Zwitterionic allylnickel complexes and their preparation and use

Abstract

The present invention provides a zwitterionic allylnickel complex and its preparation and use. The zwitterionic allylnickel complex has the structure shown in Formula I: In formula I, R1 and R1' are the same or different and each independently represent a C1-C4 alkyl group, a C6-C 15 and R2 is selected from H and C1-C6 alkyl groups. This zwitterionic allylnickel complex can be used to catalyze the copolymerization of ethylene with acrylate monomers under mild reaction conditions, with high catalytic activity, resulting in high molecular weight products and moderately branched ethylene-acrylate copolymers. [Formula 1] JPEG2026504975000035.jpg25170

Description

[Technical Field]

[0001] The present invention relates to the field of catalysis, specifically to a novel zwitterionic allylnickel complex, its preparation method and use for preparing ethylene-methyl acrylate copolymer, and the corresponding method for preparing ethylene-methyl acrylate copolymer. [Background technology]

[0002] Polyolefin materials are the most widely used polymeric materials. Introducing polar groups into nonpolar polyolefin chains can significantly improve the adhesion, dyeability, compatibility, and other properties of polyolefin materials. For example, industrialized ethylene-methyl acrylate copolymers (EMA) with an ester content of 10-30 Ω% and a branched structure have been widely used in many fields due to their excellent mechanical properties and compatibility. Industrially, EMA is obtained by radical copolymerization under harsh conditions, including high temperatures (150-300°C) and high pressures (150-300 MPa). Compared to the harsh conditions of radical copolymerization, coordination polymerization, which catalyzes the direct copolymerization of olefins with polar monomers under mild conditions, is a simple, direct, and effective method for producing functionalized polyolefins.

[0003] Late-transition metal catalysts, particularly palladium catalysts, are widely used in the copolymerization of ethylene with polar monomers. The literature reports that α-diimine palladium catalyzes the copolymerization of ethylene with methyl acrylate (MA) through a rapid chain-walking process, typically producing highly branched copolymers in which MA is located at the branch end. EMA produced with α-diimine palladium catalysts has a high degree of branching, no melting point, and poor mechanical properties, making it unusable as a thermoplastic resin. Furthermore, palladium phosphine sulfonate catalyzes the copolymerization of ethylene with MA, producing highly linear EMA with MA inserted into the main chain. However, the poor branching of EMA produced by the high-pressure radical method results in poor toughness and elasticity of the material.

[0004] Furthermore, because palladium is a precious metal and expensive, catalyzing the copolymerization of ethylene with polar monomers using inexpensive and abundant nickel catalysts is of practical industrial significance. However, due to the high electrophilicity of the nickel metal center, it is generally difficult to catalyze the copolymerization of ethylene with MA to obtain high molecular weight copolymers. For example, while α-diimine palladium can effectively catalyze the copolymerization of ethylene with methyl acrylate (MA), α-diimine nickel catalysts are ineffective at catalyzing the copolymerization of ethylene with methyl acrylate (MA). Therefore, it is of great significance to develop a nickel catalyst with weak electrophilicity through appropriate ligand design to achieve the copolymerization of ethylene with methyl acrylate (MA). To develop a nickel catalyst capable of producing EMA with a moderate degree of branching, it is necessary to comprehensively balance the electrophilicity of the metal center, thereby enabling the copolymerization of polar acrylate monomers while also generating chain walking and producing products with a structure similar to that of EMA obtained by radical polymerization. This has not yet been reported in the literature and is of great industrial significance.

[0005] CN112538098A discloses an α-sulfonic acid-β-diimine nickel complex, its preparation method, and its use as a catalyst for the copolymerization of ethylene and methyl acrylate, etc. The structure of this nickel complex is as follows:

[0006] [ka]

[0007] Here, Ar is a 2,6-diisopropylphenyl group or a 2,6-dimethylphenyl group, and X is a chlorine or bromine element. The temperature range for catalyzing the copolymerization of an olefin and a polar monomer is 0°C to 80°C, and the molar ratio of catalyst to polar monomer is 1:100 to 1:2000. Using toluene as a solvent and MAO as a cocatalyst, the copolymerization activity of ethylene and methyl acrylate was 5.09 x 10 under the conditions of a methyl acrylate concentration of 0.2 M, an aluminum to nickel molar ratio of 1500:1, an esterification agent molar ratio of 266:1, an ethylene pressure of 0.5 MPa, 50°C, and 4 hours. 3 The activity was 5.09×10 , the weight average molecular weight of EMA was 41.9 kg / mol, the molecular weight distribution was 1.39, the ester content in EMA was 0.8 mol%, and the melting temperature was 98.5°C. This technology discloses a new catalyst that can be used in the copolymerization of ethylene and methyl acrylate, and is primarily used to produce low-branched, semi-crystalline polyethylene. Acetonitrile and halogen were used as the alkyl groups coordinated to nickel, and under conditions where the molar ratio of the main catalyst to the cocatalyst reached 1:1500 to 1:5000, the copolymerization activity was 5.09×10 . 3 g / molNi-h only.

[0008] CN1727372A discloses a halogen-substituted β-diimine titanium catalyst for ethylene copolymerization, the structure of which is as follows:

[0009] [ka]

[0010] where R c is an aryl group or a halogenated alkyl group, and X is an anion-coordinating group containing a halogen, a hydrocarbon group, an aryl group, an oxygen-containing group, or a nitrogen-containing group, among which the oxygen-containing group is a propylene oxide group, a butylene oxide group, a pentene oxide group, or an acetylacetone group, particularly a secondary amine, preferably a di(C 1-16It is an alkyl amine, and has at least one halogenated hydrocarbon group, such as a trifluoromethyl group, on the benzene ring of the aniline. The copolymerization activity of ethylene and norbornene is 3.9 x 10 under the conditions of 0.1 MPa, 30 °C, and 15 minutes using toluene as a solvent and MMAO as a cocatalyst. 3 g / molTi·h, and the norbornene content in the copolymer was 16.8%. This technology discloses a halogen-substituted β-diimine titanium catalyst that can be used for the copolymerization of ethylene and norbornene. The alkyl group coordinated to the titanium is an epoxide, and the copolymerization activity is 3.9×10 3 g / molNi·h only.

[0011] CN110483329A discloses a highly sterically hindered ketimine nickel catalyst, the structure of which is as follows:

[0012] [ka]

[0013] The negative ion in the catalyst is tetra(3,5-di(trifluoromethyl)phenyl)borate anion,

[0014] [ka]

[0015] represents an allyl group connected to a nickel atom, n is an integer between 50 and 500, and has a radical Br at the distal end, and can be used to polymerize methyl methacrylate, methyl acrylate, acrylonitrile, acrylamide, styrene, or N-vinylpyrrolidone. This invention did not provide any copolymerization data.

[0016] US6897272B1 discloses a catalyst for copolymerizing ethylene with an alkenyl ester or a carboxylic acid at 20°C to 100°C to produce a polymer that can be used as an elastomer, a molding resin, an adhesive, etc. The catalyst has the following structure:

[0017] [ka]

[0018] In this patent, catalyst XXXVII uses an α-diimine ligand with a specific structure, where M is nickel and A is an allyl or benzyl group, where the allyl group has three adjacent sp2 carbon atoms bonded to the metal center at a π3 bond. These three sp carbon atoms may be substituted with other hydrocarbon groups or functional groups. Examples 200-203 show the synthesis of allyl-coordinated diimine palladium catalysts, and Examples 497-515 show the preparation of allyl-containing substituent-coordinated diimine nickel catalysts, but no experimental polymerization data are disclosed. This invention is an α-diimine nickel catalyst.

[0019] CN102105502A discloses a method for producing a diblock copolymer of a monovinyl aromatic polymer block, in which the repeating unit A is selected from the residues of one or more aliphatic hydroxycarboxylic acids and one or more cyclic carbonates, the repeating unit B is selected from the residues of a monovinyl aromatic monomer, R and Y are derived from a functional alcohol containing other functional groups besides the -OH functional group that allow for the growth or grafting of a polyvinyl aromatic compound, and R is a linking group. A large-volume, single-site β-diimine metal catalyst is used, the structure of which is as follows:

[0020] [ka]

[0021] where R 7is hydrogen, a hydrocarbon group or an inert functional group, and two or more of the groups may be linked to form a ring; X is C 1-12 The hydrocarbon group is a hydroxy group. This catalyst can be used to produce HAORYB diblock copolymers. This patent discloses an example of polylactic acid-polystyrene. This invention mainly focuses on the composition of the product, and does not disclose the details of the catalyst structure.

[0022] US2005 / 0043496 discloses an α-diimine nickel catalyst for use in copolymerizing ethylene and methyl acrylate, the structure of which is as follows:

[0023] [ka]

[0024] The resulting polymers were C1 to C6 + The copolymerization of ethylene and methyl acrylate with catalyst No. 45 was carried out at 100-120°C, 6.9 MPa, 18 h using 0.0025 mmol of catalyst, 160 equivalents of B(CF)3, 80 equivalents of NaBAF, 0.5 mL of MA, and 9.5 mL of chlorobenzene. The yields were 2.9 g and 2.59 g, respectively. The MA insertion rates were 0.53 mol% and 0.45 mol%, respectively. The weight-average molecular weights were 18,706 g / mol and 10,394 g / mol, respectively. The methyl branching accounted for 31.8% and 51.8%, respectively.

[0025] WO01 / 92347A2 discloses a [P,O]-type allylnickel catalyst or a [P,N]-type allylnickel catalyst for copolymerization of ethylene and methyl acrylate, which can also be used for copolymerization of ethylene and aryl acrylate or long-chain acrylate. The catalyst structure is as follows:

[0026] [ka]

[0027] CN1315573C discloses a β-diimine nickel catalytic dimer, the structure of which is as follows:

[0028] [ka]

[0029] where R1 and R2 are hydrogen, an alkyl group, an aryl group, an alkenyl group, or an alkylsilyl group, Ar1 and Ar2 are 2,6-dimethylphenyl or 2,6-diisopropylphenyl, and X is Cl, Br, or I, respectively. The molar ratio of the main catalyst to the cocatalyst is 1:10 to 1:40. Using toluene as the solvent and triethylaluminum as the cocatalyst, the copolymerization activity of ethylene and methyl methacrylate was 6.6 x 10 under the following conditions: a methyl methacrylate concentration of 0.015 M, an aluminum to nickel molar ratio of 20:1, an ethylene pressure of 0.8 MPa, 20°C, and 2 h. 4 The hydroxyl group of EMMA is 150 kg / mol, and the ester content in EMA is 0.7 mol%. This catalyst can be used for the copolymerization of ethylene and methyl methacrylate at a molar ratio of main catalyst to cocatalyst of 1:10 to 1:40, but the copolymerization activity is not high.

[0030] CN113680389A discloses a polydentate β-diimine rare earth metal catalyst, the structure of which is as follows:

[0031] [ka]

[0032] This catalyst is mainly used to produce urethane compounds or 2-oxazolidinone compounds, which are important intermediates for agricultural chemicals and pharmaceuticals. 2-oxazolidinone compounds are important heterocyclic compounds that have attracted attention for their antibacterial, anti-inflammatory, anticancer, and antituberculous properties.

[0033] CN105646756B discloses an α-diimine nickel catalyst, the structure of which is as follows:

[0034] [ka]

[0035] Here, Z and Y are each a C1-C4 alkyl group, or Z and Y together with the common carbon-carbon single bond form a group selected from the group consisting of unsubstituted or substituted acenaphthylenyl, phenanthryl, camphenyl, and C5-C8 cycloalkyl groups. 1 , R 2 are H, halogen, C1-C8 alkyl group, C1-C8 halogenated alkyl group, phenyl group, benzyl group, -O-Ra, -CH2-O-Ra, -SRb or -CH2-S-Rb, and R 3 and R 4 are respectively H, halogen, C1-C8 alkyl group, C1-C8 halogenated alkyl group, -O-Ra, -CH2-O-Ra, -SRb or -CH2-S-Rb, where Ra and Rb are respectively C1-C8 alkyl group, phenyl group or benzyl group, and R 1 , R 2 , R 3 and R 4 is R 1 ≠R 3 and / or R 2 ≠R 4 where X coordinated to nickel may be an allyl group, halogen, C1-C4 alkyl group, C2-C6 alkenyl group, or benzyl group. This catalyst can be used to catalyze the copolymerization of ethylene with long-chain alcohols, long-chain methoxy compounds, etc. to produce high-quality lubricating oils. Summary of the Invention

[0036] In order to solve the above problems, the object of the present invention is to provide an amphoteric allylic nickel complex and its preparation and use. This amphoteric allylic nickel complex can catalyze the copolymerization of ethylene with an acrylate monomer, and can produce a moderately branched ethylene-acrylate copolymer with mild reaction conditions, high catalytic activity, and high molecular weight.

[0037] To achieve the above object, the present invention provides a zwitterionic allylnickel complex having the structure shown in Formula I:

[0038] [ka]

[0039] In formula I, R1 and R1' are the same or different and each independently represent a C1-C4 alkyl group, a C6-C 15 and R2 is selected from H and C1-C6 alkyl groups.

[0040] According to a specific embodiment of the present invention, preferably, in Formula I, R1 and R1' are the same or different and each independently selected from a methyl group, an isopropyl group, and a diphenylmethyl group, and R2 is selected from a hydrogen atom and a methyl group.

[0041] According to a specific embodiment of the present invention, preferably in formula I, R1 and R1' are the same.

[0042] According to a specific embodiment of the present invention, preferably, in Formula I, R1 and R1' are both methyl groups and R2 is hydrogen, or R1 and R1' are both isopropyl groups and R2 is hydrogen, or R1 and R1' are both diphenylmethyl groups and R2 is a methyl group.

[0043] According to a specific embodiment of the present invention, preferably, in formula I, R1 and R1' are both isopropyl groups, and R2 is hydrogen.

[0044] The present invention further provides a method for producing the above-mentioned zwitterionic allylnickel complex, which comprises the following steps:

[0045] α-Sulfonic acid-β-diimine lithium salt compound and allylnickel precursor

[0046] [ka]

[0047] are mixed and reacted to obtain the zwitterionic allylnickel complex through the following reaction process.

[0048] [ka]

[0049] According to a specific embodiment of the present invention, the above-mentioned manufacturing method preferably includes the following steps:

[0050] (1) A β-diimine compound is reacted with n-BuLi and SO3.NMe3 (trimethylammonium sulfur trioxide copolymer) to obtain an α-sulfonic acid-β-diimine lithium salt compound, and (2) the α-sulfonic acid-β-diimine lithium salt compound is mixed with an allylnickel precursor and reacted to obtain the zwitterionic allylnickel complex through the following reaction process.

[0051] [ka]

[0052] According to a specific embodiment of the present invention, the above manufacturing method includes the following specific steps: (1) A β-diimine compound is dissolved in tetrahydrofuran, n-BuLi is added dropwise at -78°C or below (≦-78°C), and the mixture is stirred. The temperature is then raised to room temperature, stirring is continued, and the mixture is further cooled to -78°C or below (≦-78°C). SO3.NMe3 is added, the temperature is raised to room temperature, and stirring is continued to obtain an α-sulfonic acid-β-diimine lithium salt compound. The molar ratio of the β-diimine compound, n-BuLi, and SO3.NMe3 is preferably 1:1:1. (2) An α-sulfonic acid-β-diimine lithium salt compound and an allylnickel precursor are stirred in dichloromethane to obtain the zwitterionic allylnickel complex.

[0053] The present invention further provides a catalyst system comprising a main catalyst comprising the zwitterionic allylnickel complex and an activator.

[0054] According to a specific embodiment of the present invention, the molar ratio of the main catalyst to the activator is preferably 1:5 to 1:100, more preferably 1:40 to 1:80.

[0055] According to a specific embodiment of the present invention, the activator preferably includes one or a combination of two or more of methylaluminoxane (MAO), modified methylaluminoxane (MMAO), monochlorodiethylaluminum, dichloroethylaluminum, triisobutylaluminum, and tri(pentafluorophenyl)borane.

[0056] According to a specific embodiment of the present invention, preferably, the activator comprises methylaluminoxane (MAO) or a combination of both tri(pentafluorophenyl)borane and triisobutylaluminum (TIBA).

[0057] The present invention further provides a method for copolymerizing ethylene and an acrylate, comprising the steps of: using the zwitterionic allylnickel complex or the catalyst system to catalyze the copolymerization reaction of ethylene and an acrylate to obtain a branched ethylene-acrylate copolymer.

[0058] According to a specific embodiment of the present invention, the acrylate preferably includes one or a combination of two or more of methyl acrylate, ethyl acrylate, butyl acrylate, and t-butyl acrylate.

[0059] According to a specific embodiment of the present invention, preferably, the acrylate comprises methyl acrylate and / or ethyl acrylate.

[0060] According to a specific embodiment of the present invention, the polymerization temperature is preferably 0°C to 100°C, and more preferably 30°C to 80°C.

[0061] According to a specific embodiment of the present invention, preferably, in the catalyst system, the molar ratio of the main catalyst to the acrylate is 1:266 to 1:1066, more preferably 1:266 to 1:533.

[0062] According to a specific embodiment of the present invention, the pressure of ethylene is preferably 0.1 MPa to 5.0 MPa, more preferably 0.5 MPa to 3.0 MPa.

[0063] According to a specific embodiment of the present invention, preferably, the solvent used in the polymerization comprises one or a combination of two or more of toluene, hexane, cyclohexane, and heptane; more preferably, the solvent used in the polymerization is toluene and cyclohexane.

[0064] The present invention further provides an ethylene-acrylate copolymer produced by the above copolymerization method, which has a branching degree of 28 / 1000°C to 46 / 1000°C, a melting temperature of 84.6°C to 108.3°C, and has certain toughness, elasticity, adhesion, dyeability and compatibility, and has a wide range of practical applications.

[0065] According to a specific embodiment of the present invention, the weight average molecular weight of the ethylene-acrylate copolymer is preferably 1×10 5 g / mol ~ 1 × 10 6 g / mol (e.g., 1 × 105 g / mol≦weight average molecular weight<1×10 6 g / mol), the molecular weight distribution is 1.31 to 2.33, the acrylate content in the ethylene-acrylate copolymer is 3.50 mol% to 8.99 mol%, the alkyl group branch content is 30 / 1000C to 40 / 1000C, and the melting temperature of the ethylene-acrylate copolymer is 84.6°C to 98.3°C.

[0066] The zwitterionic allylnickel complex of the present invention overcomes the drawbacks of conventional palladium catalysts, such as their high cost and low polymerization activity, and the inability of conventional nickel catalyst systems to produce ethylene-acrylate copolymers with moderate branching and excellent toughness and elasticity. The zwitterionic allylnickel complex can be used as a main catalyst to catalyze the copolymerization of ethylene with acrylate monomers with the aid of an activator to produce branched ethylene-acrylate copolymer materials. The weak interaction between positive and negative ions in the zwitterionic allylnickel complex reduces the electrophilicity of the nickel metal center, improving its ability to copolymerize acrylate monomers. The nickel metal center still retains its cationic center and weak chain-walking ability, enabling the production of moderately branched ethylene-acrylate copolymers. The use of the zwitterionic allylnickel catalyst of the present invention to catalyze the copolymerization of ethylene with acrylate monomers offers mild overall reaction conditions, high catalytic activity, and high molecular weight products, offering clear technical advantages and promising industrial applications over the production of ethylene-acrylate copolymers via low-pressure coordination polymerization.

[0067] The present invention has the following beneficial effects: 1. The zwitterionic allylnickel complex provided by the present invention exists as an intramolecular positive and negative ion salt, and the metal center is an alkylated cationic active center capable of olefin coordination polymerization. Since only a small amount of expensive activator is required, industrial production has remarkable economical benefits.

[0068] 2. The zwitterionic allyl nickel catalyst provided by the present invention has a weak interaction between positive and negative ions, which reduces the electrophilicity of the nickel metal center and improves the tolerance to polar groups, thereby significantly improving the catalytic copolymerization activity of ethylene with acrylate monomers.

[0069] 3. The zwitterionic allylnickel catalyst provided by the present invention has a weak chain-walking ability because the nickel metal center still maintains a cationic center, and can produce branched ethylene-acrylate copolymers similar to those produced by the high-pressure method, which has the prospect of industrial application.

[0070] 4. The zwitterionic allyl nickel catalyst provided by the present invention catalyzes the copolymerization of ethylene and acrylate, and has significant technical advantages over industrialized high-pressure radical polymerization, such as mild reaction conditions, simple process equipment, and better control of the polymer structure. [Brief explanation of the drawings]

[0071] [Figure 1] FIG. 1 is a diagram showing the single crystal structure of the zwitterionic allylnickel complex provided by Example 8. [Figure 2] 1 is a nuclear magnetic hydrogen spectrum of ethylene-methyl acrylate (EMA) provided by Example 11. [Figure 3] FIG. 1 is a DSC analysis diagram of ethylene-methyl acrylate (EMA) provided by Example 11. DETAILED DESCRIPTION OF THE INVENTION

[0072] In order to make the technical features, objectives and beneficial effects of the present invention more clearly understood, the technical solutions of the present invention are described in detail below, but should not be understood to limit the scope of the present invention.

[0073] In the following examples, experimental methods for which specific conditions are not specified are based on standard conditions well known in the art or on conditions recommended by the equipment manufacturer. Unless otherwise specified, the raw materials, reagents, etc. used are all commercially available raw materials and reagents.

[0074] In the examples, the compounds and complexes are described as follows for simplicity.

[0075] [ka]

[0076] Formula III is a β-diimine compound, In the β-diimine compound A1, R1 and R1' are both methyl groups, and R2 is hydrogen.

[0077] In the β-diimine compound A2, R1 and R1' are both isopropyl groups, and R2 is hydrogen.

[0078] In the β-diimine compound A3, R1 and R1' are both diphenylmethyl groups, and R2 is a methyl group.

[0079] [ka]

[0080] Formula II is an α-sulfonic acid-β-diimine lithium salt compound, In the α-sulfonic acid-β-diimine lithium salt compound L1, R1 and R1′ are both methyl groups, and R2 is hydrogen.

[0081] In the α-sulfonic acid-β-diimine lithium salt compound L2, R1 and R1' are both isopropyl groups, and R2 is hydrogen.

[0082] In the α-sulfonic acid-β-diimine lithium salt compound L3, R1 and R1′ are both diphenylmethyl groups, and R2 is a methyl group.

[0083] [ka]

[0084] Formula I represents a zwitterionic allylnickel complex, In the amphoteric ionic allylnickel complex Ni-1, R1 and R1' are both methyl groups, and R2 is hydrogen.

[0085] In the amphoteric ionic allylnickel complex Ni-2, R1 and R1' are both isopropyl groups, and R2 is hydrogen.

[0086] In the amphoteric ionic allylnickel complex Ni-3, R1 and R1' are both diphenylmethyl groups, and R2 is a methyl group.

[0087] The synthesis route of the zwitterionic allylnickel complex in the examples is as follows.

[0088] [ka]

[0089] 1. Ligand Preparation Example 1 This example provides a β-diimine compound A1 substituted with a 2,6-dimethylphenyl group, and the synthesis method thereof is as follows.

[0090] A round-bottom flask was charged with acetylacetone (4.1 g, 41 mmol), 2,6-dimethylaniline (15.1 g, 85.2 mmol), ethanol (500 mL), and hydrochloric acid (12 M, 6 mL), and the mixture was heated to 100 °C in an oil bath. After 72 h, the mixture was cooled to room temperature and the solvent was removed by rotary evaporation to give a brown solid. The resulting solid was dissolved in dichloromethane (300 mL), washed twice with saturated NaHCO3 solution, extracted, and the organic phase was collected. The organic phase was dried over anhydrous magnesium sulfate, filtered, and the filtrate was collected and then rotary evaporated to give the crude product. The crude product was recrystallized from methanol to give a white solid. The yield was 87.5%. The nuclear magnetic hydrogen spectrum was as follows: 1 H NMR (CDCl3, 400 MHz) δ (ppm) : 12.19 (s, 1H, NH)), 7.03 (d, 4H, Ar-H), 6.95 (d, 2H, Ar-H), 4.88 (s, 1H, H β ), 2.16 (s, 12H, CH3), 1.69 (s, 6H, CH3). Example 2 This example provides a β-diimine compound A2 substituted with a 2,6-diisopropylphenyl group, and the synthesis method thereof is as follows.

[0091] A round-bottom flask was charged with acetylacetone (4.1 g, 41 mmol), 2,6-diisopropylaniline (10.3 g, 85.2 mmol), ethanol (500 mL), and hydrochloric acid (12 M, 6 mL), and the mixture was heated to 100 °C in an oil bath. After 72 h, the mixture was cooled to room temperature and the solvent was removed by rotary evaporation to give a brown solid. The resulting solid was dissolved in dichloromethane (300 mL), washed twice with saturated NaHCO3 solution, extracted, and the organic phase was collected. The organic phase was dried over anhydrous magnesium sulfate, filtered, and the filtrate was collected and then rotary evaporated to give the crude product. The crude product was recrystallized from methanol to give a white solid. The yield was 86.2%. The nuclear magnetic hydrogen spectrum was as follows: 1H NMR (CDCl3, 400 MHz) δ (ppm) :12.11 (s, 1H, NH), 7.13 (m, 6H, Ar-H), 4.87 (s, 1H, H β ), 3.08 (s, 4H,CHMe2), 1.72 (s, 6H, CH3), 1.21 (d, 12H, CH(CH3)2), 1.11 (d, 12H, CH(CH3)2).

[0092] Example 3 This example provides a β-diimine compound A3 substituted with 2,6-diphenylmethyl-4-methylphenyl groups, and its synthesis method was as follows:

[0093] Acetylacetone (2.0 g, 20 mmol), 2,6-diphenylmethyl-4-methylaniline (19.3 g, 44 mmol), toluene (300 mL), and p-toluenesulfonic acid (12 M, 6 mL) were sequentially placed in a round-bottom flask and heated to 120 °C in an oil bath. After 5 d of reaction, the solution was cooled to room temperature and the solvent was removed by rotary evaporation to give a brown solid. The resulting solid was dissolved in dichloromethane (300 mL), washed twice with saturated NaHCO3 solution, extracted, and the organic phase was collected. The organic phase was dried over anhydrous magnesium sulfate, filtered, and the filtrate was collected and then rotary evaporated to give the crude product. The crude product was recrystallized from methanol to give a white solid. The yield was 52.7%. The nuclear magnetic hydrogen spectrum was as follows: 1 H NMR (CDCl3, 400 MHz) δ(ppm) : 12.10 (s, NH, 1H), 7.26 (d, J = 4.3 Hz, Ar-H, 16H), 7.15 -6.95 (m, Ar-H, 24H), 6.84 (s, Ar-H, 4H), 5.94 (s, CH(Ph)2, 4H), 4.16 (s, CHNH, 1H), 2.23 (s,CH3, 6H), 0.23 (s, CH3, 6H).

[0094] Example 4 This example provides an α-sulfonic acid-β-diimine lithium salt compound L1, the synthesis method of which is as follows:

[0095] Under a nitrogen atmosphere, β-diimine compound A1 (2.88 g, 9.24 mmol) was dissolved in dry tetrahydrofuran and n-BuLi (4.3 mL, 10.75 mmol) was added dropwise at −78 °C. After stirring at −78 °C for 1 h, the resulting mixture was gradually warmed to room temperature and stirred for 30 min. The temperature was then lowered to −78 °C, and SO3.NMe3 (0.84 g, 6.04 mmol) was added. The mixture was gradually warmed to room temperature and stirred for 24 h. The solution was filtered, and the filtrate was concentrated and frozen at −30 °C to give a white precipitate. The white solid was filtered, washed twice with n-hexane, and dried in vacuo to give a white solid in 75.6% yield. The nuclear magnetic hydrogen spectrum was as follows: 1 H NMR (DMSO-d6, 400 MHz) δ (ppm):7.04-6.87 (m, 6H, Ar-H), 5.04 (s, 1H, H β ), 3.72 (m, 8H,THF), 2.08 (s, 6H, CH3), 2.05 (m, 6H, CH3),1.81 (m, 8H, THF).

[0096] Example 5 This example provides an α-sulfonic acid-β-diimine lithium salt compound L2, the synthesis method of which is as follows:

[0097] Following the synthesis method of Example 4, but replacing β-diimine compound A1 with β-diimine compound A2, a white solid was obtained. The yield was 83.7%. The nuclear magnetic hydrogen spectrum was as follows: 1 H NMR (DMSO-d6, 400 MHz) δ (ppm) :7.13-7.02 (m, 6H, Ar-H), 5.04 (s, 1H, H β), 3.72 (m, 8H, THF), 3.09 (m, 4H, CHMe2), 2.09 (s, 6H, CH3), 1.86 (m, 8H, THF), 1.15 (m, 24H, CH(CH3)2).

[0098] Example 6 This example provides an α-sulfonic acid-β-diimine lithium salt compound L3, whose synthesis method is as follows:

[0099] Following the synthesis method of Example 4, but replacing β-diimine compound A1 with β-diimine compound A3, a white solid was obtained. The yield was 72.8%. The nuclear magnetic hydrogen spectrum was as follows: 1 H NMR (DMSO-d6, 400 MHz) δ (ppm): 7.29 (d, 16H, Ar-H), 7.08-6.91 (m, 24H, Ar-H), 6.76 (s, 4H, Ar-H), 5.94 (s, 4H, CH(Ph)2), 4.58 (s, 1H, H β ), 3.72 (m, 8H,THF), 2.28 (s, 6H, CH3), 1.89 (m, 8H, THF), 0.23 (s, 6H, CH 3) .

[0100] 2. Preparation of Zwitterionic Allyl Nickel Complex Example 7 This example provides a zwitterionic allylnickel complex Ni-1, the synthesis of which was as follows.

[0101] Under a nitrogen atmosphere, α-sulfonic acid-β-diimine lithium salt compound L1 (0.97 g, 1.77 mmol), allylnickel(II) chloride dimer (0.53 g, 1.95 mmol), and dichloromethane (20 mL) were sequentially placed in a branched Schlenk bottle and stirred at room temperature for 24 hours. The filtrate obtained after filtration was concentrated and n-hexane was added to precipitate the product. The precipitate was filtered, washed twice with n-hexane, and vacuum dried to obtain a yellow powder. The yield was 81.3%. Elemental analysis (C 25H 36 N2O3SNi, %) Theoretical: C, 59.66; H, 7.21; N, 5.57. Found: C, 59.41; H, 7.08; N, 5.46. The nuclear magnetic hydrogen spectrum was as follows: 1 H NMR (CDCl3, 400 MHz) δ (ppm):6.94-6.77 (m, 6H, Ar-H), 5.48 (dt, allyl-CH , 1H), 5.31 (s, 1H, H β ), 2.08 (s, 1H, CH3), 2.05 (m, 6H, CH3), 1.96 (d, allyl-CH2, 2H). ESI-MS(m / z):444.13 [M-C3H5] + .

[0102] Example 8 This example provides a zwitterionic allylnickel complex Ni-2, the synthesis of which was as follows.

[0103] The compound L2 was obtained by reacting α-sulfonic acid-β-diimine lithium salt compound L2 with allylnickel(II) chloride dimer, and the other specific steps were the same as in Example 7. The yield was 71.8%. The single crystal structure is shown in Figure 1. Elemental analysis (C 32 H 50 N2O3SNi, %) Theoretical: C, 64.39; H, 8.52; N, 4.55. Found: C, 64.21; H, 8.44; N, 4.50. The nuclear magnetic hydrogen spectrum was as follows: 1H NMR (CDCl3, 400 MHz) δ (ppm) : 7.23 (s, Ar-H, 6H), 5.61 (dt, allyl-CH , 1H), 5.36 (s, NHCH, 1H), 3.55 (dt, CH(CH3)2, 4H), 2.19 (s, CH3, 6H), 2.01 (d, allyl-CH2, 2H), 1.46 (d, CH(CH3)2, 6H), 1.22 (d, CH(CH3)2, 12H), 1.09 (d, CH(CH3)2, 6H). ESI-MS(m / z):556.31 [M-C3H5] + .

[0104] Example 9 This example provides a zwitterionic allylnickel complex Ni-3, the synthesis of which was as follows.

[0105] The α-sulfonic acid-β-diimine lithium salt compound L3 was reacted with allylnickel(II) chloride dimer, and the other specific steps were the same as in Example 7. The yield was 68.8%. Elemental analysis (C 57 H 72 N2O3SNi, %) Theoretical: C, 79.01; H, 6.37; N, 2.46. Found: C, 78.89; H, 6.28; N, 2.33. 1 H NMR (DMSO-d6, 400 MHz) δ (ppm): 7.43 (d, 16H, Ar-H), 7.21-7.09 (m, 24H, Ar-H), 6.78 (s, 4H, Ar-H), 6.33 (s, 4H, CH(Ph)2), 5.85 (dt, allyl-CH, 1H), 4.89 (s, 1H, H β ) , 2.36(d, allyl-CH2, 2H) 2.28 (s, 6H, CH3), 0.33 (s, 6H, CH3). ESI-MS(m / z):1080.22 [M-C3H5] + .

[0106] 3. Copolymerization of ethylene with acrylate monomers In the following examples, the catalytic activity is calculated from the mass of the final copolymer obtained, the amount of metallic nickel catalyst used, and the polymerization time. The weight-average molecular weight of the produced polyolefin is measured by gel permeation chromatography, the melting point of the polymer is measured by differential scanning calorimetry, and the insertion rate of the polar monomer is calculated by nuclear magnetic hydrogen spectroscopy.

[0107] Examples 10-37 provide a method for preparing ethylene-acrylate copolymer by catalyzing the copolymerization reaction of ethylene and acrylate with nickel catalyst, and the specific reaction steps are as follows:

[0108] The autoclave was heated to 150°C and evacuated for 2 hours. After cooling to room temperature under vacuum, the autoclave was purged with ethylene three times. A certain amount of acrylate, a certain amount of activator, and 30 μmol of zwitterionic allylnickel catalyst were added to the autoclave, and finally, dry toluene was added to maintain a total volume of 40 mL. After introducing ethylene at a constant pressure, the polymerization reaction was allowed to proceed at a constant temperature for 4 hours. After the polymerization reaction reached the set time, the introduction of ethylene was stopped, the pressure was gradually released, the autoclave was opened, and the reaction system was quenched with a 5% volume fraction hydrochloric acid ethanol solution. The product was immersed in hydrochloric acid / ethanol, filtered, and washed several times with absolute ethanol. The polymer was then placed in a vacuum drying box at 60°C and dried to constant weight.

[0109] The nuclear magnetic hydrogen spectrum of the polymer sample was measured at 120°C using a Bruker Advance III 500 MHz nuclear magnetic resonance spectrometer (Bruker, USA). The deuteration reagent was deuterated o-dichlorobenzene (o-CDCl). The test sample tube was a 5 mm nuclear magnetic tube. Tetramethylsilane (TMS) was used as the internal standard. The tilt angle was 74°, the delay time was 4 s, and the sampling time was 1.5 s. The measurement method was proton decoupling.

[0110] The branching degree of the polymer sample calculated from the high-temperature hydrogen spectrum is given by the following formula:

[0111]

number

[0112] The insertion rate of methyl acrylate (MA) into the polymer is calculated by the following method. The insertion rate of the polar monomer was calculated from the ratio of the integrated areas of the nuclear magnetic hydrogen spectrum, and the calculation formula is as follows:

[0113]

number

[0114] The molecular weight (Mw) and molecular weight distribution (PDI = Mw / Mn) of the polymer were measured using high-temperature gel chromatography (GPC PL-220). The GPC PL-220 was equipped with two analytical columns (USA PLgel 10 μm MIXED-B) and a refractive index detector (RI). GPC calibration curve: Narrow-dispersion polystyrene (PS) was used as the standard. Sample test conditions: The solvent and mobile phase were 1,2,4-trichlorobenzene (with 0.125‰ of antioxidant BHT added), the test temperature was 150°C, the flow rate of the GPC mobile phase was 1.0 mL / min, and the concentration of the polymer sample was 0.5 mg / mL.

[0115] The melting point of the polymer is measured using a PerkinElmer DSC-4000 differential scanning calorimeter. Under a nitrogen atmosphere, the temperature is raised from -30°C to 200°C at a rate of 10°C / min, held at this temperature for 3 minutes, then lowered to -30°C at a rate of 10°C / min, held at this temperature for 3 minutes, and finally raised to 200°C at a rate of 10°C / min for a second heating. The melting point of the polymer is measured using the second heating curve.

[0116] Examples 10-12 provide the results of catalyzing the copolymerization of ethylene and methyl acrylate with different zwitterionic allyl nickel catalysts to produce EMA. The specific reaction conditions and polymerization results are shown in Table 1.

[0117] [Table 1]

[0118] As can be seen from Table 1, under the same polymerization conditions, Ni-2 had the highest activity and the molecular weight of the EMA copolymer was also the highest.

[0119] Examples 13-16 provide the results of catalyzing the copolymerization of ethylene and methyl acrylate with the zwitterionic allylnickel catalyst Ni-2 to produce EMA under different activator species. The specific reaction conditions and polymerization results are shown in Table 2.

[0120] The nuclear magnetic hydrogen spectrum of the ethylene-methyl acrylate (EMA) obtained in Example 11 is shown in FIG. 2, and the DSC analysis diagram is shown in FIG.

[0121] [Table 2]

[0122] Examples 17-21 provide the results of catalyzing the copolymerization of ethylene and methyl acrylate with the zwitterionic allylnickel catalyst Ni-2 at different activator / Ni ratios to produce EMA. The specific reaction conditions and polymerization results are shown in Table 3.

[0123] [Table 3]

[0124] Examples 22 and 23 provide the results of catalyzing the copolymerization of ethylene and methyl acrylate with the zwitterionic allylnickel catalyst Ni-2 at different MA monomer concentrations (MA / Ni) to produce EMA. The specific reaction conditions and polymerization results are shown in Table 4.

[0125] [Table 4]

[0126] Examples 24-27 provide the results of catalyzing the copolymerization of ethylene and methyl acrylate with the zwitterionic allyl nickel catalyst Ni-2 at different temperatures to produce EMA. The specific reaction conditions and polymerization results are shown in Table 5.

[0127] [Table 5]

[0128] Examples 28-31 provide the results of catalyzing the copolymerization of ethylene and methyl acrylate with the zwitterionic allylnickel catalyst Ni-2 under different ethylene pressures to produce EMA. The specific reaction conditions and polymerization results are shown in Table 6.

[0129] [Table 6]

[0130] Examples 32-34 provide the results of catalyzing the copolymerization of ethylene and methyl acrylate with the zwitterionic allyl nickel catalyst Ni-2 in different solvents to produce EMA. The specific reaction conditions and polymerization results are shown in Table 7.

[0131] [Table 7]

[0132] Examples 35-37 provide results of catalyzing the copolymerization of ethylene with different acrylate monomers using the zwitterionic allylnickel catalyst Ni-2. The specific reaction conditions and polymerization results are shown in Table 8.

[0133] [Table 8]

[0134] To more clearly demonstrate the beneficial effects of the catalyst of the present invention, copolymerization of ethylene was catalyzed by a structurally similar β-diimine nickel catalyst (Ni-0) as a comparative example. The β-diimine nickel was synthesized according to the method reported in Organometallics 1997, 16, 1514, and its structure is as follows:

[0135] [ka]

[0136] The synthesis method was as follows. (1) The preparation of the β-diimine compound was the same as in Example 2. Acetylacetone (4.1 g, 41 mmol), 2,6-diisopropylaniline (10.3 g, 85.2 mmol), ethanol (500 mL), and hydrochloric acid (12 M, 6 mL) were sequentially placed in a round-bottom flask. The system was heated to 100 °C in an oil bath and reacted for 72 h. After cooling to room temperature, the solvent was removed by rotary evaporation to obtain a brown solid. The resulting solid was dissolved in dichloromethane (300 mL), washed twice with saturated NaHCO3 solution, extracted, and the organic phase was collected. The organic phase was dried over anhydrous magnesium sulfate, filtered, and the filtrate was collected. The filtrate was then rotary evaporated to obtain the crude product. The crude product was recrystallized from methanol to obtain a white solid. The yield was 86.2%. The nuclear magnetic hydrogen spectrum was as follows: 1H NMR (CDCl3, 400 MHz) δ (ppm) :12.11 (s, 1H, NH), 7.13 (m, 6H, Ar-H), 4.87 (s, 1H, H β ), 3.08 (s, 4H,CHMe2), 1.72 (s, 6H, CH3), 1.21 (d, 12H, CH(CH3)2), 1.11 (d, 12H, CH(CH3)2); (2) Preparation of β-diimine nickel bromide. Under a nitrogen atmosphere, the β-diimine (1.77 mmol) obtained in step (1), nickel(II) bromide (1.95 mmol), and dichloromethane (20 mL) were sequentially placed in a branched Schlenk flask and stirred at room temperature for 24 hours. The filtrate obtained after filtration was concentrated, and n-hexane was added to precipitate the product. The precipitate was filtered, washed twice with n-hexane, and dried in vacuo to obtain the desired product.

[0137] Comparative Example 1 In this comparative example, ethylene monomer and methyl acrylate were copolymerized using 30 μmol of β-diimine nickel catalyst Ni-0 instead of the zwitterionic allyl nickel catalyst Ni-2. The polymerization method was the same as the copolymerization reaction of ethylene and methyl acrylate in Example 11. No solid polymer was obtained in this polymerization. In this comparative example, the copolymerization activity of β-diimine nickel was zero, and no ethylene-methyl acrylate copolymer was synthesized.

[0138] A comparison of the copolymerization results of Example 11 and Comparative Example 1 is specifically shown in Table 9.

[0139] [Table 9]

[0140] Compared to the examples, the β-diimine nickel catalyst Ni-0 has no polymerization activity for the copolymerization of ethylene and MA. In contrast, the zwitterionic allyl nickel catalyst has a weak interaction between the sulfonate and the metal center, which effectively controls and modifies the electrophilicity of the metal center and significantly improves the tolerance to polar monomers, allowing it to effectively catalyze the copolymerization of ethylene and acrylate monomers.

[0141] It goes without saying that the above-mentioned embodiments of the present invention are merely examples for clarifying the present invention and are not intended to limit the embodiments of the present invention. In addition to the above description, those skilled in the art can realize various changes or variations in other forms, and it is not possible to cover all embodiments here, and obvious changes or variations based on the technical solutions of the present invention are within the protection scope of the present invention.

Claims

1. A zwitterionic allylnickel complex having the structure shown in Formula I: 【Chemistry 1】 In Formula I, R 1 and R 1 ' are the same or different, and each independently, C 1 -C 4 Alkyl groups of C 6 -C 15 and R 2 is H, C 1 -C 6 The alkyl group is selected from the group consisting of:

2. In Formula I, R 1 and R 1 R ' may be the same or different and are each independently selected from a methyl group, an isopropyl group, and a diphenylmethyl group; 2 2. The zwitterionic allylnickel complex according to claim 1, wherein is selected from hydrogen and a methyl group.

3. In Formula I, R 1 and R 1 3. The zwitterionic allylnickel complex of claim 2, wherein ' are identical.

4. In Formula I, R 1 and R 1 ' are both methyl groups, and R 2 is hydrogen, or R 1 and R 1 ' are both isopropyl groups, and R 2 is hydrogen, or R 1 and R 1 ' are both diphenylmethyl groups, and R 2 The zwitterionic allylnickel complex according to claim 3, wherein is a methyl group.

5. A method for producing the zwitterionic allylnickel complex according to any one of claims 1 to 4, comprising the following steps: The α-sulfonic acid-β-diimine lithium salt compound and the allylnickel precursor are mixed and reacted to obtain the amphoteric ion type allylnickel complex through the following reaction process. 【Chemistry 2】

6. A catalyst system comprising a main catalyst comprising the zwitterionic allylnickel complex according to any one of claims 1 to 4 and an activator.

7. 7. The catalyst system of claim 6, wherein the molar ratio of the main catalyst to the activator is 1:5 to 1:

100.

8. 7. The catalyst system of claim 6, wherein the activator comprises one or a combination of two or more of methylaluminoxane, modified methylaluminoxane, monochlorodiethylaluminum, dichloroethylaluminum, triisobutylaluminum, and tri(pentafluorophenyl)borane.

9. A method for copolymerizing ethylene with an acrylate, comprising the steps of: The amphoteric ionic allylnickel complex according to any one of claims 1 to 4 or the catalyst system according to any one of claims 6 to 8 is used to catalyze the copolymerization reaction of ethylene with an acrylate to obtain a branched ethylene-acrylate copolymer.

10. 10. The copolymerization method according to claim 9, wherein the acrylate comprises one or a combination of two or more of methyl acrylate, ethyl acrylate, butyl acrylate, and t-butyl acrylate.

11. 10. The copolymerization method according to claim 9, wherein the polymerization temperature is 0°C to 100°C.

12. 10. The copolymerization method according to claim 9, wherein in the catalyst system, the molar ratio of the main catalyst to the acrylate is 1:266 to 1:1066.

13. 10. The copolymerization method according to claim 9, wherein the ethylene pressure is 0.1 MPa to 5.0 MPa.

14. 10. The copolymerization method according to claim 9, wherein the solvent used in the polymerization comprises one or a combination of two or more of toluene, hexane, cyclohexane, and heptane.

15. An ethylene-acrylate copolymer produced by the copolymerization method according to any one of claims 9 to 14, wherein the branching degree is 28 / 1000C to 46 / 1000C and the melting temperature is 84.6°C to 108.3°C.

16. The weight average molecular weight of the ethylene-acrylate copolymer is 1×10 5 g / mol to 1×10 6 g / mol, a molecular weight distribution of 1.31 to 2.33, an acrylate content of the ethylene-acrylate copolymer of 3.50 mol% to 8.99 mol%, an alkyl group branch content of 30 / 1000°C to 40 / 1000°C, and a melting temperature of the ethylene-acrylate copolymer of 84.6°C to 98.3°C.

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