A large sterically hindered pyridine amide, nickel complex, preparation method and application thereof in olefin polymerization

Abstract

The invention discloses a large sterically hindered pyridine amide, a nickel complex, a preparation method and an application thereof in olefin polymerization; the structural formula of the large sterically hindered pyridine amide is #imgabs0#Ar is one of phenyl, naphthyl and anthracene; R1 is one of C1-C20 alkyl, I, Br, Cl, F, OCH3, CF3 and NO2; R2 is H, t One of Bu, phenyl and naphthyl. The nickel complex prepared from the large sterically hindered pyridine amide can be used as a single component to initiate the homogeneous polymerization of olefins such as ethylene and the copolymerization of ethylene / polar monomers. The improvement of the steric hindrance effect ensures the thermal stability, catalytic activity and polymer molecular weight of the cationic nickel catalyst. The complex has high activity in ethylene homopolymerization, and also realizes the copolymerization of ethylene and 10-undecenoic acid methyl ester monomers, and obtains copolymers with different polar monomer insertion rates.

Description

Technical Field

[0001] The invention relates to the technical field of olefin polymerization, and in particular to a large sterically hindered pyridine amide, a nickel complex, a preparation method and application thereof in olefin polymerization. Background Art

[0002] Polyolefins are the most produced commodity materials in the world and have a variety of uses. To address the challenges faced by early transition metals, late transition metal catalysts continue to attract the attention of industrial and academic researchers. In addition, among late transition metals, cheap nickel catalysts have attracted more attention from researchers in the field because of their abundant natural reserves and low cost compared to palladium. Therefore, from this perspective, it has been explored to a series of organic frameworks, such as α-diimine, phosphine sulfonate, pyridine imine, ketone imine, salicylic imine and α-imine formamide. Since Grubbs first published the pioneering work of salicylic aldimine neutral nickel catalyzed olefin polymerization in 2000 (TR Younkin, EF Connor, JI Henderson, SK Friedrich, RH Grubbs, DA Bansleben, Neutral, Single-Component Nickel (II) Polyolefin Catalysts That Tolerate Heteroatoms, Science, 2000, 287, 460-462), N, O-type nickel systems have begun to flourish. This is mainly because this type of nickel catalyst has a stable structure, is easy to synthesize, can catalyze polymerization in a single component, and has stronger tolerance to polar functional groups. Therefore, various N,O-type nickel catalytic systems are not only suitable for homogeneous polymerization of ethylene, but also for copolymerization of ethylene and polar monomers.

[0003] Literature survey shows that amide nickel catalysts are very rare. Bazan and his colleagues introduced α-iminocarboxamide nickel catalysts (B. Lee, G. Bazan, J. Vela, and X. Bu, α-Iminocarboxamidato-Nickel (II) Ethylene Polymerization Catalysts, J. Am. Chem. Soc., 2001, 123, 5352-5353). These catalysts have low activity and can only achieve the polymerization of ethylene to form highly branched oligomers with a molecular weight of M. n The content can reach 860g / mol. This is mainly because aniline is sterically far away from the metal nickel center and has poor thermal stability. Therefore, it is difficult for this type of catalyst to have both high heat resistance and high activity. Continuously improving the catalyst structure is the key to developing new high-efficiency polyolefin metal catalysts. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a novel large sterically hindered pyridine amide and a nickel complex thereof. The obtained complex has good thermal stability, high catalytic activity for olefin polymerization, and the obtained polymer has a high molecular weight.

[0005] The present invention solves the above technical problems through the following technical means:

[0006] A large sterically hindered pyridine amide, the general structural formula of which is shown below:

[0007]

[0008] Wherein, in the general formula, Ar is selected from one of phenyl, naphthyl, anthracenyl; R1 is selected from one of C1-C20 alkyl, I, Br, Cl, F, OCH3, CF3, NO2; R2 is selected from one of H, t One of Bu, phenyl, and naphthyl.

[0009] Preferably, the bulky sterically hindered pyridine amide has the structural formula

[0010] One of them.

[0011] The present invention also provides a method for preparing the large sterically hindered pyridine amide, comprising: and After the reaction, the product is obtained; wherein Ar is selected from one of phenyl, naphthyl, and anthracenyl; R1 is selected from one of C1-C20 alkyl, I, Br, Cl, F, OCH3, CF3, and NO2.

[0012] The present invention also provides a nickel complex prepared by using the large sterically hindered pyridine amide, and its general structural formula is shown as follows:

[0013]

[0014] Wherein, in the general formula, Ar is selected from one of phenyl, naphthyl, anthracenyl; R1 is selected from one of C1-C20 alkyl, I, Br, Cl, F, OCH3, CF3, NO2; R2 is selected from one of H, t One of Bu, phenyl, and naphthyl; represents tetrakis(3,5-bis(trifluoromethyl)phenyl)borate anion, connected to Ni It represents allyl.

[0015] Preferably, in the general structural formula of the nickel complex, Ar is phenyl, R1 is one of methyl, fluorine and methoxy, and R2 is hydrogen.

[0016] Preferably, the structural formula of the nickel complex is It belongs to the triclinic system, P-1 space group, α = 69.092 (2) °, β = 82.103 (2) °, γ = 89.003 (2) °,

[0017] Or the structural formula of the nickel complex is It belongs to the triclinic system, P-1 space group, α = 69.608 (2) °, β = 82.129 (2) °, γ = 89.204 (2) °,

[0018] The present invention also provides a method for preparing the nickel complex, comprising the following steps: dissolving a large sterically hindered pyridine amide in a good solvent to obtain a ligand solution under an argon or nitrogen atmosphere; dissolving sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (NaBAF) and a metal nickel precursor in a good solvent to obtain a metal nickel precursor solution, then adding the ligand solution to the metal nickel precursor solution, reacting at room temperature, and removing the solvent to obtain the nickel complex.

[0019] Preferably, the metallic nickel precursor is allyl nickel chloride [Ni(allyl)Cl]2; the good solvent is one or a mixture of more of toluene, dichloromethane, chloroform, dichlorobenzene, and trichlorobenzene; and the reaction time is 1-12 hours.

[0020] The invention also provides an application of the nickel complex as a catalyst for olefin polymerization.

[0021] Preferably, the polymerization reaction is carried out in an organic solvent, the amount of nickel complex used is 1 to 20 μmol / L, the polymerization pressure is 0.1 to 50 MPa, the reaction temperature is controlled to be 0 to 200°C, and the reaction time is 0.05 to 5.00 hours; the polymerization reaction is a homopolymerization reaction or a copolymerization reaction with a polar monomer; the olefin is ethylene or α-olefin.

[0022] Preferably, in order to facilitate the operation of the reactor and the polymerization product, the organic solvent may be a hydrocarbon with less than 12 carbon atoms.

[0023] Preferably, the organic solvent is a mixture of one or more of toluene, hexane, n-heptane and chlorobenzene.

[0024] Preferably, the α-olefin is a terminal olefin of C3 to C18; further preferably, the α-olefin is a mixture of one or more of propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 1-decene, 1-dodecene and 1-octadecene.

[0025] Preferably, the polar monomer is a C2-C20 α-olefin containing a polar group, or a cycloolefin containing a polar group; the polar group is an organic functional group containing oxygen, nitrogen, sulfur or selenium.

[0026] Preferably, the polar group comprises a hydroxyl group, a carboxyl group, an ester group, an alkoxy group, a ketone group, an amine group, an amide group, a thioether, a silyl ether or a selenoether.

[0027] Preferably, the polymerization reaction method includes one of slurry polymerization, loop polymerization and gas phase polymerization.

[0028] The advantages of the present invention are:

[0029] The invention increases the steric hindrance around the metal and utilizes the electronic effect to introduce groups with different electronic effects at the para position of the sterically hindered aniline, designs and synthesizes a series of sterically hindered pyridine amides, and uses the pyridine amides as ligands to prepare novel nickel complexes. The obtained nickel complex is a highly efficient sterically hindered pyridine amide nickel catalyst. The catalyst regulates the electron cloud density of the metal center by adjusting the steric hindrance and the electronic effect, thereby improving the coordination and insertion ability of the metal center to olefins. The single-component cationic nickel catalyst is applied to the homogeneous polymerization of olefins such as ethylene, has high catalytic activity, good thermal stability, and high polymer molecular weight. In the homogeneous polymerization of ethylene, the cationic allyl nickel catalyst has high activity, reaching 3.73×10 6 g PE(mol Ni) -1 h -1 . Most importantly, the nickel complex catalyst realizes the copolymerization of ethylene and polar monomers such as 10-undecenoic acid methyl ester monomer, and obtains copolymers with different polar monomer insertion rates, with the maximum insertion amount reaching 1.53 mol%. Compared with the previously reported spatially open pyridine amide nickel catalyst, the activity of the cationic nickel catalyst synthesized by the present invention is increased by two orders of magnitude, the molecular weight is increased by nearly three times, and the thermal stability can reach 80°C. Therefore, the single-component nickel-based catalyst of the present invention has important industrial application value in the field of olefin polymerization. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the X-ray diffraction single crystal structure diagram of the complex prepared in Example 4 of the present invention;

[0031] Figure 2 This is the X-ray diffraction single crystal structure diagram of the complex prepared in Example 5 of the present invention;

[0032] Figure 3 The molecular weight M of the polymer prepared in item 1 of Table 1 of Application Example 1 of the present invention is n data;

[0033] Figure 4The melting point T of the polymer prepared in item 1 of Table 1 of Application Example 1 of the present invention is m data;

[0034] Figure 5 H NMR spectrum (400 MHz, CDCl3) of the ligand prepared in Example 1 of the present invention;

[0035] Figure 6 The NMR carbon spectrum (100 MHz, CDCl3) of the ligand prepared in Example 1 of the present invention;

[0036] Figure 7 H NMR spectrum (400 MHz, CDCl3) of the ligand prepared in Example 2 of the present invention;

[0037] Figure 8 The NMR carbon spectrum (100 MHz, CDCl3) of the ligand prepared in Example 2 of the present invention;

[0038] Fig. 9 H NMR spectrum (400 MHz, CDCl3) of the ligand prepared in Example 3 of the present invention;

[0039] Fig.10 The NMR carbon spectrum (100 MHz, CDCl3) of the ligand prepared in Example 3 of the present invention;

[0040] Fig.11 This is the H-NMR spectrum (400 MHz, CDCl3) of the complex prepared in Example 4 of the present invention;

[0041] Fig.12 This is the H-NMR spectrum (400 MHz, CDCl3) of the complex prepared in Example 5 of the present invention;

[0042] Fig.13 This is the H-NMR spectrum (400 MHz, CDCl3) of the complex prepared in Example 6 of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0045] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0046] The following examples illustrate the specific content of the present invention, and the data provided include the synthesis of the ligand, the synthesis of the complex, and the ethylene polymerization or copolymerization method, wherein the synthesis of the complex and the polymerization process are carried out in the absence of water and oxygen, all sensitive substances are stored in a glove box, all solvents are strictly dried and dehydrated, ethylene gas is purified by a dehydration and deoxygenation column, and 10-undecenoic acid methyl ester is purified by dehydration and deoxygenation reduced pressure distillation.

[0047] The silica gel column used 200-300 mesh silica gel, and the nuclear magnetic resonance used a Bruker 400MHz nuclear magnetic resonance instrument; the elemental analysis was determined by the Physical and Chemical Center of the University of Science and Technology of China; the molecular weight and molecular weight distribution were determined by GPC (polystyrene columns, HR2 and HR4, the box temperature was 160°C, using Water 1515 and Water 2414 pumps; the mobile phase was 1,2,4-trichlorobenzene, the flow rate was 1.0 ml per minute, and polydisperse polystyrene was used as the standard); the single crystal X-ray diffraction analysis was performed using an Oxford Diffraction Gemini SUltra CCD single crystal diffraction instrument.

[0048] Example 1

[0049] Preparation of Largely Hindered Pyridineamide Ligand (N-(2,6-Benzhydryl-4-methyl)phenyl-2-pyridinecarboxyamide) II1

[0050]

[0051] The preparation method comprises the following steps: under a nitrogen atmosphere, dissolving 2-pyridoyl chloride (1.42 g, 10 mmol) in 50 ml of dry tetrahydrofuran at 0°C to obtain a 2-pyridoyl chloride solution; dissolving 4-methyl 2,6-dibenzhydrylaniline (4.4 g, 10 mmol) in 50 ml of dry tetrahydrofuran solution to obtain a 4-methyl 2,6-dibenzhydrylaniline solution; injecting the 2-pyridoyl chloride solution into a reaction bottle, then injecting the 4-methyl 2,6-dibenzhydrylaniline solution into the reaction bottle, and then injecting triethylamine (2.0 g, 20 mmol) into the reaction bottle to obtain a reaction mixture; stirring the reaction mixture for 6 hours, then draining the tetrahydrofuran solution, adding dichloromethane solvent and extracting, concentrating the extracted solution, and passing it through a silica gel column to obtain a white solid ligand II1.

[0052] The NMR spectrum of II1 is as follows Figure 5 and Figure 6 As shown, the results are as follows: 1H NMR (400MHz, Chloroform-d): δ8.82(s,1H,-CONH),8.42–8.27(m,1H,Ar-H),8.20(d,J=7.8Hz,1H,Ar-H),7.83(td,J=7.7,1.7Hz,1H,Ar-H),7.38 (ddd,J=7.7,4.8,1.3Hz,1H,Ar-H),7.25–7.13(m,12H,Ar-H),7.08–6.97(m,8H,Ar-H),6.66(s,2H,Ar-H),5.68(s,2H,CHAr2),2.17(s,3H,-CH3). 13 CNMR(100MHz,Chloroform-d):δ162.99(-CONH),149.50,147.77,143.10,142.18,137.12,13 6.75,131.39,129.51,129.31,128.19,126.23,126.07,122.22,52.41(CHAr2),21.66(CH3).

[0053] Elem.Anal.Calcd for C 39 H 32 N2O:C,85.88;H,5.74;N,5.40.Found:C,86.52;H,5.61;N,5.53.

[0054] Example 2

[0055] Preparation of Largely Hindered Pyridineamide Ligand (N-(2,6-Benzhydryl-4-fluoro)phenyl-2-pyridinecarboxyamide) II2

[0056]

[0057] The preparation method is similar to that of Example 1, except that 10 mmol of 2,6-bis(diphenylmethyl)-4-fluoroaniline is used to replace 4-methyl 2,6-diphenylmethylaniline in Example 1 to obtain ligand II2;

[0058] The NMR spectrum of ligand II2 is shown in Figure 7 and Figure 8 As shown, the test data is as follows: 1H NMR (400MHz, Chloroform-d): δ8.82(s,1H,-CONH),8.32(dt,J=4.7,1.4Hz,1H,Ar-H),8.24–8.17(m,1H,Ar-H),7.84(td,J=7.7,1.7Hz, 1H,Ar-H),7.46–7.35(m,1H,Ar-H),7.25–7.16(m,11H,Ar-H),7.12–6.99(m,8H,Ar-H),6.60(d,J=9.5Hz,2H,Ar-H),5.70(s,2H,CHAr2). 13 CNMR(100MHz,Chloroform-d): δ163.01(CONH),149.17,147.83,145.19,145.12,142.26,137.23,129 .73,129.38,128.41,128.19,126.60,126.29,122.27,115.77,115.53,52.55(CHAr2),52.54(CHAr2).

[0059] Elem.Anal.Calcd for C 38 H 29 FN2O:C,81.90;H,5.43;N,5.83.Found:C,82.33;H,5.54;N,5.76.

[0060] Example 3

[0061] Preparation of Largely Hindered Pyridineamide Ligand (N-(2,6-Benzhydryl-4-methoxy)phenyl-2-pyridinecarboxyamide) II3

[0062]

[0063] The preparation method thereof is different from that of Example 1 only in that 10 mmol of 2,6-bis(diphenylmethyl)-4-methoxyaniline is used to replace 4-methyl-2,6-diphenylmethylaniline in Example 1, and the remaining steps are the same as those of Example 1 to obtain ligand II3;

[0064] The NMR data of ligand II3 are as follows Fig. 9 and Fig.10 As shown, the test data is as follows: 1H NMR (400MHz, Chloroform-d): δ8.85(s,1H,-CONH),8.35(dd,J=6.3Hz,2H,Ar-H),7.91(t,J=7.7Hz,1H,Ar-H),7.46(dd,J=7.6,4.7Hz ,1H,Ar-H),7.30(q,J=6.6,5.9Hz,10H,Ar-H),7.15(d,J=7.3Hz,8H,Ar-H),6.50(s,2H,Ar-H),5.78(s,2H,CHAr2),3.62(s,3H,CH3). 13 C NMR (100MHz, CDCl3): δ163.17(-CONH),158.26,149.47,147.81,143.97,142.83,137.16 ,129.48,128.28,126.93,126.39,126.13,122.24,114.24,55.07(OCH3),52.63(CHAr2).

[0065] Elem.Anal.Calcd for C 39 H 32 N2O2:C,83.54;H,5.75;N,5.00.Found:C,83.47;H,5.80;N,5.07.

[0066] Example 4

[0067] Preparation of Nickel Complex I1

[0068]

[0069] In a nitrogen atmosphere, the ligand II1 (1.0 mmol) prepared in Example 1 was dissolved in 25 mL of toluene to obtain a ligand solution; sodium tetrakis(3,5-di(trifluoromethyl)phenyl)borate NaBAF (1.1 mmol) and a metal nickel precursor [Ni(allyl)Cl]2 (0.5 mmol) were dissolved in 25 mL of toluene to obtain a metal nickel precursor solution; the ligand solution was dripped into the metal nickel precursor solution, stirred, reacted at room temperature for 2 h, filtered to obtain a brown-yellow solution, and the solvent was removed in vacuo to obtain a nickel complex having a structure of formula I1. In the structural formula: represents tetrakis(3,5-bis(trifluoromethyl)phenyl)borate anion, connected to Ni It represents allyl.

[0070] The NMR spectrum of nickel complex I1 is shown in Fig.11 As shown, the results are as follows:

[0071] 1H NMR(400MHz,Chloroform-d): δ8.04–7.69(m,11H,Ar-H),7.53(s,6H,Ar-H),7.24–6. 76(m,17H,Ar-H),6.43(s,3H,Ar-H),5.30(s,2H,CHAr2),1.23(d,J=25.6Hz,3H,CH3).

[0072] Elem.Anal.Calcd for C 74 H 47 BF 24 N2NiO:C,58.95;H,3.28;N,1.86.Found:C,58.78;H,3.08;N,1.94.

[0073] The X-ray diffraction single crystal structure of nickel complex I1 is shown in Figure 1 As shown, hydrogen atoms and tetrakis(3,5-bis(trifluoromethyl)phenyl)borate anion are omitted for clarity. The crystal data are as follows:

[0074]

[0075] Selected bond length and bond angle ( o ): Ni1-N1=1.923(7), Ni1-O006=1.930(6), Ni1-C1=1.977(12), Ni1-C2=1.898(11), Ni1-C3=1.955(11), O006-C10=1.2 54(9), N1-C9=1.364(10), C10-N2=1.301(9), O006-Ni1-N1=84.0(3), Ni1-N1-C9=112.4(5), Ni1-O006-C10=113.3(5).

[0076] Example 5

[0077] Preparation of Nickel Complex I2

[0078]

[0079] In a nitrogen atmosphere, the ligand II2 (1.0 mmol) prepared in Example 2 was dissolved in 25 mL of toluene to obtain a ligand solution; sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate NaBAF (1.1 mmol) and a metal nickel precursor [Ni(allyl)Cl]2 (0.5 mmol) were dissolved in 25 mL of toluene to obtain a metal nickel precursor solution, and the ligand solution was dropped into the metal nickel precursor solution, stirred, reacted at room temperature for 2 h, filtered to obtain a brown-yellow solution, and the solvent was removed in vacuo to obtain a nickel complex having a structure of formula I2; wherein represents tetrakis(3,5-bis(trifluoromethyl)phenyl)borate anion, connected to Ni It represents allyl.

[0080] The NMR spectrum of nickel complex I2 is as follows Fig.12 As shown, the results are as follows: 1 H NMR (400MHz, Chloroform-d): δ7.77(s,9H,-CONH),7.53(s,5H,Ar-H),7.31(s,6H,Ar- H),7.18(s,4H,Ar-H),7.11–6.84(m,7H,Ar-H),6.62(s,2H,Ar-H),5.30(s,2H,CHAr2).

[0081] Elem.Anal.Calcd for C 73 H 44 BF 25 N2NiO:C,58.01;H,3.07;N,1.85.Found:C,58.21;H,2.79;N,1.97.

[0082] The X-ray diffraction single crystal structure of nickel complex I2 is shown in Figure 2 As shown; for clarity, hydrogen atoms and tetrakis(3,5-bis(trifluoromethyl)phenyl)borate anion are omitted. Its crystal data are as follows:

[0083]

[0084]

[0085] Selected bond length and bond angle ( o): Ni1-N1=1.926(5), Ni1-O1=1.934(4), Ni1-C1=1.983(9), Ni1-C2=1.90(1), Ni1-C3=1.98(1), O1-C9=1.249(7), N1-C7=1.353(8) , C9-N2=1.312(8), O1-Ni1-N1=83.9(2), Ni1-N1-C7=113.0(3), Ni1-O1-C9=112.5(3), O1-Ni1-C1=99.9(3), N1-Ni1-C3=101.5(3).

[0086] Example 6

[0087] Preparation of Nickel Complex I3

[0088]

[0089] In a nitrogen atmosphere, the ligand II3 (1.0 mmol) prepared in Example 3 was dissolved in 25 mL of toluene to obtain a ligand solution, and sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate NaBAF (1.1 mmol) and a metal nickel precursor [Ni(allyl)Cl]2 (0.5 mmol) were dissolved in 25 mL of toluene to obtain a metal nickel precursor solution. The ligand solution was dropped into the metal nickel precursor solution, stirred, and reacted at room temperature for 2 h. The brown-yellow solution was filtered to obtain the solution, and the solvent was removed in vacuo to obtain a nickel complex having a structure of formula I3; wherein represents tetrakis(3,5-bis(trifluoromethyl)phenyl)borate anion, connected to Ni It represents allyl.

[0090] The NMR spectrum of nickel complex I3 is as follows Fig.13 As shown, the results are as follows: 1 H NMR (400MHz, Chloroform-d): δ8.14(s,1H,-CONH),7.72(s,9H,Ar-H),7.50(s,4H,Ar-H),7.17(d,J=7.6Hz,6H,Ar-H),6 .96(s,6H,Ar-H),6.37(d,J=7.6Hz,2H,Ar-H),5.87(s,1H,Ar-H),5.35–5.17(m,2H,CHAr2),3.51(d,J=7.6Hz,3H,CH3).

[0091] Elem.Anal.Calcd for C 74 H 47 BF 24N2NiO2:C,58.33;H,3.24;N,1.84.Found:C,58.31;H,3.15;N,1.92.

[0092] Application Example 1

[0093] The nickel complexes prepared in Examples 4 to 6 were respectively used as catalysts to carry out ethylene polymerization reactions. The specific polymerization methods are as follows:

[0094] In a glove box, and under a nitrogen atmosphere, 28 mL of toluene was added to a 350 mL pressure bottle (with a magnetic stirring device, an oil bath heating device and a thermometer), and then the container was connected to a high-pressure pipeline and the pipeline was evacuated and kept warm for 5 minutes; 5 μmol of the nickel complex prepared in Examples 4 to 6 was dissolved in 2 mL of dichloromethane and injected into the pressure bottle through a syringe; then the ethylene valve was opened, ethylene was introduced into the pressure bottle, and the ethylene pressure was adjusted to 8 atmospheres, and the reaction was carried out for 10 minutes; then the reaction was stopped, the pressure bottle was opened, ethanol was added to the pressure bottle to precipitate a solid, the pressure was reduced and filtered, and a white solid was dried in a vacuum drying oven.

[0095] Specific experimental conditions (catalyst Cat. and temperature T), yield (Yield), catalytic activity (Act.), polymer molecular weight (M) of the nickel complex prepared in Examples 4 to 6 of the present invention for ethylene polymerization n ), polymer molecular weight distribution (PDI), degree of branching (B) and other polymerization result data are shown in Table 1 below:

[0096] Table 1. Catalysts for ethylene polymerization a

[0097] project Cat. T / ℃ Yield / g <![CDATA[Act. b ]]> <![CDATA[T m c / ℃]]> <![CDATA[M n d ]]> <![CDATA[PDI d ]]> <![CDATA[B e / 1000C]]> 1 <![CDATA[Example 4 (I1)]]> 20 0.89 1.07 115.5 1300 1.49 21 2 <![CDATA[Example 4 (I1)]]> 40 1.78 2.14 112.8 1900 1.57 29 3 <![CDATA[Example 4 (I1)]]> 60 0.85 1.02 105.1 1400 1.74 44 4 <![CDATA[Example 4 (I1)]]> 80 0.47 0.56 63.5 800 1.83 67 5 <![CDATA[Example 5 (I2)]]> 20 1.63 1.96 121.3 1700 1.42 17 6 <![CDATA[Example 5 (I2)]]> 40 3.11 3.73 115.9 3200 1.53 22 7 <![CDATA[Example 5 (I2)]]> 60 2.17 2.60 111.7 2600 1.99 29 8 <![CDATA[Example 5 (I2)]]> 80 0.86 1.03 98.4 1200 1.37 48 9 <![CDATA[Example 6 (I3)]]> 20 1.15 1.38 118.2 1600 1.35 20 10 <![CDATA[Example 6 (I3)]]> 40 2.01 2.41 113.6 2100 1.40 25 11 <![CDATA[Example 6 (I3)]]> 60 0.96 1.15 108.4 1500 1.40 38 12 <![CDATA[Example 6 (I3)]]> 80 0.53 0.64 64.8 900 1.69 51

[0098] in, a Polymerization conditions: catalyst 5 μmol, toluene = 28 mL, dichloromethane = 2 mL, ethylene = 8 atmospheres, time = 10 minutes, b Activity=10 6 g·mol -1 ·h -1 ; c Melting points were determined using differential scanning calorimetry; d Number average molecular weight = gmol -1 The molecular weight was determined by GPC at 150°C using polystyrene as standard and trichlorobenzene as solvent. e The degree of branching refers to the number of branches per 1000 carbon atoms, which is 1 Determined by H NMR nuclear magnetic resonance method.

[0099] Figure 3 The molecular weight M of the polymer prepared in item 1 in Table 1n Data; Figure 3 It can be seen that the polymer molecular weight M n is 1300; Figure 4 The melting point T of the polymer prepared in item 1 in Table 1 is m Data; Figure 4 It can be seen that its melting point is 115.5°C.

[0100] Application Example 2

[0101] The nickel complexes prepared in Examples 4 to 6 were respectively used as catalysts to carry out copolymerization of ethylene and polar monomers. The specific polymerization method is as follows:

[0102] In a glove box, and under a nitrogen atmosphere, 28 mL of toluene was added to a 350 mL pressure bottle (with a magnetic stirring device, an oil bath heating device and a thermometer), and a polar monomer 10-undecenoic acid methyl ester was added to the desired concentration of the polar monomer content; then the container was connected to a high-pressure pipeline and the pipeline was evacuated, and the container temperature was set to 40 ° C and kept warm for 5 minutes; then 10 μmol of the nickel complex prepared in Examples 4 to 6 was dissolved in 2 mL of dichloromethane and injected into the pressure bottle through a syringe; then the ethylene valve was opened, ethylene was introduced into the pressure bottle, and the ethylene pressure was adjusted to 8 atmospheres, and the reaction was continued for 30 minutes; then the reaction was stopped, the pressure bottle was opened, ethanol was added to the pressure bottle to precipitate the solid, the pressure was reduced and filtered, and the white solid was dried in a vacuum drying oven. The obtained solid was extracted for 2 days, and the solid was drained and weighed.

[0103] The results of the polymerization of ethylene and polar monomers catalyzed by the nickel complexes prepared in Examples 4 to 6 are shown in Table 2 below, wherein Cat. represents catalyst, Co-monomer represents comonomer, MU represents the concentration of 10-undecenoic acid methyl ester, Yield represents yield, Act. represents catalytic activity, M n represents polymer molecular weight, PDI represents polymer molecular weight distribution, Incorp. represents polar monomer insertion molar ratio, T m Indicates melting point;

[0104] Table 2. Copolymerization of ethylene and polar monomers catalyzed by nickel complexes a

[0105]

[0106] in, a Polymerization conditions: catalyst 10 μmol, toluene = 28 mL, dichloromethane = 2 mL, ethylene = 8 atmospheres, time = 30 minutes, polymerization temperature 40 degrees Celsius; b Activity=10 4 g·mol -1 ·h -1; c Number average molecular weight = g mol -1 ; d The polar monomer insertion molar ratio was measured by H-NMR spectroscopy; e Melting points were determined by differential scanning calorimetry; molecular weights were determined by GPC at 150°C using polystyrene as a standard and trichlorobenzene as a solvent.

[0107] It can be seen from Table 2 that the nickel complex in the present application can catalyze the copolymerization of ethylene and polar monomers to prepare polar polyolefins under certain conditions, with the highest activity reaching 9.83×10 4 g·mol -1 ·h -1 ; Melting point is 102~114℃; The maximum number average molecular weight is 1.9×10 3 g / mol.

[0108] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sterically hindered pyridine amide, characterized in that: Its general structural formula is shown below: Wherein, in the general formula, Ar is selected from phenyl; R1 is selected from one of C1-C20 alkyl, I, Br, Cl, F, OCH3, CF3, NO2; R2 is selected from H.

2. The sterically hindered pyridine amide according to claim 1, characterized in that: Its structural formula is One of them.

3. A method for preparing a large sterically hindered pyridine amide as claimed in claim 1 or 2, characterized in that: Under nitrogen or argon, and After the reaction, the product is obtained; wherein Ar is selected from phenyl; R1 is selected from one of C1-C20 alkyl, I, Br, Cl, F, OCH3, CF3, and NO2.

4. A nickel complex prepared using the bulky hindered pyridine amide as claimed in claim 1 or 2, characterized in that: Its general structural formula is shown below: Wherein, in the general formula, Ar is selected from phenyl; R1 is selected from one of C1-C20 alkyl, I, Br, Cl, F, OCH3, CF3, and NO2; R2 is selected from H; represents tetrakis(3,5-bis(trifluoromethyl)phenyl)borate anion, connected to Ni It represents allyl.

5. The nickel complex according to claim 4, characterized in that: In the general structural formula of the nickel complex, Ar is a phenyl group, R1 is a methyl group, a fluorine group, or a methoxy group, and R2 is hydrogen.

6. The nickel complex according to claim 5, characterized in that: The structural formula of the nickel complex is It belongs to the triclinic system, P-1 space group, α = 69.092 (2) °, β = 82.103 (2) °, γ = 89.003 (2) °, Or the structural formula of the nickel complex is It belongs to the triclinic system, P-1 space group, α = 69.608 (2) °, β = 82.129 (2) °, γ = 89.204 (2) °, 7. A method for preparing the nickel complex as claimed in any one of claims 4 to 6, characterized in that: The following steps are involved: Under an argon or nitrogen atmosphere, the bulky hindered pyridine amide as claimed in claim 1 or 2 is dissolved in a good solvent to obtain a ligand solution; sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate and a metal nickel precursor [Ni(allyl)Cl]2 are dissolved in a good solvent to obtain a metal nickel precursor solution, and then the ligand solution is added to the metal nickel precursor solution, and the solvent is removed after the reaction at room temperature to obtain the nickel complex.

8. The method for preparing the nickel complex according to claim 7, characterized in that: The good solvent is one or a mixture of toluene, dichloromethane, chloroform, dichlorobenzene and trichlorobenzene; and the reaction time is 1-12 hours.

9. Use of the nickel complex as claimed in any one of claims 4 to 6 as a catalyst for olefin polymerization; the polymerization reaction is a homopolymerization reaction or a copolymerization reaction with a polar monomer 10-undecenoic acid methyl ester; the olefin is ethylene or α-olefin.

10. Use of the nickel complex according to claim 9 as a catalyst for olefin polymerization, characterized in that: The polymerization reaction is carried out in an organic solvent, the amount of the nickel complex used is 1-20 μmol / L, the polymerization pressure is 0.1-50 MPa, the reaction temperature is controlled to be 0-200° C., and the reaction time is 0.05-5.00 hours.

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