N-heterocyclic imine palladium (II) catalyst and its application in synthesis of polar functionalized hyperbranched polyethylene lubricating base oil

Abstract

The application discloses a kind of N-heterocyclic imine palladium (II) catalyst and its application in the synthesis of polar functionalized hyperbranched polyethylene lubricating base oil, belong to metal catalysis and olefin polymerization field.The catalyst of the present application uses 2-acetylpyrazine, 2-acetylpyrimidine, 2-acetylpyridine as skeleton, introduces isopropyl and flexible big steric cycloalkyl imine group, can efficiently catalyze ethylene homopolymerization and ethylene and methyl acrylate copolymerization.The molecular weight of the obtained polyethylene lubricating base oil product can be controlled at 283-1726 g / mol, the branching density is 111-164 / 1000C, the highest polarity monomer insertion rate is 14.8 mol%;100 ℃ kinematic viscosity 3.49-56.06 mm 2 / s, viscosity index 201-228, pour point < -40 DEG C, excellent low-temperature fluidity, no storage turbidity and solidification phenomenon, good compatibility with polar additives, can be widely used in high-end equipment, new energy equipment and environmental protection type lubricant field.

Description

Technical Field

[0001] This invention belongs to the fields of metal catalysis and olefin polymerization technology, specifically relating to an N-heterocyclic imine palladium(II) catalyst and its application in the synthesis of polar functionalized hyperbranched polyethylene lubricating base oil. Background Technology

[0002] Polyolefin synthetic lubricating base oils have become high-end lubricants that replace traditional mineral oils due to their good thermal stability, excellent viscosity-temperature properties, low volatility, and long service life. They mainly include three types: polyalphaolefins (PAO), hyperbranched polyolefins (HBPO), and polar functionalized polyolefins (PFPO). Among them, the hyperbranched structure can significantly improve low-temperature fluidity and shear stability, while polar functionalization can enhance lubricity and additive compatibility, making them urgently needed in the fields of new energy, high-end equipment, and energy-saving lubrication.

[0003] In existing technologies, although rigid N-triphenylpyridine-imine nickel / palladium catalysts can prepare hyperbranched polyethylene, the products are prone to problems such as turbidity and low-temperature solidification during storage, and their rheological properties and stability are difficult to meet the requirements of high-end lubrication. At the same time, traditional catalytic systems have low insertion rates for polar monomers and weak structural control capabilities, requiring post-polymerization modification, which is complex and costly.

[0004] Therefore, developing palladium catalyst systems with novel structures, stable catalytic activity, precise control over branched structure and polar function, stable product storage, and excellent low-temperature fluidity is of great significance for promoting the development of next-generation high-performance synthetic lubricating base oils. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of existing catalysts in the preparation of hyperbranched polyethylene, such as easy turbidity, easy solidification, poor low-temperature fluidity, and difficulty in polar functionalization. It provides an N-heterocyclic imine palladium(II) catalyst containing isopropyl and flexible cycloalkyl substituents and its application in the synthesis of polar functionalized hyperbranched polyethylene lubricating base oil.

[0006] The N-heterocyclic imine palladium(II) catalyst of this invention has the following general structural formula:

[0007]

[0008] in:

[0009] X1 and X2 are each independently selected from C or N;

[0010] R′ is selected from H, phenyl (Ph), methyl (Me), or ethyl (Et);

[0011] R1 is selected from isopropyl (iPr), cyclopentyl (Cp), cyclohexyl (Ch), cycloheptyl, or cyclooctyl;

[0012] R2 is selected from H, cyclopentyl (Cp), cyclohexyl (Ch), cycloheptyl, or cyclooctyl.

[0013] The following eight types are further preferred:

[0014] Pd1: X1=N, X2=C, R′=Me, R1=iPr, R2=H;

[0015] Pd2: X1=N, X2=C, R′=Me, R1=Cp, R2=Cp;

[0016] Pd3: X1=N, X2=C, R′=Me, R1=Ch, R2=Ch;

[0017] Pd4: X1=C, X2=N, R′=Me, R1=iPr, R2=H;

[0018] Pd5: X1=C, X2=N, R′=Me, R1=Cp, R2=Cp;

[0019] Pd6: X1=C, X2=N, R′=Me, R1=Ch, R2=Ch;

[0020] Pd7: X1=C, X2=C, R′=Me, R1=Cp, R2=Cp;

[0021] Pd8: X1=C, X2=C, R′=Me, R1=Ch, R2=Ch.

[0022] The method for preparing the N-heterocyclic imine palladium(II) catalyst of the present invention includes the following steps:

[0023] Step 1: Preparation of ligands

[0024] Aromatic amine (1 mmol, 1 eq) and N-heterocyclic skeleton (1.1 mmol, 1.1 eq) were added to a round-bottom flask; anhydrous zinc chloride (1.1 mmol, 1.1 eq) was dissolved in a small amount of acetic acid (<5 mL), and the solution was transferred to a reaction flask to dissolve the reactants; the mixture was stirred under reflux in an oil bath at 90 °C for 5 h, and then cooled to room temperature; the acetic acid was removed by concentration under reduced pressure, and the zinc complex solid was precipitated with diethyl ether under ultrasonic assistance and washed; the zinc complex was dissolved in dichloromethane (20 mL), and an equal volume of potassium oxalate aqueous solution (1.1 mmol, 1.1 eq) was added, and the mixture was hydrolyzed at room temperature for 1 h; the aqueous phase was extracted three times with dichloromethane, the organic phase was dried over anhydrous magnesium sulfate for 30 min, filtered through diatomaceous earth, and concentrated under reduced pressure to obtain the crude product.

[0025] The N-heterocyclic skeleton is 2-acetylpyrazine, 2-acetylpyrimidine, or 2-acetylpyrimidine.

[0026] The aromatic amine is 2,6-diisopropylaniline, 2,4,6-tricyclopentylaniline, or 2,4,6-tricyclohexylaniline.

[0027] in:

[0028] Ligands L1-L3, L5, and L7: separated by column chromatography to obtain a yellow liquid;

[0029] Ligands L4 and L6: directly yield pure yellow solids;

[0030] Ligand L8: Recrystallization from ethanol or methanol yields a yellow powder.

[0031] The structures of ligands L1-L8 are shown below:

[0032]

[0033] Step 2: Preparation of palladium complex

[0034] The ligand obtained in step 1 (0.2 mmol, 1 eq) was placed in a round-bottom flask, and an equimolar (COD) of PdMeCl and 20 mL of dichloromethane were added. The mixture was stirred overnight at room temperature, and the solution changed from yellow to orange. The solvent was removed by concentration under reduced pressure, and the solid powder was obtained by precipitating with diethyl ether: Pd1 and Pd3 were orange-yellow solids; Pd2, Pd4-Pd8 were yellow solids.

[0035] The present invention relates to the application of the N-heterocyclic imine palladium(II) catalyst in the synthesis of polar functionalized hyperbranched polyethylene lubricating base oil.

[0036] Catalytic polymerization processes include homopolymerization of ethylene or copolymerization of ethylene with methyl acrylate.

[0037] (1) Homopolymerization of ethylene

[0038] The N-heterocyclic imine palladium(II) catalyst and the co-catalyst NaBArF are arranged in a molar ratio of 1:2 to form a composite catalytic system; the amount of N-heterocyclic imine palladium(II) catalyst is 10 μmol, the ethylene pressure is 6 atm, the polymerization temperature is 30-50 ℃, and the reaction time is 3 h; the solvent is dichloromethane.

[0039] (2) Copolymerization of ethylene and methyl acrylate

[0040] The N-heterocyclic imine palladium(II) catalyst and the co-catalyst NaBArF were arranged in a molar ratio of 1:2 to form a composite catalytic system; the amount of N-heterocyclic imine palladium(II) catalyst was 10 μmol; the concentration of methyl acrylate was 0.5-1 M; the ethylene pressure was 4 atm; the polymerization temperature was 30-50 ℃; the reaction time was 3 h; and the solvent was dichloromethane.

[0041] The beneficial effects of this invention are reflected in:

[0042] 1. Precise and controllable structure: The molecular weight of the product can be adjusted from 283 to 1726 g / mol, the branching density is 111 to 164 / 1000C, and the polar monomer insertion rate is up to 14.8 mol.

[0043] 2. Excellent lubrication performance: kinematic viscosity at 100℃ is 3.49-56.06 mm. 2 / s, viscosity index 201-228, pour point < -40 ℃, significantly better than commercial PAO.

[0044] 3. Strong stability: No storage turbidity or low-temperature solidification issues; outstanding low-temperature fluidity and thermal stability.

[0045] 4. Simple process: Polar functionalized products are synthesized in one step without post-modification, making it suitable for industrial production.

[0046] 5. Good compatibility: Polar functional products and additives are highly compatible and can be used in high-end, long-lasting, and environmentally friendly lubrication systems. Attached Figure Description

[0047] Figure 1 Comparison of the yield (a), molecular weight (b), and branching density (c) of HBPEO catalyzed by different axially substituent pyrazine-imine palladium catalysts.

[0048] Figure 2 Comparison of the yield (a), molecular weight (b), and branching density (c) of HBPEO catalyzed by different cyclopentylpalladium catalysts.

[0049] Figure 3 Preparation of HBPEO for Pd3 13 C NMR spectrum.

[0050] Figure 4 Comparison of the yield (a), insertion ratio (b), molecular weight (c), and branching density (d) of PF-HBPEOs catalyzed by pyrazine-imine palladium catalysts with different axial substituents.

[0051] Figure 5 The yield (a), insertion ratio (b), molecular weight (c), and branching density (d) of PF-HBPEO catalyzed by different cyclopentylpalladium catalysts are compared.

[0052] Figure 6 Preparation of PF-HBPEO for Pd6 13 C NMR spectrum.

[0053] Figure 7 The curve shows the relationship between the molecular weight of HBPEO and its kinematic viscosity at 100 °C. Detailed Implementation

[0054] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited to these embodiments.

[0055] Example 1: Preparation of catalyst Pd1

[0056] 1. Ligand L1 Synthesis

[0057] 2-Acetylpyrazine (1.1 mmol) and 2,6-diisopropylaniline (1 mmol) were fed into the reactor, acetic acid was used as solvent, zinc chloride was used as catalyst, and the reaction was carried out under reflux at 90 °C for 5 h; post-treatment yielded a yellow liquid ligand L1 with a yield of 55%.

[0058]

[0059]

[0060] NMR analysis: 1 H NMR (400 MHz, CDCl3) δ 9.57 (d, J = 1.6 Hz, Ar-H, a1, 1H), 8.67 (d, J = 2.6 Hz, Ar-H, a2, 1H), 8.62 (dd, J = 2.6, 1.5 Hz, Ar-H, a3, 1H), 7.20 – 7.16 (m, Ar-H, a4, 2H), 7.14 – 7.09 (m, Ar-H, a5, 1H), 2.77 – 2.65 (m,-CH-, b, 2H), 2.19 (s, -CH 3, c2, 3H), 1.16 (dd, J = 7.0, 1.0 Hz, -CH3, c1,12H). 13 C NMR (101 MHz, CDCl3) δ 165.79 (C=N, a5*), 151.02 (a4*), 145.80 (a2*), 145.20 (a6*), 143.64 (a1*), 143.00 (a3*), 135.56 (a7*), 123.95 (a9*), 123.02(a8*), 28.29 (-CH-, b*), 23.18 (-CH3, c1*), 22.78(-CH3, c1*), 16.98 (-CH3,c2*).

[0061] Mass spectrometry analysis: APCI-MS (m / z): calcd for C 18 H24 N3 + : 282.1964, Found, 282.1966,[M+H] + .

[0062] 2. Synthesis of Pd1 complexes

[0063] Ligand L1 (0.2 mmol) was reacted with (COD) PdMeCl in equimolar amounts in dichloromethane at room temperature overnight; the mixture was concentrated and precipitated with diethyl ether to give an orange-red solid Pd1 in 83% yield.

[0064]

[0065]

[0066] NMR analysis: A-isomer: B-isomer > 10:1. 1 H NMR (400 MHz, CDCl3) δ 9.25(dd, J = 2.6, 1.4 Hz, Ar-H, a1, 1H), 9.17 (d, J = 1.5 Hz, Ar-H, a2, 1H), 9.07(d, J = 2.6 Hz, Ar-H, a3, 1H), 7.32 – 7.28 (m, Ar-H, a4, 1H), 7.24 (s, Ar-H,a5, 2H), 2.97 (hept, J = 7.4, 6.8 Hz, -CH-, b, 2H), 2.27 (s, -CH3, c1, 3H), 1.25 (d, J = 6.8 Hz, -CH3, c3, 6H), 1.08 (d, J = 6.9 Hz, -CH3, c3, 6H), 0.58(s, -CH3, c2, 3H). 13 C NMR (101 MHz, CDCl3) δ 172.51 (C=N, a1*), 150.47 (a2*), 147.06 (a3*), 145.32 (a4*), 142.55 (a5*), 140.92 (a6*), 138.91 (a7*), 127.94(a9*), 124.68 (a8*), 28.18 (CH, b*), 23.92 (CH3, c3*), 23.28 (CH3, c3*), 18.86(CH3, c1*), 2.90 (CH3, c2*). 1 H- 1H NOESY correlations (500 MHz, CDCl3): 2.97(hept, J = 7.4, 6.8 Hz, -CH-, b, 2H) / 0.58 (s, -CH3, c2, 3H), 1.25 (d, J = 6.8Hz, -CH3, c3, 6H) / 0.58 (s, -CH3, c2, 3H).

[0067] Example 2: Preparation of catalyst Pd2

[0068] By replacing 2,6-diisopropylaniline with 2,4,6-tricyclopentylaniline, and otherwise following the same procedure as in Example 1, ligand L2 (yield 45%) and palladium complex Pd2 (yield 85%, yellow solid) were prepared.

[0069]

[0070]

[0071] NMR analysis: 1 H NMR (400 MHz, CDCl3) δ 9.56 (d, J = 1.5 Hz, Ar-H, a1, 1H), 8.66 (d, J = 2.6 Hz, Ar-H, a2, 1H), 8.64 – 8.59 (m, Ar-H, a3, 1H), 7.03 (s,Ar-H, a4, 2H), 3.03 – 2.88 (m, -CH-, b2, 1H), 2.82 – 2.69 (m, -CH-, b1, 2H), 2.18 (s, -CH3, c, 3H), 2.10 – 2.04 (m, -CH2-, d, 2H), 1.99 (m, -CH2-, d, 2H),1.84 – 1.58 (m, -CH2-, d, 20H). 13C NMR (101 MHz, CDCl3) δ 166.07 (C=N, a5*),151.21 (a4*), 145.22 (a2*), 145.09 (a9*), 143.70 (a3*), 142.99 (a1*), 141.44(a6*), 133.09 (a7*), 122.22 (a8*), 45.98 (-CH-, b2*), 40.44 (-CH-, b1*), 34.75(-CH2-, d*), 33.86 (-CH2-, d*), 25.67 (-CH2-, d*), 25.64 (-CH2-, d*), 25.44 (-CH2-, d*), 17.18 (-CH3, c*).

[0072] Mass spectrometry analysis: APCI-MS (m / z): calcd for C 27 H 36 N3 + : 402.2903, Found, 402.2908, [M+H] + .

[0073]

[0074]

[0075] NMR analysis: A-isomer: B-isomer > 10:1. 1H NMR (400 MHz, CDCl3) δ 9.27 –9.25 (s, Ar-H, a1, 1H), 9.18 (d, J = 1.4 Hz, Ar-H, a2, 1H), 9.08 (d, J = 2.7Hz, Ar-H, a3, 1H), 7.08 (s, Ar-H, a4, 2H), 3.03 – 2.95 (m, -CH-, b, 3H), 2.24(s, -CH3, c1, 3H), 2.19 – 2.16 (m, -CH2-, d, 1H), 2.10 – 2.05 (m, -CH2-, d,2H), 1.83 – 1.74 (m, -CH2-, d, 7H), 1.72 – 1.66 (m, -CH2-, d, 5H), 1.65 – 1.61 (m, -CH2-, d, 4H), 1.57 – 1.47 (m, -CH2-, d, 5H), 0.61 (s, -CH3, c2, 3H). 13 CNMR (101 MHz, CDCl3) δ 172.72 (C=N, a1*), 149.90 (a2*), 147.17 (a3*), 145.65(a4*), 145.22 (a5*), 142.55 (a6*), 140.21 (a7*), 136.82 (a8*), 122.89 (a9*), 45.87 (CH, b1*), 39.95 (CH, b2*), 35.19 (CH2, d*), 34.58 (CH2, d*), 34.30 (CH2,d*), 26.04 (CH2, d*), 25.88 (CH2, d*), 25.44 (CH2, d*), 18.85 (CH3, c1*), 2.93(CH3, c2*). 1 H- 1 H NOESY correlations (500 MHz, CDCl3): 3.03 – 2.95 (m, -CH-, b,3H) / 0.61 (s, -CH3, c2, 3H), 2.19 – 2.16 (m, -CH2-, d, 1H) / 0.61 (s, -CH3, c2,3H).

[0076] Example 3: Preparation of Pd3 catalyst

[0077] By replacing 2,6-diisopropylaniline with 2,4,6-tricyclohexylaniline, and otherwise following the same procedure as in Example 1, ligand L3 (yield 47%) and palladium complex Pd3 (yield 99%, orange-yellow solid) were prepared.

[0078]

[0079]

[0080] NMR analysis: 1 H NMR (400 MHz, CDCl3) δ 9.53 (d, J = 1.5 Hz, Ar-H, a1, 1H), 8.67 (d, J = 2.6, Ar-H, a2, 1H), 8.63 (t, J = 2.1Hz, Ar-H, a3, 1H), 6.96 (s, Ar-H, a4, 2H), 2.47 (d, J = 3.5 Hz, -CH-, b2, 1H), 2.32 – 2.21 (m, -CH-, b1,2H), 2.17 (s, -CH3, c, 3H), 1.95 – 1.80 (m, -CH2-, d, 6H), 1.75 (m, -CH2-, d,5H), 1.64 (t, J = 7.6 Hz, -CH2-, d, 4H), 1.51 – 1.37 (m, -CH2-, d, 6H), 1.32 –1.14 (m, -CH2-, d, 9H). 13 C NMR (101 MHz, CDCl3) δ 165.79 (C=N, a5*), 151.31(a4*), 145.11 (a2*), 143.62 (a3*), 143.54 (a1*), 143.22 (a9*), 143.03 (a6*), 134.31 (a7*), 121.98 (a8*), 44.44 (-CH-, b2*), 39.31 (-CH-, b1*), 34.70 (-CH2-,d*), 33.56 (-CH2-, d*), 33.32 (-CH2-, d*), 27.14 (-CH2-, d*), 27.05 (-CH2-,d*), 27.03 (-CH2-, d*), 26.25 (-CH2-, d*), 17.13 (-CH3, c*).

[0081] Mass spectrometry analysis: APCI-MS (m / z): calcd for C 30 H 42 N3 + : 444.3373, Found, 444.3378,[M+H] + .

[0082]

[0083]

[0084] NMR analysis: A-isomer: B-isomer > 10:1. 1 H NMR (400 MHz, CDCl3) δ 9.28 (d,J = 2.6 Hz, Ar-H, a2, 1H), 9.18 (s, Ar-H, a1, 1H), 9.09 (d, J = 2.6 Hz, Ar-H,a3, 1H), 7.04 (s, Ar-H, a4, 2H), 2.51 (tt, J = 11.8, 4.0 Hz, -CH-, b, 3H), 2.25 (s, -CH3, c1, 3H), 1.98 (d, J = 12.3 Hz, -CH2-, d, 2H), 1.91 – 1.84 (m, -CH2-, d, 4H), 1.80 – 1.65 (m, -CH2-, d, 8H), 1.43 (dt, J = 23.6, 7.6 Hz, -CH2-, d, 11H), 1.32 – 1.23 (m, -CH2-, d, 4H), 1.18 (d, J = 7.2 Hz, -CH2-, d,1H), 0.58 (s, -CH3, c2, 3H). 13C NMR (101 MHz, CDCl3) δ 172.32 (C=N, a1*),150.37 (a2*), 147.09 (a3*, a4*), 145.18 (a5*), 142.70 (a6*), 138.96 (a7*), 137.48 (a8*), 123.03 (a9*), 44.41 (CH, b1*), 39.08 (CH, b2*), 34.61 (CH2, d*), 34.47 (CH2, d*), 33.25 (CH2, d*), 26.92 (CH2, d*), 26.86 (CH2, d*), 26.72 (CH2,d*), 26.12 (CH2,d*), 26.01 (CH2, d*), 18.90 (CH3, c1*), 3.06 (CH3, c2*). 1 H- 1 HNOESY correlations (500 MHz, CDCl3): 2.51 (tt, J = 11.8, 4.0 Hz, -CH-, b,3H) / 0.58 (s, -CH3, c2, 3H), 1.98 (d, J = 12.3 Hz, -CH2-, d, 2H) / 0.58 (s, -CH3,c2, 3H).

[0085] Examples 4-8: Preparation of Pd4-Pd8 catalysts

[0086] Pd4-Pd8 were prepared by replacing the skeleton with 2-acetylpyrimidine and 2-acetylpyridine respectively, while keeping the corresponding substituents consistent, with yields of 73%-98%.

[0087]

[0088] NMR analysis of ligand L4: 1H NMR (400 MHz, CDCl3) δ 8.94 (d, J = 4.8 Hz, Ar-H,a1, 2H), 7.46, 7.40 (t, J = 4.8 Hz, Ar-H, a2, 1H), 7.20 – 7.14 (m, Ar-H, a3,2H), 7.12 (m, Ar-H, a4, 1H), 2.84 – 2.76 (m, -CH-, b, 2H), 2.25 (s, -CH3, c2,3H), 1.27 (d, J = 6.8 Hz, -CH3, c1, 3H), 1.15 (dd, J = 8.3, 6.8 Hz, -CH3, c1,9H). 13 C NMR (101 MHz, CDCl3) δ 166.21 (C=N, a4*), 163.06 (a3*), 157.40 (a1*), 146.17 (a5*), 135.75 (a6*), 123.87 (a2*), 122.47 (a7*), 121.27 (a8*), 28.11 (-CH-, b*), 23.40 (-CH3, c1*), 23.32 (-CH3, c1*), 18.41 (-CH3, c2*).

[0089] Mass spectrometry analysis of ligand L4: APCI-MS (m / z): calcd for C 18 H 24 N3 + : 282.1964, Found,282.1969, [M+H] + .

[0090]

[0091] NMR analysis of Pd4 catalyst: A-isomer: B-isomer > 10:1. 11H NMR (400 MHz, CDCl3) δ 9.39 (dd, J = 5.2, 2.4 Hz, Ar-H, a1, 1H), 9.03 (dd, J = 5.0, 2.4 Hz, Ar-H,a2, 1H), 7.72 (t, J = 5.1 Hz, Ar-H, a3, 1H), 7.32 – 7.28 (m, Ar-H, a4, 1H),7.26 – 7.21 (m, Ar-H, a5, 2H), 3.03 (hept, J = 6.8 Hz, -CH-, b, 2H), 2.28 (s,-CH3, c1, 3H), 1.27 (d, J = 6.8 Hz, -CH3, c3, 6H), 1.10 (d, J = 6.9 Hz, -CH3,c3, 6H), 0.54 (s, -CH3, c2, 3H). 13 13C NMR (101 MHz, CDCl3) δ 175.37 (C=N, a1*),161.66 (a2*), 158.14 (a3*), 155.81 (a4*), 141.23 (a5*), 138.57 (a6*), 127.78(a7*), 123.98 (a8*), 123.87 (a9*), 28.16 (CH, b*), 23.88 (CH3, c3*), 23.33(CH3, c3*), 19.50 (CH3, c1*), 1.90 (CH3, c2*). 1 H- 1 1H-1H NOESY correlations (500MHz, CDCl3): 3.03 (hept, J = 6.8 Hz, -CH-, b, 2H) / 0.54 (s, -CH3, c2, 3H), 1.27(d, J = 6.8 Hz, -CH3, c3, 6H) / 0.54 (s, -CH3, c2, 3H).

[0092]

[0093] NMR analysis of ligand L5: 1H NMR (400 MHz, CDCl3) δ 8.94 (d, J = 4.9 Hz, Ar-H,a1, 2H), 7.39 (t, J = 4.8 Hz, Ar-H, a2, 1H), 7.00 (s, Ar-H, a3, 2H), 2.96 (td,J = 8.5, 7.2, 2.3 Hz, -CH-, b2, 1H), 2.87 – 2.75 (m, -CH-, b1, 2H), 2.22 (s, -CH3, c, 3H), 2.11 – 2.03 (m, -CH2-, d, 2H), 2.00 (q, J = 5.3, 4.5 Hz, -CH2-,d, 2H), 1.81 (q, J = 7.2, 5.8 Hz, -CH2-, d, 4H), 1.77 – 1.62 (m, -CH2-, d,8H), 1.62 – 1.57 (m, -CH2-, d, 2H), 1.55 – 1.45 (m, -CH2-, d, 6H). 13 C NMR (101 MHz, CDCl3) δ 166.38 (C=N, a4*), 163.24 (a3*), 157.35 (a1*), 145.78 (a8*), 141.09 (a5*), 133.11 (a6*), 121.98 (a7*), 121.15 (a2*), 45.88 (-CH-, b2*),40.18 (-CH-, b1*), 34.60 (-CH2-, d*), 34.28 (-CH2-, d*), 33.95 (-CH2-, d*),25.81 (-CH2-, d*), 25.73 (-CH2-, d*), 25.42 (-CH2-, d*), 18.51 (-CH3, c*).

[0094] Mass spectrometry analysis of ligand L5: APCI-MS (m / z): calcd for C 27 H 36 N3 + : 402.2903, Found,402.2912, [M+H] + .

[0095]

[0096] NMR analysis of Pd5 catalyst: A-isomer: B-isomer = 5:1.1 H NMR (400 MHz, CDCl3)δ 9.39 (dt, J = 4.9, 2.3 Hz, Ar-H, a1, 1H), 9.03 (dt, J = 4.7, 2.3 Hz, Ar-H,a2, 1H), 7.70 (td, J = 5.1, 2.3 Hz, Ar-H, a3, 1H), 7.08 (d, J = 2.3 Hz, Ar-H,a4, 2H), 3.05 (h, J = 7.6 Hz, -CH-, b, 3H), 2.46 (s, -CH2-, d, 1H), 2.24 (d, J= 2.1 Hz, -CH3, c1, 3H), 2.23 – 2.21 (m, -CH2-, d, (1H), 2.08 (s, -CH2-, d,2H), 1.83 – 1.60 (m, -CH2-, d, 18H), 1.50 – 1.44 (m, -CH2-, d, 1H), 0.57 (d, J= 2.4 Hz, -CH3, c2, 3H). 13 1C NMR (101 MHz, CDCl3) δ 175.62 (C=N, a1*), 161.75 (a2*), 158.09 (a3*), 155.81 (a4*), 145.46 (a5*), 140.53 (a6*), 136.46 (a7*), 123.80 (a8*), 122.83 (a9*), 45.86 (CH, b1*), 39.91 (CH, b2*), 35.19 (CH2, d*), 34.56 (CH2, d*), 34.37 (CH2, d*), 26.07 (CH2, d*), 25.91 (CH2, d*), 25.43 (CH2, d*), 19.37 (CH3, c1*), 1.93 (CH3, c1*). 1 H- 1 H NOESY correlations (500 MHz,CDCl3): 3.05 (h, J = 7.6 Hz, -CH-, b, 3H) / 0.57 (d, J = 2.4 Hz, -CH3, c2, 3H),2.23 – 2.21 (m, -CH2-, d, 1H) / 0.57 (d, J = 2.4 Hz, -CH3, c2, 3H)。

[0097]

[0098] NMR analysis of ligand L6: 1 H NMR (400 MHz, CDCl3) 8.93 (s, Ar-H, a1, 2H), 7.38 (s, Ar-H, a2, 1H), 6.92 (d, J = 3.4 Hz, Ar-H, a3, 2H), 2.45 (m, -CH-, b2, 1H), 2.35 (m, -CH-, b1, 2H), 2.20 (s, -CH3, c, 3H), 1.96 – 1.79 (m, -CH2-, d, 9H), 1.72 (m, -CH2-, d, 6H), 1.62 (d, J = 9.3 Hz, -CH2-, d, 3H), 1.42 (p, J = 11.6,10.4 Hz, -CH2-, d, 8H), 1.25 (m, -CH2-, d, 4H). 13 C NMR (101 MHz, CDCl3) δ166.14 (C=N, a4*), 163.21 (a3*), 157.62 (a1*), 144.06 (a5*), 142.86 (a2*), 134.33 (a6*), 121.80 (a7*), 121.12 (a8*), 44.31 (-CH-, b2*), 39.03 (-CH-, b1*),34.67 (-CH2-, d*), 33.67 (-CH2-, d*), 33.63 (-CH2-, d*), 27.11 (-CH2-, d*),27.03 (-CH2-, d*), 26.88 (-CH2-, d*), 26.28 (-CH2-, d*),18.41 (-CH3, c*).

[0099] Mass spectrometry analysis of ligand L6: APCI-MS (m / z): calcd for C 30 H 42 N3 + : 444.3373, Found,444.3380, [M+H] + .

[0100]

[0101] NMR analysis of Pd6 catalyst: A-isomer: B-isomer > 10:1. 11H NMR (400 MHz, CDCl3)δ 9.41 (dd, J = 5.2, 2.4 Hz, Ar-H, a1, 1H), 9.04 (dd, J = 4.9, 2.4 Hz, Ar-H, a2, 1H), 7.71 (t, J = 5.1 Hz, Ar-H, a3, 1H), 7.04 (s, Ar-H, a4, 2H), 2.61–2.47 (m, -CH-, b, 3H), 2.25 (s, -CH3, c1, 3H), 2.01 (d, J = 11.2 Hz, -CH2-, d, 2H), 1.88 (dd, J = 17.5, 6.6 Hz, -CH2-, d, 4H), 1.72 (dd, J = 32.5, 14.8 Hz,-CH2-, d, 7H), 1.53 – 1.45 (m, -CH2-, d, 3H), 1.40 (ddd, J = 12.0, 9.1, 4.0 Hz, -CH2-, d, 9H), 1.28 – 1.14 (m, -CH2-, d, 5H), 0.54 (s, -CH3, c2, 3H). 13 CNMR (101 MHz, CDCl3) δ 175.19 (C=N, a1*), 161.68 (a2*), 158.08 (a3*), 155.92 (a4*), 146.87 (a5*), 139.28 (a6*), 137.08 (a7*), 123.76 (a8*), 122.93 (a9*), 44.39 (CH, b1*), 39.02 (CH, b2*), 34.53 (CH2, d*), 34.46 (CH2, d*), 33.28 (CH2, d*), 26.87 (CH2, d*), 26.74 (CH2, d*), 26.12 (CH2, d*), 26.04 (CH2, d*), 19.54(CH3, c1*), 2.03 (CH3, c1*). 1 H- 1H NOESY correlations (500 MHz, CDCl3): 2.61 –2.47 (m, -CH-, b, 3H) / 0.54 (s, -CH3, c2, 3H), 2.01 (d, J = 11.2 Hz, -CH2-, d,2H) / 0.54 (s, -CH3, c2, 3H).

[0102]

[0103] NMR analysis of ligand L7: 1 H NMR (400 MHz, CDCl3) δ 8.69 (d, J = 4.8 Hz, Ar-H,a1, 1H), 8.39 (d, J = 8.0 Hz, Ar-H, a2, 1H), 7.83 (t, J = 7.9 Hz, Ar-H, a3,1H), 7.40 (dd, J = 7.5, 4.8 Hz, Ar-H, a4, 1H), 7.03 (s, Ar-H, a5, 2H), 3.05 –2.89 (m, -CH-, b2, 1H), 2.79 (dd, J = 12.1, 5.6 Hz, -CH-, b1, 2H), 2.22 (s, -CH3, c, 3H), 2.12 – 2.04 (m, -CH2-, d, 2H), 2.04 – 1.96 (d, J = 5.9 Hz, -CH2-,d, 2H), 1.86 – 1.78 (m, -CH2-, d, 4H), 1.76 – 1.67 (m, -CH2-, d, 6H), 1.62(dt, J = 13.9, 4.8 Hz, -CH2-, d, 2H), 1.58 – 1.46 (m, -CH2-, d, 8H). 13 C NMR(101 MHz, CDCl3) δ 167.52 (C=N, a6*), 156.33 (a5*), 148.47 (a8*), 145.41 (a1*),141.17 (a 10*), 136.59 (a7*), 133.41 (a3*), 124.80 (a4*), 122.19 (a9*), 121.50(a2*), 45.98 (-CH-, b2*), 40.38 (-CH-, b1*), 34.74 (-CH2-, d*) 33.91 (-CH2-,d*), 33.87 (-CH2-, d*), 25.70 (-CH2-, d*), 25.67 (-CH2-, d*), 25.45 (-CH2-,d*), 17.55 (-CH3, c*).

[0104] Mass spectrometry analysis of ligand L7: APCI-MS (m / z): calcd for C 28 H 37 N2 + : 401.2951, Found,401.2946, [M+H] + .

[0105]

[0106] NMR analysis of Pd7 catalyst: A-isomer: B-isomer = 7:1. 1 H NMR (400 MHz, CDCl3)δ 9.26 (dd, J = 5.1, 1.7 Hz, Ar-H, a1, 1H), 8.06 (td, J = 7.8, 1.8 Hz, Ar-H,a2, 1H), 7.88 (d, J = 7.9 Hz, Ar-H, a3, 1H), 7.76 – 7.69 (m, Ar-H, a4, 1H), 7.06 (s, Ar-H, a5, 2H), 3.08 (q, J = 8.5 Hz, -CH-, b1, 2H), 2.97 (tt, J = 9.5,7.1 Hz, -CH-, b2, 1H), 2.23 – 2.19 (m, -CH2-, d, 2H), 2.16 (s, -CH3, c1, 3H),2.07 (td, J = 8.4, 7.7, 4.8 Hz, -CH2-, d, 2H), 1.82 – 1.66 (m, -CH2-, d, 13H),1.60 – 1.52 (m, -CH2-, d, 5H), 1.49 – 1.40 (m, -CH2-, d, 2H), 0.47 (s, -CH3,c2, 3H).13 C NMR (101 MHz, CDCl3) δ 174.26 (C=N, a1*), 152.56 (a2*), 149.33(a3*), 145.16 (a4*), 140.77 (a5*), 138.61 (a6*), 136.90 (a7*), 128.40 (a8*),124.68 (a 10 *), 122.71 (a9*), 45.87 (CH, b1*), 39.85 (CH, b2*), 35.18 (CH2, d*), 34.57 (CH2, d*), 34.25 (CH2, d*), 26.07 (CH2, d*), 25.90 (CH2, d*), 25.43 (CH2,d*), 19.06 (CH3, c1*), 1.01 (CH3, c1*). 1 H- 1 H NOESY correlations (500 MHz, CDCl3): 3.08 (q, J = 8.5 Hz, -CH-, b1, 2H) / 0.47 (s, -CH3, c2, 3H), 2.23 – 2.19(m, -CH2-, d, 2H) / 0.47 (s, -CH3, c2, 3H).

[0107]

[0108] NMR analysis of ligand L8: 11H NMR (400 MHz, CDCl3) δ 8.69 (d, J = 4.8 Hz, Ar-H, a1, 1H), 8.32 (d, J = 8.0 Hz, Ar-H, a2, 1H), 7.82 (t, J = 1.8 Hz, Ar-H, a3, 1H), 7.39 (t, J = 7.4, 4.9 Hz, Ar-H, a4, 1H), 6.95 (s, Ar-H, a5, 2H), 2.47 (m, -CH-, b2, 1H), 2.29 (tt, J = 11.8, 3.3 Hz, -CH-, b1, 2H), 2.19 (s, -CH3, c, 3H), 1.94 – 1.82 (m, -CH2-, d, 6H), 1.75 (d, J = 11.7 Hz, -CH2-, d, 5H), 1.65 (d, J = 11.6 Hz, -CH2-, d, 4H), 1.51 – 1.35 (m, -CH2-, d, 6H), 1.34 – 1.16 (m, -CH2-, d, 9H). 13 13C NMR (101 MHz, CDCl3) δ 166.99 (C=N, a6*), 156.71 (a5*), 148.50 (a3*), 144.18 (a1*), 142.74 (a 10 *), 136.49 (a7*), 134.46 (a8*), 124.63 (a4*), 121.88 (a9*), 121.18 (a2*), 44.44 (-CH-, b2*), 39.20 (-CH-, b1*), 34.73 (-CH2-, d*), 33.58 (-CH2-, d*), 33.35 (-CH2-, d*), 27.13 (-CH2-, d*), 27.06 (-CH2-, d*), 26.30 (-CH2-, d*), 26.27 (-CH2-, d*), 17.42 (-CH3, c*).

[0109] Mass spectrometry analysis of ligand L8: ESI-MS (m / z): calcd for C 31 H 43 N2 + : 443.3426, Found, 443.3381, [M+H] +.

[0110]

[0111] NMR analysis of Pd8 catalyst: A-isomer: B-isomer > 10:1. 1 H NMR (400 MHz, CDCl3)δ 9.27 (dd, J = 5.2, 1.7 Hz, Ar-H, a1, 1H), 8.07 (td, J = 7.8, 1.7 Hz, Ar-H,a2, 1H), 7.89 (d, J = 7.7 Hz, Ar-H, a3, 1H), 7.72 (ddd, J = 7.7, 5.1, 1.1 Hz,Ar-H, a4, 1H), 7.01 (s, Ar-H, a5, 2H), 2.58 (ddt, J = 11.4, 7.0, 3.6 Hz, -CH-,b1, 2H), 2.48 (td, J = 9.8, 9.0, 4.9 Hz, -CH-, b2, 1H), 2.17 (s, -CH3, c1,3H), 2.00 (d, J = 10.1 Hz, -CH2-, d, 2H), 1.92 – 1.82 (m, -CH2-, d, 4H), 1.77– 1.63 (m, -CH2-, d, 7H), 1.39 (tdd, J = 18.0, 8.2, 3.0 Hz, -CH2-, d, 12H), 1.26 – 1.11 (m, -CH2-, d, 5H), 0.43 (s, -CH3, c2, 3H). 13 C NMR (101 MHz, CDCl3)δ 173.88 (C=N, a1*), 152.43 (a2*), 149.42 (a3*), 146.57 (a4*), 139.53 (a5*), 138.60 (a6*), 137.51 (a7*), 128.38 (a8*), 124.65 (a 10*), 122.82 (a9*), 44.37(CH, b1*), 38.89 (CH, b2*), 34.60 (CH2, d*), 34.47 (CH2, d*), 33.21 (CH2, d*),26.90 (CH2, d*), 26.87 (CH2, d*), 26.71 (CH2, d*), 26.12 (CH2, d*), 26.06 (CH2,d*), 19.11 (CH3, c1*), 1.04 (CH3, c2*). 1 H- 1 H NOESY correlations (500 MHz, CDCl3): 2.58 (ddt, J = 11.4, 7.0, 3.6 Hz, -CH-, b1, 2H) / 0.43 (s, -CH3, c2,3H), 2.00 (d, J = 10.1 Hz, -CH2-, d, 2H) / 0.43 (s, -CH3, c2, 3H).

[0112] Example 9: Ethylene homopolymerization (Pd1-Pd8 universal method)

[0113] The mixture was dried in a 350 mL high-pressure polymerization flask at 100 °C for 1 h. After cooling, a catalyst (10 μmol), NaBArF (20 μmol), and 10 mL of dichloromethane were added. The mixture was stirred at 30-50 °C, 6 atm ethylene, and 320 rpm for 3 h. The mixture was then depressurized and concentrated to obtain hyperbranched polyethylene oil.

[0114] Example 10: Ethylene-methyl acrylate copolymerization (Pd1-Pd8 universal method)

[0115] A catalyst (10 μmol), NaBArF (20 μmol), and a 0.5–1 M dichloromethane solution (20 mL) of methyl acrylate were added to a polymerization flask; the reaction was carried out at 30 °C and 4 atm for 3 h with ethylene; the pressure was released and the mixture was concentrated to obtain polar functionalized hyperbranched polyethylene oil.

[0116] Aggregate performance data:

[0117] The results of ethylene homopolymerization are shown in Table 1 below, and the results of ethylene-methyl acrylate copolymerization are shown in Table 2 below.

[0118]

[0119] aPolymerization conditions: 10 μmol catalyst, [Na] / [Pd] = 2, 10 mL dichloromethane, ethylene pressure of 6 atm, time = 3 hours;

[0120] b The unit of active Act is 10. 4 g·mol -1 ·h -1 ;

[0121] c Polymer molecular weight M n Depend on 1 Measured by H NMR nuclear magnetic resonance method;

[0122] d Branching degree refers to the number of methyl groups per 1000 carbon atoms, determined by... 1 Determined by H NMR nuclear magnetic resonance method.

[0123] As shown in Table 1, axial substituents have a profound impact on the catalytic behavior of catalysts with the same ligand skeleton. In the pyrazine system, replacing the traditional isopropyl substituent with a larger cyclopentyl or cyclohexyl group increases the molecular weight of HBPEO. Among these, the cyclopentyl-substituted compounds produce HBPEO with a higher molecular weight than the corresponding cyclohexyl analogs. Figure 1 This phenomenon may be attributed to the steric hindrance effect altering the balance between chain growth and chain transfer. In the pyrimidine system, the highest molecular weight was observed in the cyclopentyl-substituted compound Pd5, which produced HBPEO at 30 °C. The activity trend of traditional pyridine catalysts is similar to that of pyrazine systems, while their molecular weight and branching characteristics are closer to those of pyrimidine systems. Overall, sterically demanding cycloalkyl substituents exhibit superiority in inhibiting chain transfer. The electronic effects of the ligand skeleton significantly influence the catalytic reaction. The higher activity of the pyrazine system may be due to the reduced electron density at the palladium center, thereby lowering the energy barrier for ethylene insertion. Figure 2 Pyridine catalysts with higher electron density achieve higher molecular weights by enhancing chain transfer inhibition. Figure 2 The branching density of all ligand skeletons remained at a high level. Figure 2 ). Detailed 13 C10 NMR spectroscopy confirmed the hyperbranching characteristics of all HBPEOs: dense branched structures; dominated by long-chain branching and terminal groups; and numerous branched structures on the branches. Figure 3 Furthermore, the introduction of flexible cyclohexyl substituents significantly improved polymerization activity, molecular weight, and branching density of the resulting polyethylene oil.

[0124]

[0125] a Polymerization conditions: 10 μmol catalyst, [Na] / [Pd] = 2, total volume of dichloromethane and MA 20 mL, ethylene pressure 4 atm, time = 3 hours, polymerization temperature 30 ℃.

[0126] b The unit of active Act is 10. 3 g·mol -1 ·h -1 ;

[0127] c X MA The insertion ratio of MA represents the addition of terminal branches with functional groups to the total branches;

[0128] d Polymer molecular weight M n Depend on 1 Measured by H NMR nuclear magnetic resonance method;

[0129] e Branching degree refers to the number of methyl groups per 1000 carbon atoms, determined by... 1 Determined by H NMR nuclear magnetic resonance method.

[0130] As can be seen from Table 2, these catalysts exhibit moderate copolymerization activity (approximately 10). 3 -10 4 g·mol -1 ·h -1 Even at low MA concentrations (0.5 M), these palladium catalysts efficiently catalyze the copolymerization of MA and ethylene to produce low-molecular-weight (267-382 g / mol) polar functionalized E-MA copolymer oils with high insertion ratios (5.3-14.8 mol%). When the MA concentration is doubled, the insertion ratio increases proportionally, with only a slight increase in the molecular weight and branching density of the resulting E-MA copolymers.

[0131] For catalysts with the same skeletal structure, different axial substituents had little effect on the methyl acrylate (MA) insertion ratio, molecular weight, and branching density of the copolymer. In contrast, cycloalkyl-based palladium catalysts exhibited slightly higher molecular weights relative to their isopropyl counterparts, a trend consistent with observations from homopolymerization. PF-HBPEO 13 CNMR spectral analysis revealed that HBPEO retained its unique branched topology, including long-chain branching, terminal units, and branched-on-branching structures, and additional characteristic signals corresponding to polar functionalized long-chain branched groups appeared. Figure 6 ).

[0132] The results of the lubrication performance test are shown in Table 3 below.

[0133]

[0134] a All samples (items 1-6) are from different catalysts involved in this invention, see items 5, 11, 13, 15, 17-18 in Table 1;

[0135] b The unit of Mn is g·mol -1 ;

[0136] c KV and d VI. Kinematic viscosity was measured using an automatic kinematic viscometer TP825. 2 ( / s) measured at different temperatures;

[0137] e Pour point was tested according to ASTM D97 standard;

[0138] f The PF-HBPEO sample is from entry 18 in Table 2;

[0139] g Reference: Product specifications are from ExxonMobil SpectraSyn TM PAO10.

[0140] As can be seen from Table 3, these samples exhibit a wide range of kinematic viscosity variations and extremely high viscosity indexes. Figure 7 As shown, the molecular weight-viscosity correlation curve of HBPEO exhibits a near-linear relationship in the low molecular weight range (<1000 g / mol). However, when the molecular weight exceeds 1000 g / mol, the kinematic viscosity at 100 °C increases rapidly, showing an exponential growth trend. Notably, the PF-HBPEO sample (Table 2, item 18) exhibits extremely low kinematic viscosity (2.67 mm² / s) at 100 °C while maintaining a high viscosity index (196), demonstrating potential application value in automotive engine lubrication. All tested samples showed low pour points (-55 to -41 °C), meeting the basic requirements for lubricant applications. Comparative analysis of ExxonMobil's commercial PAO10 (Table 3, item 8) and HBPEO10 (Table 3, item 2) shows that HBPEO has significantly improved viscosity index performance (HBPEO10 is 218, while PAO10 is 137). This significant improvement in viscosity-temperature dependence demonstrates the strong potential of HBPEO in high-performance lubrication applications, especially where thermal stability and viscosity retention are critical.

Claims

1. An N-heterocyclic imine palladium(II) catalyst, characterized in that... Its general structural formula is as follows: ； in: X1 and X2 are each independently selected from C or N; R′ is selected from H, phenyl, methyl, or ethyl; R1 is selected from isopropyl, cyclopentyl, cyclohexyl, cycloheptyl, or cyclooctyl; R2 is selected from H, cyclopentyl, cyclohexyl, cycloheptyl, or cyclooctyl.

2. The N-heterocyclic imine palladium(II) catalyst according to claim 1, characterized in that: The N-heterocyclic imine palladium(II) catalyst is selected from one of the following Pd1-Pd8: Pd1: X1=N, X2=C, R′=Me, R1=iPr, R2=H; Pd2: X1=N, X2=C, R′=Me, R1=Cp, R2=Cp; Pd3: X1=N, X2=C, R′=Me, R1=Ch, R2=Ch; Pd4: X1=C, X2=N, R′=Me, R1=iPr, R2=H; Pd5: X1=C, X2=N, R′=Me, R1=Cp, R2=Cp; Pd6: X1=C, X2=N, R′=Me, R1=Ch, R2=Ch; Pd7: X1=C, X2=C, R′=Me, R1=Cp, R2=Cp; Pd8: X1=C, X2=C, R′=Me, R1=Ch, R2=Ch.

3. The method for preparing the N-heterocyclic imine palladium(II) catalyst according to claim 1, characterized in that... Includes the following steps: Step 1: Preparation of ligands Aromatic amines and N-heterocyclic skeletons were added to a reactor, anhydrous zinc chloride was dissolved in acetic acid and added to the reactor, and the mixture was refluxed in an oil bath at 90 °C for 5 h and then cooled to room temperature. The ligands were obtained by precipitation, hydrolysis, extraction, drying and purification. The N-heterocyclic skeleton is 2-acetylpyrazine, 2-acetylpyrimidine, or 2-acetylpyrimidine; The aromatic amine is 2,6-diisopropylaniline, 2,4,6-tricyclopentylaniline, or 2,4,6-tricyclohexylaniline; Step 2: Preparation of palladium complex The ligand obtained in step 1 was reacted with an equimolar (COD) of PdMeCl in dichloromethane at room temperature. After the reaction was completed, the solvent was removed by concentration under reduced pressure, and the target catalyst was obtained by precipitation with diethyl ether.

4. The application of the N-heterocyclic imine palladium(II) catalyst according to claim 1 in the synthesis of polar functionalized hyperbranched polyethylene lubricating base oil.

5. The application according to claim 4, characterized in that: Catalytic polymerization processes include homopolymerization of ethylene or copolymerization of ethylene with methyl acrylate.

6. The application according to claim 5, characterized in that: The reaction conditions for the homopolymerization of ethylene are as follows: The N-heterocyclic imine palladium(II) catalyst and the co-catalyst NaBArF are arranged in a molar ratio of 1:2 to form a composite catalytic system; the amount of N-heterocyclic imine palladium(II) catalyst is 10 μmol, the ethylene pressure is 6 atm, the polymerization temperature is 30-50 ℃, and the reaction time is 3 h.

7. The application according to claim 5, characterized in that: The reaction conditions for the copolymerization of ethylene and methyl acrylate are as follows: The N-heterocyclic imine palladium(II) catalyst and the co-catalyst NaBArF were arranged in a molar ratio of 1:2 to form a composite catalytic system; the amount of N-heterocyclic imine palladium(II) catalyst was 10 μmol; the concentration of methyl acrylate in the system was 0.5-1 M, the ethylene pressure was 4 atm; the polymerization temperature was 30-50 ℃, and the reaction time was 3 h.

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