Preparation method and application of auxiliary agent of single-site metal catalyst

Abstract

The invention belongs to the technical field of olefin polymerization, and discloses a preparation method and application of a single-site metal catalyst byproduct, and the preparation method comprises the following steps: 1) in a water-free and oxygen-free environment, adding an alkyl lithium reagent into a solution of an aromatic hydrocarbon compound capable of being converted into negative ions at the temperature of-50 DEG C or below, and reacting to obtain a reaction solution; then adding a boron compound to react for 20-60 minutes, and reacting for more than 0.5 hour after the temperature is recovered to normal temperature; 2) washing an organic phase in the reaction system obtained in the step 1) with water, and collecting a water phase; and 3) adding an amine compound, amine hydrochloride or a triphenylmethyl compound into the water phase for reaction, and treating a reaction product to obtain the single-site metal catalyst auxiliary agent. The target auxiliary agent product can be obtained by adopting simple initial raw materials through simple synthesis and treatment, the yield is high, and energy consumption and material consumption are effectively reduced, so that the cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of olefin polymerization, and in particular relates to a preparation method and application of a single-center metal catalyst auxiliary agent. Background Art

[0002] As polyolefin raw materials are abundant and cheap, and they are easy to process and shape, the annual production of polyolefin products in the world exceeds 100 million tons, becoming one of the largest industries. Polyolefin materials have relatively small density, good chemical resistance, water resistance, good mechanical strength, electrical insulation and other characteristics. They can be used for films, pipes, plates, various molded products, wires and cables, etc. They are widely used in agriculture, packaging, automobiles, electrical appliances and other daily necessities, and provide convenience for human food, clothing, housing and transportation.

[0003] Coordination polymerization represented by metallocene catalysts has developed rapidly in the polyolefin industry and gradually matured. The metallocene catalytic system is generally composed of a metallocene main catalyst precursor and a secondary agent, which also plays a vital role in olefin polymerization. Under the action of the secondary agent, the metallocene catalyst is converted into an active center to form an anion-cation pair with catalytic properties to synthesize polyolefins. The characteristics of the secondary agent will affect the activity, life, high temperature stability, solubility of the catalytic system and the structure of the polymer.

[0004] In the early 1980s, the emergence of methylaluminoxane (MAO) as an adjuvant promoted the vigorous development of metallocene catalysts, changing the problem of low activity when alkyl aluminum was used as an adjuvant in the past. However, MAO has poor solubility in alkanes, and the dosage is high and the cost is expensive. Boron-containing compounds can form a highly active catalytic system for olefin polymerization with metallocene compounds as adjuvants. The catalytic system is highly active, and the amount of boron-containing compounds only needs to be the same molar amount as the metallocene compound to achieve the activation process, which solves the problem of high cost of high MAO dosage, so the development of the preparation method of this adjuvant is very important.

[0005] Patent document CN110078753A discloses a method for synthesizing a boron-containing compound, specifically discloses a method for synthesizing a metallocene catalyst adjuvant and its application in the polymerization process of 1-decene. The organic boron compound triphenylcarbon tetrakis(pentafluorophenyl)borate (or N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate) is obtained by reacting potassium tetrakispentafluorophenylborate with trityl chloride (or N,N-dimethylaniline hydrochloride) as a metallocene catalyst adjuvant and is successfully used in the polymerization reaction of 1-decene.

[0006] At present, how to obtain boron-containing compound adjuvants with high yield and low cost is still a technical problem that needs to be solved urgently. Summary of the invention

[0007] In view of the above problems existing in the prior art, the purpose of the present invention is to provide a method for preparing a single-center metal catalyst auxiliary agent and its application, which can obtain the target product by using simple starting materials through simple synthesis and treatment.

[0008] The first aspect of the present invention provides a method for preparing a single-center metal catalyst secondary agent, the preparation method comprising the following steps:

[0009] 1) In an anhydrous and oxygen-free environment, at a temperature below -50°C, add an alkyl lithium reagent to a solution of an aromatic compound that can be converted into anions, and then add a boron compound to react for 20 to 60 minutes, return to room temperature, and react for more than 0.5 hours;

[0010] 2) washing the organic phase in the reaction system obtained in step 1) with water, and collecting the aqueous phase;

[0011] 3) adding an amine compound, an amine hydrochloride or a trityl compound to the aqueous phase for reaction, treating the reaction product to obtain the single-center metal catalyst secondary agent.

[0012] The second aspect of the present invention provides the use of the single-center metal catalyst secondary agent prepared by the above preparation method as a metallocene catalyst secondary agent.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The invention adopts simple starting materials and can obtain the target auxiliary agent product through simple synthesis and treatment. The method has high yield, effectively reduces energy consumption and material consumption, thereby reducing costs.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0016] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0017] According to a first aspect of the present invention, the present invention provides a method for preparing a single-center metal catalyst secondary agent, the preparation method comprising the following steps:

[0018] 1) In an anhydrous and oxygen-free environment, at a temperature below -50°C, add an alkyl lithium reagent to a solution of an aromatic compound that can be converted into anions, and then add a boron compound to react for 20 to 60 minutes, return to room temperature, and react for more than 0.5 hours;

[0019] 2) washing the organic phase in the reaction system obtained in step 1) with water, and collecting the aqueous phase;

[0020] 3) adding an amine compound, an amine hydrochloride or a trityl compound to the aqueous phase for reaction, treating the reaction product to obtain the single-center metal catalyst secondary agent.

[0021] In the present invention, the alkyl lithium reagent may be n-butyl lithium, isobutyl lithium or methyl lithium.

[0022] Preferably, the alkyl lithium reagent is used in the form of a solution thereof, for example, the molar concentration of the solution may be 1-3M.

[0023] According to the present invention, the structure of the aromatic compound that can be converted into a negative ion is shown in formula (1):

[0024]

[0025] In formula (1), R 1 is H, F or CF3, X 2 Chlorine, bromine or iodine.

[0026] Preferably, the solvent in the solution of the aromatic compound convertible into negative ions is selected from at least one of n-octane, n-heptane, n-hexane, isohexane, cyclohexane, methylcyclohexane, petroleum ether, ethyl ether and dibutyl ether, more preferably n-hexane or ethyl ether.

[0027] In the present invention, the structure of the boron compound is shown in formula (2):

[0028] BX 1 3 Formula (2)

[0029] In formula (2), X 1 is Cl, Br, I or OR 2 , R 2 is an alkyl group or an aryl group.

[0030] Preferably, the boron compound is used in the form of a solution thereof, and the molar concentration of the solution is 0.5-2M.

[0031] According to the present invention, the molar ratio of the alkyl lithium reagent, the aromatic hydrocarbon compound convertible into negative ions and the boron compound is (3.5-4.5):(3.5-4.5):1.

[0032] In the present invention, the reaction temperature in step 1) is preferably -100°C to -50°C, and the reaction time of adding the alkyl lithium reagent to the solution of the aromatic compound convertible into negative ions can be more than 0.2h, preferably 0.2 to 1h.

[0033] Normal temperature in the present invention is also called general temperature or room temperature, which is generally defined as 25° C. Preferably, the reaction is restored to normal temperature and then reacted for more than 8 hours, such as 12 hours, 24 hours, 36 hours, or 48 hours.

[0034] According to the present invention, step 2) further comprises: adding an alkane solvent to the reaction system, heating to remove the low boiling point solvent, and then washing the organic phase with water; the alkane solvent may be a C6-C14 straight-chain or branched alkane.

[0035] In the present invention, the amine compound can be an amine compound conventionally used in the prior art, for example, it can be selected from at least one of N,N-dimethylaniline, N-methyldiphenylamine, triethylamine, triethylaniline, N,N-dioctadecylaniline, N,N-dioctadecylmethylamine, dimethyloctadecylamine, and dimethyldioctadecylbenzene-1,4-diamine.

[0036] The hydrochloride of the amine can be a hydrochloride of an amine conventionally used in the prior art, for example, it can be selected from at least one of N,N-dimethylaniline hydrochloride, N-methyldiphenylamine hydrochloride, triethylamine hydrochloride, triethylaniline hydrochloride, N,N-dioctadecylaniline hydrochloride, N,N-dioctadecylmethylamine hydrochloride, dimethyloctadecylamine hydrochloride, and dimethyldioctadecylbenzene-1,4-diamine hydrochloride.

[0037] The trityl compound can be selected from triphenylmethane chloride, tri(methylphenyl)methane chloride, triphenylmethane bromide, tri(methylphenyl)methane bromide, tri(hexylphenyl)methane chloride, tri(octylphenyl)methane chloride, tri(decylphenyl)methane chloride, tri(dodecylphenyl)methane chloride, tri(hexylphenyl)methane bromide, tri(octylphenyl)methane bromide, tri(decylphenyl)methane bromide, tri(dodecylphenyl)methane bromide.

[0038] Preferably, the molar ratio of the boron compound to the amine compound, amine hydrochloride or trityl compound is 1:(0.8-1.2).

[0039] According to the present invention, the reaction temperature of step 3) is -20 to 60°C, which means room temperature if not specifically limited, and the reaction time is more than 0.1 hour, preferably 8 to 24 hours. The overnight reaction in the present invention generally refers to 16 hours.

[0040] In the present invention, the product needs to be treated accordingly according to the different products. The method for treating the reaction product in step 3) includes: filtering and collecting the solid, and optionally recrystallizing the solid; or optionally adding ethyl acetate for extraction, collecting the organic phase and drying it.

[0041] According to the present invention, recrystallization or extraction can be carried out in a conventional manner. Preferably, the recrystallization of the solid includes: dissolving the solid in C6-C20 benzene, toluene or xylene aromatic hydrocarbons, C1-C20 polar solvents containing halogens or oxygen polar atoms at 50-180°C, cooling to below 20°C, and filtering to obtain a precipitated solid; or dissolving the solid in C6-C20 benzene, toluene or xylene aromatic hydrocarbons, C1-C20 polar solvents containing halogens or oxygen polar atoms at room temperature, and then slowly adding C5-C24 straight-chain or branched alkane to the solution, and filtering to obtain a precipitated solid after the two solvents are mixed.

[0042] According to a second aspect of the present invention, the present invention provides a use of the single-center metal catalyst secondary agent prepared by the above-mentioned preparation method as a metallocene catalyst secondary agent.

[0043] The substances and parameters not limited in the present invention can be selected according to the prior art and belong to the conventional technical means in the field. Unless otherwise specified, the operations and processing methods involved in the present invention belong to the conventional methods in the field, the instruments used are conventional instruments in the field, and the raw materials used are commercially available.

[0044] The present invention will be further described below with reference to the following examples, but is not limited to these examples.

[0045] In the following examples and comparative examples, the determination methods of the relevant data are as follows:

[0046] 1. Structure of the single-site metal catalyst auxiliary agent: H NMR, C NMR, F NMR and B NMR spectra were tested on a Bruker-400 NMR instrument using deuterated chloroform as solvent at room temperature.

[0047] 2. Yield of single-site metal catalyst auxiliary agent: Taking the mass of the added boron compound completely converted into the product as the benchmark, the yield is obtained by dividing the actual mass of the product by the benchmark value.

[0048] Example 1

[0049] Under nitrogen protection, pentafluoro bromobenzene (2mL, 16mmol) is dissolved in anhydrous ether, the temperature is reduced to -78 ℃, the temperature is maintained, an equivalent amount of n-butyl lithium (1.6M n-hexane solution, 10mL, 16mmol) is added thereto, and stirred for 30min. Afterwards, under nitrogen protection, BCl is added thereto (1M dichloromethane solution, 3.6mL, 3.6mmol), after -78 ℃ of stirring for 30min, stirring at room temperature is restored for 1h (white turbidity appears gradually in the system). 20mL hexane is added to the above system, after being spin-dried for ether, 20mL water is used to wash the organic phase three times, and the aqueous phase is collected and added thereto relative BCl 1.1 equivalent of triethylamine hydrochloride (the system rapidly becomes milky white from white transparent) and the reaction is spent the night. Filter and collect the solid product, obtain white solid 1.75g ​​after recrystallization, and the productive rate is 61%.

[0050] 1 H NMR (500MHz, Chloroform-d) δ9.86, δ2.96, δ1.22. 11 B NMR (160MHz, Chloroform-d) δ-16.65. 19 F NMR (500MHz, Chloroform-d) δ-132.95, δ-161.91. δ-166.22.

[0051] Example 2

[0052] Under nitrogen protection, pentafluoro bromobenzene (1.5mL, 12mmol) is dissolved in anhydrous normal hexane, lower the temperature to-78 ℃, keep the temperature, drip equivalent n-butyl lithium (2.4M n-hexane solution, 5mL, 12mmol), stir 30min. Subsequently under the condition of nitrogen protection, drip BCl3 (1M dichloromethane solution, 2.73mL, 2.73mmol), after-78 ℃ of stirring 30min, recover stirring at room temperature 48h (system gradually appears white turbidity). Add 20mL hexane to the above system, after being spin-dried for solvent, use 20ml water to wash organic phase three times, collect water and add relative BCl3 1.1 equivalents of triethylamine hydrochloride (system becomes milky white rapidly by white transparent) reaction overnight. Filter and collect white solid, obtain white solid 1.54g, productive rate 72%.

[0053] Example 3

[0054] Under nitrogen protection, pentafluoro bromobenzene (0.5mL, 4mmol) was dissolved in anhydrous ether, cooled to -78°C, maintained at this temperature, an equivalent amount of n-butyl lithium (1.6M n-hexane solution, 2.5mL, 4mmol) was added dropwise thereto, and stirred for 60min (the system changed from colorless to light blue). Subsequently, under nitrogen protection, BCl3 (1M dichloromethane solution, 0.9mL, 0.9mmol) was added dropwise thereto, stirred at -78°C for 30min, and then stirred at room temperature for 48h (the system gradually became white and turbid). 20mL of hexane was added to the above system, and after being spin-dried for ether, the organic phase was washed three times with 20mL of water, and the aqueous phase was collected (a white viscous liquid was obtained), 138mg of triethylamine hydrochloride was added to the aqueous phase, and the organic phase was collected and spin-dried after the reaction was spent overnight to obtain 0.49g of a white granular solid with a yield of 70%.

[0055] Example 4

[0056] Under nitrogen protection, pentafluoro bromobenzene (2g, 7.46mmol) is dissolved in anhydrous dibutyl ether, cooled to -78 ℃, maintained at this temperature, n-butyl lithium (2.4M n-hexane solution, 3.42mL, 8.2mmol) is added dropwise thereto, and stirred for 60min. Subsequently, under nitrogen protection, BCl3 (1M dichloromethane solution, 1.86mL, 1.86mmol) is added dropwise thereto, and after -78 ℃ of stirring for 30min, room temperature stirring is restored for 48h (white turbidity gradually appears in the system). Water is added to wash the organic phase of the above system, and the aqueous phase is collected and triethylamine hydrochloride (256mg, 1.86mmol) is added thereto. After the reaction is spent the night, 20mL ethyl acetate is added for extraction. The organic phase is collected and spin-dried to obtain 0.86g of white granular solid, with a productive rate of 59%.

[0057] Example 5

[0058] Under nitrogen protection, pentafluoro bromobenzene (1mL, 8mmol) is dissolved in anhydrous ether, lower the temperature to-78 ℃, keep this temperature, drip n-butyl lithium (1.6M n-hexane solution, 5mL, 8mmol) of equivalent amount wherein, stir 30min.Subsequently under the condition of nitrogen protection, drip BCl3 (1M dichloromethane solution, 1.83mL, 1.8mmol) wherein, stir 30min after-78 ℃ and recover stirring at room temperature 48h (white turbidity appears gradually in the system).In the above-mentioned system, add 20mL hexane, after being spin-dried for ether, use 20mL water to wash organic phase three times, collect water and add triethylamine hydrochloride (274mg, 2mmol) wherein, react and collect solid product 0.97g after spending the night, productive rate 70%.

[0059] Example 6

[0060] [CH3N(C18 H 37 )2HJ[B(C6F5)4]: Under nitrogen protection, pentafluorobromobenzene (0.5mL, 4mmol) was dissolved in anhydrous ether, cooled to -78°C, maintained at this temperature, an equivalent amount of n-butyl lithium (1.6M n-hexane solution, 2.5mL, 4mmol) was added dropwise thereto, and stirred for 60min. Subsequently, under nitrogen protection, BCl3 (1M dichloromethane solution, 0.9mL, 0.9mmol) was added dropwise thereto, stirred at -78°C for 30min, and then stirred at room temperature for 48h (the system gradually became white and turbid). 20mL of hexane was added to the above system, and after the ether was spin-dried, the organic phase was washed with water, the aqueous phase was collected and a dichloromethane solution of 536mg N,N-dioctadecylmethylamine was added thereto, and the organic phase was collected and spin-dried after reacting overnight to obtain a light yellow oily liquid with a yield of 88%.

[0061] 1 H NMR (400MHz, Chloroform-d) δ4.23 (s, 1H), 2.77 (dd, J=9.4, 6.8Hz, 4H), 1.27 (d, J=10.8Hz, 64H), 0.88 (t, J=6.8Hz, 6H). 19 F NMR (377MHz, Chloroform-d) δ-132.65--132.96 (m), -162.11 (t, J=20.6Hz), -166.32 (t, J=18.2Hz). 11 B NMR(160MHz, Chloroform-d)δ-16.61.

[0062] Example 7

[0063] [PhNH(Me)2][B(C6F5)4]: Under nitrogen protection, pentafluorobromobenzene (1.5mL, 12mmol) was dissolved in anhydrous ether, cooled to -78°C, maintained at this temperature, an equivalent amount of n-butyl lithium (2.4M n-hexane solution, 5mL, 12mmol) was added dropwise thereto, and stirred for 60min. Subsequently, under nitrogen protection, BCl3 (1M dichloromethane solution, 2.8mL, 2.8mmol) was added dropwise thereto, stirred at -78°C for 30min, and then stirred at room temperature for 48h (the system gradually became white and turbid). 20mL of hexane was added to the above system, and after the ether was spin-dried, the organic phase was washed three times with 20mL of water, the aqueous phase was collected and N, N-dimethylaniline hydrochloride (471mg, 3mmol) was added thereto, and after the reaction was spent overnight, 20mL of ethyl acetate was added for extraction, the organic phase was separated and spin-dried to obtain 1.17g of a light yellow oily liquid with a yield of 52%.

[0064] 1H NMR (400MHz, Chloroform-d) δ7.57-7.49 (m, 3H), 7.34-7.29 (m, 2H), 6.10 (s, 1H), 3.22 (s, 6H). 11 B NMR(160MHz, Chloroform-d)δ-16.68. 19 F NMR (471MHz, Chloroform-d) δ-132.85--133.05 (m), -162.63 (t, J=20.5Hz), -166.80 (t, J=17.8Hz). 13 C NMR (126MHz, Chloroform-d) δ142.08, 131.14, 130.10, 118.53, 46.67.

[0065] Example 8

[0066] [PhN(C 18 H 37 )2H][B(C6F5)4]: Under nitrogen protection, pentafluorobromobenzene (1.2mL, 9.6mmol) was dissolved in anhydrous ether, the temperature was lowered to -78°C, and the temperature was maintained. An equivalent amount of n-butyl lithium (2.4M n-hexane solution, 4mL, 9.6mmol) was added dropwise thereto, and stirred for 30min. Subsequently, under nitrogen protection, BCl3 (1M dichloromethane solution, 2.18mL, 2.18mmol) was added dropwise thereto, and the mixture was stirred at -78°C for 30min and then stirred at room temperature for 48h (white turbidity gradually appeared in the system). 20mL of hexane was added to the above system, and the ether was removed under vacuum. The organic phase was washed three times with 20mL of water, and the aqueous phase was collected and a dichloromethane solution of 1.43g N,N-dioctadecylaniline was added thereto. After reacting overnight, the organic phase was collected and spin-dried to obtain a light yellow oily liquid. The yield was 66%.

[0067] 1 H NMR (600MHz, Chloroform-d) δ10.86 (s, 1H), 7.56 (p, J=3.6Hz, 3H), 7.51-7.45 (m, 2H), 1.33-1.10 (m, 62H), 0.87 (t, J=7.0Hz, 6H). 11 B NMR (193MHz, Chloroform-d) δ-16.63. 19 F NMR (565MHz, Chloroform-d) δ-132.37--132.72(m), -162.68(t, J=20.6Hz), -166.53(t, J=17.7Hz).

[0068] Example 9

[0069] {Ph[N(C 18 H 37 )(CH3)]2H}[B(C6F5)4]: Under nitrogen protection, pentafluorobromobenzene (0.3mL, 2.4mmol) was dissolved in anhydrous ether, the temperature was lowered to -78°C, and the temperature was maintained. An equivalent amount of n-butyl lithium (2.4M n-hexane solution, 1mL, 2.4mmol) was added dropwise thereto, and stirred for 30min. Subsequently, under nitrogen protection, BCl3 (1M dichloromethane solution, 0.55mL, 0.55mmol) was added dropwise thereto, and after stirring at -78°C for 30min, the mixture was stirred at room temperature for 48h (white turbidity gradually appeared in the system). 20mL of hexane was added to the above system, and after the ether was spin-dried, the organic phase was washed three times with 20mL of water, the aqueous phase was collected, and a dichloromethane solution of 384mg of dimethyldioctadecylbenzene-1,4-diamine was added thereto (the organic phase quickly changed from light yellow to dark green), and the organic phase was collected and spin-dried after reacting overnight to obtain a dark green oily liquid. Yield: 56%.

[0070] 1 H NMR (400MHz, Chloroform-d) δ7.06 (t, J=7.3Hz, 1H), 6.11 (d, J=6.9Hz, 2H), 6.01 (s, 1H), 2.89 (s, 6H), 1.25 (s, 64H), 0.88 (t, J=6.8Hz, 6H). 19 F NMR (377MHz, Chloroform-d) δ -133.14 (s), -162.31 (d, J=11.7Hz), -166.60 (t, J=17.8Hz).

[0071] Example 10

[0072] Under nitrogen protection, pentafluoro bromobenzene (2g, 7.46mmol) is dissolved in anhydrous ether, cooled to-78 ℃, keep this temperature, drip n-butyl lithium (2.4M n-hexane solution, 3.42mL, 8.2mmol), stir 60min.Subsequently under the condition of nitrogen protection, drip BCl wherein (1M dichloromethane solution, 1.86mL, 1.86mmol), after-78 ℃ of stirring 30min, recover stirring at room temperature 48h (system gradually appears white turbidity).In above-mentioned system, add 20mL hexane, after being spin-dried for ether, use 20mL water to wash organic phase three times, collect water and add Ph wherein CCl (520mg, 1.86mmol), after reaction spends the night, add 20mL ethyl acetate extraction, separate organic phase and be spin-dried for, finally obtain yellow solid 0.78g, productive rate 45.6%.

[0073] 1 H NMR (400MHz, Chloroform-d) δ7.33-7.25(m). 13 C NMR (100MHz, Chloroform-d) δ146.09, 127.94, 127.29, 82.05. 19 F NMR (377MHz, Chloroform-d) δ -133.36 (d, J=44.8Hz), -162.07 (t, J=20.6Hz), -166.36 (s).

[0074] Comparative Example 1

[0075] In 45 mL of n-hexane, C6F5Br (4.45 g, 18 mmol) was stirred and n-BuLi (2.5 M, 7.2 mL, 18 mmol) was added dropwise at -80 °C for 15 minutes. The resulting colorless suspension was stirred at this temperature for 40 minutes. Boron trichloride / n-hexane solution (1.41 g, 50% (w / w), 6 mmol) was then added quickly with a syringe, stirred at this temperature for 10 minutes, and then slowly heated to room temperature for one hour. The solvent was removed in vacuo to produce a colorless residue. In order to remove impurities and LiCl, the residue was sublimated in a vacuum at 60-70 °C for 24 hours, during which the liquid was collected to the semi-solid part, which was continuously removed and discarded. The temperature was then raised to 110 to 120 °C, and sublimation for 24 hours gave 2.15 g of pure B (C6F5) 3 colorless crystalline solid with a yield of 70%.

[0076] To a stirred solution of C6F5Br (1.01 g, 4.1 mmol) in diethyl ether (20 mL), n-BuLi (2.5 M, 1.64 mL, 4.1 mmol) was added dropwise at -80 degrees Celsius for 5 minutes. The resulting colorless suspension was stirred at this temperature for 30 minutes. Then a suspension of B(C6F5)3 (2.05 g, 4.0 mmol) in diethyl ether (10 mL) was added. The resulting colorless suspension was stirred at this temperature for 10 minutes and then slowly heated to room temperature for one hour. The solvent was removed in vacuo to obtain a colorless crystalline residue, which was washed twice with 10 mL of n-pentane and then dried in vacuo. The crystallized residue was slowly heated to 120 degrees Celsius in vacuo to produce 2.99 g [B(C6F5)4]·Et2O (3.94 mmol, 98%) of a colorless solid.

[0077] Lithium tetrakis(pentafluorophenyl)borate diethyl ester [B(C6F5)4]·Et2O (3.04 g, 4.0 mmol) and triethylamine hydrochloride (0.551 g, 4.0 mmol) were mixed and dissolved in a mixture of n-pentane (50 mL) and dichloromethane (10 mL). The resulting suspension was heated to reflux for two hours. The solvent was then removed in vacuo, the residue was suspended in dichloromethane (15 mL), and filtered to obtain a transparent solution. Slow addition of n-pentane (20 mL) will precipitate a yellow microcrystalline solid. The supernatant was removed with a syringe, the residue was redissolved in dichloromethane (4 mL), and n-pentane (6 mL) was added for precipitation. This process was repeated twice. Drying in vacuo gave 3.15 g (3.42 mmol, 85%) of the target product as a white solid. The total yield of the target product was 56.5%.

[0078] Compared with the comparative example, the method of the present invention is simpler to operate, reduces the use of reaction vessels, saves operation time, and has a higher product yield, which can even be increased to more than 70%.

[0079] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing a single-center metal catalyst auxiliary agent, characterized in that: The preparation method comprises the following steps: 1) In an anhydrous and oxygen-free environment, at a temperature below -50°C, add an alkyl lithium reagent to a solution of an aromatic compound that can be converted into anions, and then add a boron compound to react for 20 to 60 minutes, return to room temperature, and react for more than 0.5 hours; 2) washing the organic phase in the reaction system obtained in step 1) with water, and collecting the aqueous phase; 3) adding an amine compound, an amine hydrochloride or a trityl compound to the aqueous phase for reaction, treating the reaction product to obtain the single-center metal catalyst secondary agent.

2. The method for preparing a single-center metal catalyst secondary agent according to claim 1, wherein: The alkyl lithium reagent is n-butyl lithium, isobutyl lithium or methyl lithium; Preferably, the alkyl lithium reagent is used in the form of a solution thereof, and the molar concentration of the solution is 1-3M.

3. The method for preparing a single-site metal catalyst secondary agent according to claim 1, wherein: The structure of the aromatic compound that can be converted into anions is shown in formula (1): In formula (1), R 1 is H, F or CF3, X 2 is chlorine, bromine or iodine; Preferably, the solvent in the solution of the aromatic compound convertible into negative ions is selected from at least one of n-octane, n-heptane, n-hexane, isohexane, cyclohexane, methylcyclohexane, petroleum ether, diethyl ether and dibutyl ether.

4. The method for preparing a single-center metal catalyst secondary agent according to claim 1, wherein: The structure of the boron compound is shown in formula (2): BX 1 Formula 3 (2) In formula (2), X 1 is Cl, Br, I or OR 2 , R 2 is an alkyl group or an aryl group; Preferably, the boron compound is used in the form of a solution thereof, and the molar concentration of the solution is 0.5-2M.

5. The method for preparing a single-site metal catalyst secondary agent according to claim 1, wherein: The molar ratio of the alkyl lithium reagent, the aromatic hydrocarbon compound convertible into negative ions and the boron compound is (3.5-4.5):(3.5-4.5):

1.

6. The method for preparing a single-site metal catalyst secondary agent according to claim 1, wherein: In step 1), the reaction time of adding the alkyl lithium reagent to the solution of the aromatic compound convertible into negative ions is more than 0.2 h.

7. The method for preparing a single-site metal catalyst secondary agent according to claim 1, wherein: Step 2) further comprises: adding an alkane solvent to the reaction system, heating to remove the low boiling point solvent, and then washing the organic phase with water; The alkane solvent is a C6-C14 straight-chain or branched alkane.

8. The method for preparing a single-site metal catalyst secondary agent according to claim 1, wherein: The amine compound is selected from at least one of N,N-dimethylaniline, N-methyldiphenylamine, triethylamine, triethylaniline, N,N-dioctadecylaniline, N,N-dioctadecylmethylamine, dimethyloctadecylamine, and dimethyldioctadecylbenzene-1,4-diamine; The hydrochloride of the amine is selected from at least one of N,N-dimethylaniline hydrochloride, N-methyldiphenylamine hydrochloride, triethylamine hydrochloride, triethylaniline hydrochloride, N,N-dioctadecylaniline hydrochloride, N,N-dioctadecylmethylamine hydrochloride, dimethyloctadecylamine hydrochloride and dimethyldioctadecylbenzene-1,4-diamine hydrochloride; The trityl compound is selected from triphenylmethane chloride, tri(methylphenyl)methane chloride, triphenylmethane bromide, tri(methylphenyl)methane bromide, tri(hexylphenyl)methane chloride, tri(octylphenyl)methane chloride, tri(decylphenyl)methane chloride, tri(dodecylphenyl)methane chloride, tri(hexylphenyl)methane bromide, tri(octylphenyl)methane bromide, tri(decylphenyl)methane bromide, tri(dodecylphenyl)methane bromide; Preferably, the molar ratio of the boron compound to the amine compound, amine hydrochloride or trityl compound is 1:(0.8-1.2).

9. The method for preparing a single-site metal catalyst secondary agent according to claim 1, wherein: The reaction temperature of step 3) is -20 to 60°C, and the reaction time is more than 0.1 hour; The method for treating the reaction product in step 3) comprises: filtering and collecting the solid, and optionally recrystallizing the solid; or optionally adding ethyl acetate for extraction, collecting the organic phase and spinning it to dryness.

10. Use of the single-center metal catalyst auxiliary agent obtained by the preparation method according to any one of claims 1 to 9 as a metallocene catalyst auxiliary agent.

Images