Norbornene pcnp ligand, method for preparing the same, and use thereof

Abstract

The application discloses a norbornene PCNP ligand, a preparation method thereof and application of the norbornene PCNP ligand in the field of ethylene oligomerization, and the catalyst comprises a norbornene PCNP ligand shown as a structure of formula I and a transition metal compound. The catalytic system can use a boron compound as a cocatalyst, greatly reduces the cost while keeping high activity, and the by-product polyolefins of the catalytic system are all oligomers, so that the reaction system is a homogeneous reaction, and the problem of reactor blockage is fundamentally solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ethylene oligomerization, and particularly relates to a norbornene PCNP ligand, a preparation method thereof and application thereof. BACKGROUND

[0002] Linear alpha-olefins are important chemical raw materials, which can be used as polyolefin comonomers, PVC plasticizers, surfactants, lubricating oil additives and many other fields. Among them, the amount of comonomer accounts for more than half of the consumption of alpha-olefins, and the polyolefin products of 1-octene and 1-hexene have good mechanical properties and excellent processing performance, and have a large demand in industrial production.

[0003] The selectivity of the selective oligomerization process of 1-octene and 1-hexene is more than 90% of the total product, which has good selectivity and high conversion rate, and is suitable for industrial production. At present, the main reason affecting ethylene oligomerization is the high cost of alkyl aluminum cocatalyst. The production process of alkyl aluminum is only mastered by a few companies in the world, and its production capacity is limited, so the alkyl aluminum cocatalyst has always maintained a high price.

[0004] Another problem is that the polymer problem has not been properly solved. One of the main problems faced by the selective oligomerization industrialization is the blockage problem caused by the wall hanging and kettle hanging of by-product polymers. Once the reaction kettle is blocked, it will inevitably affect the continuous reaction, and the cleaning will affect the product quality and the economy of the device, and even cause a greater device risk due to pipeline pressure. SUMMARY

[0005] In order to solve the above problems, the application provides a norbornene PCNP ligand, a preparation method thereof and application thereof in the field of ethylene oligomerization. The catalyst system obtained by using the ligand of the application can use boron compounds as cocatalysts, which greatly reduces the cost while maintaining high activity, and the by-product polyolefins of the catalyst system are all oligomers, so that the reaction system is a homogeneous reaction, which fundamentally solves the problem of reactor blockage.

[0006] The application provides a norbornene PCNP ligand, which has the structure as shown in formula I:

[0007]

[0008] Among them, R1 is selected from phenyl with 20 carbons or less, C1-C20 alkyl, C1-C20 alkoxy, halogen, preferably selected from methyl, ethyl, methoxy, isopropyl, tert-butyl, trifluoromethyl, p-methylphenyl, 3,5-di-tert-butylphenyl and the like.

[0009] R2 is selected from aryl and its derivatives, preferably C1-C10 alkyl-substituted phenyl, C1-C6 alkoxy-substituted phenyl, fluorine-substituted phenyl, more preferably 2-methylphenyl, 4-methylphenyl, 2,4-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, 4-ethylphenyl, 2,4-diethylphenyl, 2,6-diethylphenyl, 2-isopropylphenyl, 4-isopropylphenyl, 2,4-diisopropylphenyl, 2,6-diisopropylphenyl, 2-butylphenyl, 4-butylphenyl, 2,4-dibutylphenyl, 2,6-dibutylphenyl, 4-methoxyphenyl, o-methoxyphenyl, 4-ethoxyphenyl, o-ethoxyphenyl, 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl.

[0010] The present application also provides a preparation method of the ligand, comprising the following steps:

[0011] (1) taking cyclopentadiene and 2-bromopropenal, adding a catalyst, and reacting at -5-0°C for 1-5h, then adding water to quench the reaction, and purifying and treating the reaction solution to obtain product one, i.e. 1-bromonorbomenyl aldehyde;

[0012] The reaction equation is shown as follows:

[0013]

[0014] (2) dissolving product one and substituted bromoaniline in solvent A, heating and refluxing for 24-48h, and purifying and treating the reaction solution to obtain product two, i.e. dibromoimine ligand,

[0015] The reaction equation is shown as follows:

[0016]

[0017] (3) under anhydrous and anaerobic conditions, dissolving product two obtained in step (2) in solvent B, slowly adding alkyl lithium at -5-0°C, reacting at -5-0°C for 1-5h, after the reaction is completed, adding phenyl chlorophosphine, and reacting for 1-10h, and purifying and treating the reaction solution to obtain product three, i.e. norbornene PCNP ligand.

[0018] The reaction route is shown as follows:

[0019]

[0020] In the present application, the structural formula of 1-bromonorbomenyl aldehyde is as follows:

[0021]

[0022] In the present application, the structural formula of product two is shown as formula III:

[0023]

[0024] In the present application, the product III is a norbornene PCNP ligand with the structure of formula I.

[0025] wherein R1 and R2 are defined as the same as formula I.

[0026] Preferably, the molar ratio of the cyclopentadiene to 2-bromoacrolein is 1:1-1.5, and more preferably 1:1-1.2.

[0027] Preferably, the catalyst in step (1) is a Lewis acid, and more preferably one or more of aluminum trichloride, dimethylaluminum chloride, and diethylaluminum chloride, and the molar ratio of the substrate to the catalyst is 1:0.01-0.05.

[0028] Preferably, the solvent A is one or more of methanol, ethanol, isopropanol, dichloromethane, or ethyl acetate, and more preferably methanol, ethanol, or isopropanol.

[0029] Preferably, in step (2), the molar ratio of the product I to the substituted bromoaniline is 1:1-1.5, and more preferably 1:1-1.2.

[0030] Preferably, the substituted bromoaniline has the following structure:

[0031] Preferably, the solvent B is one or more of diethyl ether, tetrahydrofuran, dioxane, or tetrahydropyran, and more preferably diethyl ether or tetrahydrofuran.

[0032] Preferably, the molar ratio of the product II to the phenylphosphine chloride is 1:2-2.4, and more preferably 1:2-2.2.

[0033] Preferably, the amount of the alkyl lithium added is 2-2.4 times of the product II, and more preferably 1:2-2.1.

[0034] The purification process of the present application includes column chromatography purification of the reaction solution to obtain the target product, and recrystallization of the target product, wherein the column chromatography purification uses a column with a height-to-diameter ratio of 5-10 and a residence time of 10-60 min, and the recrystallization uses a mixed solvent of ethanol and ethyl acetate.

[0035] The present application also provides the use of the ligand as an olefin polymerization catalyst, in particular for ethylene oligomerization.

[0036] Preferably, the catalyst comprises the ligand of the present application and a transition metal, and the ligand and the transition metal can be added to the reaction system in situ or prepared by the following method:

[0037] The ligand is dissolved in solvent C, the transition metal compound is added, and the reaction is carried out at 20-30°C for 1-10h. The product, the tridentate phosphine pyrrolidine chromium catalyst, is obtained after purification of the reaction solution.

[0038] Preferably, the transition metal is selected from one or more of chromium, zirconium and nickel.

[0039] Preferably, the solvent C comprises one of dichloromethane, n-hexane, 1,2 dichloroethane.

[0040] Preferably, the transition metal compound is selected from one or more of acetylacetone chromium, chromium chloride, tris (tetrahydrofuran) chromium trichloride, 2-ethylhexanoic acid chromium (III), octanoic acid chromium (III), hexacarbonyl chromium, (benzene) tricarbonyl chromium, zirconium tetrachloride.

[0041] The olefin polymerization reaction also comprises an auxiliary catalyst. The auxiliary catalyst is a borane auxiliary catalyst. The borane auxiliary catalyst is selected from one or more of tris-pentafluorophenyl boron, tris-octadecyl boron, tris-pentafluorophenyl tert-butyl oxygen boron, tris-pentafluorophenyl methoxy boron, tris-silyl modified tris-pentafluorophenyl boron.

[0042] In the catalyst of the present application, the molar ratio of the transition metal compound to the norbornene PCNP ligand is 1:1-3, preferably 1:1-2; the molar ratio of the borane auxiliary catalyst to the transition metal compound is 1-20:1, preferably 1-5:1.

[0043] In some preferred embodiments of the present application, the method for the ethylene oligomerization reaction is as follows: the reaction kettle is heated to 110-160°C before the reaction, vacuumized for 1-4h, replaced with nitrogen, and then cooled to room temperature. Ethylene is replaced, and then solvent D and the borane auxiliary catalyst are added, followed by the addition of the transition metal compound and the PCPN ligand. After the temperature reaches the reaction temperature, 0-0.8Mpa hydrogen and 2MPa-7MPa ethylene are introduced in sequence to start the reaction. The reaction temperature is 35-90°C, preferably 40-70°C, and the reaction time is 10min-240min, preferably 20min-100min.

[0044] The ethylene oligomerization reaction solvent D is selected from one or more of n-butane, isobutane, n-pentane, cyclopentane, methylcyclopentane, methylene cyclopentane, n-hexane, cyclohexane, methylcyclohexane, n-heptane, n-octane, n-nonane, benzene, toluene, xylene.

[0045] In a more specific embodiment, the polymerization process of the catalyst composition described in the present application is as follows: the polymerization is carried out in a 300 mL high-pressure reactor, and refined alkanes are used as solvent D. Before the reaction, the reactor is heated to 130°C, vacuumized for 1-3 h, and replaced with nitrogen three times. When the temperature cools to room temperature, ethylene is replaced twice, and then dehydrated and deoxygenated solvent D and a quantitative amount of borane cocatalyst are added, followed by the addition of a transition metal compound, a norbornene PCNP ligand. When the temperature is constant at the reaction temperature, 0.2-0.7 MPa hydrogen and 2 MPa-7 MPa ethylene are introduced in sequence to start the reaction. The reaction temperature is 35-90°C, preferably 40-70°C, and the reaction time is 10 min-240 min, preferably 20 min-100 min. After the reaction is completed, the ethylene inlet valve is closed, an ice water bath or liquid nitrogen is used to rapidly cool, the pressure is slowly released, and the reactor is unloaded to obtain the ethylene oligomerization product.

[0046] The amount of catalyst added is 10-25 μmol / L (solvent) of the molar concentration of the transition metal compound in the ethylene oligomerization reaction system, preferably 15-20 μmol / L (solvent).

[0047] Moreover, compared with the prior art, the ethylene oligomerization catalyst system of the present application has an activity of more than 3305 g / (g Cr h) for ethylene oligomerization, a total selectivity of 1-hexene and 1-octene of up to 91.5%, and a PE selectivity of less than 0.05 wt%. Most significantly, the present catalyst system uses borane as a cocatalyst, greatly reducing the cost, and the byproduct polymer is low molecular weight polyethylene wax, which can be dissolved in solution, thereby fundamentally solving the problem of polymer clogging the reactor and pipelines. DETAILED DESCRIPTION

[0048] The following specific examples only illustrate the present application, but these examples are only part of the present application and do not limit the application of the present application in other fields.

[0049] The raw materials used in the examples are all conventional raw materials in the art, and the purity specifications used are analytical or chemical pure.

[0050] Raw material source information:

[0051] 2-bromopropyl aldehyde: 98%, Anjie Chemical Co., Ltd.

[0052] 2-bromoaniline: 99%, Shanghai Maikelin Biochemical Technology Co., Ltd.

[0053] Cyclopentadiene: 98%, Zhengzhou Jakes Chemical Products Co., Ltd.

[0054] Diphenylchlorophosphine: 98%, Beijing Ino Kai Technology Co., Ltd.

[0055] Tris(pentafluorophenyl)boron: 98%, Shanghai McLean Biochemical Science and Technology Co., Ltd.

[0056] 2-bromo-4-methylaniline: 98%, Shanghai Haohong Biomedicine Technology Co., Ltd.

[0057] diethylaluminum chloride: 99%, Beijing Ino Kai Technology Co., Ltd.

[0058] bis(4-methylphenyl)phosphine chloride: 98%, Beijing Ino Kai Technology Co., Ltd.

[0059] bis(3,5-di-tert-butyl-4-methoxyphenyl)phosphine chloride: Beijing Ino Kai Technology Co., Ltd.

[0060] 2-bromo-4-methoxyaniline: Beijing Yiteng Chemical Technology Co., Ltd.

[0061] The catalyst activity of the oligomerization reaction was determined by qualitative and quantitative analysis of the components in the reaction solution. The GC analysis instrument used the following conditions:

[0062] Instrument model: Shimadzu GC2010

[0063] Chromatographic column: DB-5 (30 m 0.25 mm 0.25 μm)

[0064] Column temperature program: first hold at 35°C for 10 min, then increase to 250°C at a rate of 10°C / min, and hold at this temperature for 10 min.

[0065] Detector temperature: 300°C

[0066] Carrier gas: 1 bar

[0067] Air: 0.3 bar

[0068] Fuel gas (H2): 0.3 bar

[0069] Sample mass analysis was performed using an internal standard method. There should be:

[0070]

[0071] where m1 is the mass of a certain product, m is the mass of the internal standard, a1 is the peak area detected in the gas chromatograph for the product, a is the peak area of the internal standard, and k is a correction factor related to the measured substance and the detection conditions.

[0072] Ligand preparation

[0073] Example 1

[0074] Preparation of dibromoimine ligand a: The relevant solvents were deoxygenated before use.

[0075] Preparation of chlorophosphine bridged ligand: Take 150 mmol of cyclopentadiene and 150 mmol of 2-bromopropenal into a round bottom flask, add 1.5 mmol of aluminum chloride, stir at room temperature for 2 h. Remove the insoluble by filtration, add 150 mmol of 2-bromoaniline, add 100 ml of ethanol, heat to 75°C in an oil bath, react for 2 h, filter, and remove the mother liquor with ethanol. Remove the solvent under vacuum to obtain the dibromoimine ligand a

[0076] Dissolve 100 mmol of dibromoimine ligand a in 100 ml of tetrahydrofuran, add 200 mmol of hexyllithium at 0°C, keep at 0°C for 1 h, add 220 mmol of diphenyl chlorophosphine, keep at 0°C for 2 h. After the reaction is completed, raise the temperature to room temperature, quench the reaction with water, and purify the product to obtain ligand a

[0077] Remove the solvent under vacuum to obtain the ligand, the structure of which is shown below:

[0078]

[0079] The nuclear magnetic resonance data of the above ligand are as follows: 1H NMR (400 MHz, CDCl3): 8.49 (s, 1H) 7.38-7.05 (m, 24H), 6.51 (d, 2H), 2.84-1.42 (m, 6H)

[0080] Ethylene oligomerization:

[0081] Before the reaction, heat 500 ml of the reaction kettle to 150°C, vacuumize for 3 h, and replace with nitrogen three times. When the temperature cools to room temperature, replace with ethylene twice, first add 300 ml of dehydrated and deoxygenated solvent methylcyclohexane and 67.5 μmol of tri-pentafluorophenyl boron, then add 13.5 μmol of the ligand prepared in this example and 10.5 μmol of acetylacetone chromium, and when the temperature is constant at 45°C, sequentially introduce 0.5 MPa of hydrogen and 5 MPa of ethylene to start the reaction. The reaction temperature is 45°C, and the reaction time is 60 min. After the reaction is completed, close the ethylene inlet valve, rapidly cool to below 5°C with an ice water bath or the like, slowly release the pressure, and unload the kettle to obtain the ethylene oligomerization product.

[0082] The product is analyzed by GC, the activity is 3311 kg / g Cr.h, and the (1-hexene + 1-octene) selectivity is 85.5 wt%.

[0083] Example 2

[0084] Preparation of dibromoimine ligand b: The relevant solvents are dehydrated and deoxygenated before use.

[0085] Preparation of chlorophosphine bridged ligand: Take 150 mmol of cyclopentadiene and 150 mmol of 2-bromopropenyl aldehyde into a round bottom flask, add 1.5 mmol of diethyl aluminum chloride, stir at room temperature for 2 h. Remove the insoluble matter by filtration, add 180 mmol of 2-bromo-4-methylaniline, add 100 ml of methanol, heat to 75 °C in an oil bath, react for 2 h, filter, and remove the mother liquor with ethanol. Remove the solvent under vacuum to obtain the dibromo imine ligand b

[0086] Dissolve 100 mmol of the dibromo imine ligand b in 100 ml of dioxane, add 210 mmol of hexyllithium at 0 °C, keep at 0 °C for 1 h, add 220 mmol of diphenyl chlorophosphine, keep at 0 °C for 2 h. After the reaction is completed, raise the temperature to room temperature, quench the reaction with water, and purify the product to obtain the ligand 2

[0087] Remove the solvent under vacuum to obtain the ligand, the structure of which is shown below:

[0088]

[0089] The NMR data of the above ligand are as follows: 1H NMR (400 MHz, CDCl3): 8.50 (s, 1H) 7.36-7.07 (m, 24H), 6.51 (d, 2H), 2.15 (s, 3H) 2.84-1.42 (m, 6H)

[0090] Ethylene oligomerization:

[0091] Before the reaction, heat the 500 ml reactor to 150 °C, vacuumize for 3 h, and replace with nitrogen three times. When the temperature cools to room temperature, replace with ethylene twice, first add 300 ml of dehydrated and deoxygenated solvent methylcyclohexane and 13.5 μmol of tri-pentafluorophenyl boron, then add 13.5 μmol of the ligand prepared in this example and 10.5 μmol of acetylacetone chromium, and when the temperature is constant at 45 °C, sequentially introduce 0.5 MPa of hydrogen and 5 MPa of ethylene to start the reaction. The reaction temperature is 45 °C, and the reaction time is 60 min. After the reaction is completed, close the ethylene inlet valve, rapidly cool to below 5 °C with an ice water bath or the like, slowly release the pressure, and unload the reactor to obtain the ethylene oligomerization product.

[0092] The product is analyzed by GC, the activity is 3028 kg / g Cr.h, and the (1-hexene + 1-octene) selectivity is 91.2 wt%.

[0093] Example 3

[0094] Preparation of dibromo imine ligand c: The relevant solvents are dehydrated and deoxygenated before use.

[0095] Preparation of chlorophosphine bridged ligand: Take 150 mmol of cyclopentadiene and 150 mmol of 2-bromopropenal into a round bottom flask, add 7.5 mmol of aluminum trichloride, stir the reaction at room temperature for 2 h. Remove the insoluble matter by filtration, add 150 mmol of 2-bromo-4-methoxyaniline, add 100 ml of ethanol, heat to 75 °C in an oil bath, react for 2 h, filter, and remove the mother liquor with ethanol. Remove the solvent under vacuum to obtain the dibromimine ligand c

[0096] Dissolve 100 mmol of dibromimine ligand c in 100 ml of tetrahydrofuran, add 200 mmol of hexyllithium at 0 °C, keep the temperature at 0 °C for 1 h, add 200 mmol of diphenyl chlorophosphine, keep the temperature at 0 °C for 2 h. After the reaction is completed, raise the temperature to room temperature, quench the reaction with water, and purify the product to obtain the ligand 1

[0097] Remove the solvent under vacuum to obtain the ligand, the structure of which is shown below:

[0098]

[0099] The nuclear magnetic resonance data of the above ligand are as follows: 1H NMR (400 MHz, CDCl3): 8.51 (s, 1H) 7.40-7.05 (m, 24H), 6.50 (d, 2H), 3.89 (s, 3H) 2.84-1.42 (m, 6H)

[0100] Ethylene oligomerization:

[0101] Before the reaction, heat a 500 ml reaction kettle to 150 °C, vacuumize for 3 h, and replace with nitrogen three times. When the temperature cools to room temperature, replace with ethylene twice, first add 300 ml of dehydrated and deoxygenated solvent methylcyclohexane and 27 μmol of tri-pentafluorophenyl boron, then add 13.5 μmol of the ligand prepared in this example and 10.5 μmol of acetylacetone chromium, and when the temperature is constant at 45 °C, sequentially introduce 0.5 MPa of hydrogen and 5 MPa of ethylene to start the reaction. The reaction temperature is 45 °C, and the reaction time is 60 min. After the reaction is completed, close the ethylene inlet valve, rapidly cool to below 5 °C with an ice water bath or the like, slowly release the pressure, and unload the kettle to obtain the ethylene oligomerization product.

[0102] The product is analyzed by GC, the activity is 2850 kg / g Cr.h, and the (1-hexene + 1-octene) selectivity is 90.5 wt%.

[0103] Example 4

[0104] The dibromoimine ligand a 100 mmol was dissolved in 100 ml of tetrahydrofuran, and hexyllithium 200 mmol was added at 0°C under low temperature, and the reaction was kept at 0°C for 1 h, and dimethylphenyl phosphine chloride 200 mmol was added, and the reaction was kept at 0°C for 2 h. After the reaction was completed, the temperature was raised to room temperature, water was added to quench the reaction, and the product was purified to obtain the ligand 1

[0105] The solvent was removed under vacuum to obtain the ligand, and the structure of the compound is shown below:

[0106]

[0107] The nuclear magnetic resonance data of the above ligand are as follows: 1H NMR (400 MHz, CDCl3): 8.51 (s, 1H) 7.36-7.05 (m, 20H), 6.50 (d, 2H), 2.84-1.42 (m, 6H) 1.31 (s, 9H)

[0108] Ethylene oligomerization:

[0109] Before the reaction, a 500 ml reactor was heated to 150°C, vacuumized for 3 h, and replaced with nitrogen three times. When the temperature was cooled to room temperature, ethylene was replaced twice, 300 ml of dehydrated and deoxygenated solvent methylcyclohexane and 27 μmol of trifluorophenyl boron were added first, then 13.5 μmol of the ligand prepared in this example and 10.5 μmol of acetylacetone chromium were added, and when the temperature was kept constant at 45°C, 0.5 MPa of hydrogen and 5 MPa of ethylene were introduced to start the reaction. The reaction temperature was 45°C, and the reaction time was 60 min. After the reaction was completed, the ethylene inlet valve was closed, and the reactor was rapidly cooled to below 5°C with an ice water bath or slowly depressurized to obtain the ethylene oligomerization product.

[0110] The product was analyzed by GC, and the activity was 3100 kg / g Cr.h, and the (1-hexene + 1-octene) selectivity was 87.2 wt%.

[0111] Example 5

[0112] The dibromoimine ligand a 100 mmol was dissolved in 100 ml of tetrahydrofuran, and hexyllithium 200 mmol was added at 0°C under low temperature, and the reaction was kept at 0°C for 1 h, and dimethylphenyl phosphine chloride 200 mmol was added, and the reaction was kept at 0°C for 2 h. After the reaction was completed, the temperature was raised to room temperature, water was added to quench the reaction, and the product was purified to obtain the ligand 1

[0113]

[0114] The NMR data of the above ligand is as follows:1H NMR (400 MHz, CDCl3): 8.51 (s, 1H) 7.36-7.05 (m, 12H), 6.50 (d, 2H), 3.35 (s, 12H) 2.84-1.40 (m, 6H) 1.31 (s, 72H)

[0115] Ethylene oligomerization:

[0116] Before reaction, 500 ml reactor was heated to 150℃, vacuumized for 3h, replaced by nitrogen for 3 times. When the temperature cooled to room temperature, ethylene was replaced for 2 times, 300 ml dehydrated and deoxidized solvent methylcyclohexane and 27 μmol dipentafluorophenylmethoxy boron were added first, then 13.5 μmol ligand prepared in this example and 10.5 μmol acetylacetone chromium were added. When the temperature was constant at 45℃, 0.5 MPa hydrogen and 5 MPa ethylene were introduced to start the reaction. The reaction temperature was 45℃, and the reaction time was 60 min. After the reaction, the valve of ethylene was closed, and the reactor was cooled to below 5℃ by ice water bath or rapidly, slowly depressurized, and unloaded to obtain the ethylene oligomerization product.

[0117] The product was analyzed by GC, the activity was 3255 kg / g Cr.h, and the (1-hexene + 1-octene) selectivity was 89.9 wt%.

Claims

1. A norbornene PCNP ligand, characterized in that, The structure is shown in Equation I: Wherein, R1 is selected from C1-C20 alkyl groups and C1-C20 alkoxy groups; R2 is selected from alkyl-substituted phenyl groups of C1-C10 and alkoxy-substituted phenyl groups of C1-C6.

2. The ligand according to claim 1, characterized in that, R1 is selected from methyl, ethyl, methoxy, isopropyl, and tert-butyl. R2 is selected from 2-methylphenyl, 4-methylphenyl, 2,4-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, 4-ethylphenyl, 2,4-diethylphenyl, 2,6-diethylphenyl, 2-isopropylphenyl, 4-isopropylphenyl, 2,4-diisopropylphenyl, 2,6-diisopropylphenyl, 2-butylphenyl, 4-butylphenyl, 2,4-dibutylphenyl, 2,6-dibutylphenyl, 4-methoxyphenyl, o-methoxyphenyl, 4-ethoxyphenyl, o-ethoxyphenyl.

3. A norbornene PCNP ligand, characterized in that, The structure of the norbornene PCNP ligand is selected from the following structures:

4. The method for preparing the ligand according to claim 1, characterized in that, It includes the following steps: (1) Take cyclopentadiene and 2-bromopropenal, add catalyst, react at -5-0℃ for 1-5h, add water to quench the reaction, purify the reaction solution to obtain product one, which is 1-bromonorbornenal; the catalyst in step (1) is Lewis acid. (2) Dissolve product one and substituted bromoaniline in solvent A, heat under reflux for 24-48 h, and purify the reaction solution to obtain product two, which is the dibromoimine ligand. (3) Under anhydrous and oxygen-free conditions, the product two obtained in step (2) is dissolved in solvent B, and alkyl lithium is slowly added dropwise at -5-0℃. The reaction is carried out at -5-0℃ for 1-5 hours. After the reaction is completed, phenylphosphine chloride is added and the reaction is carried out for 1-10 hours. The reaction solution is purified to obtain product three, which is norbornene PCNP ligand. The structural formula of 1-bromonorbornene is: The structural formula of the substituted bromoaniline is: The structural formula of product 2 is shown in formula III: The structure of the phenylphosphine chloride is PR2Cl; The definitions of R1 and R2 are the same as in Equation I.

5. The preparation method according to claim 4, characterized in that, The molar ratio of cyclopentadiene to 2-bromopropenal is 1:1-1.

5.

6. The preparation method according to claim 5, characterized in that, The molar ratio of cyclopentadiene to 2-bromopropenal is 1:1-1.

2.

7. The preparation method according to claim 4, characterized in that, In step (1), the catalyst is one or more of aluminum trichloride, dimethyl aluminum chloride, and diethyl aluminum chloride, and the molar ratio of substrate to catalyst is 1:0.01-0.

05.

8. The preparation method according to claim 4, characterized in that, Solvent A is one or more of methanol, ethanol, isopropanol, dichloromethane, or ethyl acetate.

9. The preparation method according to claim 8, characterized in that, Solvent A is methanol, ethanol or isopropanol.

10. The preparation method according to claim 4, characterized in that, In step (2), the molar ratio of product one to substituted bromoaniline is 1:1-1.

5.

11. The preparation method according to claim 10, characterized in that, In step (2), the molar ratio of product one to substituted bromoaniline is 1:1-1.

2.

12. The preparation method according to claim 4, characterized in that, In step (3), solvent B is one or more of diethyl ether, tetrahydrofuran, dioxane, or tetrahydropyran.

13. The preparation method according to claim 12, characterized in that, Solvent B is diethyl ether or tetrahydrofuran.

14. The preparation method according to claim 4, characterized in that, The molar ratio of product 2 to phenylphosphine chloride is 1:2-2.

4.

15. The preparation method according to claim 14, characterized in that, The molar ratio of product 2 to phenylphosphine chloride is 1:2-2.

2.

16. The preparation method according to claim 4, characterized in that, The purification process includes column chromatography to purify the reaction solution to obtain the target product and recrystallization of the target product. The column chromatography used for purification has a height-to-diameter ratio of 5-10 and a residence time of 10-60 min. The solvent used for recrystallization is a mixture of ethanol and ethyl acetate.

17. The application of a ligand according to any one of claims 1-3 or a ligand prepared by the preparation method according to any one of claims 4-16, used as an olefin polymerization catalyst, said catalyst comprising the ligand according to any one of claims 1-3 or a ligand prepared by the preparation method according to any one of claims 4-16 and a transition metal, wherein a co-catalyst is further added to the olefin polymerization reaction, wherein... The cocatalyst is a borane cocatalyst, and the transition metal is selected from one or more of chromium, zirconium, and nickel.

18. The application according to claim 17, wherein it is used in an ethylene oligomerization reaction.

19. The application according to claim 17, wherein the ligand and transition metal are respectively added to the reaction system for in-situ synthesis or prepared by the following method: The ligand is dissolved in solvent C, a transition metal compound is added, and the reaction is carried out at 20-30°C for 1-10 hours. The reaction solution is purified to obtain the product, which is the catalyst.

20. The application according to claim 19, wherein the solvent C is selected from one or more of dichloromethane, n-hexane, and 1,2-dichloroethane.

21. The application according to claim 19, wherein the transition metal compound is selected from one or more of chromium acetylacetone, chromium chloride, chromium tri(tetrahydrofuran)trichloride, chromium(III) 2-ethylhexanoate, chromium(III) octanoate, chromium hexacarbonyl, chromium (benzene)tricarbonyl, and zirconium tetrachloride.

22. The application according to claim 17, wherein the boron cocatalyst is selected from one or more of tris(pentafluorophenylboron), octadecylboron, dipentafluorophenyl tert-butylboron, dipentafluorophenyl methoxyboron, and trimethylsilyl-modified tris(pentafluorophenylboron).

23. In the application according to claim 19, the molar ratio of the transition metal compound to the norbornene PCNP ligand is 1:1-3.

24. In the application according to claim 23, the molar ratio of the transition metal compound to the norbornene PCNP ligand is 1:1-2.

25. In the application according to claim 19, the molar ratio of the borane co-catalyst to the transition metal compound is 1-20:

1.

26. In the application according to claim 25, the molar ratio of the borane co-catalyst to the transition metal compound is 1-5:1.

Images