Phosphorus-phenol ligand, phosphorus-phenol complex, preparation method and application of phosphorus-phenol ligand and phosphorus-phenol complex, and ethylene polymerization method

Abstract

The invention belongs to the field of ethylene polymerization, and particularly relates to a phosphorus-phenol ligand, a phosphorus-phenol complex, a preparation method and application of the phosphorus-phenol ligand and the phosphorus-phenol complex, and an ethylene polymerization method. The invention provides a phosphorus-phenol ligand and a phosphorus-phenol complex which respectively have chemical structures as shown in a formula I and a formula II. When the phosphorus-phenol complex provided by the invention is used for catalytic polymerization of ethylene, electron-rich phosphorus and pyridine are mutually reversed, so that separation of pyridine can be promoted, coordination of an ethylene monomer and a metal center is facilitated, and the phosphorus-phenol complex has higher activity; the invention further provides an ethylene polymerization method, ethylene polymerization can be initiated by adopting the single-component catalyst provided by the invention, and linear high molecular weight polyethylene is obtained; meanwhile, ethylene polymerization can be successfully initiated in traditional organic solvents such as methylbenzene and heptane and biomass organic solvents such as dimethyl carbonate, methyl tetrahydrofuran and dimethyl succinate. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the field of ethylene polymerization, and particularly relates to a phosphophenol ligand, a phosphophenol complex, a preparation method and application thereof, and an ethylene polymerization method. Background Art

[0002] Polyethylene (PE) is the most widely used synthetic polymer material. Due to its good mechanical properties, light weight, easy processing and low production cost, polyethylene and its composites have been applied in many fields such as automobiles, packaging, medical devices and electronics. Various application scenarios of polyethylene materials have put forward different requirements for their performance and preparation processes. In order to achieve the efficient preparation of polyethylene and make it meet the usage standards in various fields, scientific researchers have carried out continuous and in-depth research in catalyst design, polymer structure regulation and post-modification. During the ethylene polymerization process, non-polar reagents such as toluene and hexane are usually selected as reaction solvents. However, these traditional organic solvents are volatile, highly flammable and neurotoxic, which will cause harm to the environment and human body. Out of concern for the concept of sustainable polymerization, the problem of using a large amount of traditional organic solvents in the polymerization process cannot be ignored.

[0003] Green solvents refer to solvents that have a minimum toxicity to human health and the environment and will not cause environmental pollution due to different treatment methods. Green solvents have the characteristics of being renewable, recyclable, easily biodegradable, low-toxic, cheap and easily available, and are ideal choices to replace traditional organic solvents. At present, olefin polymerization has been achieved in supercritical carbon dioxide, water, ionic liquids, deep eutectic solvents and polar solvents (such as tetrahydrofuran, diethyl ether and 1,4-dioxane) through free radical initiators, anionic initiators or homogeneous catalysts. These experiments of successfully polymerizing olefins in green solvents have pointed the way for future ethylene polymerization in biomass solvents such as methyltetrahydrofuran (2-MeTHF), dimethyl succinate (DMS) and dimethyl carbonate (DMC).

[0004] The catalysts for coordination polymerization are usually transition metal complexes. According to the coordination-insertion mechanism of ethylene polymerization, the main challenge faced in the polymerization process using biomass solvents is that the oxygen atoms in the solvents have a strong coordination tendency to the metal cation centers. Especially for transition metals with strong Lewis acidity, trace amounts of oxygen in the polymerization system will poison the transition metals, thereby inhibiting the coordination and insertion of ethylene monomers, and there is a defect that the activity of the catalyst in biomass solvents is low. Summary of the Invention

[0005] The purpose of the present invention is to provide a phosphophenol ligand, a phosphophenol complex, a preparation method and application thereof, and an ethylene polymerization method. When the phosphophenol complex prepared by the phosphophenol ligand of the present invention is used to catalyze ethylene polymerization, the catalyst has high activity during homopolymerization and can catalyze the production of linear high-molecular-weight polyethylene.

[0006] To achieve the object of the present invention, the present invention provides the following technical solutions:

[0007] A phosphorus phenol ligand, having the chemical structure shown in Formula I:

[0008]

[0009] In Formula I, Ar is a nitrogen-containing heterocyclic group; R 1 is one of hydrogen, fluorine, an alkyl group with 1 to 4 carbon atoms, and a substituted phenyl group; R 2 is hydrogen, fluorine, or a fluorinated alkyl group with 1 to 3 carbon atoms.

[0010] Preferably, the alkyl group with 1 to 4 carbon atoms includes one of methyl, ethyl, isopropyl, n-propyl, tert-butyl, sec-butyl, isobutyl, and n-butyl;

[0011] The substituted phenyl group includes pentafluorophenyl, mesityl oxide phenyl, 2,6-difluorophenyl, p-fluorophenyl, m-fluorophenyl, o-fluorophenyl, 3,4,5-trifluorophenyl, 3,5-difluorophenyl, 2,6-dimethylphenyl, mesityl oxide methyl phenyl, and 2,6-diisopropylphenyl;

[0012] The fluorinated alkyl group with 1 to 3 carbon atoms includes one of trifluoromethyl, perfluoroethyl, perfluoro-n-propyl, and perfluoro-isopropyl.

[0013] Preferably, the Ar includes one of imidazole groups, pyrazole groups, pyrrole groups, thiazole groups, and oxazole groups.

[0014] Preferably, the imidazole in the imidazole group includes one of 1-phenylimidazole, 1-(2,6-dimethoxyphenyl)-imidazole, 1-(2,4,6-trimethoxyphenyl)-imidazole, 1-(2,4,6-trimethylphenyl)-imidazole, 1-(2,6-dimethylphenyl)-imidazole, 1-(2,6-diisopropoxyphenyl)-imidazole, 1-(2,6-dicyclohexyloxyphenyl)-imidazole, 1-(2,6-bis(dimethylamino)phenyl)-imidazole, and 2-phenylimidazole;

[0015] The pyrazole in the pyrazole group includes one of 1-phenylpyrazole, 1-(2,6-dimethoxyphenyl)-pyrazole, 1-(2,4,6-trimethoxyphenyl)-pyrazole, 1-(2,4,6-trimethylphenyl)-pyrazole, 1-(2,6-dimethylphenyl)-pyrazole, 1-(2,6-diisopropoxyphenyl)-pyrazole, 1-(2,6-dicyclohexyloxyphenyl)-pyrazole, 1-(2,6-bis(dimethylamino)phenyl)-pyrazole, and 3-phenylpyrazole;

[0016] The pyrrole in the pyrrole group includes one of 1-phenylpyrrole, 1-(2,6-dimethoxyphenyl)-pyrrole, 1-(2,4,6-trimethoxyphenyl)-pyrrole, 1-(2,4,6-trimethylphenyl)-pyrrole, 1-(2,6-dimethylphenyl)-pyrrole, 1-(2,6-diisopropoxyphenyl)-pyrrole, 1-(2,6-dicyclohexyloxyphenyl)-pyrrole, 1-(2,6-bis(dimethylamino)phenyl)-pyrrole, and N-methylpyrrole;

[0017] The thiazole in the thiazole group is 4-phenylthiazole;

[0018] The oxazole in the oxazole group is 4-phenyloxazole.

[0019] The present invention also provides a preparation method of the phosphophenol ligand described in the above technical solution, including the following steps:

[0020] Mix a phenol compound and 3,4-dihydro-2H-pyran, and perform hydroxy protection to obtain a compound 1 containing a tetrahydropyranyl group;

[0021] Mix the compound 1 and n-BuLi, and perform lithiation reaction to obtain an aryllithium compound 2;

[0022] Mix PhPCl 2 and the aryllithium compound 2, and perform a nucleophilic substitution reaction to obtain a monochlorophosphorus suspension 3;

[0023] Mix a nitrogen-containing heterocyclic compound and n-BuLi, and perform lithiation reaction to obtain a nitrogen heterocyclic lithiation reaction solution 4 containing a carbanion;

[0024] Mix the monochlorophosphorus suspension 3 and the nitrogen heterocyclic lithiation reaction solution 4, and perform a nucleophilic substitution reaction to obtain a phosphophenol intermediate 5 containing a tetrahydropyranyl group;

[0025] After removing the phenolic protecting group from the phosphophenol intermediate 5, the phosphophenol ligand is obtained;

[0026] When R 1 is pentafluorophenyl, mix the phosphophenol intermediate 5 with R 1 being hydrogen and n-BuLi, and perform lithiation reaction to obtain a compound 6;

[0027] Mix the compound 6 and hexafluorobenzene, and successively perform a substitution reaction and remove the phenolic protecting group to obtain a phosphophenol ligand with R 1 being pentafluorophenyl.

[0028] The present invention provides a phosphophenol complex with the chemical structure shown in Formula II specifically:

[0029]

[0030] In formula II, Ar is a nitrogen-containing heterocyclic group; R 1 is one of hydrogen, fluorine, an alkyl group having 1 to 4 carbon atoms, and a substituted phenyl group; R 2 is hydrogen, fluorine, or a fluorinated alkyl group having 1 to 3 carbon atoms; M is Ni or Pd.

[0031] The present invention provides a method for preparing the phosphine-phenol complex described in the above technical solution, including the following steps;

[0032] Mix the phosphine-phenol ligand described in the above technical solution or the phosphine-phenol ligand prepared by the preparation method described in the above technical solution, pyridine, and an alkyl nickel or alkyl palladium solution, and carry out an alkyl elimination reaction to obtain the phosphine-phenol complex.

[0033] Preferably, the molar ratio of the phosphine-phenol ligand to pyridine is 1:1.1 to 30;

[0034] The molar ratio of the phosphine-phenol ligand to alkyl nickel or alkyl palladium is 1:1.05 to 1.5.

[0035] The present invention also provides the application of the phosphine-phenol complex described in the above technical solution in the catalytic polymerization of ethylene.

[0036] The present invention also provides a method for polymerizing ethylene, including the following steps; Mix ethylene, a catalyst, and an organic solvent, and carry out polymerization to obtain polyethylene;

[0037] The catalyst is the phosphine-phenol complex described in the above technical solution; the organic solvent includes toluene, hexane, n-heptane, and a biomass solvent; the biomass solvent is dimethyl carbonate, methyltetrahydrofuran, and dimethyl succinate.

[0038] The present invention provides a phosphine-phenol ligand and a phosphine-phenol complex, which have the chemical structures shown in formula I and formula II respectively. When the phosphine-phenol complex provided by the present invention is used for the polymerization of ethylene, the electron-rich phosphorus and pyridine are in the trans position to each other, which can promote the departure of pyridine, is beneficial to the coordination of ethylene monomers with the metal center, and has higher activity; when the phosphine-phenol complex provided by the present invention is used for the polymerization of ethylene, the electron cloud density of the phosphorus ligand at the para position of pyridine can be changed by regulating the structure of the nitrogen-containing heterocycle. The electron-donating nitrogen-containing heterocycle makes the phosphine-phenol ligand richer in electrons, the electron cloud density of the P-M bond increases, and the electron cloud density of the M-Py bond relatively weakens, which is beneficial to the departure of pyridine and the coordination of ethylene. The better the electron-donating ability of the nitrogen-containing heterocycle, the faster the pyridine leaving rate, and the higher the activity of the phosphine-phenol complex in initiating olefin polymerization.

[0039] The present invention also provides a method for ethylene polymerization. The single-component catalyst provided by the present invention can initiate ethylene polymerization to obtain linear high-molecular-weight polyethylene, which provides an idea for the preparation of high-molecular-weight polyethylene. At the same time, the present invention can successfully initiate ethylene polymerization in biomass organic solvents such as dimethyl carbonate, methyltetrahydrofuran, and dimethyl succinate, and the catalytic activity in dimethyl carbonate can reach 2.7×10 7 g PE ·mol Ni -1 · h -1 , with relatively high activity, and the molecular weight of the prepared polyethylene can reach 3.7×10 5 g·mol -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0041] Figure 1 In the present invention, when Ar = 1-phenylimidazole, R 1 = tert-butyl, R 2 = H, the molecular crystal structure diagram of the nickel phosphophenolate complex (Application Example 1);

[0042] Figure 2 In the present invention, when Ar = 1-(2,4,6-trimethoxyphenyl)-imidazole, R 1 = tert-butyl, R 2 = H, the molecular crystal structure diagram of the nickel phosphophenolate complex;

[0043] Figure 3 In the present invention, when Ar = 1-(2,4,6-trimethylphenyl)-imidazole, R 1 = tert-butyl, R 2 = H, the molecular crystal structure diagram of the nickel phosphophenolate complex;

[0044] Figure 4 In the present invention, when Ar = 1-phenylpyrazole, R 1 = tert-butyl, R 2 = H, the molecular crystal structure diagram of the nickel phosphophenolate complex (Application Examples 2, 4, and 5);

[0045] Figure 5 In the present invention, when Ar = 1-phenylpyrrole, R 1 = tert-butyl, R 2When = H, crystal structure diagram of nickel phosphophenolate complex molecule;

[0046] Figure 6 In the present invention, Ar = 1-(2,6-dimethoxyphenyl)-pyrrole, R 1 = tert-butyl, R 2 When = H, crystal structure diagram of nickel phosphophenolate complex (Application Example 3) molecule;

[0047] Figure 7 In the present invention, Ar = 1-(2,6-dimethoxyphenyl)-pyrrole, R 1 = pentafluorophenyl, R 2 = trifluoromethyl, crystal structure diagram of nickel phosphophenolate complex (Examples 5 and Application Example 6) molecule;

[0048] Figure 8 In the present invention, Ar = 1-phenylpyrazole, R 1 = tert-butyl, R 2 When = H, crystal structure diagram of palladium phosphophenolate complex (Example 6) molecule;

[0049] Figure 9 In the present invention, Ar = 1-phenylpyrrole, R 1 = tert-butyl, R 2 When = H, crystal structure diagram of palladium phosphophenolate complex (Application Example 7) molecule;

[0050] Figure 10 In the present invention, Ar = 1-(2,6-dimethoxyphenyl)-pyrrole, R 1 = tert-butyl, R 2 When = H, crystal structure diagram of palladium phosphophenolate complex molecule;

[0051] Figure 11 Linear polyethylene with a linear structure in Application Example 2 of the present invention 13 13C NMR spectrum;

[0052] Figure 12 Molecular weight distribution diagram of linear polyethylene in Application Example 4 of the present invention. Detailed implementation mode

[0053] The present invention provides a phosphophenol ligand with the chemical structure shown in Formula I specifically:

[0054]

[0055] In Formula I, Ar is a nitrogen-containing heterocyclic group; R 1 is one of hydrogen, fluorine, an alkyl group with 1 to 4 carbon atoms, and a substituted phenyl group; R 2 is hydrogen, fluorine, or a fluorinated alkyl group with 1 to 3 carbon atoms.

[0056] In the present invention, the alkyl group having 1 to 4 carbon atoms includes one of methyl, ethyl, isopropyl, n-propyl, tert-butyl, sec-butyl, isobutyl, and n-butyl; the substituted phenyl group includes pentafluorophenyl, mesityl trifluoride, 2,6-difluorophenyl, p-fluorophenyl, m-fluorophenyl, o-fluorophenyl, 3,4,5-trifluorophenyl, 3,5-difluorophenyl, 2,6-dimethylphenyl, mesityl trimethyl, and 2,6-diisopropylphenyl; the alkyl group having 1 to 3 fluorinated carbon atoms is one of trifluoromethyl, perfluoroethyl, perfluoro-n-propyl, and perfluoro-isopropyl.

[0057] The present invention also provides a preparation method of the phosphine phenol ligand described in the above technical solution, including the following steps:

[0058] Mix a phenol compound and 3,4-dihydro-2H-pyran, and perform hydroxyl protection to obtain a compound 1 containing a tetrahydropyranyl group;

[0059] Mix the compound 1 and n-BuLi, and perform lithiation reaction to obtain an aryllithium compound 2;

[0060] Mix PhPCl 2 and the aryllithium compound 2, and perform a nucleophilic substitution reaction to obtain a monochlorophosphorus suspension 3;

[0061] Mix a nitrogen-containing heterocyclic compound and n-BuLi, and perform lithiation reaction to obtain a nitrogen heterocyclic lithiation reaction solution 4 containing a carbanion;

[0062] Mix the monochlorophosphorus suspension 3 and the nitrogen heterocyclic lithiation reaction solution 4, and perform a nucleophilic substitution reaction to obtain a phosphine phenol intermediate 5 containing a tetrahydropyranyl group;

[0063] After removing the phenolic protecting group from the phosphine phenol intermediate 5, the phosphine phenol ligand is obtained;

[0064] When R 1 is pentafluorophenyl, mix the phosphine phenol intermediate 5 with R 1 being hydrogen and n-BuLi, and perform lithiation reaction to obtain a compound 6;

[0065] Mix the compound 6 and hexafluorobenzene, and after performing a substitution reaction and removing the phenolic protecting group in sequence, a phosphine phenol ligand with R 1 being pentafluorophenyl is obtained. In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well-known to those skilled in the art or are prepared by preparation methods well-known to those skilled in the art.

[0066] The present invention mixes a phenol compound and 3,4-dihydro-2H-pyran for hydroxyl protection to obtain a compound 1 containing a tetrahydropyranyl group. In the present invention, the phenol compounds include o-tert-butylphenol, o-sec-butylphenol, o-isobutylphenol, o-n-butylphenol, o-isopropylphenol, o-n-propylphenol, o-ethylphenol, o-methylphenol or phenol; p-trifluoromethylphenol, 4-perfluoroethylphenol, 4-perfluoropropylphenol, 4-perfluoroisopropylphenol, 2-(2’,4’,6’-trifluorophenyl)-phenol, 2-(2’,6’-difluorophenyl)-phenol, 2-(4’-fluorophenyl)-phenol, 2-(3’-fluorophenyl)-phenol, 2-(2’-fluorophenyl)-phenol, 2-(3’,4’,5’-trifluorophenyl)-phenol, 2-(3’,5’-difluorophenyl)-phenol, 2-(2’,6’-dimethylphenyl)-phenol, 2-(2’,4’,6’-trimethylphenyl)-phenol, 2-(2’,6’-diisopropylphenyl)-phenol; the phenol compounds containing an R 1 group and 3,4-dihydro-2H-pyran have a molar ratio of 1:1 to 3, and in a specific embodiment, it can be 1:1.5. In the present invention, it also includes mixing the phenol compounds containing an R 1 group, 3,4-dihydro-2H-pyran and concentrated hydrochloric acid; the temperature of the mixing is -20 to 0 °C, and in a specific embodiment, it can be -10 °C, and the mixing is carried out in an ice-salt bath; the reaction temperature for hydroxyl protection is room temperature, and the time is 8 to 20 h, and in a specific embodiment, it can be 12 h; after the hydroxyl protection reaction, it also includes purifying the obtained product, and the purification method is column chromatography.

[0067] In the present invention, when the phenol compound is o-tert-butylphenol, the hydroxyl protection process is as follows:

[0068]

[0069] When the phenol compound is p-trifluoromethylphenol, the hydroxyl protection process is as follows:

[0070]

[0071] After obtaining the compound 1 containing a tetrahydropyran group, the present invention mixes the compound 1 with n-BuLi to carry out a lithiation reaction to obtain an aryllithium compound 2. In the present invention, the compound 1 is used in the form of an ether solution of the compound 1, and the concentration of the compound 1 is 0.4 to 1.5 mmol / mL. In a specific embodiment, it can be 0.6 mmol / mL; the n-BuLi is a hexane solution of n-BuLi with a concentration of 1.6 to 2.7 M. In a specific embodiment, it can be 2.5 M; the molar ratio of the compound 1 to n-BuLi is 1:1 to 1.3. In a specific embodiment, it can be 1:1.1. In the present invention, the mixing is carried out in a low-temperature ice bath; the temperature of the lithiation reaction is room temperature, and the time is 2 to 8 h. In a specific embodiment, it can be 2 h.

[0072] In the present invention, when the phenol compound is o-tert-butylphenol, the lithiation reaction process is as follows:

[0073]

[0074] When the phenol compound is p-trifluoromethylphenol, the lithiation reaction process is as follows:

[0075]

[0076] After obtaining the aryllithium compound 2, the present invention mixes PhPCl 2 with the compound 2 to carry out a nucleophilic substitution reaction to obtain a monochlorophosphorus suspension 3. In the present invention, PhPCl 2 is used in the form of an ether solution of PhPCl 2 , and the concentration of the PhPCl 2 is 1 to 5 mmol / mL. In a specific embodiment, it can be 1.6 mmol / mL; the molar ratio of the aryllithium compound 2 to PhPCl 2 is 1:1.1 to 1.3. In a specific embodiment, it can be 1:1.1. In the present invention, the temperature of the mixing is -80 to -75 °C. In a specific embodiment, it can be -78 °C; the temperature of the nucleophilic substitution reaction is room temperature, and the time is 6 to 24 h. In a specific embodiment, it can be 8 h; the mixing and the nucleophilic substitution reaction are carried out under a nitrogen atmosphere.

[0077] In the present invention, when the phenol compounds are o-tert-butylphenol and p-trifluoromethylphenol respectively, the nucleophilic substitution reaction process is as follows:

[0078]

[0079] In the present invention, a nitrogen-containing heterocyclic compound and n-BuLi are mixed to carry out a lithiation reaction, obtaining a nitrogen heterocyclic lithiation reaction solution 4 containing carbanions. In the present invention, the nitrogen-containing heterocyclic compound is used in the form of a nitrogen-containing heterocyclic compound solution, the solvent is tetrahydrofuran, the concentration is 0.4 - 1.5 mmol / mL, and in a specific embodiment, it can be 0.6 mmol / mL; the n-BuLi is the same as the above-mentioned n-BuLi; the molar ratio of the nitrogen-containing heterocyclic compound to n-BuLi is 1:1 - 1.3, and in a specific embodiment, it can be 1.0:1.1; the temperature of the lithiation reaction is from room temperature to 55 °C, and the time is 2 - 4 h.

[0080] In the present invention, the monochlorophosphorus suspension 3 and the nitrogen heterocyclic lithiation reaction solution 4 are mixed to carry out a nucleophilic substitution reaction, obtaining a phosphine phenol intermediate 5 containing a tetrahydropyran group. In the present invention, the mixing is carried out under ice bath conditions; the temperature of the nucleophilic substitution reaction is room temperature, and the time is 8 - 24 h; the nucleophilic substitution reaction further includes drying and purifying the obtained reaction product; the drying is carried out by rotary evaporation; the purification is column chromatography.

[0081] In the present invention, when the phenol compound is o-tert-butylphenol and p-trifluoromethylphenol respectively, the lithiation reaction and the nucleophilic substitution reaction are as follows:

[0082]

[0083]

[0084] In the present invention, after removing the phenolic protecting group from the phosphine phenol intermediate 5, the phosphine phenol ligand is obtained. The removal of the phenolic protecting group includes: adding an ethyl acetate solvent and dropping concentrated hydrochloric acid for removal; after quenching the reaction, extracting the organic phase, drying, filtering, concentrating and purifying are carried out in sequence to obtain the phosphine phenol ligand. In the present invention, the reagent used for quenching the reaction is saturated NaHCO 3 aqueous solution; the reagent used for drying is anhydrous Na 2 SO 4 ; the present invention has no special limitation on drying, filtering and concentrating, and the methods well-known to those skilled in the art can be adopted.

[0085] In the present invention, when R 1 is tert-butyl, the process of removing the phenolic protecting group is as follows:

[0086]

[0087] In the present invention, when R 1 is pentafluorophenyl, the R 1The phosphine phenol intermediate for hydrogen is mixed with n-BuLi to carry out a lithiation reaction to obtain Compound 6; Compound 6 is mixed with hexafluorobenzene to carry out a substitution reaction, and after removing the protecting group of the phenol, R is obtained. 1 The phosphine phenol ligand for the pentafluorophenyl group. The R 1 The phosphine phenol intermediate for hydrogen is used in the form of a phosphine phenol intermediate solution, the solvent is tetrahydrofuran, and the concentration is 0.4 - 1.5 mmol / mL; the R 1 The molar ratio of the phosphine phenol intermediate for hydrogen to n-BuLi is 1:1 - 1.3. In a specific embodiment, it can be 1.0:1.1; the R 1 The molar ratio of the phosphine phenol intermediate 5 for hydrogen to hexafluorobenzene is 1:1 - 10. In a specific embodiment, it can be 1.0:5.0. In the present invention, the R 1 The mixing of the phosphine phenol intermediate for hydrogen and n-BuLi is carried out under an ice bath condition; the temperature of the lithiation reaction is room temperature, and the time is 2 - 4 h; the mixing temperature of Compound 6 and hexafluorobenzene is -80 - -75 °C; the temperature of the substitution reaction is room temperature, and the time is 8 - 24 h; the method for removing the protecting group of the phenol is the same as the above method for removing the protecting group of the phenol, and will not be elaborated here.

[0088] In the present invention, when R 1 is the pentafluorophenyl group, the processes of the lithiation reaction, substitution reaction, and removal of the protecting group of the phenol are as follows:

[0089]

[0090] The present invention also provides a phosphine phenol complex with the chemical structure shown in Specific Formula II:

[0091]

[0092] In Formula II, Ar is a nitrogen-containing heterocyclic group; R 1 is one of hydrogen, fluorine, an alkyl group with 1 - 4 carbon atoms, and a substituted phenyl group; R 2 is hydrogen, fluorine, or a fluorinated alkyl group with 1 - 3 carbon atoms; M is Ni or Pd.

[0093] In the present invention, the phosphine phenol complex has the following chemical structure:

[0094]

[0095]

[0096]

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104] The present invention also provides a preparation method of the phosphine phenol complex described in the above technical solution, including the following steps;

[0105] Mix a phosphine phenol ligand, pyridine, and an alkyl nickel or alkyl palladium solution, and carry out an alkyl elimination reaction to obtain the phosphine phenol complex.

[0106] In the present invention, the alkyl nickel solution is (TMEDA)NiMe 2 or [(CH 3 ) 3 SiCH 2 ) 2 Ni(pyridine) 2 , and the alkyl palladium solution is (TMEDA)PdMe 2 .

[0107] In the present invention, the solvent used for preparing the alkyl nickel or alkyl palladium solution is diethyl ether, the solvent for dissolving the residue is benzene, and the temperature during preparation is room temperature; the molar ratio of the phosphine phenol ligand to pyridine is 1:1.1 to 30, and in specific embodiments, it can be 1:5, 1:10, 1:15, or 1:25; the molar ratio of the phosphine phenol ligand to alkyl nickel or alkyl palladium is 1:1.05 to 1.5, and in specific embodiments, it can be 1:1.1. In the present invention, the temperature of the alkyl elimination reaction is room temperature, and the time is 2 to 4 h.

[0108] In the present invention, the preparation process of the phosphine phenol complex is as follows:

[0109]

[0110] The present invention also provides a method for ethylene polymerization, including the following steps; Mix ethylene, a catalyst, and an organic solvent, and carry out polymerization to obtain polyethylene;

[0111] The catalyst is the phosphine phenol complex described in the above technical solution; the organic solvents include toluene, hexane, n-heptane, and biomass solvents; the biomass solvents are dimethyl carbonate, methyltetrahydrofuran, and dimethyl succinate.

[0112] In the present invention, the dosage of the catalyst is 5 - 100 μmol / L, and in a specific embodiment, it can be 10 μmol / L; the temperature of the polymerization is 30 - 90 °C, and in a specific embodiment, it can be 30 °C, 50 °C or 70 °C; the time of the polymerization is 20 - 240 min, and in a specific embodiment, it can be 20 min, 60 min or 120 min; the ethylene pressure is 5 - 40 bar, and in a specific embodiment, it can be 5 bar, 10 bar, 15 bar, 20 bar or 40 bar; the polymerization further includes precipitating the obtained product, and the reagent used for precipitation is methanol and / or ethanol.

[0113] To further illustrate the present invention, the phosphophenol ligand, phosphophenol complex, their preparation methods and applications, and the ethylene polymerization method provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0114] Example 1

[0115] Ar = 1 - phenylimidazole, R 1 = tert - butyl, R 2 = H, the structural formula of the phosphophenol ligand is as follows:

[0116]

[0117] The specific synthesis steps of the phosphophenol ligand are as follows:

[0118] In an air atmosphere, o - tert - butylphenol (15.1 g, 0.1 mol, 1.0 equiv) and 3,4 - dihydro - 2H - pyran (12.7 g, 0.15 mol, 1.5 equiv) are mixed and stirred. The reaction flask is placed in an ice - salt bath at - 10 °C, and two drops of concentrated hydrochloric acid are added to gradually restore the reaction to room temperature. After 12 h, the compound 1 with a tetrahydropyran group is obtained by column chromatography;

[0119] Take the product compound 1 (2.34 g, 10 mmol, 1.0 equiv) in a reaction tube. Under a nitrogen atmosphere, 15 mL of ether is added, and after placing it in an ice bath, n - BuLi (2.5 M hexane solution, 4.4 mL, 11 mmol, 1.1 equiv) is added dropwise. After the addition is completed, the reaction solution is gradually restored to room temperature and reacted for 2 h to obtain a milky white suspension of compound 2;

[0120] Take a new reaction tube. Under a nitrogen atmosphere, PhPCl 2(1.97 g, 11 mmol, 1.1 equiv) and 7 mL of diethyl ether. The reaction tube was placed in a cryogenic bath at -78 °C, and then the above-mentioned milky white suspension of compound 2 was added dropwise into this reaction tube. After the addition was completed, it was slowly allowed to return to room temperature and reacted for 8 h to obtain a suspension of monochlorophosphorus;

[0121] Take a new reaction tube. Under a nitrogen atmosphere, add 1-phenylimidazole (1.44 g, 10 mmol, 1.0 equiv) and 15 mL of tetrahydrofuran, and place it in an ice bath. Then, 4.4 mL of n-BuLi (2.5 M hexane solution, 11 mmol, 1.1 equiv) was added dropwise. After the addition was completed, the reaction solution was gradually allowed to return to room temperature. After reacting for 2 h, an orange lithiated reaction solution of the nitrogen-containing heterocyclic compound was obtained;

[0122] Under ice bath conditions, the suspension of monochlorophosphorus was transferred into the above-mentioned lithiated reaction solution of the nitrogen-containing heterocyclic compound, slowly allowed to return to room temperature and stirred overnight. After monitoring the reaction by TLC and drying the reaction solution by rotary evaporation, the residue was redissolved in ethyl acetate, and 0.5 mL of concentrated hydrochloric acid was added and stirred for 2 h. Then, saturated NaHCO 3 aqueous solution was added to quench the reaction. The organic phase was extracted with ethyl acetate, dried over anhydrous Na 2 SO 4 filtered, concentrated, and purified by column chromatography to obtain 2.4 g of a white solid with a yield of 60%.

[0123] Example 2

[0124] Ar = 1-(2,4,6-trimethylphenyl)-pyrazole, R 1 = tert-butyl, R 2 = H, the structural formula of the phosphine phenol ligand is as follows:

[0125]

[0126] The specific synthesis steps of the phosphine phenol ligand are as follows:

[0127] Take a reaction flask, add 2,4,6-trimethyl iodobenzene (12.31 g, 50 mmol, 1.0 equiv), pyrazole (5.45 g, 80 mmol, 1.6 equiv), cesium carbonate (40.73 g, 125 mmol, 2.5 equiv), and then add copper iodide (1.91 g, 10 mmol, 0.2 equiv) in a glove box. The reaction flask was taken out of the glove box and, under a nitrogen atmosphere, ultra-dry dimethyl sulfoxide (100 mL, 0.5 M) was added. Stir, set the heating temperature to 120 °C, and react for 72 h. The reaction flask was cooled to room temperature. After monitoring the reaction by TLC and diluting the reaction solution with ethyl acetate and saturated brine, it was filtered through diatomaceous earth. The filtrate was extracted with ethyl acetate, and the organic phase was collected and dried over anhydrous Na2 SO 4 It was dried, filtered, concentrated, and purified by column chromatography to obtain 1-(2,4,6-trimethylphenyl)-pyrazole, 6.3 g of white solid, with a yield of 67%;

[0128] 1-(2,4,6-Trimethylphenyl)-pyrazole (1.87 g, 10 mmol, 1.0 equiv) was added to a reaction tube. Under a nitrogen atmosphere, 15 mL of tetrahydrofuran was injected, and it was placed in a low-temperature bath at 0 °C. Then, n-BuLi (2.5 M hexane solution, 4.4 mL, 11 mmol, 1.1 equiv) was added dropwise. After the addition was complete, the reaction solution was gradually restored to room temperature. After reacting for 4 h, a lithiated reaction solution containing the nitrogen heterocyclic compound was obtained;

[0129] The phosphorus monochloride suspension was prepared according to the preparation method described in Example 1. Under ice bath conditions, the obtained phosphorus monochloride suspension was transferred into the above lithiated reaction solution, and it was slowly restored to room temperature and stirred overnight. TLC was used to monitor the end of the reaction. After the reaction solution was dried by a rotary evaporator, an appropriate amount of ethyl acetate was added to dilute the residue, and 0.5 mL of concentrated hydrochloric acid was added and stirred for 2 h. Then, saturated NaHCO 3 aqueous solution was added to quench the reaction. The organic phase was extracted with ethyl acetate, and anhydrous Na 2 SO 4 It was dried, filtered, concentrated, and purified by column chromatography to obtain 1.9 g of white solid, with a yield of 42%.

[0130] Example 3

[0131] Ar = 1-phenylpyrrole, R 1 = tert-butyl, R 2 = H, the structural formula of the phosphine phenol ligand is as follows:

[0132]

[0133] The specific synthesis steps of the phosphine phenol ligand are as follows:

[0134] 1-Phenylpyrrole (1.44 g, 10 mmol, 1.0 equiv) was added to a reaction tube. Under a nitrogen atmosphere, TMEDA (1.28 g, 11 mmol, 1.1 equiv) and n-hexane (20 mL, 0.5 M) were injected, and it was stirred for 0.5 h. Then, it was placed in a hot water bath at 50 °C, and n-BuLi (2.5 M hexane solution, 4.4 mL, 11 mmol, 1.1 equiv) was added dropwise. After the addition was complete, the reaction continued for 2 h, and a lithiated reaction solution of the nitrogen heterocyclic compound that was white and yellowish was obtained;

[0135] Prepare the phosphorus monochloride suspension according to the preparation method described in Example 1. Under ice bath conditions, transfer the obtained phosphorus monochloride suspension into the above-mentioned lithiated reaction solution, slowly restore to room temperature and stir overnight. Monitor the reaction by TLC. After drying the reaction solution with a rotary evaporator, under a nitrogen atmosphere, add an appropriate amount of ethyl acetate to dilute the residue, and dropwise add 0.5 mL of concentrated hydrochloric acid and stir for 4 h. Add saturated NaHCO 3 aqueous solution to quench the reaction. Extract the organic phase with ethyl acetate, and use anhydrous Na 2 SO 4 to dry, filter, concentrate, and perform column chromatography to obtain 2.2 g of white solid with a yield of 55%.

[0136] Example 4

[0137] Ar = 1-(2,6-dimethoxyphenyl)-pyrrole, R 1 = pentafluorophenyl, R 2 = trifluoromethyl, the structural formula of the phosphine phenol ligand is as follows:

[0138]

[0139] The specific synthesis steps of the phosphine phenol ligand are as follows:

[0140] Under an air atmosphere, mix p-trifluoromethylphenol (16.2 g, 0.1 mol, 1.0 equiv) and 3,4-dihydro-2H-pyran (12.7 g, 0.15 mol, 1.5 equiv), stir, place the reaction flask in an ice-salt bath at -10 °C, and dropwise add two drops of concentrated hydrochloric acid to gradually restore the reaction to room temperature. After 12 h, perform column chromatography to obtain compound 1 with a tetrahydropyran group;

[0141] Take compound 1 (2.46 g, 10 mmol, 1.0 equiv) in a reaction tube. Under a nitrogen atmosphere, add 15 mL of diethyl ether, place it in an ice bath, and then dropwise add n-BuLi (2.5 M hexane solution, 4.4 mL, 11 mmol, 1.1 equiv). After the addition is complete, gradually restore the reaction solution to room temperature and react for 2 h to obtain a milky white suspension of compound 2;

[0142] Take a new reaction tube. Under a nitrogen atmosphere, add PhPCl 2 (1.97 g, 11 mmol, 1.1 equiv) and 7 mL of diethyl ether. Place the reaction tube in a low-temperature bath at -78 °C, and then dropwise add the above-mentioned suspension of compound 2 into this reaction tube. After the addition is complete, slowly restore it to room temperature and react for 8 h to obtain a phosphorus monochloride suspension;

[0143] Take a reaction flask, add 2-iodo-1,3-dimethoxybenzene (7.92 g, 30 mmol, 1.0 equiv), pyrrole (3.22 g, 48 mmol, 1.6 equiv), cesium carbonate (24.44 g, 75 mmol, 2.5 equiv), and then add copper(I) iodide (1.15 g, 6 mmol, 0.2 equiv) inside the glove box. Take the reaction flask out of the glove box, and under a nitrogen atmosphere, add ultra-dry dimethyl sulfoxide (60 mL, 0.5 M), stir, set the heating temperature to 120 °C, react for 72 h, cool the reaction flask to room temperature, monitor the end of the reaction by TLC, dilute the reaction solution with ethyl acetate and saturated brine, filter through diatomaceous earth, extract the filtrate with ethyl acetate, collect the organic phase, and dry with anhydrous Na 2 SO 4 dry, filter, concentrate, and perform column chromatography to obtain 1-(2,6-dimethoxyphenyl)-pyrrole, 5.6 g of brown solid, with a yield of 92%.

[0144] Add 1-(2,6-dimethoxyphenyl)-pyrrole (2.03 g, 10 mmol, 1.0 equiv) to a reaction tube. Under a nitrogen atmosphere, inject TMEDA (1.28 g, 11 mmol, 1.1 equiv) and n-hexane (20 mL, 0.5 M), stir for 0.5 h, use a 55 °C water bath, and then dropwise add n-BuLi (2.5 M hexane solution, 4.4 mL, 11 mmol, 1.1 equiv). After the addition is complete, continue the reaction for 2 h to obtain a grayish-white lithiated reaction solution of the nitrogen-containing heterocyclic compound;

[0145] Transfer the obtained suspension of phosphorus monochloride suspension to the above lithiated reaction solution, slowly return to room temperature and stir overnight, monitor the end of the reaction by TLC, spin-dry the reaction solution with a rotary evaporator, and directly perform column chromatography to obtain a phosphine intermediate containing a tetrahydropyran group, with a yield of 63%;

[0146] Take a new reaction tube, add the phosphine intermediate (1.67 g, 3.0 mmol, 1.0 equiv). Under a nitrogen atmosphere, add 15 mL of tetrahydrofuran, place it in an ice bath, and then dropwise add n-BuLi (2.5 M hexane solution, 1.32 mL, 3.3 mmol, 1.1 equiv). After the addition is complete, allow the reaction solution to gradually return to room temperature and react for 2 h to obtain a bright yellow reaction solution. Place the reaction tube in a -78 °C low-temperature bath. And add C 6 F 6(2.80 g, 15 mmol, 5.0 equiv) was added dropwise into the reaction tube. After the addition was completed, it was slowly restored to room temperature and reacted for 8 h to obtain a reaction solution. When the reaction was monitored by TLC to be completed, the reaction solution was dried by rotary evaporation. Under a nitrogen atmosphere, an appropriate amount of ethyl acetate was added to dilute the residue, and 0.5 mL of concentrated hydrochloric acid was added dropwise and stirred for 4 h. Saturated NaHCO 3 aqueous solution was added to quench the reaction, and the organic phase was extracted with ethyl acetate. Anhydrous Na 2 SO 4 was used for drying, filtration, concentration, and column chromatography to obtain 1.4 g of a white solid with a yield of 73%.

[0147] Example 5

[0148] Ar = 1-(2,6-dimethoxyphenyl)-pyrrole, R 1 = pentafluorophenyl, R 2 = trifluoromethyl, the structural formula of the nickel phosphonophenolate complex is as follows:

[0149]

[0150] The specific synthesis steps of the nickel phosphonophenolate complex are as follows:

[0151] Inside the glove box, the ligand obtained in Example 4 (127.5 mg, 200 μmol, 1.0 equiv) and pyridine (0.4 g, 5 mmol, 25 equiv) were mixed, diluted with a small amount of ether, and added dropwise to an ether solution of [(TMEDA)NiMe 2 (45.1 mg, 220 μmol, 1.1 equiv). Bubbles were observed to generate. After stirring at room temperature for 2 - 4 h, the reaction solvent was dried by suction. The residue was dissolved in ether again and dried by suction, and this was repeated three times. Finally, the residue was dissolved in benzene, and the supernatant was taken by centrifugation and placed in a Schlenk tube and freeze-dried to obtain 140.5 mg of a yellow solid powder with a yield of 89%. The crystal structure diagram of the obtained nickel phosphonophenolate complex is as Figure 7 shown.

[0152] Example 6

[0153] Ar = 1-phenylpyrazole, R 1 = tert-butyl, R 2 = H, the structural formula of the palladium phosphonophenolate complex is as follows:

[0154]

[0155] The specific synthesis steps of the palladium phosphonophenolate complex are as follows:

[0156] In the glove box, the corresponding ligand (80.1 mg, 200 μmol, 1.0 equiv) and pyridine (0.4 g, 5 mmol, 25 equiv) were mixed, diluted with a small amount of diethyl ether, and added dropwise to a diethyl ether solution of [(TMEDA)PdMe 2 (55.6 mg, 220 μmol, 1.1 equiv). Bubbles were observed to form. After stirring at room temperature for 2 - 4 h, the reaction solvent was evaporated to dryness. The residue was redissolved in diethyl ether and evaporated to dryness again, and this was repeated three times. Finally, the residue was dissolved in benzene, and the supernatant was taken by centrifugation and placed in a Schlenk tube and freeze-dried to obtain 109.2 mg of a yellow solid powder with a yield of 91%. The crystal structure diagram of the obtained phosphine-palladium complex is as shown in Figure 8 Figure

[0157] Example 7

[0158] Ar = 1-phenylimidazole, R 1 = tert-butyl, R 2 = H, the phosphine-nickel complex:

[0159]

[0160] The specific synthesis procedure of the phosphine-nickel complex is as follows:

[0161] In the glove box, the ligand obtained in Example 1 (80.1 mg, 200 μmol, 1.0 equiv) and pyridine (0.4 g, 5 mmol, 25 equiv) were mixed, diluted with a small amount of diethyl ether, and added dropwise to a diethyl ether solution of [(TMEDA)NiMe 2 (45.1 mg, 220 μmol, 1.1 equiv). Bubbles were observed to form. After stirring at room temperature for 2 - 4 h, the reaction solvent was evaporated to dryness. The residue was redissolved in diethyl ether and evaporated to dryness again, and this was repeated three times. Finally, the residue was dissolved in benzene, and the supernatant was taken by centrifugation and placed in a Schlenk tube and freeze-dried to obtain 105.0 mg of a yellow solid powder with a yield of 95%.

[0162] Example 8

[0163] Ar = 1-phenylpyrazole, R 1 = tert-butyl, R 2 = H, the phosphine-nickel complex:

[0164]

[0165] The specific synthesis procedure of the phosphine-nickel complex is as follows:

[0166] In the glove box, the corresponding ligand (80.1 mg, 200 μmol, 1.0 equiv) and pyridine (0.4 g, 5 mmol, 25 equiv) were mixed, diluted with a small amount of diethyl ether, and added dropwise to an ether solution of [(TMEDA)NiMe 2 (45.1 mg, 220 μmol, 1.1 equiv). Bubbles were observed to form. After stirring at room temperature for 2 - 4 h, the reaction solvent was evaporated to dryness. The residue was redissolved in diethyl ether and evaporated to dryness again, and this was repeated three times. Finally, the residue was dissolved in benzene, the supernatant was taken by centrifugation and placed in a Schlenk tube, and freeze-dried to obtain 101.7 mg of a yellow solid powder with a yield of 92%.

[0167] Example 9

[0168] Ar = 1-(2,6-dimethoxyphenyl)-pyrrole, R 1 = tert-butyl, R 2 = H, the nickel phosphine complex:

[0169]

[0170] The specific synthesis procedure of the nickel phosphine complex is as follows:

[0171] In the glove box, the corresponding ligand (92.0 mg, 200 μmol, 1.0 equiv) and pyridine (0.4 g, 5 mmol, 25 equiv) were mixed, diluted with a small amount of diethyl ether, and added dropwise to an ether solution of [(TMEDA)NiMe 2 (45.1 mg, 220 μmol, 1.1 equiv). Bubbles were observed to form. After stirring at room temperature for 2 - 4 h, the reaction solvent was evaporated to dryness. The residue was redissolved in diethyl ether and evaporated to dryness again, and this was repeated three times. Finally, the residue was dissolved in benzene, the supernatant was taken by centrifugation and placed in a Schlenk tube, and freeze-dried to obtain 112.5 mg of a yellow solid powder with a yield of 92%.

[0172] Example 10

[0173] Ar = 1-phenylpyrrole, R 1 = tert-butyl, R 2 = H, the palladium phosphine complex:

[0174]

[0175] The specific synthesis procedure of the palladium phosphine complex is as follows:

[0176] In the glove box, the ligand obtained in Example 3 (79.9 mg, 200 μmol, 1.0 equiv) and pyridine (0.4 g, 5 mmol, 25 equiv) were mixed, diluted with a small amount of diethyl ether, and added dropwise to an ether solution of [(TMEDA)PdMe 2 (55.6 mg, 220 μmol, 1.1 equiv). Bubbles were observed to form. After stirring at room temperature for 2 - 4 h, the reaction solvent was evaporated to dryness. The residue was redissolved in diethyl ether and evaporated to dryness again, and this was repeated three times. Finally, the residue was dissolved in benzene, and the supernatant was obtained by centrifugation and placed in a Schlenk tube and freeze-dried to obtain 100.3 mg of a yellow solid powder with a yield of 84%.

[0177] Example 11

[0178] Ar = 1-phenylpyrrole, R 1 = tert-butyl, R 2 = H, the nickel phosphine complex:

[0179]

[0180] The specific synthesis procedure of the nickel phosphine complex is as follows:

[0181] In the glove box, the corresponding ligand (79.9 mg, 200 μmol, 1.0 equiv) and pyridine (0.4 g, 5 mmol, 25 equiv) were mixed, diluted with a small amount of diethyl ether, and added dropwise to an ether solution of [(TMEDA)NiMe 2 (45.1 mg, 220 μmol, 1.1 equiv). Bubbles were observed to form. After stirring at room temperature for 2 - 4 h, the reaction solvent was evaporated to dryness. The residue was redissolved in diethyl ether and evaporated to dryness again, and this was repeated three times. Finally, the residue was dissolved in benzene, and the supernatant was obtained by centrifugation and placed in a Schlenk tube and freeze-dried to obtain 101.4 mg of a yellow solid powder with a yield of 92%.

[0182] Application Example 1

[0183] In this application example, when Ar = 1-phenylimidazole, R 1 = tert-butyl, R 2 = H, the nickel phosphine complex catalyzes the polymerization of ethylene in toluene. The specific steps are as follows:

[0184]

[0185] The reaction kettle was evacuated at 90 °C for 0.5 h. After replacing the nitrogen atmosphere, the temperature of the reaction kettle was set to 47 °C. Then, 100 mL of toluene and 2 mL of a toluene solution containing 1 μmol of nickel phosphonophenolate complex were successively injected into the reaction kettle. The stirring was set to 1000 rmp, and then 20 bar of ethylene gas was introduced. The reaction temperature was controlled at 50 °C. After reacting for 20 min, the pressure was released, and methanol was poured into the reaction system to precipitate polyethylene, which was then filtered and dried in vacuo at 60 °C to obtain polyethylene.

[0186] The obtained product was subjected to thermal analysis and molecular weight characterization. The test results showed that 0.07 g of polyethylene was obtained in the application example of the present invention, with a melting point of 137 °C and a molecular weight of 1.2×10 5 g·mol -1 , and the molecular weight distribution was 1.7.

[0187] Application Example 2

[0188] In this application example, when Ar = 1-phenylpyrazole, R 1 = tert-butyl, and R 2 = H, the nickel phosphonophenolate complex catalyzed the polymerization of ethylene in toluene. The specific steps were as follows:

[0189]

[0190] The reaction kettle was evacuated at 90 °C for 0.5 h. After replacing the nitrogen atmosphere, the temperature of the reaction kettle was set to 63 °C. Then, 100 mL of toluene and 2 mL of a toluene solution containing 1 μmol of nickel phosphonophenolate complex were successively injected into the reaction kettle. The stirring was set to 1000 rmp, and then 20 bar of ethylene gas was introduced. The reaction temperature was controlled at 70 °C. After reacting for 20 min, the pressure was released, and methanol was poured into the reaction system to precipitate polyethylene, which was then filtered and dried in vacuo at 60 °C to obtain polyethylene.

[0191] The obtained product was subjected to thermal analysis and molecular weight characterization. The test results showed that 4.4 g of polyethylene was obtained in the application example of the present invention, with a melting point of 135 °C and a molecular weight of 8.4×10 4 g·mol -1 , and the molecular weight distribution was 1.8.

[0192] Figure 11 is the polyethylene with a linear structure in Application Example 2 of the present invention 13 13C NMR spectrum; as can be seen from the figure, the polyethylene prepared in this application example has a good linear structure.

[0193] Application Example 3

[0194] In this application example, when Ar = 1-(2,6-dimethoxyphenyl)-pyrrole, R 1 = tert-butyl, and R 2When = H, the nickel phosphonophenolate complex catalyzes the polymerization of ethylene in toluene, and the specific steps are as follows:

[0195]

[0196] The reaction kettle is evacuated at 90 °C for 0.5 h. After replacing the nitrogen atmosphere, the temperature of the reaction kettle is set to 27 °C. Then, 100 mL of toluene and a toluene solution (2 mL) of 1 μmol of nickel phosphonophenolate complex are successively injected into the reaction kettle. The stirring is set to 1000 rmp, and then 20 bar of ethylene gas is introduced. The reaction temperature is controlled at 30 °C. After reacting for 20 min, the pressure is released, methanol is poured into the reaction system to precipitate polyethylene, filtered, and dried in vacuo at 60 °C to obtain polyethylene.

[0197] The above-obtained product is subjected to thermal analysis and molecular weight characterization. The test results show that 1.3 g of polyethylene is obtained in the application example of the present invention, the melting point is 139 °C, and the molecular weight is 7.1×10 5 g·mol -1 , and the molecular weight distribution is 1.7.

[0198] Application Example 4

[0199] In this application example, Ar = 1-phenylpyrazole, R 1 = tert-butyl, R 2 = H, the nickel phosphonophenolate complex catalyzes the polymerization of ethylene in dimethyl carbonate, and the specific steps are as follows:

[0200]

[0201] The reaction kettle is evacuated at 90 °C for 0.5 h. After replacing the nitrogen atmosphere, the temperature of the reaction kettle is set to 47 °C. Then, 100 mL of dimethyl carbonate and a dimethyl carbonate solution (2 mL) of 1 μmol of nickel phosphonophenolate complex are successively injected into the reaction kettle. The stirring is set to 1000 rmp, and then 20 bar of ethylene gas is introduced. The reaction temperature is controlled at 50 °C. After reacting for 20 min, the pressure is released, ethanol is poured into the reaction system to precipitate polyethylene, filtered, and dried in vacuo at 60 °C to obtain polyethylene.

[0202] 8.9 g of polyethylene is obtained in the application example of the present invention. The melting point of the product is measured by DSC to be 135 °C. According to the corresponding GPC elution curve, the number-average molecular weight of the product is 2.0×10 5 g·mol -1 , and the molecular weight distribution is 1.8.

[0203] Figure 12 It is the molecular weight distribution diagram of linear polyethylene in Application Example 4 of the present invention.

[0204] Application Example 5

[0205] In this application example, Ar = 1-phenylpyrazole, R 1 = tert-butyl, R 2 = H, the nickel phosphonophenolate complex catalyzes the polymerization of ethylene in dimethyl succinate, and the specific steps are as follows:

[0206]

[0207] The reaction kettle is evacuated at 90 °C for 0.5 h. After replacing the nitrogen atmosphere, the temperature of the reaction kettle is set to 47 °C. Then, 100 mL of dimethyl succinate and a dimethyl succinate solution (2 mL) of 1 μmol of nickel phosphonophenolate complex are injected into the reaction kettle in sequence. The stirring is set to 1000 rmp, and then 20 bar of ethylene gas is introduced. The reaction temperature is controlled at 50 °C. After reacting for 20 min, the pressure is released. Ethanol is poured into the reaction system to precipitate polyethylene, filtered, and dried in vacuo at 60 °C to obtain polyethylene.

[0208] The above-obtained product is subjected to thermal analysis and molecular weight characterization. The test results show that 6.3 g of polyethylene is obtained in the embodiment of the present invention, the melting point is 136 °C, and the molecular weight is 2.3×10 5 g·mol -1 , and the molecular weight distribution is 1.8.

[0209] Application Example 6

[0210] In this application example, Ar = 1-(2,6-dimethoxyphenyl)-pyrrole, R 1 = pentafluorophenyl, R 2 = trifluoromethyl, the nickel phosphonophenolate complex catalyzes the polymerization of ethylene in methyltetrahydrofuran, and the specific steps are as follows:

[0211]

[0212] The reaction kettle is evacuated at 90 °C for 0.5 h. After replacing the nitrogen atmosphere, the temperature of the reaction kettle is set to 47 °C. Then, 100 mL of methyltetrahydrofuran and a methyltetrahydrofuran solution (2 mL) of 1 μmol of the nickel phosphonophenolate complex obtained in Example 5 are injected into the reaction kettle in sequence. The stirring is set to 1000 rmp, and then 20 bar of ethylene gas is introduced. The reaction temperature is controlled at 50 °C. After reacting for 20 min, the pressure is released. Ethanol is poured into the reaction system to precipitate polyethylene, filtered, and dried in vacuo at 60 °C to obtain polyethylene.

[0213] The above-obtained product is subjected to thermal analysis and molecular weight characterization. The test results show that 0.4 g of polyethylene is obtained in the embodiment of the present invention, the melting point is 141 °C, and the molecular weight is 2.9×10 5 g·mol -1 , and the molecular weight distribution is 1.7.

[0214] Application Example 7

[0215] In this application example, Ar = 1-phenylpyrrole, R 1 = tert-butyl, when R 2 = H, the phosphine-phenol palladium complex catalyzes the polymerization of ethylene in toluene, and the specific steps are as follows:

[0216]

[0217] The reaction kettle is evacuated at 90 °C for 0.5 h. After replacing the nitrogen atmosphere, the temperature of the reaction kettle is set to 63 °C. Then, 100 mL of toluene and a toluene solution (2 mL) of 1 μmol of the phosphine-phenol palladium complex are successively injected into the reaction kettle. The stirring is set to 1000 rmp, and then 10 bar of ethylene gas is introduced. The reaction temperature is controlled at 70 °C. After reacting for 20 min, the pressure is released. Ethanol is poured into the reaction system to precipitate polyethylene, filtered, and dried in vacuo at 60 °C to obtain polyethylene.

[0218] The above-obtained product is subjected to thermal analysis and molecular weight characterization. The test results show that 0.1 g of polyethylene is obtained in the application example of the present invention, and the molecular weight is 1.3×10 4 g·mol -1 , and the molecular weight distribution is 1.5.

[0219] Application Example 8

[0220] In this application example, Ar = 1-phenylpyrrole, R 1 = tert-butyl, when R 2 = H, the phosphine-phenol nickel complex catalyzes the polymerization of ethylene in dimethyl carbonate, and the specific steps are as follows:

[0221]

[0222] The reaction kettle is evacuated at 90 °C for 0.5 h. After replacing the nitrogen atmosphere, the temperature of the reaction kettle is set to 27 °C. Then, 100 mL of dimethyl carbonate and a dimethyl carbonate solution (2 mL) of 1 μmol of the phosphine-phenol nickel complex are successively injected into the reaction kettle. The stirring is set to 1000 rmp, and then 20 bar of ethylene gas is introduced. The reaction temperature is controlled at 30 °C. After reacting for 20 min, the pressure is released. Ethanol is poured into the reaction system to precipitate polyethylene, filtered, and dried in vacuo at 60 °C to obtain polyethylene.

[0223] The above-obtained product is subjected to thermal analysis and molecular weight characterization. The test results show that 0.4 g of polyethylene is obtained in the example of the present invention, the melting point is 139 °C, and the molecular weight is 3.7×10 5 g·mol -1 , and the molecular weight distribution is 1.8.

[0224] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all of them. People can also obtain other embodiments based on this embodiment without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A phosphophenol ligand, characterized in that The chemical structure shown in the specific formula I: In formula I, Ar is a nitrogen-containing heterocyclic group; R1 is one of hydrogen, fluorine, an alkyl group having 1 to 4 carbon atoms and a substituted phenyl group; and R2 is hydrogen, fluorine or a fluorinated alkyl group having 1 to 3 carbon atoms.

2. The phosphophenol ligand according to claim 1, characterized in that The alkyl group having 1 to 4 carbon atoms includes one of methyl, ethyl, isopropyl, n-propyl, tert-butyl, sec-butyl, isobutyl and n-butyl; The substituted phenyl groups include pentafluorophenyl, trifluorophenyl, 2,6-difluorophenyl, p-fluorophenyl, m-fluorophenyl, o-fluorophenyl, 3,4,5-trifluorophenyl, 3,5-difluorophenyl, 2,6-dimethylphenyl, trimethylphenyl and 2,6-diisopropylphenyl; The fluorinated alkyl group having 1 to 3 carbon atoms includes one of a trifluoromethyl group, a perfluoroethyl group, a perfluoro-n-propyl group and a perfluoro-isopropyl group.

3. The phosphophenol ligand according to claim 1, characterized in that The Ar includes one of an imidazole group, a pyrazole group, a pyrrole group, a thiazole group and an oxazole group.

4. The phosphophenol ligand according to claim 3, characterized in that The imidazole in the imidazole group includes one of 1-phenylimidazole, 1-(2,6-dimethoxyphenyl)-imidazole, 1-(2,4,6-trimethoxyphenyl)-imidazole, 1-(2,4,6-trimethylphenyl)-imidazole, 1-(2,6-dimethylphenyl)-imidazole, 1-(2,6-diisopropoxyphenyl)-imidazole, 1-(2,6-dicyclohexyloxyphenyl)-imidazole, 1-(2,6-bis-dimethylaminophenyl)-imidazole and 2-phenylimidazole; The pyrazole in the pyrazole group includes one of 1-phenylpyrazole, 1-(2,6-dimethoxyphenyl)-pyrazole, 1-(2,4,6-trimethoxyphenyl)-pyrazole, 1-(2,4,6-trimethylphenyl)-pyrazole, 1-(2,6-dimethylphenyl)-pyrazole, 1-(2,6-diisopropoxyphenyl)-pyrazole, 1-(2,6-dicyclohexyloxyphenyl)-pyrazole, 1-(2,6-bis(dimethylaminophenyl)-pyrazole and 3-phenylpyrazole; The pyrrole in the pyrrole group includes one of 1-phenylpyrrole, 1-(2,6-dimethoxyphenyl)-pyrrole, 1-(2,4,6-trimethoxyphenyl)-pyrrole, 1-(2,4,6-trimethylphenyl)-pyrrole, 1-(2,6-dimethylphenyl)-pyrrole, 1-(2,6-diisopropoxyphenyl)-pyrrole, 1-(2,6-dicyclohexyloxyphenyl)-pyrrole, 1-(2,6-bis(dimethylaminophenyl)-pyrrole and N-methylpyrrole; The thiazole in the thiazole group is 4-phenylthiazole; The oxazole in the oxazole group is 4-phenyloxazole.

5. The method for preparing the phosphophenol ligand according to any one of claims 1 to 4, characterized in that: The following steps are involved: The phenol compound and 3,4-dihydro-2H-pyran are mixed and the hydroxyl group is protected to obtain a compound 1 containing a tetrahydropyran group; Compound 1 and n-BuLi are mixed and subjected to lithiation reaction to obtain aryl lithium compound 2; PhPCl2 and the aryl lithium compound 2 are mixed to carry out a nucleophilic substitution reaction to obtain a phosphorus monochloride suspension 3; The nitrogen-containing heterocyclic compound and n-BuLi are mixed to perform a lithiation reaction to obtain a nitrogen-containing heterocyclic lithiation reaction solution 4 containing a carbon anion; The phosphorus monochloride suspension 3 and the nitrogen heterocycle lithiation reaction solution 4 are mixed to carry out a nucleophilic substitution reaction to obtain a phosphorus phenol intermediate 5 containing a tetrahydropyran group; After removing the phenol protecting group from the phosphophenol intermediate 5, the phosphophenol ligand is obtained; When R1 is pentafluorophenyl, the phosphophenol intermediate 5 wherein R1 is hydrogen and n-BuLi are mixed and subjected to lithiation reaction to obtain compound 6; The compound 6 and hexafluorobenzene are mixed, and substitution reaction and removal of the protecting group of phenol are carried out in sequence to obtain a phosphophenol ligand in which R1 is a pentafluorophenyl group.

6. A phosphorus phenol complex, characterized in that The chemical structure shown in the specific formula II: In formula II, Ar is a nitrogen-containing heterocyclic group; R1 is one of hydrogen, fluorine, an alkyl group having 1 to 4 carbon atoms and a substituted phenyl group; R2 is hydrogen, fluorine or a fluorinated alkyl group having 1 to 3 carbon atoms; and M is Ni or Pd.

7. The method for preparing the phosphorus phenol complex according to claim 6, characterized in that: The steps include: The phosphophenol ligand described in any one of claims 1 to 4 or the phosphophenol ligand prepared by the preparation method described in claim 5 and pyridine, as well as an alkyl nickel or alkyl palladium solution are mixed and subjected to an alkyl elimination reaction to obtain the phosphophenol complex.

8. The preparation method according to claim 7, characterized in that: The molar ratio of the phosphophenol ligand to pyridine is 1:1.1-30; The molar ratio of the phosphophenol ligand to the alkyl nickel or alkyl palladium is 1:1.05-1.

5.

9. Use of the phosphorus phenol complex according to claim 6 in catalyzing ethylene polymerization.

10. An ethylene polymerization method, characterized in that: The method comprises the following steps: mixing ethylene, a catalyst and an organic solvent, and polymerizing to obtain polyethylene; The catalyst is the phosphophenol complex according to claim 6; the organic solvent includes toluene, hexane, n-heptane and a biomass solvent; the biomass solvent is dimethyl carbonate, methyltetrahydrofuran and dimethyl succinate.

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