefin polymerization method, the method comprising: performing a polymerization reaction of ethylene and optionally an α-olefin in the presence of the above-described olefin polymerization catalyst.

[0029] The metal compound containing tetradentate ligands described in this invention introduces sterically hindered substituents such as adamantyl and tert-butyl, possessing a single catalytic active center. The molecular weight of the polymer can be effectively controlled through ligand structure design and polymerization condition regulation. This compound combines high catalytic activity and stable performance, maintaining the high catalytic activity of traditional phenoxyimine-based non-metallocene olefin polymerization catalysts (FI catalysts) while exhibiting lower sensitivity to water and oxygen, making it easier to store and use compared to metallocene catalysts. By rationally designing the substituents, the steric hindrance and electronic effects of the ligands can be controlled, thereby precisely adjusting the molecular weight and distribution of the polymer, enabling the preparation of polyethylene and ethylene-α-olefin copolymers with different molecular weight grades.

[0030] Furthermore, the preparation method of the metal compound containing tetradentate ligands described in this invention features mild reaction conditions, a simple synthetic route, a convenient preparation process, and low production costs, making it suitable for industrial production. This compound can be efficiently used as a catalyst in the homopolymerization of ethylene and the copolymerization of ethylene with α-olefins, exhibiting advantages such as high catalytic activity, good thermal stability, and strong ability to regulate the molecular weight of polyolefins. It can meet the temperature requirements of industrial production and has broad prospects for industrial application. Attached Figure Description

[0031] Figure 1 This is the 1H NMR spectrum of the bisimine compound B1 prepared in Example 1; Figure 2 This is the carbon NMR spectrum of the bisimine compound B1 prepared in Example 1; Figure 3 This is the mass spectrum of the bisimine compound B1 prepared in Example 1; Figure 4 This is the 1H NMR spectrum of ligand B3 prepared in Example 1; Figure 5 This is the carbon NMR spectrum of ligand B3 prepared in Example 1; Figure 6 This is the mass spectrometry of ligand B3 prepared in Example 1; Figure 7 This is the 1H NMR spectrum of compound C1 prepared in Example 1; Figure 8 This is the carbon NMR spectrum of compound C1 prepared in Example 1; Figure 9 This is the mass spectrum of compound C1 prepared in Example 1; Figure 10 This is the 1H NMR spectrum of compound C2 prepared in Example 2; Figure 11 This is the carbon NMR spectrum of compound C2 prepared in Example 2; Figure 12 This is the mass spectrum of compound C2 prepared in Example 2; Figure 13 This is the 1H NMR spectrum of compound Ad1 prepared in Example 5; Figure 14 This is the 1H NMR spectrum of compound Ad2 prepared in Example 5; Figure 15 This is the 1H NMR spectrum of compound Ad3 prepared in Example 5; Figure 16 This is the carbon NMR spectrum of compound Ad3 prepared in Example 5; Figure 17 This is the mass spectrum of compound Ad3 prepared in Example 5; Figure 18 This is the 1H NMR spectrum of compound Ad5 prepared in Example 5; Figure 19 This is the carbon NMR spectrum of compound Ad5 prepared in Example 5; Figure 20 This is the mass spectrum of compound Ad5 prepared in Example 5; Figure 21 The results are GPC results for the polymer prepared in Example 14. Figure 22 The results are from the polymer GPC prepared in Example 17. Detailed Implementation

[0032] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0033] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] The structural formula of the metal compound containing tetradentate ligands described in this invention is shown in formula (Ⅰ);

[0035] Equation (I) Wherein, R is methyl, ethyl, propyl, butyl, or benzyl; R 1 Selected from hydrogen or C1-C6 alkanes; G is tert-butyl (t-Bu), adamantyl (Ad), cyclopentyl or cyclohexyl; X is halogen, Me or -NMe2; M is Ti or Zr; n is 0, 1 or 2.

[0036] In this invention, the C1-C6 alkyl group is a straight-chain, branched, or isomerized alkyl group containing 1-6 carbons, such as methyl (Me), ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, sec-pentyl, tert-pentyl, n-hexyl, isohexyl, neohexyl, sec-hexyl, etc.

[0037] In this invention, the halogen can be fluorine (-F), chlorine (-Cl), bromine (-Br) or iodine (-I).

[0038] It should be noted that the adamantyl group refers to a monovalent alkyl substituent formed by removing a hydrogen atom from a saturated polycyclic alkane with a rigid cage structure. It is a typical sterically hindered rigid group that can effectively stabilize the catalytic active center, improve the stability of the compound, and regulate the molecular weight and distribution of the polymer during the polymerization process.

[0039] In this invention, in the structure shown in formula (Ⅰ), the above-mentioned R, R 1 G, M, X, and n can be selected from the above range. As a specific example, the metal compound containing the tetradentate ligand is at least one of the following compounds: Compound C1: The compound shown in formula (I), wherein R is methyl, R 1 H is H, G is tert-butyl, M is Ti, X is Cl, and n is 1; its structural formula is shown below;

[0040] Compound C2: The compound shown in formula (I), wherein R is methyl, R 1 H is H, G is tert-butyl, M is Zr, X is Cl, and n is 1; its structural formula is shown below.

[0041] Compound C3: The compound shown in formula (I), wherein R is a methyl group, R 1 H is H, G is tert-butyl, M is Ti, X is Me, and n is 1; its structural formula is shown in the following formula;

[0042] Compound C4: The compound shown in formula (I), wherein R is a methyl group, R1 H is H, G is tert-butyl, M is Zr, X is Me, and n is 1; its structural formula is shown below;

[0043] Compound C5: The compound shown in formula (I), wherein R is methyl, R 1 H is H, G is tert-butyl, M is Ti, X is Cl, and n is 0; its structural formula is shown below;

[0044] Compound C6: The compound shown in formula (I), wherein R is methyl, R 1 H is H, G is tert-butyl, M is Ti, X is Cl, and n is 2; its structural formula is shown below;

[0045] Compound C7: The compound shown in formula (I), wherein R is methyl, R 1 G is tert-butyl, M is adamantyl, X is Cl, and n is 1; its structural formula is shown below.

[0046] The metal compound containing tetradentate ligands described in this invention introduces sterically hindered substituents such as adamantyl and tert-butyl at multiple sites, possessing a single catalytic active center. The molecular weight of the polymer can be effectively controlled through ligand structure design and polymerization condition regulation. It has the advantages of high catalytic activity and stable performance. It can not only maintain the high catalytic activity of traditional phenoxyimine-based non-metallocene olefin polymerization catalysts (FI catalysts), but also has lower sensitivity to water and oxygen, and is easier to store and use than metallocene catalysts.

[0047] The present invention also provides a method for preparing the above-mentioned metal compound containing a tetradentate ligand, the method comprising the following steps: (1) Under an inert atmosphere, the substituted salicylaldehyde shown in formula (II) is mixed with a diamine compound and reacted to obtain a diimine compound; (2) The diimine compound was reduced with a reducing agent under an inert atmosphere to obtain a reduction product; (3) Under an inert atmosphere, the reduction product, formaldehyde or haloalkanes, acetic acid, sodium borohydride and organic solvent are mixed and reacted to obtain the ligand; (4) The ligand is mixed with M(X)4 and reacted under an inert atmosphere;

[0048] Formula (II) Among them, R 1Selected from hydrogen or C1-C6 alkanes; G is tert-butyl, adamantyl, cyclopentyl, or cyclohexyl; The diamine compound is selected from one of ethylenediamine, 1,3-propanediamine, and 1,4-butanediamine; The halohydrocarbon is selected from one of haloethane, halopropane, halobutane and benzyl halide; X is a halogen or -NMe2; M is either Ti or Zr.

[0049] In some preferred embodiments, the substituted salicylaldehyde represented by formula (II) can be 3-tert-butylsalicylaldehyde or 3-adamantyl-5-tert-butylsalicylaldehyde.

[0050] In some embodiments, the substituted salicylic acid is 3-tert-butylsalicylaldehyde. The 3-tert-butylsalicylaldehyde is a commercially available product or prepared using methods conventional in the art.

[0051] In some embodiments, the substituted salicylic acid is 3-adamantyl-5-tert-butylsalicylaldehyde. The preparation method of the 3-adamantyl-5-tert-butylsalicylaldehyde includes the following steps: a1. Mix tert-butylphenol, 1-adamantanol with an organic solvent, then cool the resulting mixture to -10℃~0℃, add concentrated sulfuric acid, and then heat the resulting mixture to 20~30℃ and react for 10-25h to obtain 3-adamantyl-5-tert-butylphenol. a2. Mix the 3-adamantyl-5-tert-butylphenol, anhydrous MgCl2, triethylamine and organic solvent, then mix the resulting mixture with paraformaldehyde and react at 70-90°C for 10-20 h.

[0052] Specifically, in step a1, the molar ratio of tert-butylphenol to 1-adamantanol is 1:0.8~1.2, preferably 1:0.9~1.1.

[0053] Specifically, the process of step a1 further includes: first neutralizing the organic phase in the reaction product with 0.5-1.5M NaOH, adjusting the pH to 7-8, and then sequentially performing extraction, drying, vacuum concentration and column chromatography purification to obtain the 3-adamantyl-5-tert-butylphenol.

[0054] Specifically, in step a2, the molar ratio of 3-adamantyl-5-tert-butylphenol to paraformaldehyde is 1:5~20, preferably 1:5~10. The weight-average molecular weight of the paraformaldehyde is 300-500.

[0055] Specifically, step a2 further includes: first cooling the obtained reaction product to room temperature and quenching the reaction, and then sequentially performing extraction, drying and column chromatography purification to obtain the 3-adamantyl-5-tert-butylsalicylaldehyde.

[0056] Specifically, there are no particular restrictions on the types of organic solvents used in steps a1 and a2; they can be selected according to actual needs.

[0057] In some embodiments, in step (1), the molar ratio of the substituted salicylaldehyde represented by formula (II) to the diamine compound is 1:0.1 to 1, preferably 1:0.2 to 0.8, and more preferably 1:0.3 to 0.7. As a specific example, the molar ratio of the substituted salicylaldehyde represented by formula (II) to the diamine compound can be 1:0.3, 1:0.4, 1:0.5, 1:0.6, or 1:0.7.

[0058] In some embodiments, in step (1), the conditions for the mixing reaction include: a temperature of 10~120℃, preferably 20~100℃; and a time of 1~20h, preferably 1~10h. As specific examples, the temperature of the mixing reaction can be 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, or 100℃; and the time of the mixing reaction can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10h. In this invention, the mixing reaction is carried out under reflux conditions.

[0059] In some embodiments, in step (1), the substituted salicylaldehyde of formula (II) is reacted with the diamine compound in a solvent. The solvent may be a conventional organic solvent in the art, such as ethanol. The amount of solvent is not particularly limited and may be adjusted appropriately according to the actual reaction conditions.

[0060] In some embodiments, the specific process of step (1) further includes: freezing, crystallizing, washing and drying the obtained mixed reaction product in sequence to obtain the diimine compound.

[0061] In some embodiments, the specific process of reducing the diimine compound with the reducing agent in step (2) includes: mixing the diimine compound with an organic alcohol solvent, then adding the reducing agent under an ice-water bath, and then heating to 30~90°C and reacting for 1~5 hours.

[0062] In some preferred embodiments, the specific process of reducing the diimine compound with the reducing agent in step (2) includes: mixing the diimine compound with an organic alcohol solvent, then adding the reducing agent under an ice-water bath, then removing the ice-water bath and raising the temperature to room temperature, then raising the temperature to 40~60℃ and reacting for 1~2 hours.

[0063] In the method described in this invention, in step (2), the reducing agent is selected from at least one of lithium aluminum hydride (LiAlH4), sodium borohydride, NaH, and CaH2. In a further preferred embodiment, the reducing agent is sodium borohydride.

[0064] In the method described in this invention, the type of organic alcohol solvent in step (2) is not limited, and commonly used organic alcohol solvents in the art can be used. Preferably, the organic alcohol solvent is at least one selected from methanol, ethanol, propanol, butanol, and benzyl alcohol.

[0065] In some embodiments, in step (2), the molar ratio of the diimine compound to the reducing agent is 1:1 to 10, preferably 1:2 to 8, and more preferably 1:3 to 7. As a specific example, the molar ratio of the diimine compound to the reducing agent can be 1:3, 1:4, 1:5, 1:6, or 1:7.

[0066] In some embodiments, the specific process of step (2) further includes: sequentially extracting the organic alcohol solvent from the obtained reaction mixture, adding water to quench it, extracting, drying, filtering and evaporating to obtain the reduction product.

[0067] In some embodiments, the specific process of mixing and reacting the reduction product, the formaldehyde or chlorinated hydrocarbon, acetic acid, sodium borohydride and organic solvent in step (3) includes: mixing the reduction product, the formaldehyde or chlorinated hydrocarbon, acetic acid and the organic solvent, then adding the sodium borohydride under an ice-water bath, and then heating to 25~80°C and reacting for 5~20 hours.

[0068] In the method described in this invention, the haloalkanes can be bromoalkanes, chloroalkanes, and iodoalkanes, preferably iodoalkanes. The halopropanes are selected from chloropropane, bromopropane, and iodopropane, wherein the iodopropanes include 1-iodopropane and 2-iodopropane, preferably iodopropane. The halobutanes are selected from fluorobutane, chlorobutane, bromobutane, and iodobutane, preferably iodobutane. The benzyl halide is selected from benzyl chloride, benzyl bromide, and benzyl iodide, preferably benzyl iodide.

[0069] In some embodiments, in step (3), the molar ratio of the reduction product to the formaldehyde or chlorinated hydrocarbon is 1:2 to 20, preferably 1:7 to 18, and more preferably 1:8 to 15. As a specific example, the molar ratio of the reduction product to the formaldehyde or chlorinated hydrocarbon can be 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, or 1:15.

[0070] In some embodiments, in step (3), the molar ratio of the reduction product to the acetic acid is 1:2 to 20, preferably 1:7 to 18, and more preferably 1:8 to 15. As a specific example, the molar ratio of the reduction product to the acetic acid can be 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, or 1:15.

[0071] In some embodiments, in step (3), the molar ratio of the reduction product to the sodium borohydride is 1:0.5 to 10, preferably 1:2 to 8, and more preferably 1:3 to 7. As a specific example, the molar ratio of the reduction product to the sodium borohydride can be 1:3, 1:4, 1:5, 1:6, or 1:7.

[0072] In the method described in this invention, the type of organic solvent is not limited, and commonly used organic solvents in the art can be used. Preferably, the organic solvent is selected from at least one of acetonitrile, ethanol, propanol, benzyl alcohol, and butanol. In a further preferred embodiment, the organic solvent is acetonitrile.

[0073] In some preferred embodiments, the specific process of mixing and reacting the reduction product, the alkyl aldehyde, acetic acid, sodium borohydride and the organic solvent in step (3) includes: mixing the reduction product, the formaldehyde or halogenated hydrocarbon, acetic acid and the organic solvent, then adding the sodium borohydride under an ice-water bath, then removing the ice bath and gradually restoring the room temperature, and then raising the temperature to 25~80℃ and reacting for 8~15h.

[0074] In some embodiments, the specific process of step (3) further includes: quenching, extracting, drying, filtering, evaporating and recrystallizing the obtained reaction product in sequence to obtain the ligand.

[0075] In some embodiments, the specific process of mixing the ligand with the M(X)4 in step (4) includes: mixing the ligand with the M(X)4 at -100℃ to -10℃, and then heating to 40 to 80℃ for 1 to 20 hours.

[0076] In some embodiments, in step (4), the molar ratio of the ligand to the M(X)4 is 1 to 2:1, preferably 1 to 1.5:1. As a specific example, the molar ratio of the ligand to the M(X)4 can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5.

[0077] In some embodiments, the M(X)4 is selected from at least one of TiCl4, Ti(NMe2)4, ZrCl4 and Zr(NMe2)4.

[0078] In some embodiments, in step (4), when X is a halogen, the ligand needs to be pre-activated. The specific pre-activation process is as follows: under an inert atmosphere, the ligand is mixed with alkyl lithium and reacted to obtain a ligand lithium salt.

[0079] In some embodiments, the specific process of mixing the ligand with the alkyllithium in step (4) includes: mixing the ligand with the alkyllithium at -80℃ to -30℃, removing the ice bath and gradually restoring the room temperature, and reacting for 5-15 hours.

[0080] In some embodiments, in step (4), the molar ratio of the ligand to the alkyllithium is 1:2 to 3, preferably 1:2.1 to 3.8. As specific examples, the molar ratio of the ligand to the alkyllithium can be 1:2.1, 1:2.2, 1:2.4, 1:2.5, 1:2.6, 1:2.8, 1:3, 1:3.2, 1:3.4, 1:3.5, 1:3.6, or 1:3.8.

[0081] In some preferred embodiments, the alkyl lithium is methyl lithium and / or butyl lithium. In a further preferred embodiment, the alkyl lithium is n-butyl lithium.

[0082] In some embodiments, step (4) further includes recrystallizing the obtained reaction product.

[0083] In some embodiments, X is Me, and the specific process of step (4) further includes: at ~50℃-~20℃, the target product obtained by reacting TiCl4 or ZrCl4 with the ligand lithium salt is mixed with methyl magnesium bromide, then the temperature is raised to room temperature and the reaction continues for 1~3h, and then the obtained reaction product is recrystallized.

[0084] The present invention further provides an olefin polymerization catalyst comprising a main catalyst and a co-catalyst, wherein the main catalyst is the aforementioned metal compound containing a tetradentate ligand.

[0085] In some embodiments, the cocatalyst is alkylaluminum and / or alkoxyaluminum. In a preferred embodiment, the cocatalyst is methylaluminoxane.

[0086] In some embodiments, the molar ratio of the main catalyst (calculated as M) to the co-catalyst (calculated as Al) is preferably 1:50~2000, more preferably 1:800~1500.

[0087] The olefin polymerization catalyst described in this invention can be efficiently applied to ethylene homopolymerization and copolymerization of ethylene and α-olefins, exhibiting advantages such as high catalytic activity, good thermal stability, and strong ability to regulate the molecular weight of polyolefins.

[0088] The present invention further provides an olefin polymerization method, comprising: polymerizing ethylene and optionally an α-olefin in the presence of the above-mentioned olefin polymerization catalyst. Specifically, in the catalytic homopolymerization of ethylene, the ethylene polymerization activity exceeds 0.1 × 10⁻⁶. 6 The resulting polymer has a molecular weight of 1.00 × 10⁻⁶ g / mol Cat / h. 4 -9.00×10 5 g / mol; In the catalytic copolymerization of ethylene and α-olefins, the polymerization activity exceeds 0.1 × 10⁻⁶ g / mol. 6 g / mol Cat / h, the α-olefin insertion rate in the polymer is 1.0~10.0 mol.

[0089] The following examples further illustrate the metal compounds containing tetradentate ligands, their preparation methods, and applications according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0090] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0091] Paraformaldehyde was purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd., brand name Aldrich-441244; Unless otherwise specified, the reaction process in the following examples and comparative examples was carried out under argon protection.

[0092] Example 1 A metal compound C1 containing a tetradentate ligand was prepared. The molecular formula of compound C1 is: 1,3-{[bis(N-Me,N-(2-O-3-tert-butyl)C6H3-CH2)]C3H6}TiCl2; the synthetic route of compound C1 is as follows:

[0093] The specific preparation process of compound C1 is as follows: (1) Add a magnetic bar to a 50 mL round-bottom flask, and add 3-tert-butylsalicylaldehyde (1.78 g, 10 mmol), 20 mL ethanol, and 1,3-propanediamine (0.37 g, 5 mmol) to the flask in sequence. Heat to 100 °C and reflux for 8 h. After stopping the reaction, remove part of the solution and freeze overnight. A yellow solid appears. Filter, wash repeatedly with ice-cold ethanol, and dry to obtain the diimine compound B1 with a yield of 82%.

[0094] Figure 1 The 1H NMR spectrum of the bisimine compound B1 is shown below. 1 HNMR(400MHz,DMSO)δ14.36(s,2H),8.57(s,2H),7.27(dd, J =7.3, 2.8 Hz, 4H), 6.81(t, J =7.6Hz,2H),3.69(t, J =6.5Hz,4H),2.09–2.01(m,2H),1.36(s,18H).

[0095] Figure 2 The carbon NMR spectrum of the bisimine compound B1 is shown below: 13 CNMR(101MHz,DMSO)δ166.96(s),160.10(s),136.32(s),129.98(s),129. 03(s),118.33(s),117.69(s),55.80(s),34.34(s),31.43(s),29.14(s).

[0096] Figure 3 The mass spectrum of the bisimine compound B1 is shown, and the results are as follows: MS(EI), m / z:C 25 H 34 N2O2,Calcd.,394.3;Found,394.3.

[0097] (2) Add a magnetic stir bar to a 50 mL round-bottom flask, add 1.20 g (3 mmol) of diimine compound B1 and 20 mL of methanol to the flask in sequence, and slowly add sodium borohydride (0.57 g (15 mmol) under an ice-water bath. Remove the ice bath and gradually restore the room temperature, then heat to 50 °C. The solution gradually changes from yellow to colorless. After 1 h, stop the reaction, remove the solution, add water to quench, extract with dichloromethane, dry with anhydrous sodium sulfate, filter, and evaporate to dryness to obtain the reduction product B2, which can be used directly in the next step.

[0098] (3) Add a magnetic stir bar to a 50 mL round-bottom flask, and add the reduction product B2 (0.92 g, 2.31 mmol), 30 mL of acetonitrile, 1.9 mL (25 mmol) of 37% formaldehyde aqueous solution, and 1.5 mL (26 mmol) of acetic acid in sequence. Stir for 30 min. Add sodium borohydride (0.37 g, 10 mmol) slowly under an ice-water bath, remove the ice bath and gradually restore to room temperature (25 °C), and stir overnight. Quench with 2 N sodium hydroxide, extract with dichloromethane, dry with anhydrous sodium sulfate, filter, evaporate to dryness, and recrystallize with methanol to obtain ligand B3 with a yield of about 65%.

[0099] Figure 4 The 1H NMR spectrum of ligand B3 is shown, and the results are as follows: 1 HNMR(400MHz, CDCl3)δ7.20(d,J=7.4Hz,2H),6.84(d,J=7.0Hz,2H),6.72(t,J=7.5Hz, 2H),3.67(s,4H),2.46(t,J=6.6Hz,4H),2.29(s,6H),1.88–1.72(m,2H),1.42(s,18H).

[0100] Figure 5 The carbon NMR spectrum of ligand B3 is shown, and the results are as follows: 13 CNMR(101MHz, CDCl3)δ156.90(s),136.52(s),126.68(s),125.95(s),122.12( s),118.31(s),61.92(s),54.40(s),41.19(s),34.68(s),29.53(s),24.57(s).

[0101] Figure 6 The mass spectrum of ligand B3 is shown, and the results are as follows: HRMS(EI),m / z:C 27 H 42 N2O2,Calcd.,426.3246;Found,427.3326([M+H] + ).

[0102] (4) Add a magnetic ball to a 50 mL Shrek flask, evacuate the flask three times, add B3 (0.68 g, 1.60 mmol) and 15 mL of toluene to the flask in sequence, add n-butyllithium (1.4 mL, 2.5 M, 3.5 mmol) under liquid nitrogen-acetone bath, remove the liquid nitrogen-acetone bath and gradually restore room temperature, stir overnight; add titanium tetrachloride (1.59 mmol, 0.30 g) at -78 °C, remove the liquid nitrogen-acetone bath and gradually restore room temperature, heat to 65 °C, and bubble with argon gas to remove HCl, react for 6 h, remove some toluene, place in the lower layer of the refrigerator at -20 °C for recrystallization, and obtain red solid compound C1 with a yield of 25%.

[0103] Figure 7 The 1H NMR spectrum of compound C1 is shown, and the results are as follows: 1 HNMR(400MHz,CDCl3)δ7.28(d,J=1.2Hz,2H),6.99(d,J=6.2Hz,2H),6.89(t,J=7.6Hz,2H),5.49(d,J=13.1Hz,2H),3.81(t,J=12.5Hz,2H ),2.97(d,J=13.2Hz,2H),2.59(s,6H),2.52(dd,J=12.4,4.9Hz,2H),2.36(d,J=6.6Hz,1H),1.81(dd,J=11.8,5.0Hz,1H),1.57(s,18H).

[0104] Figure 8 The carbon NMR spectrum of compound C1 is shown, and the results are as follows: 13 CNMR(151MHz,CDCl3)δ162.33(s),136.01(s),129.13(s),126.93(s),125.92( s),121.68(s),66.99(s),63.22(s),49.77(s),34.63(s),30.10(s),20.97(s).

[0105] Figure 9 The mass spectrum of compound C1 is shown, and the results are as follows: HRMS(EI),m / z:C 27 H 40 N2O2Cl2Ti,Calcd.,542.1945;Found,542.1941[M-Cl]†.

[0106] Example 2 The metal compound C2 containing a tetradentate ligand was prepared. The molecular formula of compound C2 is: 1,3-{[bis(N-Me,N-(2-O-3-tert-butyl)C6H3-CH2)]C3H6}ZrCl2; the synthetic route of compound C2 is as follows:

[0107] The specific preparation process of compound C2 is as follows: A magnetic flask was placed in a 50 mL Shrek flask, and the flask was evacuated three times. Ligand B3 (0.68 g, 1.60 mmol), 15 mL of tetrahydrofuran, and n-butyllithium (1.40 mL, 2.5 M, 3.5 mmol) were added sequentially to the flask under ice bath conditions. The ice bath was removed, and the mixture was gradually brought to room temperature and stirred overnight. Zirconium tetrachloride (1.59 mmol, 0.37 g) was added at -78 °C. The mixture was brought to room temperature and then refluxed at 80 °C for 18 h. The mixture was dried under vacuum, and dichloromethane was added. After standing and filtration, the mixture was recrystallized from n-hexane to give a white solid compound C2 with a yield of approximately 28%.

[0108] Figure 10 The 1H NMR spectrum of compound C2 is shown, and the results are as follows: 1 HNMR (400MHz, CDCl3) δ7.30(t,J=9.4Hz,2H),6.99(d,J=7.6Hz,2H),6.81(t,J=7.6Hz,2H),5.29(dd,J=26.0,16.3Hz,2H),3.87(t ,J=12.4Hz,2H),3.03(t,J=13.9Hz,2H),2.56(d,J=5.3Hz,2H),2.54(s,6H),2.43~2.29(m,1H),1.95~1.82(m,1H),1.51(s,18H).

[0109] Figure 11 The carbon NMR spectrum of compound C2 is shown below. 13 CNMR(151MHz,CDCl3)δ162.33(s),136.01(s),129.13(s),126.93(s),125.92( s),121.68(s),66.99(s),63.22(s),49.77(s),34.63(s),30.10(s),20.97(s).

[0110] Figure 12 The mass spectrum of compound C2 is shown, and the results are as follows: HRMS(EI),m / z:C 27 H 40N2O2Cl2Zr,Calcd.,585.1587;Found,585.1560.

[0111] Example 3 Prepare a metal compound C3 containing a tetradentate ligand. The molecular formula of compound C3 is 1,3-{[bis(N-Me,N-(2-O-3-tert-butyl)C6H3-CH2)]C3H6}TiMe2; The specific preparation process of compound C3 is as follows: 542 mg of compound C1 was dissolved in 100 mL of THF, stirred at -30 °C, and 2.0 mL of methyl magnesium bromide solution (1.0 M, diethyl ether solution) was added. The mixture was heated to room temperature and stirred for 2 h. The solvent was removed under reduced pressure, and the mixture was extracted with 10 mL of hexane to give a red solid compound C3 in 90% yield.

[0112] The mass spectrometry results for compound C3 are as follows: HRMS(EI,m / z):Calcdfor[C 29 H 46 N2O2Ti]:502.3039;Found:502.3010.

[0113] Example 4 Prepare a metal compound C4 containing a tetradentate ligand. The molecular formula of compound C4 is 1,3-{[bis(N-Me,N-(2-O-3-tert-butyl)C6H3-CH2)]C3H6}ZrMe2; The specific preparation process of compound C4 is similar to that of compound C3, except that compound C2 is used instead of compound C1 to obtain a light yellow solid compound C4 with a yield of 80%.

[0114] The mass spectrometry results for compound C4 are as follows: HRMS(EI,m / z):Calcdfor[C 29 H 46 N2O2Zr]:544.2606;Found:544.2611.

[0115] Example 5 The metal compound C7 containing a tetradentate ligand was prepared. The molecular formula of compound C7 is 1,3-{[bis(N-Me,N-(2-O-3-Ad)C6H3-CH2)]C3H6}TiMe2. The synthetic route of compound C7 is as follows:

[0116]

[0117] The specific preparation process of compound C7 is as follows: (1) The mixture was heated three times under an argon atmosphere in a 50 mL Shrek flask. 2.0 g of tert-butylphenol (13.3 mmol) and 1-adamantanol (2.0 g, 13.3 mmol) were added, and the mixture was purged once. 20 mL of dichloromethane was added to dissolve the mixture. The solution was cooled to 0 °C, and concentrated sulfuric acid (0.8 mL, 15.0 mmol) was added dropwise. The reaction mixture was heated to 22 °C and stirred for 18 h. The organic phase was neutralized with 1 M NaOH, the pH was adjusted to 7.5, and the mixture was extracted with dichloromethane, dried over anhydrous Na2SO4, concentrated under vacuum, and purified by column chromatography (petroleum ether: ethyl acetate = 50:1). The resulting white solid was compound Ad1, with a yield of 66%.

[0118] Figure 13 The 1H NMR spectrum of compound Ad1 is shown, and the results are as follows: 1HNMR (400MHz, CDCl3) δ7.26(s,1H),7.08(dd,J=8.2,2.3Hz,1H),6.58(d,J=8.2Hz,1H),4.61(s,1H),2.15(d,J=2.4Hz,6H),2.10(s,3H),1.31(s,9H).

[0119] (2) The mixture was heated three times under an argon atmosphere in a 50 mL Shrek flask. Compound Ad-1 (1.42 g, 5.0 mmol) and anhydrous MgCl2 (1.43 g, 15.0 mmol) were added, and the mixture was purged once. 30 mL of THF was added to dissolve the mixture. Et3N (2.0 g, 20 mmol) was added dropwise, and the mixture was stirred at room temperature for 15 min. Dry paraformaldehyde (1.05 g, 35.0 mmol) was added, and the mixture was heated to 80 °C. o Refluxed at C overnight. After cooling to room temperature, the reaction was quenched by adding saturated NH4Cl. Extracted with ethyl acetate, dried over anhydrous Na2SO4, and subjected to column chromatography with a mixed solvent of petroleum ether:ethyl acetate = 60:1 to give a pale yellow solid compound Ad2 in 71% yield.

[0120] Figure 14 The 1H NMR spectrum of compound Ad-2 is shown below: 1 HNMR(400MHz, CDCl3)δ11.69(s,1H),9.87(s,1H),7.54(d, J =2.3Hz, 1H), 7.33(d, J =2.4Hz,1H),2.15(s,6H),2.10(s,3H),1.80(s,6H),1.33(s,9H).

[0121] (3) A magnetic stir bar was added to a 50 mL round-bottom flask. Ad2 (3.12 g, 10 mmol), 30 mL of ethanol, and 1,3-propanediamine (0.37 g, 5 mmol) were added sequentially to the flask. The mixture was heated to 100 °C and refluxed for 8 h. After the reaction was stopped, the mixture was filtered to obtain a yellow solid. The solid was washed several times with ice-cold ethanol and dried to obtain a yellow solid compound Ad3 with a yield of 80%.

[0122] Figure 15 The 1H NMR spectrum of compound Ad3 is shown, and the results are as follows: 1 HNMR(400MHz, CDCl3)δ13.90(s,2H),8.40(s,2H),7.34(d, J =2.4Hz, 2H), 7.09(d, J =2.4Hz,2H),3.70(t, J =6.4Hz,4H),2.21(d, J =1.8Hz,12H),2.11(s,8H),1.86–1.77(m,12H),1.32(s,18H).

[0123] Figure 16 The carbon NMR spectrum of compound Ad3 is shown below. 13 CNMR(101MHz, CDCl3)δ156.90(s),136.52(s),126.68(s),125.95(s),122.12(s),118.31(s),7 7.41(s),77.09(s),76.77(s),61.92(s),54.40(s),41.19(s),34.68(s),29.53(s),24.57(s).

[0124] Figure 17 The mass spectrum of compound Ad3 is shown, and the results are as follows: HRMS(EI,m / z):Calcdfor[C 45 H 62 O2N2]:662.4811;Found:662.4797.

[0125] (4) Add a magnetic ball to a 50 mL round-bottom flask, and add Ad3 (1.99 g, 3 mmol), 10 mL methanol and 20 mL THF to the flask in sequence. Add sodium borohydride (0.57 g, 15 mmol) slowly under an ice-water bath. Remove the ice bath and gradually restore room temperature. Then heat to 50 °C. The solution gradually changes from yellow to colorless. After 1 h, stop the reaction, remove the solution, add water to quench, extract with dichloromethane, dry with anhydrous sodium sulfate, filter, and evaporate to dryness to obtain compound Ad4, which can be used directly in the next step.

[0126] (5) Add a magnetic stir bar to a 50 mL round-bottom flask, and add Ad4 (0.92 g, 2.0 mmol), 30 mL of acetonitrile, 1.9 mL of 37% formaldehyde aqueous solution, and 1.5 mL of acetic acid in sequence. Stir for 30 min. Slowly add sodium borohydride (0.37 g, 10 mmol) under an ice-water bath, remove the ice bath and gradually restore to room temperature, stirring overnight. Quench with 2N sodium hydroxide, extract with dichloromethane, dry with anhydrous sodium sulfate, filter, evaporate to dryness, recrystallize from methanol and dichloromethane to give a white solid compound Ad5, with a yield of approximately 45%.

[0127] Figure 18 The 1H NMR spectrum of compound Ad5 is shown, and the results are as follows: 1 HNMR (400MHz, CDCl3) δ 7.15 (d, J =2.3Hz,2H),6.81(d, J =2.2Hz,2H),5.30(s,1H),3.65(s,4H),2.47(s,4H),2.28(s,6H),2.17(s,12H),2.07(d, J =7.5Hz,6H),1.84–1.74(m,14H),1.28(s,18H).

[0128] Figure 19 The carbon NMR spectrum of compound Ad5 is shown below. 13 CNMR(101MHz, CDCl3)δ154.54(s),140.59(s),135.84(s),123.13(s),122.75(s),121.32(s),77.37(s),77.05(s),7 6.73(s),62.33(s),54.62(s),41.34(s),40.47(s),37.26(s),37.01(s),34.21(s),31.73(s),29.21(s),24.48(s).

[0129] Figure 20The mass spectrum of compound Ad5 is shown, and the results are as follows: HRMS(EI,m / z):Calcdfor[C 47 H 70 O2N2]:694.5437;Found:694.5435.

[0130] (6) Similar to the synthesis of C1, the amount of Ad5 added was 1.4 g (2.0 mmol), and the amount of TiCl4 added was 0.38 g (2.0 mmol), to obtain a red solid compound C7, 0.8 g, with a yield of 60%.

[0131] The mass spectrometry results for compound C7 are as follows: HRMS(EI,m / z):Calcdfor[C 47 H 68 O2N2Cl2Ti]:810.4173;Found:675.2960[M-Ad]†.EI:CalcdC,69.53;H,8.44;N,3.45.Found:C,69.49;H,8.40;N,3.38.

[0132] Application Examples 1-11 The process of using the compound prepared in the above examples as the main catalyst to catalyze the homopolymerization of ethylene at different temperatures specifically includes the following steps (taking compound C1 as an example): Compound C1 was accurately weighed into a Shrek flask in a glove box and dissolved in 50 mL of toluene using ultrasonication to prepare a 1 μmol / mL solution. After the reactor was anhydrous and oxygen-free, the following steps were taken: toluene and MAO were injected into the reactor to maintain a total volume of 100 mL. The reactor was heated, and ethylene gas was introduced while stirring. Once the reaction temperature reached the preset temperature, the prepared compound C1 solution was added. The polymerization system pressure was maintained, and the polymerization reaction was carried out for 30 min. Then, the ethylene gas was turned off, stirring was stopped, and the pressure was slowly released. After slight cooling, the reactor was opened, and a quenching agent was slowly added dropwise. The resulting polymer was poured into a beaker, stirred overnight, and filtered. The solid was placed in a vacuum drying oven and heated to 60 °C. It was kept as a low-boiling-point substance for 10 h. After constant weight, it was removed, weighed, and stored in a sealed bag for subsequent characterization experiments.

[0133] The polymerization conditions were as follows: pressure 2.0 MPa, [Al] / [M] = 1000, n(Cat.) = 5 μmol, total volume 50 mL, and t = 30 min.

[0134] The weight-average molecular weight data of the prepared polymer were determined by gel permeation chromatography (GPC) in this invention, and the results are shown in Table 1.

[0135] The polymerization activity of the prepared polymer was determined by weighing method in this invention, and the results are shown in Table 1.

[0136] Table 1

[0137] As can be seen from the results in Table 1, the catalyst prepared in this invention can effectively catalyze the polymerization of ethylene, and the polymer has a high molecular weight.

[0138] Application Examples 12-22 The process of using the compound prepared in the above examples as the main catalyst to catalyze the copolymerization reaction of ethylene and 1-octene at different temperatures specifically includes the following steps (taking compound C1 as an example): Compound C1 was accurately weighed into a Shrek flask in a glove box and dissolved in 50 mL of toluene using ultrasonication to prepare a 1 μmol / mL solution. After the reactor was anhydrous and oxygen-free, the following steps were taken: toluene, MAO, and octene were injected into the reactor, maintaining a total volume of 50 mL. The reactor was heated, and ethylene gas was introduced while stirring. Once the reaction temperature reached the preset temperature, the prepared compound C1 solution was added. The polymerization system pressure was maintained, and the polymerization reaction was carried out for 30 min. Then, the ethylene gas was turned off, stirring was stopped, and the pressure was slowly released. After slight cooling, the reactor was opened, and a quenching agent was slowly added dropwise. The resulting polymer was poured into a beaker, stirred overnight, and filtered. The solid was placed in a vacuum drying oven and heated to 60 °C. It was kept as a low-boiling-point substance for 10 h. After constant weight, it was removed, weighed, and stored in a sealed bag for subsequent characterization experiments.

[0139] The polymerization conditions were as follows: pressure 2.0 MPa, [Al] / [M] = 1000, n(Cat.) = 5 μmol, total volume 50 mL, and t = 30 min.

[0140] The weight-average molecular weight data of the prepared polymer were determined by the GPC method in this invention, and the results are shown in Table 2.

[0141] in, Figure 21 GPC results for the polymer prepared in Application Example 14 are presented; Figure 22 Results of the polymer GPC prepared in Application Example 17 are presented.

[0142] Depend on Figure 21 and Figure 22 The results show that the polymer obtained by copolymerizing ethylene and 1-octene with the catalyst prepared in this invention is a broadly distributed polymer, which will be beneficial to the subsequent processing. At the same time, the polymer molecular weight reaches more than 170,000, which can maintain good mechanical properties. The introduction of 1-octene branches affects the crystalline region of polyethylene, enhances the polymer's performance as an elastomer, and enables the polymer to be used as a new type of linear low-density material.

[0143] The polymerization activity of the prepared polymer was determined by weighing method in this invention, and the results are shown in Table 2.

[0144] The insertion rate of octene in the prepared polymer was determined by high-temperature quantitative carbon NMR spectroscopy in this invention, and the results are shown in Table 2.

[0145] Table 2

[0146] As can be seen from the results in Table 2, the catalyst of the present invention can effectively catalyze the polymerization of ethylene and 1-octene to obtain a wide-distribution high molecular weight polyolefin product. In particular, it can maintain high catalytic activity at 120°C, which generally exceeds that of the classic Cp2TiCl2 catalyst. More importantly, it overcomes the defect that Cp2TiCl2 cannot catalyze the copolymerization of ethylene and α-olefins.

[0147] Comparative Example 1 The method described in Application Example 1 was implemented, except that Cp2TiCl2 (purchased from Merrill) was used instead of C1 as the main catalyst to catalyze the homopolymerization of ethylene. The polymerization results are shown in Table 1.

[0148] Comparative Example 2 The method described in Application Example 11 was implemented, using Cp2TiCl2 compound instead of C1 as the main catalyst to catalyze the copolymerization of ethylene and octene. The polymerization results are shown in Table 2.

[0149] The results in Tables 1 and 2 show that the catalyst prepared in this application can catalyze the polymerization of ethylene and 1-octene, and it maintains high catalytic activity, especially at high temperatures, indicating that the catalyst structure is more stable than that of classic restricted configuration catalysts.

[0150] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A metal compound containing a tetradentate ligand, characterized in that, The structural formula of the compound is shown in formula (Ⅰ). Equation (I) Wherein, R is methyl, ethyl, propyl, butyl, or benzyl; R 1 Selected from hydrogen or C1-C6 alkanes; G is tert-butyl, adamantyl, cyclopentyl, or cyclohexyl; X is a halogen, Me, or -NMe2; M is Ti or Zr; n is 0, 1, or 2.

2. The metal compound containing a tetradentate ligand according to claim 1, characterized in that, The metal compound containing the tetradentate ligand is at least one of the following compounds: Compound C1: The compound shown in formula (I), wherein R is methyl, R 1 H is H, G is tert-butyl, M is Ti, X is Cl, and n is 1; Compound C2: The compound shown in formula (I), wherein R is methyl, R 1 H is H, G is tert-butyl, M is Zr, X is Cl, and n is 1; Compound C3: The compound shown in formula (I), wherein R is a methyl group, R 1 H is H, G is tert-butyl, M is Ti, X is Me, and n is 1; Compound C4: The compound shown in formula (I), wherein R is a methyl group, R 1 H is H, G is tert-butyl, M is Zr, X is Me, and n is 1; Compound C5: The compound shown in formula (I), wherein R is methyl, R 1 H is H, G is tert-butyl, M is Ti, X is Cl, and n is 0; Compound C6: The compound shown in formula (I), wherein R is methyl, R 1 H is H, G is tert-butyl, M is Ti, X is Cl, and n is 2; Compound C7: The compound shown in formula (I), wherein R is methyl, R 1 G is tert-butyl, M is adamantyl, X is Cl, and n is 1.

3. A method for preparing the metal compound containing the tetradentate ligand as described in claim 1 or 2, characterized in that, The method includes the following steps: (1) Under an inert atmosphere, the substituted salicylaldehyde shown in formula (II) is mixed with a diamine compound and reacted to obtain a diimine compound; (2) The diimine compound was reduced with a reducing agent under an inert atmosphere to obtain a reduction product; (3) Under an inert atmosphere, the reduction product, formaldehyde or haloalkanes, acetic acid, sodium borohydride and organic solvent are mixed and reacted to obtain the ligand; (4) The ligand is mixed with M(X)4 and reacted under an inert atmosphere; Formula (II) Among them, R 1 Selected from hydrogen or C1-C6 alkanes; G is tert-butyl, adamantyl, cyclopentyl, or cyclohexyl; The diamine compound is selected from one of ethylenediamine, 1,3-propanediamine, and 1,4-butanediamine; The halohydrocarbon is selected from one of haloethane, halopropane, halobutane and benzyl halide; X is a halogen or -NMe2; M is either Ti or Zr.

4. The method according to claim 3, characterized in that, In step (1), the molar ratio of the substituted salicylaldehyde represented by formula (II) to the diamine compound is 1:0.1~1; and / or In step (1), the conditions for the mixing reaction include: a temperature of 10~120℃ and a time of 1~20h.

5. The method according to claim 3 or 4, characterized in that, In step (2), the specific process of reducing the diimine compound with the reducing agent includes: mixing the diimine compound with an organic alcohol solvent, then adding the reducing agent under an ice-water bath, and then heating to 30~90℃ and reacting for 1~5 hours; Preferably, the molar ratio of the diimine compound to the reducing agent is 1:1 to 10; Preferably, the reducing agent is selected from at least one of lithium aluminum hydride, sodium borohydride, NaH and CaH2.

6. The method according to any one of claims 3-5, characterized in that, In step (3), the molar ratio of the reduction product to the formaldehyde or haloalkanes is 1:2~20; and / or The molar ratio of the reduction product to the acetic acid is 1:2~20; and / or The molar ratio of the reduction product to the sodium borohydride is 1:0.5~10; Preferably, the specific process of mixing and reacting the reduction product, the formaldehyde or haloalkanes, acetic acid, sodium borohydride and the organic solvent includes: mixing the reduction product, formaldehyde or haloalkanes, acetic acid and the organic solvent, then adding the sodium borohydride under an ice-water bath, and then heating to 25~80℃ and reacting for 5~20h. Preferably, the organic solvent is selected from at least one of acetonitrile, ethanol, propanol, benzyl alcohol, and butanol.

7. The method according to any one of claims 3-6, characterized in that, In step (4), the molar ratio of the ligand to the M(X)4 is 1~2:1; and / or The specific process of the ligand and the M(X)4 mixing reaction includes: mixing the ligand and the M(X)4 at -100℃ to -10℃, then heating to 40~80℃ and reacting for 1~20h.

8. The method according to any one of claims 3-7, characterized in that, In step (4), when X is a halogen, the ligand needs to be pre-activated first; Preferably, the specific process of the pre-activation is as follows: under an inert atmosphere, the ligand is mixed and reacted with alkyl lithium to obtain a ligand lithium salt; Preferably, the molar ratio of the ligand to the alkyllithium is 1:2~3; Preferably, the alkyl lithium is methyl lithium and / or butyl lithium.

9. An olefin polymerization catalyst, characterized in that, The olefin polymerization catalyst includes a main catalyst and a co-catalyst, wherein the main catalyst is a metal compound containing a tetradentate ligand as described in claim 1 or 2; Preferably, the co-catalyst is alkylaluminum and / or alkoxyaluminum; Preferably, the molar ratio of the main catalyst (calculated as M) to the co-catalyst (calculated as Al) is 1:50~2000.

10. A method for olefin polymerization, characterized in that, The method includes: polymerizing ethylene and optionally α-olefins in the presence of the olefin polymerization catalyst of claim 9.

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