Preparation method and application of quinoline pyridine nickel precatalyst

Abstract

The invention provides a quinoline pyridine nickel pre-catalyst as well as a preparation method and application thereof, and the nickel pre-catalyst is 8-(2, 6-bis (aryl)-3, 4, 5-trifluorophenyl) imido-5, 6, 7-trihydroquinoline pyridine. Under the protection of inert gas, 5, 6, 7-trihydroquinoline-8-ketone reacts with the synthesized aniline A to prepare a ligand L, and the ligand L reacts with DME NiBr2 to prepare a series of nickel precatalysts NiR; the nickel pre-catalyst is activated by methylaluminoxane (MAO) and used for an ethylene polymerization catalytic performance experiment, the nickel pre-catalyst shows high catalytic activity (3.1 * 10 < 6 > g mol <-1 > h <-1 >), and polyethylene with adjustable chain walking (branching degree = 58-90 / 1000 C), chain transfer (polymer Mw = 0.7-2.8 kg mol <-1 >), chain termination reaction (vinylidene / vinyl = 83.4-93.6%) and the like is produced. It is worthy of noting that the beta-elimination reaction in the system is a main chain termination mode, so that the change of the polymerization temperature in the obtained polyethylene from polyethylene wax to viscous oily matter becomes possible, and then polyethylene with a high internal double bond ratio is generated.

Description

Technical Field

[0001] The invention relates to an olefin polymerization catalyst, in particular to a quinoline pyridine nickel precatalyst for obtaining low molecular weight branched polyethylene by enhancing steric hindrance and electronic effect, and a preparation method and application thereof. Background Art

[0002] The discovery of nickel / palladium catalyzed ethylene polymerization, coupled with the introduction of the chain walking concept, has made it possible to synthesize a variety of polyethylene products from ethylene alone. Chain walking reactions can produce oligomers with branches, as well as high to ultra-high molecular weight polyethylenes with different alkyl branches. It is worth noting that this process can transfer the β-elimination reaction from the terminal position to other positions within the polymer chain, producing polyethylene with vinyl, vinylidene or vinylidene branches. These highly branched low molecular weight polyethylene waxes are widely used in additives, lubricants, comonomers, functionalized polymers and coatings. This is all due to the effective control of the chain walking characteristics and related reactions during the polymerization process. Studies have shown that the effective regulation of chain walking and related reactions during the polymerization process can be achieved by changing the ligand structure and reaction conditions. Among them, α-diimine and iminopyridine catalysts show a strong tendency for chain walking reactions. Unlike α-diimine nickel catalysts, iminopyridine-based nickel catalysts are prone to chain transfer, resulting in low molecular weight polyethylene, which may be due to the less spatial protection of the active species on the axial site. Summary of the invention

[0003] The purpose of the present invention is to provide a quinoline pyridine nickel precatalyst and a preparation method and application thereof. The complex is used as a catalyst for preparing low molecular weight branched polyethylene.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A quinoline pyridine nickel precatalyst, the structural formula of which is:

[0006]

[0007] The preparation method of quinoline pyridine nickel precatalyst. The specific steps are as follows:

[0008] (1) Synthesis of aniline compounds: After 3,4,5-trifluoroaniline and benzhydrol compounds are stirred evenly, anhydrous zinc chloride hydrochloric acid solution is slowly added dropwise, and the reaction is continued at 140° C. to 160° C. for 0.5 to 4 hours. The reaction product is purified to obtain a solid product A;

[0009] (2) Preparation of ligand: 5,6,7-trihydroquinolin-8-one, the synthesized aniline compound A and a catalytic amount of 4-methylbenzenesulfonic acid were mixed, and toluene was added as a solvent. After stirring and refluxing at 110°C for 10-12 hours, all volatiles were removed under reduced pressure; the obtained mixture was purified and then eluted with silica gel column chromatography using an eluent (n-hexane: ethyl acetate = 25:1) to collect the yellow powdery ligand L;

[0010] (3) Preparation of nickel precatalyst: Under an inert atmosphere, equimolar amounts of L and (DME)NiBr2 were added to a Schlenk tube, and then 10 ml of anhydrous dichloromethane was added; the mixture was stirred at room temperature for 24 hours, and the solvent was removed under reduced pressure; the complex was precipitated by adding ether, the complex was filtered, washed three times with ether, and dried to obtain a solid nickel precatalyst Ni R .

[0011] In the step (1), the molar ratio of 3,4,5-trifluoroaniline to benzhydrol compounds is 1:2; anhydrous zinc chloride hydrochloric acid solution is used as a catalytic amount, the reaction temperature is 140°C to 160°C, and the reaction time is 0.5 to 4 hours. In the step (2), the molar ratio of 5,6,7-trihydroquinolin-8-one to the synthesized aniline compound A is 1:1, and the reaction time is 10-12 hours; in the step (3), the molar ratio of L to (DME)NiBr2 is 1:1-1.5.

[0012] The invention discloses an application of a quinoline pyridine nickel precatalyst in ethylene polymerization. The application is to use the quinoline pyridine nickel precatalyst as a main catalyst, an alkylaluminoxane (methylaluminoxane MAO, modified methylaluminoxane MMAO) or an alkylaluminum chloride (diethylaluminum chloride DEAC, sesquiethylaluminum chloride EASC) as a cocatalyst, the molar ratio of the main catalyst to the cocatalyst is 1:200-1:3000, the polymerization temperature is 0-100°C, the polymerization time is 5-60min, and the polymerization pressure is 0.1-1.0MPa, to catalyze ethylene polymerization.

[0013] The preferred application of the present invention is to use quinoline pyridine nickel precatalyst as the main catalyst and methylaluminoxane MAO as the cocatalyst. The preferred conditions are: the main catalyst and the cocatalyst are in a molar ratio of 1:2000 to form a composite catalytic system, the reaction temperature is controlled at 30-50°C, the reaction time is 5-60min, and the polymerization pressure is 0.1-1.0MPa to catalyze ethylene polymerization.

[0014] Compared with the prior art, the present invention has the following beneficial effects: the quinoline pyridine nickel precatalyst of the present invention can achieve the regulation of polymer molecular weight, branching degree and melt temperature by enhancing steric hindrance and electronic effect. The complex is applied to ethylene polymerization reaction, and its catalytic activity is as high as 3.1×10 6 g mol-1 h -1 , and produce polymers with chain walking (branching degree = 58-90 / 1000C), chain transfer (polymer M w =0.7~2.8kg mol -1 ) and chain termination reactions (vinylidene / vinyl = 83.4-93.6%). It is worth noting that the chain walking reaction and chain termination rate during the polymerization process vary with the reaction temperature, making it possible for the physical state of the resulting polyethylene to vary from polyethylene wax to viscous oil. Most importantly, the β-elimination reaction is the main chain termination method and produces polyethylene with a high internal double bond ratio (vinylidene / vinyl up to 93.6%). BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The complex Ni prepared in Example 1 (3) F Schematic diagram of the crystal structure.

[0016] Figure 2 The thermal NMR carbon spectrum and microstructure of the polymer obtained in Example 5 (1).

[0017] Figure 3 The H-NMR spectrum and microstructure of the polymer obtained in scheme (2) of Example 5. DETAILED DESCRIPTION

[0018] The present invention is described below by means of specific embodiments, but the protection scope of the present invention is not limited thereto.

[0019] The experimental methods used in the following examples are all conventional methods, the raw materials used are all available from the market, and the ligands and complexes synthesized below are all confirmed by nuclear magnetic resonance, infrared and elemental analysis.

[0020] The synthesis of the ligand and nickel precatalyst in the following examples is carried out according to the following reaction equation:

[0021]

[0022] Example 1

[0023] Preparation of complexes

[0024] (1) Preparation of aniline A: 3,4,5-trifluoroaniline (40 mmol) and benzhydrol (80 mmol) were added to a 300 mL round-bottom flask, the oil bath temperature was raised to 70°C, and the mixture was stirred until it melted. The temperature was then raised to 160°C, and 2 mL of hydrochloric acid solution containing anhydrous zinc chloride was slowly added dropwise. The reaction was continued for 1 h, and the reaction product was purified to obtain a white powder AH.

[0025] AF, A-Cl, A-Me and A- t The preparation method of Bu is the same as that of AH

[0026] Characterization data of aniline AH: 1 H NMR (400MHz, Chloroform-d) δ7.26 (dd, J=13.9, 6.7Hz, 13H), 7.15 (d, J=7.4Hz, 8H), 5.83 (s, 2H), 3.43 (s, 2H).

[0027] Characterization data of aniline AF: 1 H NMR (600MHz, Chloroform-d) δ7.10 (dd, J=8.6, 5.3Hz, 8H), 7.04–6.96 (m, 8H), 5.75 (s, 2H), 3.41 (s, 2H).

[0028] Characterization data of aniline A-Cl: 1 H NMR (300MHz, Chloroform-d) δ7.28 (d, J = 8.4Hz, 8H), 7.05 (d, J = 8.3Hz, 8H), 5.71 (s, 2H), 3.39 (s, 2H).

[0029] Characterization data of aniline A-Me: 1 H NMR (400MHz, Chloroform-d) δ7.09(d,J=7.9Hz,8H),7.03(d,J=8.0Hz,8H),5.74(s,2H),3.45(s,2H),2.33(s,12H).

[0030] Aniline A- t Characterization data of Bu: 1 H NMR (600MHz, Chloroform-d) δ7.28(d,J=8.5Hz,8H),7.08(d,J=8.4Hz,8H),5.80(s,2H),3.44(s,2H),1.30(s,36H).

[0031] (2) Preparation of ligand L: 5,6,7-trihydroquinolin-8-one (3.40 mmol), 2,6-diphenylmethyl-3,4,5-trifluoroaniline (3.40 mmol) and a catalytic amount of p-toluenesulfonic acid (1 mmol) were mixed, and toluene was added as a solvent. After stirring and refluxing at 110° C. for 12 hours, all volatiles were removed under reduced pressure. The purified product obtained the target ligand LH as a light yellow crystalline solid.

[0032] LF, L-Cl, L-Me and L- tThe preparation method of Bu is the same as that of LH

[0033] Characterization data of ligand LH: 1 H NMR (600MHz, CDCl3.TMS) δ8.79(s,1H),7.49(s,1H),7.30(d,J=46.3Hz,4H),7.09–6.82(m,1 6H),5.44(d,J=2.5Hz,2H),3.17–3.01(m,1H),2.17(d,J=7.3Hz,1H),1.41(t,J=7.3Hz,2H). 13 C NMR(151MHz,Chloroform-d)δ143.46,140.59,129.67,128.92,128.57,128.02,126.89,126.21,125.62,49.09,31.16,28.83,20.40.FT-IR(KBr,cm -1 ):3438.5(s),1649.8(νC=N,s),1605(m),1495.5(s),1479.3(s),1449.8(m),1221. 8m),1121.5(m),1107.7(m),1034.6(w),1008.1(w),983.5(m),702.7(s),680.9(w).

[0034] Anal.Calcd.for C 41 H 31 F3N2[H2O+MeOH]:C,76.58;H,5.66;N,4.25;Found.C,77.17;H,5.24;N,4.33.

[0035] Characterization data of ligand LF: 1 H NMR (600MHz, CDCl3.TMS) δ8.79(d,J=4.5Hz,1H),7.52(d,J=7.6Hz,1H),7.41–7.33(m ,1H),7.24–6.80(m,16H),5.47(s,2H),2.41(t,J=6.0Hz,2H),0.99(t,J=6.2Hz,2H). 1313C NMR (151 MHz, Chloroform-d) δ 162.69, 162.36, 161.05, 160.73, 138.71, 136.19, 131.03, 130.97, 129.98, 129.93, 125.93, 115.98, 115.84, 115.02, 114.88, 47.61, 31.31, 28.87, 20.58. FT-IR (KBr, cm -1 ): 3434.5 (s), 1656.9 (νC=N, m), 1606 (m), 1509 (s), 1483 (s), 1310 (s), 1228 (m), 1218.5 (m), 1181 (s), 1008 (w), 922 (w), 672 (w), 570 (m). Anal. Calcd. for C 41 H 27 F7N2[CH2Cl2 + H2O]: C, 64.38; H, 3.99; N, 3.57; Found. C, 64.22; H, 3.80; N, 3.68.

[0036] Characterization data of ligand L-Cl: 1 1H NMR (600 MHz, Chloroform-d) δ 8.83–8.73 (m, 1H), 7.53 (d, J=7.8 Hz, 1H), 7.37 (dd, J=7.8, 4.6 Hz, 1H), 7.25–6.94 (m, 16H), 5.43 (s, 2H), 2.43 (t, J=6.1 Hz, 2H), 1.03–0.97 (m, 2H), 0.74 (p, J=6.1 Hz, 2H). 13 13C NMR (151 MHz, Chloroform-d) δ 141.13, 138.57, 133.15, 132.45, 130.80, 129.84, 129.22, 128.36, 47.86, 45.91, 31.40, 29.85, 28.87, 20.58, 1.17. FT-IR (KBr, cm -1 ): 3052 (w), 2957 (m), 1642 (νC=N, m), 1600 (m), 1565 (w), 1500 (s), 1403 (m), 1259 (m), 1094 (m), 815 (s), 732 (w), 684 (w). Anal. Calcd. for C 41 H 27 Cl4F3N2[EtOH + 2H2O]: C, 62.33; H, 4.50; N, 3.38; Found. C, 62.73; H, 4.85; N, 3.41.

[0037] Characterization data of ligand L-Me: 1 H NMR(600MHz,Chloroform-d)δ8.80–8.72(m,1H),7.47(d,J=7.7Hz,1H),7.37–7.28(m,1H),7.03–6.97(m,8H),6.95(t,J= 7.2Hz, 8H), 5.44 (s, 2H), 2.28 (d, J = 8.0Hz, 12H), 1.42 (t, J = 7.3Hz, 2H), 0.90 (q, J = 7.8, 7.0Hz, 2H), 0.61 (p, J = 6.3Hz, 2H). 13 C NMR(151MHz,Chloroform-d)δ140.73,137.77,136.24,135.56,129.48,129.45,128.68 ,128.45,125.45,48.33,45.92,31.14,28.92,21.13,20.39,8.76,1.16.FT-IR(KBr,cm -1 ):3090(w),3049(w),2928(w),1639(νC=N,m),1598(s),1515(m),1480(s),1436(w),1327(m),1 297(m),1265(w),1188(m),1044(w),1024(m),988(w),817(m),732(w),688(w).Anal.Calcd.For C 45 H 39 F3N2[ethyl acetate]:C,78.18;H,6.29;N,3.72;Found.C,78.07;H,5.94;N,4.07.

[0038] Characterization data of ligand L-tBu: 1 H NMR(600MHz,Chloroform-d)δ8.76(d,J=4.5Hz,1H),7.45(d,J=7.6Hz,1H),7.31(d,J=8.3Hz,1H),7.22(d,J=8.2Hz,4H),7.18(d,J=8.0Hz,4H),6.99(d d,J=8.4,2.0Hz,8H),5.45(s,2H),2.26(t,J=6.1Hz,2H),1.31(d,J=1.2Hz, 2H), 1.27 (d, J = 1.1Hz, 18H), 1.26 (d, J = 3.2Hz, 2H), 1.24 (d, J = 1.2Hz, 18H).13 C NMR(151MHz,Chloroform-d)δ149.56,148.73,140.55,137.88,129.25,128.14,125 .71,124.82,48.24,34.52,34.45,31.52,31.49,31.01,20.36,1.16.FT-IR(KBr,cm -1 ):2963(w),2860(w),1642(νC=N,m),1596(w),1518(m),1480(s),1362(w),1274(m),1106(m),991(w),844(m),697(w).Anal.Calcd.for C 57 H 63 F3N2[2EtOH]:C,79.18;H,8.17;N,3.03;Found.C,79.27;H,8.02;N,3.12.

[0039] (3) Nickel precatalyst Ni R Preparation: Under inert gas protection, LH (0.49 mmol) and (DME) NiBr2 (0.49 mmol) were added to a Schlenk tube, followed by 10 ml of anhydrous dichloromethane. The mixture was stirred at room temperature for 12 hours, and the solvent was removed under reduced pressure. The complex was precipitated by adding ether and filtered to obtain a dark red solid powder Ni H .

[0040] Ni F ,Ni Cl , Ni Me and Ni tBu The preparation method is the same as Ni H

[0041] The characterization data are as follows:

[0042] Pre-catalyst Ni H Characterization data: FT-IR (KBr, cm -1 ):3058(w),3019(w),1609(νC=N,m),1586(w),1483(s),1450(m),1350(w),1300( w),1212(w),1109(m),1035(w),988(m),947(m),832(w),767(w).Anal.Calcd.for C 41 H 31F3N2NiBr2[CH2Cl2]:C,55.31;H,3.65;N,3.07;Found.C,55.89;H,3.93;N,3.16.

[0043] Pre-catalyst Ni F Characterization data: FT-IR (KBr, cm -1 ):3055(w),2966(w),1603(νC=N,m),1583(w),1512(s),1486(s),1344(w),1294( w),1224(s),1168(m),1100(m),994(m),847(m),729(w),611(w).Anal.Calcd.for C 41 H 27 F7N2NiBr2:C,54.77;H,3.03;N,3.12;Found.C,54.59;H,3.00;N,3.14.

[0044] Pre-catalyst Ni Cl Characterization data: FT-IR (KBr, cm -1 ):3052(w),2957(m),1614(νC=N,m),1576(m),1488(m),1400(m),1343(w),1259(m),1094(m),815(s),732(w),684(w).Anal.Calcd.For C 41 H 27 Cl4F3N2NiBr2[CH2Cl2+MeOH]:C,47.74;H,3.07;N,2.59;Found.C,47.44;H,3.07;N,2.69.

[0045] Pre-catalyst Ni Me Characterization data: FT-IR (KBr, cm -1 ):3016(w),1615(νC=N,s),1586(m),1512(s),1486(s),1330(w),1297(w),1212(w),1112(s),997(m),815(m),720(m),573(m).Anal.calcd for C 45 H 39 F3N2NiBr2[CH2Cl2+MeOH]:C,56.44;H,4.53;N,2.80;Found.C,56.83;H,4.55;N,3.25.

[0046] Pre-catalyst NitBu Characterization data: FT-IR (KBr, cm -1 ):3055(w),2966(m),1612(νC=N,m),1577(m),1479(m),1365(m),1271(w),1259(m),1094(m),815(s),732(w),684(w).Anal.Calcd.For C 57 H 63 F3N2NiBr2[2H2O]:C,62.94;H,6.21;N,2.58;Found.C,62.94;H,5.34;N,2.85.

[0047] Example 2

[0048] Using pre-catalyst Ni F Ethylene polymerization with different cocatalysts:

[0049] (1) In an ethylene atmosphere, 20 mL of toluene and 30 mL of nickel catalyst Ni F (3μmol) of toluene solution and 3.60mL of co-catalyst MAO (1.67mol / L toluene solution) were added to a 300mL stainless steel autoclave in sequence, and 50ml of toluene was added to make the total volume of the reaction solution reach 100ml. At this time, Al / Ni=2000. When the polymerization temperature reaches 30°C, ethylene is filled into the reactor and the polymerization reaction begins. The ethylene pressure is maintained at 10atm at 30°C and the reaction time is 30min. The reaction solution is neutralized with 5% hydrochloric acid ethanol solution, filtered, and the polymer precipitate is obtained. It is washed several times with ethanol, vacuum dried and weighed. Polymerization activity: 10.1×10 5 g mol -1 h -1 , polymer T m =76℃(T m is the melting temperature of the polymer, obtained by DSC test), the polymer molecular weight M w =1.4 kg·mol -1 , M w / M n =1.80(M w is the weight average molecular weight of the polymer, obtained by temperature-raising GPC test).

[0050] (2) The implementation method is the same as above, except that 2.31 mL of MMAO (2.60 mol / L toluene solution) is used as the co-catalyst, and Al / Ni=2000. Polymerization activity: 8.0×10 5 g mol -1 h -1 , polymer Tm =99.0℃, polymer molecular weight M w =1.8kg·mol -1 , M w / M n =1.44, polymer T m =71℃,.

[0051] (3) The implementation method is the same as above, except that 0.9 mL of DEAC (2.0 mol / L n-hexane solution) is used as the co-catalyst, and Al / Ni=600. Polymerization activity: 2.6×10 5 g mol -1 h -1 , polymer T m =71℃, polymer molecular weight M w =2.8kg·mol -1 , M w / M n =1.65, polymer T m =87℃ / 119℃.

[0052] (4) The implementation method is the same as above, except that 4.5 mL of EASC (0.4 mol / L n-hexane solution) is used as the co-catalyst, and Al / Ni=600. Polymerization activity: 2.0×10 5 g mol -1 h -1 , polymer T m =93.2℃, polymer molecular weight M w =2.2kg·mol -1 , M w / M n =1.56, polymer T m =88℃.

[0053] Example 3

[0054] Using pre-catalyst Ni F Ethylene polymerization with different Al / Ni cocatalysts MAO:

[0055] (1) The implementation method is the same as that of Example 2, except that: 1.80 mL of the cocatalyst MAO (1.67 mol / L toluene solution) is used, and Al / Ni=1000. Polymerization activity: 4.0×10 5 g·mol –1 ·h –1 , polymer molecular weight M w =1.8kg·mol -1 ,M w / M n =1.53, polymer T m=74℃ / 112℃.

[0056] (2) The implementation method is the same as above, except that: the amount of co-catalyst MAO (1.67 mol / L toluene solution) is 2.70 mL, and Al / Ni is 1500. Polymerization activity: 4.3×10 5 g·mol –1 ·h –1 , polymer M w =1.7 kg·mol –1 , M w / M n =1.64 1 , polymer T m =75℃ / 110℃.

[0057] (3) The implementation method is the same as above, except that: the amount of co-catalyst MAO (1.67 mol / L toluene solution) is 3.15 mL, and Al / Ni is 1750. Polymerization activity: 7.7×10 5 g·mol –1 ·h –1 , polymer M w =1.5kg·mol –1 , M w / M n =1.62, polymer T m =70℃ / 110℃.

[0058] (4) The implementation method is the same as above, except that: the amount of co-catalyst MAO (1.67 mol / L toluene solution) is 4.04 mL, and Al / Ni is 2250. Polymerization activity: 6.0×10 5 g·mol –1 ·h –1 , polymer M w =0.8kg·mol –1 , M w / M n =2.00.

[0059] (5) The implementation method is the same as above, except that: the amount of co-catalyst MAO (1.67 mol / L toluene solution) is 4.49 mL, and Al / Ni is 2500. Polymerization activity: 5.3×10 5 g·mol –1 ·h –1 , polymer M w =0.7 kg·mol –1 , M w / M n =1.59.

[0060] Example 4

[0061] Using pre-catalyst Ni F Ethylene polymerization at different temperatures with cocatalyst MAO:

[0062] (1) The implementation method is the same as that of Example 2, except that: 3.60 mL of the cocatalyst MAO (1.67 mol / L toluene solution) was used, Al / Ni=2000, the reaction time was 30 min, the polymerization temperature was 40° C., and the polymerization activity was 0.3×10 5 g·mol –1 ·h –1 , polymer M w =0.9 kg·mol –1 , M w / M n =1.53, polymer T m =73℃ / 119℃.

[0063] (2) The implementation method is the same as above, except that: polymerization activity: 0.1×10 5 g·mol –1 ·h –1 , polymer M w =0.9 kg·mol –1 , M w / M n =1.33.

[0064] Example 5

[0065] Ethylene polymerization under optimal conditions using five nickel precatalysts and cocatalyst MAO:

[0066] (1) The implementation method is the same as in Example 2, except that: the nickel catalyst Ni H As the main catalyst, the amount of co-catalyst MAO (1.67 mol / L toluene solution) was 3.60 mL, Al / Ni = 2000, the reaction time was 30 min, the polymerization temperature was 30 ° C, and the polymerization activity was 1.0 × 10 5 g·mol –1 ·h –1 , polymer M w =1.6kg·mol –1 , M w / M n =1.83.

[0067] (2) The implementation method is the same as above, except that the nickel catalyst Ni Cl As the main catalyst, the amount of co-catalyst MAO (1.67 mol / L toluene solution) was 3.60 mL, Al / Ni = 2000, the reaction time was 30 min, the polymerization temperature was 30 ° C, and the polymerization activity was 1.1 × 10 5g·mol –1 ·h –1 , polymer M w =1.6kg·mol –1 , M w / M n =1.84.

[0068] (3) The implementation method is the same as above, except that the nickel catalyst Ni Me As the main catalyst, the amount of co-catalyst MAO (1.67 mol / L toluene solution) was 3.60 mL, Al / Ni = 2000, the reaction time was 30 min, the polymerization temperature was 30 ° C, and the polymerization activity was 1.8 × 10 5 g·mol –1 ·h –1 , polymer M w =1.7 kg·mol –1 , M w / M n =1.83.

[0069] (4) The implementation method is the same as above, except that the nickel catalyst Ni tBu As the main catalyst, the amount of co-catalyst MAO (1.67 mol / L toluene solution) was 3.60 mL, Al / Ni = 2000, the reaction time was 30 min, the polymerization temperature was 30 ° C, and the polymerization activity was 1.7 × 10 5 g·mol –1 ·h –1 , polymer M w =2.2kg·mol –1 , M w / M n =1.61.

Claims

1. A quinoline pyridine nickel precatalyst, characterized in that The structural formula is: Wherein: R is independently selected from one of hydrogen, alkyl, aryl, alkaryl, aralkyl and alkoxy groups having 1 to 10 carbon atoms.

2. A quinoline pyridine nickel precatalyst as claimed in claim 1, characterized in that: The R's are each independently selected from a hydrogen atom, a methyl group, a tert-butyl group, a fluorine atom and a chlorine atom.

3. A method for preparing a quinoline pyridine nickel precatalyst as claimed in claim 1 or 2, characterized in that: The steps include: (1) Synthesis of aniline compounds: After 3,4,5-trifluoroaniline and benzhydrol compounds are stirred evenly, anhydrous zinc chloride hydrochloric acid solution is slowly added dropwise, and the reaction is continued at 140° C. to 160° C. for 0.5 to 4 hours. The reaction product is purified to obtain a solid product aniline A; (2) Preparation of ligand: 5,6,7-trihydroquinolin-8-one, synthesized aniline A and a catalytic amount of 4-methylbenzenesulfonic acid were mixed, and toluene was added as a solvent. After stirring and refluxing at 110°C for 10-12 hours, all volatiles were removed under reduced pressure; the obtained mixture was purified, and then chromatographed on a silica gel column with an eluent to collect the yellow powdery ligand L; (3) Preparation of nickel complex: Under an inert atmosphere, equimolar amounts of ligand L and (DME)NiBr2 were added to a Schlenk tube, and then 10 ml of anhydrous dichloromethane was added; the mixture was stirred at room temperature for 24 hours, and the solvent was removed under reduced pressure; the complex was precipitated by adding diethyl ether, the complex was filtered, washed three times with diethyl ether, and dried to obtain a solid nickel complex Ni R That is, nickel pre-catalyst.

4. The method according to claim 3, characterized in that In the step (1), the molar ratio of 3,4,5-trifluoroaniline to benzhydrol compounds is 1:2; anhydrous zinc chloride hydrochloric acid solution is used as a catalytic amount, the reaction temperature is 140°C to 160°C, and the reaction time is 0.5 to 4 hours. In the step (2), the molar ratio of 5,6,7-trihydroquinolin-8-one to the synthesized aniline A is 1:1, and the reaction time is 10-12 hours; the raw materials and the ratio of the eluent are: n-hexane: ethyl acetate = 25:1; in the step (3), the molar ratio of the ligand L to (DME)NiBr2 is 1:1-1.

5.

5. Use of a quinolinepyridine nickel precatalyst as claimed in claim 1 in ethylene polymerization.

6. The use according to claim 5, characterized in that: The method uses quinoline pyridine nickel precatalyst as the main catalyst, alkylaluminoxane or alkylaluminum chloride as the cocatalyst, the molar ratio of the main catalyst to the cocatalyst is 1:200-1:3000, the polymerization temperature is 0-100°C, the polymerization time is 5-60 minutes, the polymerization pressure is 0.1-1.0MPa, and catalyzes ethylene polymerization.

7. The use according to claim 6, characterized in that: The alkylaluminoxane is methylaluminoxane MAO or modified methylaluminoxane MMAO; the alkylaluminum chloride is diethylaluminum chloride DEAC or sesquiethylaluminum chloride EASC.

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