Nickel ethylene homopolymerization and copolymerization catalysts with oxygen / sulfur fused heteroaromatic ring substituted unsymmetrical POCOP type phosphinophenol

Abstract

This invention relates to the field of polyethylene catalyst technology, and discloses an asymmetric POCOP-type phosphonophenol-nickel homopolymer and copolymer catalyst containing oxygen / sulfur fused heterocyclic aromatic rings. The catalyst is prepared by protecting 2-tert-butylphenol, coupling it with a diarylchlorophosphine intermediate, and then acid-deprotecting it. The target ligand is then reacted with a nickel precursor in toluene and recrystallized to obtain the catalyst. This catalyst utilizes a rigid asymmetric POCOP pincer framework and the secondary weak interaction between heteroatoms O / S and the nickel center to synergistically regulate the steric hindrance and electronic effects of the metal center. At 130℃ and 8 atm, this catalyst exhibits excellent thermal stability and high catalytic activity in ethylene homopolymerization and copolymerization with tert-butyl acrylate. It has a high comonomer insertion rate, achieving precise control over the polymer molecular weight and microstructure. Furthermore, the synthetic route is clear, the yield is high, and it is suitable for large-scale preparation.

Description

Technical Field

[0001] This invention relates to the field of polyethylene catalyst technology, specifically to asymmetric POCOP-type phosphonophenol nickel ethylene homopolymer and copolymer catalysts containing oxygen / sulfur fused heterocyclic aromatic rings. Background Technology

[0002] Polyethylene (PE) is one of the most produced and widely used polymer materials. Post-transition metal nickel catalysts have attracted much attention in the preparation of functionalized polyolefins through ethylene homopolymerization and copolymerization with polar monomers due to their good tolerance to polar groups and low cost.

[0003] POCOP-type (phosphine-oxy-phosphine) pincer ligands stabilize the nickel center through tripentate chelation, and their asymmetric structure allows for modulation of catalytic performance by adjusting the substituents on the phosphorus atom. However, existing asymmetric POCOP nickel catalysts still suffer from the following problems:

[0004] Insufficient thermal stability: Some nickel-based polymerization catalysts are prone to β-H elimination or ligand decomposition at high temperatures (such as 130℃), resulting in rapid catalyst deactivation and making it difficult to meet the process requirements of high-temperature solution polymerization.

[0005] Limited structural tunability: Currently reported asymmetric POCOP nickel catalysts have substituents on phosphorus atoms that are mostly limited to simple hydrocarbon aromatic rings such as phenyl, alkyl or common naphthyl, lacking effective means of electronic effect regulation.

[0006] Low copolymerization insertion rate: When ethylene is copolymerized with polar monomers (such as acrylates), the polar groups are prone to coordination competition or poisoning with the metal active center. Existing catalysts often cannot achieve a high proportion of polar monomer insertion, which limits the performance improvement of functionalized polyolefins. Summary of the Invention

[0007] The purpose of this invention is to provide an asymmetric POCOP-type phosphonophenol nickel ethylene homopolymer and copolymer catalyst containing oxygen / sulfur fused heterocyclic aromatic rings, which has the effects of high efficiency, high temperature resistance and high copolymerization ability.

[0008] The above-mentioned technical objective of this invention is achieved through the following technical solution: an asymmetric POCOP-type phosphonophenol nickel catalyst with oxygen / sulfur-containing fused aromatic ring substitution, having the structures shown in formulas (I1) to (I7), corresponding to catalysts Ni1 to Ni7:

[0009]

[0010] (I1) (I2) (I3)

[0011]

[0012] (I4) (I5) (I6)

[0013]

[0014] (I7)

[0015] Equation (I1) corresponds to Ni1, which is obtained from the reaction of ligand L1 with nickel precursor;

[0016] Equation (I2) corresponds to Ni2, and is obtained from the reaction of ligand L2 with nickel precursor;

[0017] Equation (I3) corresponds to Ni3, which is obtained from the reaction of ligand L3 with nickel precursor;

[0018] Equation (I4) corresponds to Ni4, which is obtained from the reaction of ligand L4 with nickel precursor;

[0019] Formula (I5) corresponds to Ni5, which is obtained from the reaction of ligand L5 with nickel precursor;

[0020] Formula (I6) corresponds to Ni6, which is obtained by reacting ligand L6 with a nickel precursor;

[0021] Formula (I7) corresponds to Ni7, which is obtained by reacting ligand L7 with nickel precursor.

[0022] An asymmetric POCOP-type phosphonophenol ligand with oxygen / sulfur-containing fused aromatic ring substitution has the structures shown in formulas (I8) to (I14), corresponding to ligands L1 to L7:

[0023]

[0024] (I8) (I9) (I10)

[0025]

[0026] (I11) (I12)

[0027]

[0028] (I13) (I14)

[0029] Formula (I8) corresponds to ligand L1, with a 2-benzofuran group attached to its phosphorus atom;

[0030] Formula (I9) corresponds to ligand L2, with a 5-benzofuran group attached to its phosphorus atom;

[0031] Formula (I10) corresponds to ligand L3, which has a 7-benzofuran group attached to its phosphorus atom;

[0032] Formula (I11) corresponds to ligand L4, which has a 2-benz[b]thiophene group attached to its phosphorus atom;

[0033] Formula (I12) corresponds to ligand L5, which has a 3-benz[b]thiophene group attached to its phosphorus atom;

[0034] Formula (I13) corresponds to ligand L6, with a 4-benzo[b]thiophene group attached to its phosphorus atom;

[0035] Formula (I14) corresponds to ligand L7, which has a 6-benziro[b]thiophene group attached to its phosphorus atom.

[0036] A method for synthesizing an oxygen / sulfur-containing fused aromatic ring-substituted asymmetric POCOP-type phosphonophenol ligand includes the following steps:

[0037] S1: 2-tert-butylphenol was reacted with dried dichloromethane and 3,4-dihydro-2H-pyran under PPTS catalysis to prepare intermediate a with protected hydroxyl groups;

[0038] S2: 2-Bromo-2,6-dimethoxybiphenyl was lithiated with n-butyllithium and then reacted with phosphorus trichloride to prepare the diarylphosphine intermediate Cl2PPh(Ar).

[0039] S3: The brominated heteroaryl hydrocarbon is lithiated with n-butyllithium and then reacted with Cl2PPh(Ar), followed by reaction with the lithiation product of intermediate a, and finally deprotected by PTSA acid to obtain the target ligands L1 to L7.

[0040] A further setting of the present invention is as follows: the acid deprotection in step S3 is carried out by stirring p-toluenesulfonic acid monohydrate in deoxymethanol solvent, and after 2 hours, TLC plate detection is performed. Then, it is extracted with dichloromethane to remove salt and water, and purified by column chromatography. The yield of the ligands L1 to L7 is 63% to 72%.

[0041] A method for synthesizing an oxygen / sulfur-containing fused aromatic ring-substituted asymmetric POCOP-type phosphonophenol nickel catalyst involves dissolving an oxygen / sulfur-containing fused aromatic ring-substituted asymmetric POCOP-type phosphonophenol ligand with 1.5 equivalents of [Py2NiMe2] in toluene under inert gas N2 protection. The reaction mixture is stirred at room temperature for 3–5 hours. After the reaction, dried diatomaceous earth is placed in a sand core, which is then mounted on a 100 ml Shrek flask. A pump is connected, and the reaction mixture is filtered. A cooling neck is then attached, and the toluene solution is dried. The solution is then recrystallized from dried n-hexane and filtered to obtain a yellow solid target catalyst.

[0042] An olefin polymerization method using an asymmetric POCOP-type phosphonophenol nickel catalyst with oxygen / sulfur-containing fused heterocyclic aromatic ring substitution to carry out homopolymerization of ethylene or copolymerization of ethylene with polar monomers in an olefin polymerization reaction.

[0043] A further setting of the present invention is that the temperature of the homopolymerization reaction of ethylene is 130°C and the ethylene pressure is 8 atm.

[0044] A further provision of the present invention is that, in the copolymerization reaction of ethylene with a polar monomer, the polar monomer is selected from tert-butyl acrylate compounds.

[0045] A further provision of the present invention is that the solvent for the polymerization reaction is a mixture of toluene and n-heptane.

[0046] In summary, the present invention has the following beneficial effects:

[0047] 1. This invention employs a rigid asymmetric POCOP clamp-shaped framework, which effectively locks the nickel metal center through the tridentate chelation of the two phosphorus atoms and the central phenolic oxygen atom, significantly inhibiting catalyst decomposition and deactivation at high temperatures. Experiments have shown that the catalyst provided by this invention can still maintain high activity at ethylene polymerization temperatures as high as 130°C, achieving efficient polymerization under high-temperature conditions.

[0048] 2. This invention introduces benzofuran and benzothiophene-type oxygen / sulfur fused aromatic rings into the asymmetric phosphonol nickel system for the first time. On the one hand, the unique conjugated system of the fused aromatic ring changes the electron cloud distribution of the ligands and enhances the electron density of the metal center. On the other hand, the heteroatoms (O or S) can generate weak intramolecular secondary coordination with the nickel center. This "secondary interaction" can effectively intervene in the monomer insertion and chain growth steps during polymerization, thereby precisely controlling the microstructure of the polymer.

[0049] 3. By altering the linkage sites of the fused aromatic rings on the phosphorus atom, this invention provides seven ligands with different structures, L1 to L7, and their corresponding Ni1 to Ni7 catalysts. Due to the different linkage sites, the cavity size, steric hindrance, and electronic effects around the metallic nickel undergo systematic changes, resulting in significant structure-activity relationships in the catalyst activity, comonomer insertion rate, and molecular weight of the resulting polymer. This site heterogeneity strategy provides a rich structural library for "on-demand design" of polyolefin materials.

[0050] 4. Thanks to the secondary coordination effect of heteroatoms (S or O), the catalyst of this invention exhibits excellent tolerance and high insertion rate when copolymerizing ethylene with polar monomers such as tert-butyl acrylate; this makes it possible to prepare functionalized polyethylene materials containing polar functional groups with excellent adhesion and compatibility, greatly expanding the downstream application range of polyolefin materials. Attached Figure Description

[0051] Figure 1 This is the synthetic route for the nickel-based catalyst of the present invention;

[0052] Figure 2 This is the 1H NMR spectrum of ligand L1 of this invention;

[0053] Figure 3 This is the phosphorus NMR spectrum of ligand L1 of the present invention;

[0054] Figure 4 This is the 1H NMR spectrum of ligand L2 of this invention;

[0055] Figure 5 This is the phosphine NMR spectrum of ligand L2 of this invention;

[0056] Figure 6 This is the 1H NMR spectrum of ligand L3 of this invention;

[0057] Figure 7 This is the phosphorus NMR spectrum of ligand L3 of this invention;

[0058] Figure 8 This is the 1H NMR spectrum of ligand L4 of this invention;

[0059] Figure 9 This is the phosphorus NMR spectrum of ligand L4 of this invention;

[0060] Figure 10 This is the 1H NMR spectrum of ligand L5 of this invention;

[0061] Figure 11 This is the phosphorus NMR spectrum of ligand L5 of this invention;

[0062] Figure 12 This is the 1H NMR spectrum of ligand L6 of this invention;

[0063] Figure 13 This is the phosphorus NMR spectrum of ligand L6 of this invention;

[0064] Figure 14 This is the 1H NMR spectrum of ligand L7 of this invention;

[0065] Figure 15 This is the phosphorus NMR spectrum of ligand L7 of this invention. Detailed Implementation

[0066] The present invention will be further described below with reference to the accompanying drawings in the embodiments of the present invention.

[0067] Example 1: Synthesis of compound a

[0068] 1.0 eq. of 2-tert-butylphenol was added to a Schlenk flask, followed by a suitable amount of dichloromethane, and then 0.5 eq. of pyridine 4-methylbenzenesulfonic acid (PPTS). The flask was purged with air using a double-row tube, and 5 eq. of 3,4-dihydro-2H-pyran was slowly added after inserting a nitrogen balloon. The reaction was carried out at room temperature for 12 hours. After the reaction was completed, post-treatment and column chromatography were performed to obtain an oily product a with a yield of 80%.

[0069] Example 2: Synthesis of Cl2PPh(Ar) intermediate

[0070] In a Schlenk flask, n-BuLi (220 mmol, 2.5 M) was added to a calcium-hydrogen-dried tetrahydrofuran (300 mL) solution of 2-bromo-2,6-dimethoxybiphenyl (200 mmol) and incubated at -78 °C. After stirring the reaction mixture for 3 hours, the resulting suspension was slowly added dropwise to a calcium-hydrogen-dried tetrahydrofuran (200 mL) solution of phosphorus(III) chloride (600 mmol) while maintaining the temperature at -78 °C. After the addition was complete, the mixture was slowly heated to room temperature and stirred overnight. After the reaction was complete, the solvent was removed by double-row tubes, and the product was recrystallized in calcium-hydrogen-dried n-hexane. The crystals were filtered through a glove box to obtain a white solid product Cl2PPh(Ar), which was dried and stored in a glove box for later use.

[0071] Example 3: Synthesis of ligand L1

[0072]

[0073] Synthesis of ligand L1: In a Schlenk flask, n-BuLi (220 mmol) was added to a tetrahydrofuran solution of 2-bromo-2,6-dimethoxybiphenyl (200 mmol), and the flask was placed at -78°C. o At a temperature of -78°C, the reaction mixture was stirred for 3 hours, and the resulting suspension was added dropwise to a tetrahydrofuran solution of phosphorus(III) chloride (600 mmol). o C. Slowly heat the mixture to room temperature overnight. After the reaction is complete, remove the solvent using a double-row tube, recrystallize with dried n-hexane, and filter through a glove box to obtain a clean white solid product, Cl2PPh(Ar). Remove the solid and store in a glove box for later use. In a Schlenk flask, add 10 mmol of 2-bromo-1-benzofuran to a tetrahydrofuran solution at room temperature. n-BuLi (11 mmol) is added at -78°C. o The solution was slowly added dropwise at C. After reacting for 3 hours, it was introduced into a suspension of tetrahydrofuran containing Cl2PPh(Ar) and reacted at -78°C. o React at C for 3 hours to obtain a mixed suspension. Take another Schlenk flask and react at 0°C. on-BuLi (11 mmol) was slowly added dropwise to a (10 mmol) THF solution at C. After reacting for 3 hours, it was added to the suspension of the above mixture, and then the solution was changed from 0. o The mixture was naturally heated to room temperature and reacted for 12 hours. After the reaction, the mixture was concentrated under vacuum. The residue was dissolved in 50 mL of degassed methanol and 2 mL of concentrate, and 0.3 g of p-toluenesulfonic acid monohydrate (PTSA) was added. The mixture was stirred at room temperature for 3 hours, concentrated under vacuum, and then extracted. The combined organic phase was concentrated under vacuum, and the residue was subjected to column chromatography on silica gel with petroleum ether / ethyl acetate = 20 / 1 as the eluent to give pure L1 white solid (68%).

[0074] NMR analysis: 1 H NMR (400 MHz, CDCl3) δ 7.48 – 7.37 (m, 4H), 7.33 – 7.28(m, 1H), 7.23 (d, J = 5.2 Hz, 2H), 7.19 – 7.12 (m, 3H), 6.79 (t, J = 7.6 Hz, 1H), 6.67 (s, 1H), 6.55 (d, J = 8.3 Hz, 1H), 6.41 (d, J = 13.0, 9.6 Hz, 2H), 3.60 (s, 3H, -OCH3), 3.27 (s, 3H, -OCH3), 1.37 (s, 9H, -C(CH3)3). 31 P NMR (162MHz, CDCl3) δ -53.98.

[0075] Example 4: Synthesis of ligand L2

[0076]

[0077] Synthesis of ligand L2: The same experimental procedure as for the synthesis of L1 ligand was followed, with the addition of 5-bromobenzofuran (10 mmol) to obtain L2 as a pure white solid (66%).

[0078] NMR analysis: 1H NMR (400 MHz, CDCl3) δ 7.46 (q, J = 6.5 Hz, 3H), 7.38 (d, J = 5.8 Hz, 1H), 7.36 – 7.27 (m, 3H), 7.24 – 7.05 (m, 3H), 6.80 (t, J =7.5 Hz, 1H), 6.66 (s, 1H), 6.57 (d, J = 8.0 Hz, 1H), 6.43 (d, J = 8.3 Hz,1H), 6.36 (d, J = 11.1 Hz, 1H), 3.64 (s, 3H -OCH3), 3.28 (s, 3H, -OCH3), 1.35(s, 9H, -C(CH3)3). 31 P NMR (162 MHz, CDCl3) δ -53.30.

[0079] Example 5: Synthesis of ligand L3

[0080]

[0081] Synthesis of ligand L3: The same experimental procedure as for the synthesis of L1 ligand was followed, and 7-bromobenzofuran (10 mmol) was added to obtain L3 as a pure white solid (72%).

[0082] NMR analysis: 1 H NMR (400 MHz, CDCl3) δ 7.28 (td, J = 3.8, 1.5 Hz, 2H), 7.24 – 7.21 (m, 1H), 7.14 – 7.04 (m, 5H), 7.01 – 6.95 (m, 2H), 6.62 (t, J =7.6 Hz, 1H), 6.49 (s, 1H), 6.38 (d, J = 8.3 Hz, 1H), 6.28 – 6.16 (m, 2H), 3.44 (s, 3H, -OCH3), 3.10 (d, J = 1.7 Hz, 3H, -OCH3), 1.19 (d, J = 2.2 Hz, 9H-C(CH3)3). 31 P NMR (162 MHz, CDCl3) δ -53.97.

[0083] Example 6: Synthesis of ligand L4

[0084]

[0085] Synthesis of ligand L4: The same experimental procedure as for the synthesis of L1 ligand was followed, with the addition of 2-bromobenzo[b]thiophene (10 mmol) to obtain L4 as a pure white solid (63%).

[0086] NMR analysis: 1 H NMR (400 MHz, CDCl3) δ 7.72 – 7.64 (m, 1H), 7.64 – 7.57(m, 1H), 7.36 (m, J = 9.6, 6.3, 3.7 Hz, 2H), 7.22 (m, J = 6.6, 4.7 Hz, 4H), 7.18 – 7.11 (m, 3H), 7.03 – 6.96 (m, 1H), 6.71 (m, J = 7.6, 2.2 Hz, 1H), 6.49 (d, J = 8.3 Hz, 1H), 6.37 (m, J = 8.3, 2.2 Hz, 1H), 3.49 (d, J = 1.4 Hz, 3H -OCH3), 3.25 (d, J = 2.5 Hz, 3H -OCH3), 1.26 (d, J = 2.0 Hz, 9H, -C(CH3)3). 31 PNMR (162 MHz, CDCl3) δ -54.03.

[0087] Example 7: Synthesis of ligand L5

[0088]

[0089] The same experimental procedure as the synthesis of L1 ligands was followed, and 3-bromobenzo[b]thiophene (10 mmol) was added to obtain L5 pure white solid (72%).

[0090] NMR analysis: 1H NMR (400 MHz, CDCl3) δ 7.77 – 7.70 (m, 1H), 7.66 (m, J =6.7, 2.2 Hz, 1H), 7.41 (m, J = 7.7, 5.0 Hz, 2H), 7.31 – 7.27 (m, 2H), 7.24(t, J = 4.2 Hz, 2H), 7.22 (d, J = 1.7 Hz, 1H), 7.20 – 7.16 (m, 1H), 7.04 (m,J = 7.6, 4.7, 1.6 Hz, 1H), 6.76 (t, J = 7.6 Hz, 1H), 6.54 (d, J = 8.3 Hz,1H), 6.42 (d, J = 8.4 Hz, 1H), 6.30 (d, J = 10.7 Hz, 1H), 3.54 (s, 3H -OCH3), 3.30 (s, 3H -OCH3), 1.31 (s, 9H -C(CH3)3). 31 P NMR (162 MHz, CDCl3) δ -48.04.

[0091] Example 8: Synthesis of ligand L6

[0092]

[0093] The same experimental procedure as the synthesis of L1 ligands was followed, and 4-bromobenzo[B]thiophene (10 mmol) was added to obtain L6 pure white solid (74%).

[0094] NMR analysis: 1 H NMR (400 MHz, CDCl3) δ 7.65 (m, J = 12.4, 6.9 Hz, 1H), 7.43 (t, J = 7.4 Hz, 3H), 7.33 – 7.26 (m, 3H), 7.25 – 7.18 (m, 3H), 7.05 (t,J = 6.2 Hz, 1H), 6.81 – 6.75 (m, 1H), 6.54 (d, J = 3.5 Hz, 1H), 6.43 (d, J =8.3 Hz, 1H), 6.31 (m, J = 16.6, 10.6 Hz, 1H), 3.54 (s, 3H, -OCH3), 3.32 (s,3H, -OCH3), 1.33 (s, 9H, -C(CH3)3). 31P NMR (162 MHz, CDCl3) δ -47.91.

[0095] Example 9: Synthesis of ligand L7

[0096]

[0097] The same experimental procedure as the synthesis of L1 ligands was followed, with the addition of 6-bromobenzo[b]thiophene (10 mmol) to obtain L7 pure white solid (75%).

[0098] NMR analysis: 1 H NMR (400 MHz, CDCl3) δ 7.72 – 7.65 (m, 1H), 7.53 – 7.34(m, 3H), 7.32 – 7.26 (m, 3H), 7.24 – 7.17 (m, 3H), 7.07 – 7.00 (m, 1H), 6.77(t, J = 7.6 Hz, 1H), 6.55 (d, J = 8.3 Hz, 1H), 6.43 (m, J = 8.4, 1.8 Hz, 1H), 6.31 (m, J = 21.2, 10.6 Hz, 1H), 3.54 (s, 3H, -OCH3), 3.31 (s, 3H, -OCH3),1.32 (s, 9H, -C(CH3)3). 31 P NMR (162 MHz, CDCl3) δ -47.86.

[0099] Example 10: Synthesis of Catalyst Ni1

[0100]

[0101] Synthesis of catalyst Ni1: Under nitrogen conditions in a glove box, ligand L1 (583 mg, 1 mmol) and 1.3 equivalents of Py2NiMe2 were dissolved in a suitable amount of toluene solution and stirred at room temperature for 4 hours. The toluene solution was removed by filtration, and the solution was recrystallized from dry n-hexane to yield a yellow solid Ni1 (70% yield).

[0102] Example 11: Synthesis of Ni2 catalyst

[0103]

[0104] Synthesis of Ni2 catalyst: Under nitrogen atmosphere in a glove box, ligand L2 (593 mg, 1 mmol) and 1.3 equivalents of Py2NiMe2 were dissolved in a suitable amount of toluene solution and stirred at room temperature for 4 hours. The toluene solution was removed by filtration, and the solution was recrystallized from dry n-hexane to yield yellow solid Ni2 (yield 80%).

[0105] Example 12: Synthesis of Ni3 catalyst

[0106]

[0107] Synthesis of Ni3 catalyst: Under nitrogen conditions in a glove box, ligand L3 (593 mg, 1 mmol) and 1.3 equivalents of Py2NiMe2 were dissolved in a suitable amount of toluene solution and stirred at room temperature for 4 hours. The toluene solution was removed by filtration, and the solution was recrystallized from dry n-hexane to yield yellow solid Ni3 (yield 76%).

[0108] Example 13: Synthesis of Ni4 catalyst

[0109]

[0110] Synthesis of Ni4 catalyst: Under nitrogen atmosphere in a glove box, ligand L4 (593 mg, 1 mmol) and 1.3 equivalents of Py2NiMe2 were dissolved in a suitable amount of toluene solution and stirred at room temperature for 4 hours. The toluene solution was removed by filtration, and the solution was recrystallized from dry n-hexane to yield yellow solid Ni4 (yield 73%).

[0111] Example 14: Synthesis of Ni5 catalyst

[0112]

[0113] Synthesis of catalyst Ni5: Under nitrogen conditions in a glove box, ligand L5 (593 mg, 1 mmol) and 1.3 equivalents of Py2NiMe2 were dissolved in a suitable amount of toluene solution and stirred at room temperature for 4 hours. The toluene solution was removed by filtration, and the solution was recrystallized from dry n-hexane to yield yellow solid Ni5 (yield 82%).

[0114] Example 15: Synthesis of Ni6 catalyst

[0115]

[0116] Synthesis of Ni6 catalyst: Under nitrogen atmosphere in a glove box, ligand L6 (593 mg, 1 mmol) and 1.3 equivalents of Py2NiMe2 were dissolved in a suitable amount of toluene solution and stirred at room temperature for 4 hours. The toluene solution was removed by filtration, and the solution was recrystallized from dry n-hexane to yield yellow solid Ni6 (yield 81%).

[0117] Example 16: Synthesis of Ni7 catalyst

[0118]

[0119] Synthesis of Ni7 catalyst: Under nitrogen atmosphere in a glove box, ligand L7 (593 mg, 1 mmol) and 1.3 equivalents of Py2NiMe2 were dissolved in a suitable amount of toluene solution and stirred at room temperature for 4 hours. The toluene solution was removed by filtration, and the solution was recrystallized from dry n-hexane to yield yellow solid Ni7 (yield 77%).

[0120] Example 17: Ethylene Homopolymerization Data Sheet

[0121] Weigh 10 μmol of nickel catalyst into a 20 mL glass vial in a glove box. Dissolve 10 mL of dried toluene solution in the same vial using a syringe. Place both vials on a stirring table for later use. Add 28 mL of toluene solvent to a dry, pressure-resistant polymer bottle and add a stirrer. Seal the pressure-resistant polymerization bottle and catalyst out of the glove box. Transfer the bottle to a magnetic stirrer with an oil bath heating function and connect it to the polymerization pipeline. Heat the system to the reaction temperature. Once the temperature stabilizes, open the ethylene valve and adjust the pressure to two atmospheres. Turn on the vacuum pump, evacuate and purge three times to remove air from the polymerization pipeline. Using a 5 mL syringe, take 2 mL of a mixed solvent of toluene and catalyst. Replace the syringe with a long needle and quickly inject the solution into the polymer bottle, then close the valve. Adjust the ethylene pressure to eight atmospheres and stop the polymerization after 0.5 hours. Slowly release the pressure, remove the polymerization bottle, slowly release the pressure, open the reactor, add ethanol to precipitate the polymer, filter, and dry. Obtain the desired polymer, weigh it, and calculate the yield and activity. The results are shown in Table 1.

[0122] Table 1. Results of ethylene polymerization at 130 °C a

[0123] 1 Ni1 3.08 1.23 1.3 2.1 124.5 2 Ni2 2.88 1.15 1.8 2.0 124.1 3 Ni3 2.60 1.04 2.1 1.7 124.8 4 Ni4 2.01 0.80 1.5 2.2 123.3 5 Ni5 1.92 0.77 1.7 1.8 123.1 6 Ni6 1.90 0.76 1.9 1.7 123.6 7 Ni7 1.84 0.74 2.3 1.5 123.9

[0124] a Conditions: 5 µmol nickel catalyst; 2 mL toluene; 28 mL heptane; rotation speed 450 rpm; ethylene pressure 8 atm; reaction time t = 30 min.

[0125] b 10 active units 6 g mol -1 h -1 .

[0126] c Number average molecular weight is in units of 10 4 g mol -1M n The molecular weight distribution was determined by gel permeation chromatography in 1,2,4-trichlorobenzene at 160 °C.

[0127] d The determination was performed using differential scanning calorimetry (second heating curve).

[0128] Example 18: Ethylene / Polar Monomer Copolymerization

[0129] Add the weighed comonomer (dried and filtered with CaH2) and a certain amount of heptane to a 350 mL pressure-resistant polymer bottle, bringing the total volume to 20 mL. Add a stirrer. Weigh 10 μmol of catalyst and dissolve it in 2 mL of toluene. Transfer the pressure-resistant polymerization bottle to a magnetic stirrer with an oil bath heating function and connect it to the polymerization pipeline. Then heat the system to the reaction temperature. After the temperature stabilizes, open the ethylene valve and adjust to two atmospheres. Turn on the vacuum pump, evacuate and replace it three times to remove air from the polymerization pipeline. Replace the syringe with a long needle and quickly inject it into the polymer bottle, then close the valve. Adjust the ethylene pressure to the desired value and stop the polymerization after 0.5 hours. After slowly releasing the pressure, remove the polymerization bottle, slowly release the pressure, open the reactor, add ethanol to precipitate the polymer, filter and dry. Obtain the desired polymer, weigh it, and calculate the yield and activity.

[0130] Table 2 Results of copolymerization of ethylene with polar monomers a

[0131] 1 Ni1 0.1 0.64 1.28 2.11 123.4 2.0 1.7 2 Ni2 0.1 0.71 1.42 2.03 120.1 2.1 1.4 3 Ni3 0.1 0.73 1.46 1.99 119.8 2.4 1.6 4 Ni4 0.1 0.61 1.22 2.15 124.2 1.9 1.7 5 Ni5 0.1 0.66 1.32 2.07 122.1 2.3 1.9 6 Ni6 0.1 0.63 1.26 2.01 123.3 2.1 1.5 7 Ni7 0.1 0.71 1.42 1.93 121.9 2.4 1.6

[0132] a Conditions: 10 µmol nickel catalyst; temperature = 130 ℃; ethylene pressure = 8 atm; 2 mL toluene; 18 mL heptane and polar monomer; rotation speed = 450 rpm; reaction time = 30 min.

[0133] b 10 active units 5 g mol -1 h -1 .

[0134] c Determined by ¹H NMR analysis.

[0135] d The determination was performed using differential scanning calorimetry (second heating curve).

[0136] e Number average molecular weight unit 10 4 g mol -1Number-average molecular weight and molecular weight distribution were determined by gel permeation chromatography in 1,2,4-trichlorobenzene at 160 °C.

[0137] The above description is only a preferred embodiment of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of this patent application are included in the scope of this patent application.

Claims

1. An asymmetric POCOP-type phosphonophenol nickel catalyst containing oxygen / sulfur-containing fused aromatic rings, characterized in that, Having the structures shown in formulas (I1) to (I7), corresponding to catalysts Ni1 to Ni7: (I1) (I2) (I3) (I4) (I5) (I6) （I7） Equation (I1) corresponds to Ni1, which is obtained from the reaction of ligand L1 with nickel precursor; Equation (I2) corresponds to Ni2, and is obtained from the reaction of ligand L2 with nickel precursor; Equation (I3) corresponds to Ni3, which is obtained from the reaction of ligand L3 with nickel precursor; Equation (I4) corresponds to Ni4, which is obtained from the reaction of ligand L4 with nickel precursor; Formula (I5) corresponds to Ni5, which is obtained from the reaction of ligand L5 with nickel precursor; Formula (I6) corresponds to Ni6, which is obtained by reacting ligand L6 with a nickel precursor; Formula (I7) corresponds to Ni7, which is obtained by reacting ligand L7 with nickel precursor.

2. An asymmetric POCOP-type phosphonophenol ligand containing oxygen / sulfur-containing fused aromatic rings, characterized in that, It has the structures shown in formulas (I8) to (I14), corresponding to ligands L1 to L7: (I8) (I9) (I10) (I11) (I12) (I13) (I14) Formula (I8) corresponds to ligand L1, with a 2-benzofuran group attached to its phosphorus atom; Formula (I9) corresponds to ligand L2, with a 5-benzofuran group attached to its phosphorus atom; Formula (I10) corresponds to ligand L3, which has a 7-benzofuran group attached to its phosphorus atom; Formula (I11) corresponds to ligand L4, which has a 2-benz[b]thiophene group attached to its phosphorus atom; Formula (I12) corresponds to ligand L5, which has a 3-benz[b]thiophene group attached to its phosphorus atom; Formula (I13) corresponds to ligand L6, which has a 4-benzo[b]thiophene group attached to its phosphorus atom; Formula (I14) corresponds to ligand L7, which has a 6-benziro[b]thiophene group attached to its phosphorus atom.

3. A method for synthesizing an asymmetric POCOP-type phosphonophenol ligand containing oxygen / sulfur-containing fused aromatic ring substitution, characterized in that, Includes the following steps: S1: 2-tert-butylphenol was reacted with dried dichloromethane and 3,4-dihydro-2H-pyran under PPTS catalysis to prepare intermediate a with protected hydroxyl groups; S2: 2-Bromo-2,6-dimethoxybiphenyl was lithiated with n-butyllithium and then reacted with phosphorus trichloride to prepare the diarylphosphine intermediate Cl2PPh(Ar). S3: The brominated heteroaryl hydrocarbon is lithiated with n-butyllithium and then reacted with Cl2PPh(Ar), followed by reaction with the lithiation product of intermediate a, and finally deprotected by PTSA acid to obtain the target ligands L1 to L7.

4. The method for synthesizing the asymmetric POCOP-type phosphonol ligand containing oxygen / sulfur-fused heterocyclic aromatic rings according to claim 3, characterized in that, The acid deprotection in step S3 involves stirring p-toluenesulfonic acid monohydrate in deoxymethanol solvent for 2 hours, followed by TLC plate detection, extraction with dichloromethane for desalting and dehydration, and purification by column chromatography; the yields of ligands L1 to L7 are 63% to 72%.

5. A method for synthesizing an oxygen / sulfur-containing fused aromatic ring-substituted asymmetric POCOP-type phosphonophenol nickel catalyst, characterized in that, Under the protection of inert gas N2, an asymmetric POCOP-type phosphonophenol ligand containing oxygen / sulfur fused aromatic rings was dissolved in toluene with 1.5 equivalents of [Py2NiMe2]. The reaction was stirred at room temperature for 3–5 hours. After the reaction, dried diatomaceous earth was placed in a sand core, which was then installed on a 100 ml Shrek flask. A pump was connected, and the above reaction liquid was filtered. A cold neck was connected, and the toluene solution was dried. The solution was then recrystallized with dried n-hexane and filtered to obtain a yellow solid target catalyst.

6. A method for olefin polymerization, characterized in that, Asymmetric POCOP-type phosphonophenol nickel catalysts with oxygen / sulfur-containing fused aromatic rings are used to carry out homopolymerization of ethylene or copolymerization of ethylene with polar monomers in olefin polymerization reactions.

7. The olefin polymerization method according to claim 6, characterized in that, The homopolymerization reaction of ethylene was carried out at a temperature of 130°C and an ethylene pressure of 8 atm.

8. The olefin polymerization method according to claim 6, characterized in that, In the copolymerization reaction of ethylene with a polar monomer, the polar monomer is selected from tert-butyl acrylate compounds.

9. The olefin polymerization method according to claim 6 or 7, characterized in that, The solvent for the polymerization reaction is a mixture of toluene and n-heptane.

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