A catalyst for the selective tetramerization of ethylene containing a diphosphine ligand, its preparation and use

Abstract

The present application relates to a catalyst for selective tetramerization of ethylene, which comprises a diphosphine ligand, a transition metal compound and an activator, and a preparation method and application thereof, wherein the chemical structure of the ligand is shown in the following formula (I): wherein, groups R 1 and R 2 are each independently selected from hydrogen, an alkyl group, an ester group or an aromatic group; groups R 3 to R 5 are each independently selected from an alkyl group, an alkoxy group, an alkenyl group or an aromatic group, and R 3 to R 5 are not simultaneously an aromatic group; groups R 6 to R 9 are each independently selected from hydrogen, halogen, an alkyl group, an alkoxy group, an alkenyl group or an aromatic group, and the catalyst is used for selective tetramerization of ethylene to generate 1-octene. Compared with the prior art, the present application can improve the selectivity of 1-octene, reduce the content of cyclic C6 and reduce the content of polymers.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ethylene oligomerization, in particular to a catalyst containing a bidentate phosphine ligand for selective ethylene tetramerization and its preparation method and application. BACKGROUND

[0002] Linear alpha-olefins (LAO) are important chemical raw materials, which can be used to prepare lubricating oil, surfactant, etc. 1-hexene and 1-octene are indispensable comonomers in the synthesis of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE) (the comonomer content in LLDPE is generally 8-10%, and the comonomer content in HDPE is 1-2%). Ethylene oligomerization is an important method for producing linear alpha-olefins, which has great improvement in product quality compared with traditional methods such as wax cracking, coal extraction, and extraction separation, and has been widely used in industrial production.

[0003] Traditional ethylene oligomerization catalysts mainly use metal titanium, zirconium, iron, etc. These catalyst systems mainly follow the Cossee-Arlman mechanism, that is, ethylene molecules are inserted into the linear chain growth of the catalyst metal center, and the obtained linear alpha-olefins are usually normally distributed, which must be separated and purified according to the needs in industrial applications. Ethylene high-selective oligomerization mainly follows the metal cyclization mechanism, so that the produced alpha-olefins are Schulz-Flory distributed, and the product at the peak has a high content. This method provides an important way to produce alpha-olefins with specific carbon number. In recent years, the increasing demand for 1-hexene and 1-octene has made ethylene selective oligomerization a hot spot in industrial and academic research.

[0004] Currently, the reported selective oligomerization of ethylene mainly includes dimerization, trimerization, tetramerization to 1-butene, 1-hexene and 1-octene. In these catalytic systems, the structure regulation of catalyst plays a key role in the product distribution, and the regulation of catalyst structure depends on the change of ligand skeleton and substituent group. In recent years, the research in this field has focused on the catalytic mechanism of selective oligomerization of ethylene and the design of ligand, and some important achievements have been made. In 2002, British Petroleum reported the selective preparation of 1-hexene using Cr / PNP catalytic system (Chem. Commun. 2002, 858). In 2003, Phillips Petroleum developed Phillips trimerization chromium catalyst and realized the industrialization of ethylene trimerization (US5523507). Sinopec (Yanshan) and PetroChina (Daqing) also realized the industrial production of 1-hexene using similar catalytic system. The selective preparation of 1-octene by ethylene tetramerization has not yet been realized in industrial production. 1-Octene can be used to prepare high-quality polyethylene (PE), polyolefin elastomer (POE), lubricating oil base oil (PAO), plasticizer, surfactant and other fields. Compared with 1-hexene, 1-octene has higher economic value. In 2004, Sasol developed a selective tetramerization catalyst system for ethylene using Cr / PNP catalyst (WO2004056478), and the selectivity of 1-octene reached about 70%, and about 13% of 1-hexene was generated. However, there are more cyclic C6 by-products, which leads to the low comprehensive selectivity of 1-hexene and 1-octene with high added value. Moreover, the polymer content is more than 2%, which is easy to cause polymer wall hanging, stirring paddle entanglement and other phenomena, affecting the continuous operation of the industrial device. The formation of polymer is due to the general stability of the catalyst, and the degradation products of the catalyst make the ethylene polymerize to obtain the polymer.

[0005] Since the catalyst system was discovered, a large number of studies have focused on the modification of PNP ligands, in which the ortho substituents of the phenyl group connected to the phosphorus atom have a significant impact on the catalytic results. The introduction of methoxy groups changes the system from tetramerization to trimerization (Chem. Commun., 2005, 622). In 2010, SK Energy Company of South Korea developed a series of dimethyl-substituted, chiral skeleton-containing DPPE-type ligands for catalyzing the selective tetramerization of ethylene (Organometallics 2010, 29, 5805), but the activity was low, with the highest activity reaching 238 kg / (g Cr / h). In 2013, Zhang et al. designed and synthesized a series of ethenyl-bridged bisphosphine ligands containing bisphenylphosphine groups (-PPh2), Ph2P(R)C=C(H)PPh2, for catalyzing the selective trimerization and tetramerization of ethylene, which showed good catalytic activity for ethylene trimerization and tetramerization (ACS Catal., 2013, 3, 2311). In 2014, Sasol Company introduced F atoms into the ortho position of the phenyl group connected to the phosphorus atom in the PNP ligand (CN101646684A), which effectively reduced the content of cyclic C6 in the product. In 2019, SK Energy Company of South Korea introduced fluorine atoms into the ortho position of the phenyl group in the ethenyl-bridged bisphosphine ligand (Catalysis Communications, 2019, 121, 15), which increased the activity of the system and reduced the content of cyclic C6 in the product, thereby increasing the total selectivity of 1-C6 and 1-C8 (up to 90%), but the introduction of F atoms reduced the content of 1-octene to about 50%, while the content of 1-octene with similar ligands without F atoms was up to 65%. SUMMARY

[0006] The purpose of the present application is to overcome the defects of the prior art and provide a bisphosphine ligand-containing catalyst for selective tetramerization of ethylene, which can improve the selectivity of 1-octene, reduce the content of cyclic C6, and reduce the content of polymers, as well as a preparation method and application thereof.

[0007] The purpose of the present application can be achieved by the following technical solutions:

[0008] The application is further to improve the selectivity of 1-octene and the activity of the catalytic system, and the alkyl with adjustable steric hindrance and the ortho halogenated aryl are simultaneously introduced into the ethenyl bridged biphosphine ligand. By introducing the ortho halogenated aryl and the alkyl with smaller steric hindrance, the 1-octene selectivity of the catalytic system is successfully improved to 80%, and the total selectivity of 1-hexene and 1-octene is improved to 96%, which can effectively improve the selectivity of 1-octene while reducing the cyclic C6. In addition, due to the stronger electron-donating ability of the alkyl than the phenyl, the introduction of the alkyl in the ligand increases the electron cloud density of the phosphorus atom, which can significantly increase the stability of the chromium metal active center, prolong the catalyst life, and effectively improve the activity of the catalytic system. The improvement of the catalyst life also reduces the degradation of the catalyst, and the content of the polymer in the reaction is reduced to 0.04-0.02%, and the specific scheme is as follows:

[0009] An ethylene selective tetramerization catalyst containing a biphosphine ligand, the catalyst comprising a ligand, a transition metal compound and an activator, wherein the chemical structure of the ligand is shown as formula (I):

[0010]

[0011] In the formula,

[0012] The group R 1 and R 2 are each independently selected from hydrogen, an alkyl group, an ester group or an aromatic group;

[0013] The group R 3 to R 5 are each independently selected from an alkyl group, an alkoxy group, an alkenyl group or an aromatic group, and R 3 to R 5 are not simultaneously aromatic groups;

[0014] The group R 6 to R 9 are each independently selected from hydrogen, halogen, an alkyl group, an alkoxy group, an alkenyl group or an aromatic group.

[0015] Further, R 3 to R 5 are at least one alkyl group or alkenyl group.

[0016] Further, the alkyl group is a C1-C 30 alkyl group, specifically including a methyl group, an ethyl group, a n-propyl group, an iso-propyl group, a n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, a sec-pentyl group, an iso-pentyl group, a cyclopentyl group, a n-hexyl group, a sec-hexyl group, an iso-hexyl group, a cyclohexyl group, a n-heptyl group, a cycloheptyl group, a n-octyl group, a n-decyl group, a 2-methylcyclopentyl group or a 2,6-dimethylcyclohexyl group;

[0017] The alkenyl group is a C1-C30 alkenyl groups, including specifically vinyl, allyl, 1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-2 butenyl, 2-methyl-1-butenyl, 3-methyl-2-butenyl, 5-hexenyl, 2-cyclohexenyl, 3-cyclohexenyl, or 2-methyl-2-cyclohexenyl;

[0018] said aromatic group is a C4-C 30 aryl groups and derivatives thereof, including specifically phenyl, p-fluorophenyl, o-fluorophenyl, m-fluorophenyl, p-chlorophenyl, o-chlorophenyl, m-chlorophenyl, 2,6-difluorophenyl, 2,5-difluorophenyl, 2,4-difluorophenyl, 2,3-difluorophenyl, 3,4-difluorophenyl, 3,5-difluorophenyl, 2,6-dichlorophenyl, 2,5-dichlorophenyl, 2,4-dichlorophenyl, 2,3-dichlorophenyl, 3,4-dichlorophenyl, 3,5-dichlorophenyl, p-ethylphenyl, o-ethylphenyl, m-ethylphenyl, 2,4-dimethylphenyl, 2,4-diisopropylphenyl, 2,4-di-t-butylphenyl, 2,6-dimethylphenyl, 2,6-diisopropylphenyl, 3,5-dimethylphenyl, 3,5-di-t-butylphenyl, 2,4,6-trimethylphenyl, naphthyl, anthryl, biphenyl, 7-fluoro-1-naphthyl, 8-fluoro-1-naphthyl, 7-chloro-1-naphthyl, 8-chloro-1-naphthyl, 9-fluoro-1-anthryl, 9-chloro-1-anthryl, 8-fluoro-1-anthryl, or 8-chloro-1-anthryl;

[0019] said halogen is fluorine, chlorine, bromine, or iodine, preferably fluorine, chlorine, or bromine.

[0020] The ligand compound is one of the following, but it is understood that the scope of the present application is not limited to these examples:

[0021]

[0022]

[0023]

[0024] The transition metal in the catalyst system of the present application can be a transition metal compound commonly used in the art, the metal atom in the transition metal compound is the metal active center, which plays an important role in the catalytic process.

[0025] Further, the transition metal in the transition metal compound is selected from iron, cobalt, nickel, copper, titanium, vanadium, chromium, manganese, molybdenum, tungsten, nickel, or palladium. More preferably, the transition metal in the transition metal compound is selected from chromium, specifically, any chromium compound that can enable oligomerization can be used, and the optional chromium compound includes a compound represented by the general formula CrR n in which Rn R is an organic anion or neutral molecule n R generally contains 1 to 15 carbon atoms, n is an integer from 0 to 6, and Cr has a valence of 0 to 6. Specific R n groups are organic compounds containing carboxyl, β-diketonate, and hydrocarbon groups or other groups. From the viewpoint of ease of solubility and ease of handling, more suitable chromium compounds include one of chromium trichloride-tris(tetrahydrofuran) complex, (benzene)tricarbonyl chromium, chromium (III) octoate, chromium hexacarbonyl, chromium (III) acetylacetonate, chromium (III) naphthenate, chromium (III) 2-ethylhexanoate, chromium (III) acetate, chromium (III) 2,2,6,6-tetramethylheptanedionate, and chromium (III) chloride. Preferably, the chromium compound is selected from the group consisting of chromium trichloride-tris(tetrahydrofuran) complex, chromium (III) acetylacetonate, and chromium (III) 2-ethylhexanoate.

[0026] The activator in the catalyst system of the present application functions to activate the catalyst system. The activator useful in the present application can be any compound that forms an active catalyst when mixed with a ligand and a transition metal compound. The activator can be used alone or in combination.

[0027] Further, the activator includes one or a mixture of an alkyl aluminum compound, an aluminoxane compound, or an organic boron compound.

[0028] Further, the activator includes one or a mixture of an alkyl aluminum compound, an aluminoxane compound, an organic boron compound, an inorganic acid, or an inorganic salt.

[0029] Specifically, the activator can be an alkyl aluminum compound, which can be various trialkylaluminums such as trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, or tri-n-octylaluminum; the alkyl aluminum compound can also be an alkyl aluminum halide, an alkyl aluminum hydride, or an alkyl aluminum sesquichloride such as dichlorodiethylaluminum (AlEt2Cl) and trichlorotriethylaluminum (Al2Et3Cl3).

[0030] Specifically, the activator can be an aluminoxane compound, which can be generally prepared by mixing water with an alkyl aluminum compound (e.g., trimethylaluminum). The prepared aluminoxane oligomer compound can be a straight chain compound, a cyclic compound, a cage compound, or a mixture thereof. Suitable aluminoxane compounds can be selected from the group consisting of methylaluminoxane (MAO), ethylaluminoxane, isobutylaluminoxane, modified aluminoxane, and DMAO (methylaluminoxane from which volatile components are removed), etc.

[0031] Specifically, suitable boron compounds can include boroxin, triethylborane, triphenylborane, tris(pentafluorophenyl)borane, etc. The organic boron compound can be used in a form mixed with an organic aluminum compound.

[0032] Preferably, the activator can be selected from methylaluminoxane (MAO), ethylaluminoxane, isobutylaluminoxane and modified methylaluminoxane (MMAO).

[0033] Further, the aluminoxane compound specifically includes modified methylaluminoxane MMAO-3A.

[0034] Further, the molar ratio of the ligand to the transition metal element in the transition metal compound is (0.01-100): 1, preferably (0.1-10): 1, more preferably (0.5-2): 1;

[0035] The molar ratio of the activator to the transition metal element in the transition metal compound is (1-10000): 1, preferably (1-2000): 1, more preferably (600-1000): 1, and most preferably (400-700): 1.

[0036] A method for preparing a catalyst for selective tetramerization of ethylene containing a bisphosphine ligand as described above, which method comprises mixing the ligand, the transition metal compound and the activator in advance or directly adding them to the reaction system for in-situ synthesis, thereby obtaining the catalyst for selective tetramerization of ethylene containing a bisphosphine ligand.

[0037] In some embodiments, the ligand of formula (I), the transition metal compound and the activator can be mixed simultaneously or in any order, with or without solvent, to provide an active catalyst. The mixing of the catalyst components can be carried out at -20 to 250°C, and the presence of olefin during the mixing of the catalyst components generally shows a protective effect, thereby providing improved catalytic performance. Further, the mixing of the catalyst components can be carried out at a temperature range of about 20-100°C.

[0038] In some embodiments, the isolatable metal-ligand complex can be prepared in-situ from the transition metal compound and the ligand of formula (I). The metal-ligand complex is then added to the reaction medium. Alternatively, the chromium compound and the ligand can be added separately to the reactor, thereby preparing the chromium-ligand complex in-situ. The in-situ preparation of the complex means that the complex is prepared in the medium in which the catalytic reaction takes place, and finally, the activator is added.

[0039] A use of a catalyst for selective tetramerization of ethylene containing a bisphosphine ligand as described above, which catalyst is used for the selective tetramerization of ethylene to produce 1-octene.

[0040] Further, the reaction is carried out in an inert solvent at a temperature of 0-200°C, preferably 10-120°C, more preferably 15-100°C, further preferably 20-80°C, and finally preferably 20-50°C, and at a pressure of 10-5000 psig, preferably 100-2000 psig, more preferably 300-1000 psig, and finally preferably 400-600 psig, and the concentration of the transition metal in the inert solvent is 0.01-10000 μmol / L, preferably 1-500 μmol / L, and more preferably 0.1-10 μmol / L.

[0041] Further, the inert solvent includes one or a mixture of several of alkanes, arenes, alkenes, or ionic liquids. Typical solvents include, but are not limited to, benzene, toluene, xylene, cumene, chlorobenzene, dichlorobenzene, fluorobenzene, n-heptane, n-hexane, methylcyclohexane, cyclohexane, 1-hexene, 1-octene, etc., and preferably toluene, methylcyclohexane.

[0042] Compared with the prior art, the present application has the following advantages:

[0043] (1) The present application creatively introduces adjustable alkyl and ortho-halogenated aryl into the ethenyl-bridged diphosphine ligand. By introducing alkyl with less steric hindrance and ortho-halogenated aryl, the present application successfully reduces the content of cyclic C6, improves the total selectivity of 1-hexene and 1-octene under the condition of ensuring high 1-octene selectivity. Since the electron-donating ability of alkyl is stronger than that of phenyl, the introduction of alkyl into the ligand increases the electron cloud density of the phosphorus atom, significantly increases the stability of the chromium metal active center, prolongs the catalyst life, and effectively improves the activity of the catalytic system. The improvement of catalyst life also reduces the degradation of the catalyst, and thus the content of polymer in the reaction can be reduced to as low as 0.02%;

[0044] (2) In the activator aspect, the present application uses modified methylaluminoxane modified in a special way, so that the catalyst system also achieves very high reactivity without the need to add water;

[0045] (3) The present application can further improve the selectivity of 1-octene by optimizing the process parameters. DETAILED DESCRIPTION

[0046] The following will give a detailed description of the embodiments of the present application, which are implemented on the premise of the technical solution of the present application, and give detailed implementation modes and specific operation processes, but the protection scope of the present application is not limited to the following embodiments.

[0047] Example 1

[0048] (1) Preparation of (2-F-Ph)2PCl

[0049] Magnesium powder (0.88 g, 36 mmol) was placed in a Schlenk reaction tube and tetrahydrofuran (10 mL) was added under nitrogen protection. Five drops of 1,2-dibromoethane was added dropwise to the solution. After 3 minutes of reaction, a solution of o-bromofluorobenzene (5.25 g, 30 mmol) in tetrahydrofuran (40 mL) was slowly added at 0 °C. After 1 hour of reaction, a gray-black o-fluorophenyl magnesium bromide (30 mmol) tetrahydrofuran solution was obtained by filtration. Phosphorus trichloride (2.06 g, 15 mmol) was dissolved in tetrahydrofuran (10 mL) and cooled to -78 °C. The above prepared o-fluorophenyl magnesium bromide (30 mmol) tetrahydrofuran solution (50 mL) was slowly added to the solution. After the dropwise addition was completed, the solution was slowly warmed to room temperature and stirred for 5 hours. After the reaction was completed, the solvent was removed by suction. The product was obtained as a light yellow oil after dissolution in ethyl ether (40 mL), anhydrous and anaerobic filtration, and solvent removal by suction.

[0050] (2) Preparation of (2-F-Ph)2PH

[0051] (2-F-Ph)2PCl (2.6 g, 10 mmol) was added dropwise to a solution of lithium aluminum hydride (152.0 mg, 4 mmol) in diethyl ether (15 mL) at -78 °C and stirred for 30 minutes. The mixture was then warmed to room temperature and stirred overnight. The mixture was then suctioned to remove the solvent. The crude product was obtained as an oil after dissolution in n-hexane (10 mL) and diethyl ether (3 mL), filtration, and suctioning to remove the solvent under reduced pressure.

[0052] (3) Preparation of the ligand L 1

[0053] In an argon-filled 50 mL Schlenk flask, tert-butyl acetylene (821.4 mg, 10.0 mmol) and 10 mL of freshly distilled tetrahydrofuran were added, stirred, and cooled to 0 °C. N-butyllithium (4.00 mL, 2.5 M hexane solution, 10.0 mmol) was slowly added to the solution, which was stirred at this temperature for 30 minutes. Then, Et2PCl (1.2 g, 10.0 mmol) was added dropwise, and the mixture was warmed to ambient temperature and stirred for 1 hour. After removing the volatiles under vacuum, the mixture was extracted with petroleum ether (30 mL). The resulting mixture was then filtered to remove insoluble salts, and the filtrate was dried under vacuum and purified by silica gel column chromatography to obtain the product as a white solid (1.67 g, 98.0%).

[0054] ​In a Schlenk tube filled with argon, the above white solid product (595.4 mg, 3.5 mmol), cuprous iodide (34.0 mg, 0.2 mmol), cesium carbonate (114.0 mg, 0.4 mmol) and dry and degassed DMF (15 mL) were added, stirred, and finally the (2-F-Ph)2H crude product (777.1 mg) was added. The resulting mixture was stirred at 90 °C for 6 h. After cooling to room temperature, water (20 mL) was added, and the product was extracted with ethyl acetate (15 mL x 3). The combined organic layers were dried over magnesium sulfate and concentrated under reduced pressure to remove the solvent, and the resulting residue was purified by silica gel column separation to obtain the product L 1 (439.2 mg, 32.0%). 1 H NMR (400 MHz, CDC13) δ 0.96-1.13 (m, 6H), 1.32-1.58 (m, 9H), 1.48-1.63 (m, 4H), 6.23-6.29 (m, 1H), 7.19-7.39 (m, 6H), 7.61-7.65 (m, 2H).

[0055]

[0056] (4) Preparation of complex 1

[0057] In a dry and argon-filled Schlenk reaction tube, ligand L 1 (196.1 mg, 0.5 mmol) and CrCl3(THF)3(187.3 mg, 0.5 mmol) were added, and dichloromethane (10 mL) was added thereto, and stirred at room temperature for 2 h. After the reaction was completed, it was filtered, the filtrate was dried, washed with n-hexane (5 mL x 3), and dried to obtain a blue powder 236.1 mg (0.43 mmol, 86.0%).

[0058] Example 2

[0059] (1) Preparation of (2-F-Ph)(Ph)PCl

[0060] Phosphorus dichloride (1.25 g, 7 mmol) was dissolved in tetrahydrofuran (10 mL) and cooled to -78 °C, and the above prepared o-fluorophenyl magnesium bromide (7 mmol) tetrahydrofuran solution (10 mL) was slowly added thereto, and after the dropwise addition was completed, it was slowly warmed to room temperature and stirred for 5 h, and the reaction was completed, the solvent was dried, dissolved in diethyl ether (40 mL), and filtered under anhydrous and anaerobic conditions, and the solvent was dried to obtain the product as a light yellow oil.

[0061] (2) Preparation of (2-F-Ph)(Ph)PH

[0062] (2-F-Ph)(Ph)PCI (2.4 g, 10 mmol) was added dropwise to a solution of lithium tetrahydroaluminate (152.0 mg, 4 mmol) in diethyl ether (15 mL) at -78 °C and stirred for 30 min, then warmed to room temperature and stirred overnight. The mixture was then solvent-stripped, and then dissolved in n-hexane (10 mL) and diethyl ether (3 mL), filtered to give a filtrate which was solvent-stripped under reduced pressure to give an oily crude product which was used directly in the next step.

[0063] (3) Preparation of ligand L 2

[0064] In an argon-filled 50 mL Schlenk flask, tert-butyl acetylene (821.4 mg, 10.0 mmol) and 10 mL of freshly distilled tetrahydrofuran were added, stirred and cooled to 0 °C, and n-butyllithium (4.00 mL, 2.5 M in hexane, 10.0 mmol) was slowly added to the solution, which was stirred at this temperature for 30 min. Then Et2PCI (1.2 g, 10.0 mmol) was added dropwise, and the mixture was warmed to ambient temperature and stirred for 1 h. After removing the volatiles under vacuum, the mixture was extracted with petroleum ether (30 mL). The resulting mixture was then filtered to remove insoluble salts, and the filtrate was dried under vacuum and purified by column chromatography on silica gel to give a white solid product (1.67 g, 98.0%).

[0065] In an argon-filled Schlenk tube, the above white solid product (595.4 mg, 3.5 mmol), cuprous iodide (34.0 mg, 0.2 mmol), cesium carbonate (114.0 mg, 0.4 mmol) and dry and degassed DMF (15 mL) were added, stirred, and finally the crude product of (2-F-Ph)(Ph)PH (714.2 mg) was added. The resulting mixture was stirred at 90 °C for 6 h. After cooling to room temperature, water (20 mL) was added, and the product was extracted with ethyl acetate (15 mL x 3). The combined organic layers were dried over magnesium sulfate and concentrated under reduced pressure to remove the solvent, and the resulting residue was purified by column chromatography on silica gel to give the product L as a colorless oil (353.6 mg, 27.0%). 2 1 H NMR (400 MHz, CDC13) δ 0.85-1.06 (m, 6H), 1.22-1.46 (m, 9H), 1.82-1.99 (m, 4H), 6.46-6.58 (m, 1H), 7.25-7.48 (m, 8H), 7.70-7.75 (m, 1H).

[0066]

[0067] (4) Preparation of complex 2

[0068] ​​In a dry and argon-filled Schlenk tube, ligand L 2 (187.1 mg, 0.5 mmol) and CrCl3(THF)3(187.3 mg, 0.5 mmol) was added to which was added distilled dichloromethane (10 mL) and stirred at room temperature for 2 h. After the reaction was completed, it was filtered, the filtrate was dried, and the solid was washed with n-hexane (5 mL x 3) and dried to obtain a blue powder 201.8 mg (0.38 mmol, 76.0%).

[0069] Example 3

[0070] (1) Preparation of ligand L 3

[0071] Reference ligand L 2 The preparation method of reference ligand L was used, and cyclohexylethynyl (1.1 g, 10.0 mmol) was used instead of tert-butylethynyl to obtain the product L 3 (539.3 mg, 38.5%). 1 H NMR (400 MHz, CDC13) δ 0.90-1.20 (m, 6H), 1.23-1.68 (m, 14H), 2.12-2.22 (m, 1H), 5.90-6.03 (m, 1H), 7.20-7.49 (m, 5H), 7.55-7.68 (m, 4H).

[0072]

[0073] (2) Preparation of complex 3

[0074] In a dry and argon-filled Schlenk tube, ligand L 3 (200.1 mg, 0.5 mmol) and CrCl3(THF)3(187.3 mg, 0.5 mmol) was added to which was added distilled dichloromethane (10 mL) and stirred at room temperature for 2 h. After the reaction was completed, it was filtered, the filtrate was dried, and the solid was washed with n-hexane (5 mL x 3) and dried to obtain a blue powder 231.2 mg (0.42 mmol, 83.0%).

[0075] Example 4

[0076] (1) Preparation of (Ph)(Et)PCl

[0077] ​In a dry 50 mL Schlenk tube, phenylphosphorous dichloride (1.79 g, 10 mmol) was added and dissolved in 10 mL of THF, then the solution was cooled to -78 °C, ethylmagnesium chloride (10.0 mL, 1.0 M in THF, 10 mmol) was added slowly, after the addition was completed, the reaction was continued at this temperature for 30 min, then it was raised to room temperature for 8 h. The reaction was used directly without purification.

[0078] (2) Preparation of ligand L 4

[0079] Reference ligand L 2 was prepared according to the procedure of ligand L, using (Ph)(Et)PCI (3.6 mmol) instead of diethylphosphorous chloride to give product L as a colorless solid. 4 (552.2 mg, 35.2 %). 1 H NMR (CDC13) δ 0.90-1.02 (m, 3H), 1.12-1.68 (m, 12H), 2.23-2.32 (m, 1H), 5.02-5.22 (m, 1H), 7.25-7.42 (m, 7H), 7.45-7.59 (m, 7H).

[0080]

[0081] (3) Preparation of complex 4

[0082] In a dry Schlenk tube purged and filled with argon, ligand L 4 (224.1 mg, 0.5 mmol) and CrCl3(THF)3(187.3 mg, 0.5 mmol) were added, and then the reaction was stirred at room temperature for 2 h. After the reaction was completed, the mixture was filtered, and the filtrate was dried under vacuum to give a solid, which was washed with n-hexane (5 mL x 3) and dried under vacuum to give a blue powder 272.3 mg (0.45 mmol, 90.0 %).

[0083] Example 5

[0084] (1) Preparation of ligand L 5

[0085] ​​In a 50 mL Schlenk flask purged and maintained with argon, cyclohexylethynyl (1.1 g, 10.0 mmol) and 10 mL of freshly distilled tetrahydrofuran were added, stirred and cooled to 0 °C, n-butyllithium (4.00 mL, 2.5 M in hexane, 10.0 mmol) was slowly added to the solution, stirred at this temperature for 30 min. Then (2-F-Ph)(Ph)PCl (2.4 g, 10.0 mmol) was added dropwise, and the mixture was warmed to ambient temperature and stirred for 1 h. After removal of the volatiles in vacuo, the mixture was extracted with petroleum ether (30 mL). The resulting mixture was then filtered to remove insoluble salts, the filtrate was dried in vacuo, and purified by column chromatography on silica gel to give the product as a white solid (2.8 g, 90.0%).

[0086] In a Schlenk tube purged and maintained with argon, the above white solid product (1.1 g, 3.5 mmol), cuprous iodide (34.0 mg, 0.2 mmol), cesium carbonate (114.0 mg, 0.4 mmol) and dry and degassed DMF (15 mL) were added, stirred, and finally diethyl phosphine (360.4 mg, 4.0 mmol) was added. The resulting mixture was stirred at 90 °C for 6 h. After cooling to room temperature, water (20 mL) was added, and the product was extracted with ethyl acetate (15 mL x 3). The combined organic layers were dried over magnesium sulfate and concentrated under reduced pressure to remove the solvent, and the resulting residue was purified by column chromatography on silica gel to give the product L 5 (714.3 mg, 51.0%). 1 H NMR (400 MHz, CDC13) δ = 0.91-1.13 (m, 6H), 1.48-1.54 (m, 14H), 2.12-2.18 (m, 1H), 5.25-5.37 (dd, 1H), 7.11-7.27 (m, 5H), 7.39-7.49 (m, 3H), 7.51-7.61 (m, 1H).

[0087]

[0088] (2) Preparation of complex 5

[0089] In a dry and argon-purged Schlenk reaction tube, ligand L 5 (200.1 mg, 0.5 mmol) and CrCl3(THF)3(187.3 mg, 0.5 mmol) were added, to which was added freshly distilled dichloromethane (10 mL), stirred at room temperature for 2 h. After the reaction was completed, it was filtered, the filtrate was dried under suction, and the solid was washed with n-hexane (5 mL x 3) and dried under suction to give a blue powder 221.4 mg (0.40 mmol, 79.5%).

[0090] Example 6

[0091] (1) Preparation of ligand L 6

[0092] Reference ligand L 3 i Pr2PCl (1.5 g, 10.0 mmol) instead of Et2PCl to give product L as colorless oil 6 (583.8 mg, 39.2%). 1 H NMR (400 MHz, CDC13) δ 0.90-1.10 (m, 12H), 1.21-1.63 (m, 12H), 2.10-2.20 (m, 1H), 5.91-6.07 (m, 1H), 7.09-7.39 (m, 5H), 7.39-7.45 (m, 3H), 7.57-7.63 (m, 1H).

[0093]

[0094] (2) Preparation of complex 6

[0095] In a dry and argon-filled Schlenk tube, ligand L 6 (214.2 mg, 0.5 mmol) and CrCl3(THF)3(187.3 mg, 0.5 mmol) were added, and dichloromethane (10 mL) was added thereto, and stirred at room temperature for 2 h. After the reaction was completed, it was filtered, the filtrate was dried, washed with n-hexane (5 mL x 3), and dried to obtain a blue powder 250.9 mg (0.43 mmol, 85.5%).

[0096] Example 7

[0097] (2) Preparation of ligand L 7

[0098] Reference ligand L 3 7 (553.6 mg, 40.1%). 1 H NMR (400 MHz, CDC13) δ 0.92-1.11 (m, 6H), 1.23-1.62 (m, 4H), 5.92-6.09 (m, 1H), 7.07-7.25 (m, 5H), 7.35-7.45 (m, 8H), 7.56-7.64 (m, 1H).

[0099]

[0100] ​​​​(2) Preparation of complex 7

[0101] In a dry and argon-filled Schlenk tube, ligand L 7 (197.2 mg, 0.5 mmol) and CrCl3(THF)3(187.3 mg, 0.5 mmol) were added, and dichloromethane (10 mL) was added thereto, and stirred at room temperature for 2 h. After the reaction was completed, it was filtered, the filtrate was dried, washed with n-hexane (5 mL x 3), and dried to obtain a blue powder 210.3 mg (0.38 mmol, 76.1%).

[0102] Example 8

[0103] (1) Preparation of allyl phenyl phosphorus chloride

[0104] Allyl dichlorophosphine (0.90 g, 7 mmol) was dissolved in tetrahydrofuran (10 mL) and cooled to -78°C, and phenyl magnesium bromide (3.5 mL, 2M tetrahydrofuran solution, 7 mmol) was slowly added thereto, and after the dropwise addition was completed, it was slowly raised to room temperature and stirred for 5 hours, and the reaction was completed, the solvent was dried, dissolved in diethyl ether (40 mL), and filtered under anhydrous and anaerobic conditions, and the solvent was dried to obtain a yellowish oil product.

[0105] (2) Preparation of ligand L 8

[0106] Reference ligand L 3 was prepared according to the preparation method of ligand L 8 (643.8 mg, 41.2%). 1 H NMR (400 MHz, CDC13) δ 1.21-1.63 (m, 10H), 2.01-2.21 (m, 1H), 5.01-5.17 (m, 1H), 5.21-5.43 (m, 3H), 7.12-7.26 (m, 7H), 7.42-7.54 (m, 6H), 7.61-7.69 (m, 1H).

[0107]

[0108] (3) Preparation of complex 8

[0109] In a dry and argon-filled Schlenk tube, ligand L 8 ​To the mixture was added redistilled dichloromethane (10 mL), and the mixture was stirred at room temperature for 2 h. After the reaction, the mixture was filtered and the filtrate was drained. The resulting solid was washed with n-hexane (5 mL x 3) and dried to give 196.9 mg (0.32 mmol, 65.1%) of a blue powder.

[0110] Example 9

[0111] (1)(2-F-4- t Preparation of Bu-Ph)(Ph)PCl

[0112] Phenylphosphonium dichloride (1.25 g, 7 mmol) was dissolved in tetrahydrofuran (10 mL) and cooled to -78°C. (2-Fluoro-4-tert-butyl)phenylmagnesium bromide (3.5 mL, 2 M tetrahydrofuran solution, 7 mmol) was slowly added thereto. After the addition was complete, the temperature was slowly raised to room temperature and stirred for 5 hours. After the reaction was complete, the solvent was drained, the product was dissolved in ether (40 mL), filtered in anhydrous and oxygen-free conditions, and the solvent was drained to obtain a light yellow oily product.

[0113] (2)(2-F-4- t Preparation of Bu-Ph)(Ph)PH

[0114] -78℃ t Bu-Ph)(Ph)PCl (2.9 g, 10 mmol) was added dropwise to a solution of lithium aluminum tetrahydride (152.0 mg, 4 mmol) in diethyl ether (15 mL) and stirred for 30 minutes. The mixture was then heated to room temperature and stirred overnight. The solvent was removed from the mixture, and then n-hexane (10 mL) and diethyl ether (3 mL) were added to dissolve the mixture. The filtrate was filtered and dried under reduced pressure to obtain an oily crude product, which was used directly in the next step.

[0115] (3) Ligand L 9 Preparation

[0116] Reference ligand L 3 The preparation method is to use the above crude oily product (1.7 g, 10.0 mmol) instead of (2-F-Ph)(Ph)PH to obtain a colorless oily product L 9 (488.9mg, 30.6%). 1 H NMR (400MHz, CDCl3) δ0.91-1.03(m,6H),1.29-1.59(m,23H),2.01-2.13(m,1H),5.81-5.94(m,1H),7.01-7.16(m,5H),7.42-7.54(m,3H).

[0117]

[0118] (3) Preparation of complex 9

[0119] In a dry and argon-filled Schlenk tube, ligand L 9 (228.3mg, 0.5mmol) and CrCl3(THF)3(187.3mg, 0.5mmol) were added, and dichloromethane (10 mL) was added thereto, and stirred at room temperature for 2h. After the reaction was completed, it was filtered, the filtrate was dried, washed with n-hexane (5 mL x 3), and dried to obtain a blue powder 184.8mg (0.30mmol, 60.1%).

[0120] Example 10

[0121] (1) Preparation of diallyl phosphorus chloride

[0122] Phosphorus trichloride (0.96g, 7mmol) was dissolved in tetrahydrofuran (10mL) and cooled to -78℃, and allyl magnesium bromide (7mL, 2M tetrahydrofuran solution, 14mmol) was slowly added thereto, and after the dropwise addition was completed, it was slowly raised to room temperature and stirred for 5 hours, and the reaction was completed, and the solvent was dried, dissolved in diethyl ether (40mL), and filtered under anhydrous and anaerobic conditions, and the solvent was dried to obtain a yellowish oil product.

[0123] (2) Preparation of ligand L 10

[0124] Reference to the preparation method of ligand L 3 , the above yellowish oil liquid (1.7g, 10.0mmol) was used instead of Et2PCl to obtain a colorless oil product L 10 (776.5mg, 56.0%). 1 H NMR (400MHz, CDC13) δ 1.20-1.61 (m, 10H), 2.01-2.23 (m, 1H), 5.52-5.64 (m, 4H), 5.89-5.97 (m, 1H), 6.11-6.23 (m, 2H), 7.11-7.27 (m, 5H), 7.40-7.47 (m, 3H), 7.61-7.65 (m, 1H).

[0125]

[0126] (3) Preparation of complex 10

[0127] In a dry and argon-filled Schlenk tube, ligand L 9 ​(198.2 mg, 0.5 mmol) and CrCl3(THF)3(187.3 mg, 0.5 mmol), to which was added redistilled dichloromethane (10 mL) and stirred at room temperature for 2 h. After the reaction was completed, it was filtered, the filtrate was evaporated to dryness, and the solid was washed with n-hexane (5 mL x 3) and evaporated to dryness to give a blue powder 124.8 mg (0.22 mmol, 45.0%).

[0128] Example 11

[0129] (1) Preparation of (2,4-2F-Ph)(Ph)PCl

[0130] Phosphorus dichloride (1.25 g, 7 mmol) was dissolved in tetrahydrofuran (10 mL) and cooled to -78°C, to which was slowly added (2,4-difluoro)phenylmagnesium bromide (3.5 mL, 2M tetrahydrofuran solution, 7 mmol), after the dropwise addition was completed, it was slowly warmed to room temperature and stirred for 5 hours, the reaction was complete, the solvent was evaporated, dissolved in diethyl ether (40 mL), filtered under anhydrous and anaerobic conditions, and the solvent was evaporated to give a yellowish oily product.

[0131] (2) Preparation of (2,4-2F-Ph)(Ph)PH

[0132] (2,4-2F-Ph)(Ph)PCl (2.6 g, 10 mmol) was added dropwise to a solution of lithium aluminum hydride (152.0 mg, 4 mmol) in diethyl ether (15 mL) at -78°C and stirred for 30 minutes, then warmed to room temperature and stirred overnight, the mixture was evaporated to dryness, then dissolved in n-hexane (10 mL) and diethyl ether (3 mL), filtered to give a filtrate which was evaporated to dryness under reduced pressure to give an oily crude product which was used directly in the next step.

[0133] (3) Preparation of Ligand L 11

[0134] Reference Ligand L 3 The preparation method of Ligand L was used, and the above oily crude product (2.2 g, 10.0 mmol) was used instead of (2-F-Ph)(Ph)PH to give a colorless oily product L 11 (622.4 mg, 42.5%). 1 H NMR (400 MHz, CDCl3) δ 0.90-1.03 (m, 6H), 1.23-1.51 (m, 14H), 2.03-2.13 (m, 1H), 5.85-5.93 (m, 1H), 6.71-6.79 (m, 1H), 7.11-7.29 (m, 4H), 7.42-7.51 (m, 3H).

[0135] ​

[0136] (3) Preparation of complex 11

[0137] In a dry and argon-filled Schlenk reactor, ligand L 11 (209.2mg, 0.5mmol) and CrCl3(THF)3(187.3mg, 0.5mmol) were added, and then dichloromethane (10 mL) was added. The mixture was stirred at room temperature for 2 h. After the reaction was completed, the mixture was filtered, and the filtrate was dried under vacuum to obtain a solid. The solid was washed with n-hexane (5 mL x 3) and dried under vacuum to obtain blue powder 101.5 mg (0.18 mmol, 35.2%).

[0138] Example 12

[0139] (1) Preparation of ligand L 12

[0140] In a 50 mL argon-filled Schlenk flask, cyclohexylethynyl (1.1 g, 10.0 mmol) and 10 mL of freshly distilled tetrahydrofuran were added, stirred and cooled to 0°C, and n-butyllithium (4.00 mL, 2.5 M hexane solution, 10.0 mmol) was slowly added to the solution, which was stirred at this temperature for 30 minutes. Then Et2PCl (1.2 g, 10.0 mmol) was added dropwise, and the mixture was warmed to ambient temperature and stirred for 1 hour. After removing the volatiles under vacuum, the mixture was extracted with petroleum ether (30 mL). Then the resulting mixture was filtered to remove insoluble salts, and the filtrate was dried under vacuum and purified by silica gel column separation to obtain white solid product (1.92 g, 98.0%).

[0141] In an argon-filled Schlenk tube, the above white solid product (686.5 mg, 3.5 mmol), cuprous iodide (34.0 mg, 0.2 mmol), cesium carbonate (114.0 mg, 0.4 mmol) and dry and degassed DMF (15 mL) were added, stirred, and finally diphenylphosphine (0.7 g, 3.9 mmol) was added. The resulting mixture was stirred at 90°C for 6 hours. After cooling to room temperature, water (20 mL) was added, and the product was extracted with ethyl acetate (15 mL x 3). The combined organic layers were dried over magnesium sulfate and concentrated under reduced pressure to remove the solvent, and the resulting residue was purified by silica gel column separation to obtain white solid product L 12 (0.43 g, 32.0%). 1 H NMR (400 MHz, CDC13) δ = 7.45-7.40 (m, 6H), 7.20-7.15 (m, 4H), 6.00 (d, J = 29.4 Hz, 1H), 1.58-1.50 (m, 4H), 1.50-1.36 (m, 11H), 0.93-0.90 (m, 6H).​

[0142]

[0143] (2) Preparation of complex 12

[0144] In a dry and argon-filled Schlenk tube, ligand L 12 (191.1 mg, 0.5 mmol) and CrCl3(THF)3(187.3 mg, 0.5 mmol) were added, and heavy dichloromethane (10 mL) was added thereto, and stirred at room temperature for 2 h. After the reaction was completed, it was filtered, the filtrate was dried, and the solid was washed with n-hexane (5 mL x 3), and dried to obtain a blue powder 268.9 mg (0.44 mmol, 87.0%).

[0145] Example 13

[0146] (1) Preparation of ligand L 13

[0147] Reference ligand L 3 was prepared according to the preparation method of ligand L 13 (703.3 mg, 40.5%). 1 H NMR (400 MHz, CDC13) δ = 1.24-1.48 (m, 10H), 2.12-2.18 (m, 1H), 5.25-5.37 (dd, 1H), 7.12-7.28 (m, 9H), 7.35-7.47 (m, 9H), 7.51-7.61 (m, 1H).

[0148]

[0149] (2) Preparation of complex 13

[0150] In a dry and argon-filled Schlenk tube, ligand L 13 (248.1 mg, 0.5 mmol) and CrCl3(THF)3(187.3 mg, 0.5 mmol) were added, and heavy dichloromethane (10 mL) was added thereto, and stirred at room temperature for 2 h. After the reaction was completed, it was filtered, the filtrate was dried, and the solid was washed with n-hexane (5 mL x 3), and dried to obtain a blue powder 268.9 mg (0.44 mmol, 87.0%).

[0151] Example 14

[0152] (1) Preparation of catalyst

[0153] ​In a dry and argon filled Schlenk tube, complex 1 (0.40 mg, 0.8 μmol) and anhydrous methylcyclohexane (20 ml) were added, stirred for 5 min and then MMAO-3A (0.4 mmol, 1.12 mol / L) was added. The mixture was stirred for 5 min at room temperature and then used as such.

[0154] (2) Ethylene oligomerization reaction

[0155] A 350 mL stainless steel high pressure gas reactor was evacuated for 3 hours on an oil bath at 120 °C to ensure an anhydrous and oxygen free environment, then cooled to the reaction temperature and purged three times with ethylene gas. The catalyst solution prepared above was immediately injected into the reactor using a dry glass syringe. The reactor was sealed, the stirring was started and the ethylene gas was introduced and the pressure was adjusted to 500 psig. The reaction was carried out at 40 °C for 30 min. After the reaction was completed, the ethylene supply valve was closed, the reactor was cooled to 0 °C, depressurized and opened. A known amount of internal standard, n-decane, was added and stirred well. The reaction was quenched with about 30 mL of 10 wt% aqueous HC1 solution. A small amount of the organic phase was filtered and analyzed by GC. The remaining mixture in the reactor was filtered and the solid was added to 10 wt% aqueous HC1 solution and stirred for 2 hours. The solid was filtered, oven dried to constant weight and weighed. The data are shown in Table 1.

[0156] Example 15

[0157] The difference from Example 14 is that complex 1 was replaced by complex 2 (0.42 mg, 0.8 μmol). The data are shown in Table 1.

[0158] Example 16

[0159] The difference from Example 14 is that complex 1 was replaced by complex 3 (0.45 mg, 0.8 μmol). The data are shown in Table 1.

[0160] Example 17

[0161] The difference from Example 14 is that complex 1 was replaced by complex 4 (0.48 mg, 0.8 μmol). The data are shown in Table 1.

[0162] Example 18

[0163] The difference from Example 14 is that complex 1 was replaced by complex 5 (0.48 mg, 0.8 μmol). The data are shown in Table 1.

[0164] Example 19

[0165] The difference from Example 14 is that complex 1 was replaced by complex 6 (0.48 mg, 0.8 μmol). The data are shown in Table 1.

[0166] Example 20

[0167] The difference with example 14 is that complex 1 is replaced by complex 7 (0.48 mg, 0.8 μmol), the data are reported in table 1.

[0168] Example 21

[0169] The difference with example 14 is that complex 1 is replaced by complex 8 (0.48 mg, 0.8 μmol), the data are reported in table 1.

[0170] Example 22

[0171] The difference with example 14 is that complex 1 is replaced by complex 9 (0.48 mg, 0.8 μmol), the data are reported in table 1.

[0172] Example 23

[0173] The difference with example 14 is that complex 1 is replaced by complex 10 (0.48 mg, 0.8 μmol), the data are reported in table 1.

[0174] Example 24

[0175] The difference with example 14 is that complex 1 is replaced by complex 11 (0.48 mg, 0.8 μmol), the data are reported in table 1.

[0176] Example 25

[0177] The difference with example 16 is that the ethylene oligomerization reaction is carried out at 20°C, the data are reported in table 1.

[0178] Example 26

[0179] The difference with example 16 is that the ethylene oligomerization reaction is carried out at 60°C, the data are reported in table 1.

[0180] Example 27

[0181] The difference with example 16 is that the amount of MMAO-3A is 0.32 mmol, the data are reported in table 1.

[0182] Example 28

[0183] The difference with example 16 is that the amount of MMAO-3A is 0.56 mmol, the data are reported in table 1.

[0184] Example 29

[0185] The difference with example 16 is that the reaction pressure for the ethylene oligomerization is 400 psig, the data are reported in table 1.

[0186] Example 30

[0187] The difference between Example 16 and Example 30 is that the reaction pressure of ethylene oligomerization is 300 psig, and the data are shown in Table 1.

[0188] Comparative Example 1

[0189] The difference between Example 16 and Comparative Example 1 is that the complex 3 used is replaced by complex 12 (0.43 mg, 0.8 μmol), and the data are shown in Table 1.

[0190] Comparative Example 2

[0191] The difference between Example 16 and Comparative Example 2 is that the complex 3 used is replaced by complex 13 (0.52 mg, 0.8 μmol), and the data are shown in Table 1.

[0192] Table 1

[0193]

[0194]

[0195] As can be seen from Table 1, the catalyst provided by the present application has high catalytic activity, which can reach 6280 Kg / g Cr / h at the highest, and the selectivity of 1-octene reaches 75.1%, which can reach 80.2% at the highest. By comparing Example 16 and Comparative Example 1, it can be seen that the introduction of fluorine atoms at the ortho position of the phenyl group can effectively reduce the content of cyclic C6, effectively improve the total selectivity of 1-hexene and 1-octene, and the introduction of fluorine atoms at the ortho position of the phenyl group can significantly improve the catalytic activity. By comparing Example 16 and Comparative Example 2, it can be seen that the introduction of alkyl groups with smaller steric hindrance can effectively improve the selectivity of 1-octene. In addition, since the electron-donating ability of alkyl group is stronger than that of phenyl group, the introduction of alkyl group in the ligand increases the electron cloud density of phosphorus atom, which can significantly increase the stability of chromium metal active center, prolong the service life of the catalyst, and effectively improve the activity of the catalytic system. The improvement of the service life of the catalyst also reduces the degradation of the catalyst, thereby reducing the content of the polymer in the reaction to 0.04-0.02%.

[0196] The above description is only the preferred embodiment of the present application, and does not limit other forms of the present application. Any person skilled in the art can use the disclosed technical content to make changes or modifications to equivalent embodiments. However, any simple modification, equivalent change and modification made to the above embodiments without departing from the technical solution of the present application, and according to the technical essence of the present application, still belongs to the protection scope of the technical solution of the present application.

Claims

1. A catalyst for selective tetramerization of ethylene containing a bisphosphine ligand, characterized in that: The catalyst comprises a ligand, a transition metal compound and an activator, wherein the chemical structure of the ligand is shown in the following formula (I): Where, Group R 1 and R 2 are each independently selected from hydrogen, an alkyl group, an ester group, or an aromatic group; Group R 3 to R 5 are each independently selected from an alkyl group, an alkoxy group, an alkenyl group or an aromatic group, and R 3 to R 5 Not all aromatic groups; Group R 6 to R 9 are each independently selected from hydrogen, halogen, alkyl, alkoxy, alkenyl or aromatic groups; R 3 to R 5 At least one is an alkyl group or an alkenyl group; The alkyl group is C1-C 30 The alkyl group specifically includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, cyclopentyl, n-hexyl, sec-hexyl, isohexyl, cyclohexyl, n-heptyl, cycloheptyl, n-octyl, n-decyl, 2-methylcyclopentyl or 2,6-dimethylcyclohexyl; The alkenyl group is C1-C 30 The alkenyl group specifically includes vinyl, allyl, 1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-2-butenyl, 2-methyl-1-butenyl, 3-methyl-2-butenyl, 5-hexenyl, 2-cyclohexenyl, 3-cyclohexenyl or 2-methyl-2-cyclohexenyl; The aromatic group is C4-C 30 Aryl and its derivatives, specifically including phenyl, p-fluorophenyl, o-fluorophenyl, m-fluorophenyl, p-chlorophenyl, o-chlorophenyl, m-chlorophenyl, 2,6-difluorophenyl, 2,5-difluorophenyl, 2,4-difluorophenyl, 2,3-difluorophenyl, 3,4-difluorophenyl, 3,5-difluorophenyl, 2,6-dichlorophenyl, 2,5-dichlorophenyl, 2,4-dichlorophenyl, 2,3-dichlorophenyl, 3,4-dichlorophenyl, 3,5-dichlorophenyl, p-ethylphenyl, o-ethylphenyl, m-ethylphenyl phenyl, 2,4-dimethylphenyl, 2,4-diisopropylphenyl, 2,4-di-tert-butylphenyl, 2,6-dimethylphenyl, 2,6-diisopropylphenyl, 3,5-dimethylphenyl, 3,5-di-tert-butylphenyl, 2,4,6-trimethylphenyl, naphthyl, anthracenyl, biphenyl, 7-fluoro-1-naphthyl, 8-fluoro-1-naphthyl, 7-chloro-1-naphthyl, 8-chloro-1-naphthyl, 9-fluoro-1-anthracenyl, 9-chloro-1-anthracenyl, 8-fluoro-1-anthracenyl or 8-chloro-1-anthracenyl; The halogen is fluorine, chlorine, bromine or iodine; The transition metal in the transition metal compound is selected from iron, cobalt, nickel, copper, titanium, vanadium, chromium, manganese, molybdenum, tungsten, nickel or palladium; The activator includes an alkyl aluminum compound, an aluminoxane compound or an organic boron compound.

2. The catalyst for selective tetramerization of ethylene containing a bisphosphine ligand according to claim 1, wherein: The aluminoxane compound specifically includes modified methylaluminoxane MMAO-3A.

3. The catalyst for selective tetramerization of ethylene containing a bisphosphine ligand according to claim 1, wherein: The molar ratio of the ligand to the transition metal element in the transition metal compound is (0.01-100):1; The molar ratio of the activator to the transition metal element in the transition metal compound is (1-10000):

1.

4. A method for preparing a catalyst for selective tetramerization of ethylene containing a bisphosphine ligand according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: pre-mixing a ligand, a transition metal compound and an activator or directly adding them into a reaction system for in-situ synthesis, thereby obtaining a catalyst for selective tetramerization of ethylene containing a diphosphine ligand.

5. Use of a catalyst for selective tetramerization of ethylene containing a bisphosphine ligand as claimed in any one of claims 1 to 3, characterized in that: The catalyst is used for the selective tetramerization of ethylene to produce 1-octene.

6. Use of a catalyst for selective tetramerization of ethylene containing a bisphosphine ligand according to claim 5, characterized in that: The reaction is carried out in an inert solvent at a temperature of 0-200° C., a pressure of 10-5000 psig, and a concentration of the transition metal in the transition metal compound in the inert solvent of 0.01-10000 μmol / L. The inert solvent includes one or more of alkanes, aromatic hydrocarbons, alkenes or ionic liquids.

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