Rigid skeleton bridged metallocene-fluorene metal compound and preparation method thereof

Abstract

The invention relates to the technical field of catalysts, and provides a rigid skeleton bridged metallocene-fluorene metal compound and a preparation method thereof.The rigid skeleton bridged metallocene-fluorene metal compound adopts a rigid skeleton structure with larger steric hindrance and an alkoxy-alkoxy group with electron donating ability is introduced to a fluorene ring, the inactivation reaction of the compound is effectively prevented, and the service life of the compound is prolonged; the cocatalyst has higher high-temperature resistance and longer service life, the stability of the active center of the compound activated by the cocatalyst can be improved, and the activity is still kept for a longer time. When the rigid skeleton bridged metallocene-fluorene metal compound provided by the invention is used as a catalyst in olefin polymerization, a chain transfer reaction can be inhibited, so that a polymer with higher molecular weight is prepared.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to a rigid skeleton bridged cyclopentadienyl-fluorene metal compound and a preparation method thereof. Background Art

[0002] In olefin polymerization, metallocene catalysts are often used to prepare polyethylenes of different molecular weights, different densities, and different molecular weight distributions, such as patent applications CN111295400A, CN113748141A, CN115003707A, and CN113748141A, which use metallocene-fluorene metal compounds with different bridge groups; wherein, olefin groups with different carbon atoms and different structures are introduced into the metallocene ring of the metallocene-fluorene metal compound, and the olefin groups can coordinate with the metal center, which is beneficial to protect the stability of the active center, so that this type of catalyst still maintains high activity at a higher temperature (>90°C), and is used in combination with other metal compounds to prepare polyethylenes of the desired structure. In these prior arts, metallocene compounds have super high activity when catalyzing olefin polymerization under the action of a cocatalyst, but often also have the disadvantages that the active center of the metallocene catalyst is easily deactivated, resulting in a short catalyst life and a significant decrease in activity over time. In addition, the synthesis process of metallocene compounds involves multi-step reactions and ligand separation and purification, which greatly reduces the yield of the final product. There are many types of solvents used, and the solvent treatment (dehydration and deoxygenation) and solvent recovery processes are complicated, which increases production costs. It also brings about the problem of solvents polluting the atmosphere with waste gas emissions and the treatment of waste solvents affecting the environment.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The invention provides a rigid skeleton bridged cyclopentadienyl-fluorene metal compound and a preparation method thereof, which are used to solve the defects of the prior art that the cyclopentadienyl-fluorene metal compound has a short catalytic life and its activity significantly decreases with time, and realizes the preparation of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound. The compound adopts a rigid skeleton structure with greater steric hindrance and introduces an alkoxy alkoxy group with electron-donating ability on the fluorene ring, which not only effectively prevents its deactivation reaction and has higher high temperature resistance and life, but also can improve the stability of the active center of the compound after the activation of the co-catalyst, and still maintains its activity for a long time.

[0005] Specifically, the present invention provides a rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the general structural formula of which is shown in Formula I:

[0006]

[0007] Among them, linker is or

[0008] R1 is independently selected from an ether group containing at least one oxygen atom and 2 to 20 carbon atoms;

[0009] R2 is a C1 to C18 hydrocarbon group;

[0010] M is Zr or Hf;

[0011] Each X is independently selected from chlorine, bromine or iodine.

[0012] Through a large number of experiments, it was found that in the linker structure of the present invention, the connection between the two benzene rings has a great influence on the performance of the metallocene-fluorene compound. Through the linker structure and the introduction of alkoxy alkoxy groups on the fluorene ring, the high temperature resistance and life of the catalyst can be significantly improved, especially the stability of the active center of the compound after the activation of the co-catalyst is improved, and the activity can be maintained for a long time.

[0013] According to the rigid skeleton bridged cyclopentane-fluorene metal compound provided by the present invention, R1 is methoxymethyl, ethoxymethyl, propoxymethyl, methoxyethoxymethyl, methoxyethyl, methoxyethoxyethyl, ethoxyethyl, ethoxyethoxyethyl, methoxypropyl, ethoxypropyl, methoxybutyl or methoxypentyl.

[0014] According to the rigid skeleton bridged cyclopentane-fluorene metal compound provided by the present invention, R1 is methoxymethyl, ethoxymethyl, methoxyethyl, methoxyethoxyethyl, ethoxyethyl, methoxypropyl, methoxybutyl or methoxypentyl; preferably, R1 is methoxymethyl, methoxyethyl, methoxyethoxyethyl, methoxypropyl or methoxybutyl.

[0015] According to the rigid skeleton bridged cyclopentane-fluorene metal compound provided by the present invention, R2 is a C1 to C8 hydrocarbon group; preferably, R2 is methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, 2-pentyl, 3-pentyl, 2-methyl-1-butyl, 3-methyl-1-butyl, hexyl, heptyl, octyl, nonyl, decyl, vinyl, allyl, butylene, pentyl, hexylene, heptylene, octylene or nonylene.

[0016] According to the rigid skeleton bridged cyclopentene-fluorene metal compound provided by the present invention, R2 is a C1 to C5 hydrocarbon group; preferably, R2 is methyl, ethyl, n-propyl, isopropyl, n-butyl, allyl, butylene or pentyl; preferably, R2 is n-butyl, allyl, butylene or pentyl.

[0017] According to the rigid skeleton bridged cyclopentadienyl-fluorene metal compound provided by the present invention, X is chlorine.

[0018] The rigid skeleton bridged cyclopentadienyl-fluorene metal compound provided by the present invention is selected from one of the following compounds:

[0019]

[0020]

[0021]

[0022] The present invention also provides a method for preparing the rigid skeleton bridged cyclopentadienyl-fluorene metal compound as described above, comprising: first reacting compound a with organic lithium to prepare substituted fluorenyl lithium; then reacting a fulvene compound with the substituted fluorenyl lithium to obtain a mixed solution; then adding organic lithium to the mixed solution, and finally adding MX4 to react to generate the rigid skeleton bridged cyclopentadienyl-fluorene metal compound; preferably, the molar ratio of compound a to organic lithium is 1:(1.0-1.1); the molar ratio of fulvene compound to the substituted fluorenyl lithium is 1:1, and the molar amounts of the subsequently added organic lithium and MX4 are the same as the molar amount of compound a;

[0023] The structural formula of the compound a is: Wherein, R1 is independently selected from an ether group containing at least one oxygen atom and 2 to 20 carbon atoms;

[0024] The structural formula of the fulvene compound is:

[0025] or Wherein, R2 is a C1 to C18 hydrocarbon group;

[0026] Preferably, the organic lithium is one or more of n-butyl lithium, sec-butyl lithium, tert-butyl lithium, methyl lithium, and phenyl lithium, and the preferred alkyl lithium is n-butyl lithium;

[0027] Preferably, the MX4 is a zirconium or hafnium halide, more preferably zirconium tetrachloride or hafnium tetrachloride.

[0028] According to the preparation method of the rigid skeleton bridged fluorene-fluorene metal compound provided by the present invention, the preparation process of the compound a includes: reacting 2,7-dihydroxyfluorene with a monohalogenated ether compound under the action of a base; preferably, the molar ratio of 2,7-dihydroxyfluorene to the monohalogenated ether compound is: 1:(2.0-2.2), and the base is in excess.

[0029] The base is one or more of sodium methoxide, sodium ethoxide, butyl lithium, methyl lithium, phenyl lithium, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate or cesium carbonate, preferably one or more of lithium carbonate, sodium carbonate, potassium carbonate or cesium carbonate, preferably potassium carbonate;

[0030] The monohalogenated ether compound is one or more of chloromethyl methyl ether, 1-chloromethyl ethyl ether, 1-chloromethyl propyl ether, 2-methoxyethoxymethyl chloride, 1-bromo-2-methoxyethane, 1-(2-chloroethoxy)-2-methoxyethane, 2-ethoxyethyl bromide, 2-(2-ethoxyethoxy)ethyl bromide, 1-bromo-3-methoxypropane, 1-bromo-3-ethoxypropane, 1-bromo-4-methoxybutane and 1-bromo-5-methoxypentane.

[0031] According to the preparation method of the rigid skeleton bridged cyclopentadiene-fluorene metal compound provided by the present invention, the preparation process of the fulvene compound includes: reacting monosubstituted cyclopentadiene with ketone compound b under the action of a strong base to obtain; preferably, the molar ratio of monosubstituted cyclopentadiene to ketone compound b is: 1 to 2:1, and the base is in excess.

[0032] The substituent on the monosubstituted cyclopentadiene is a C1 to C18 hydrocarbon group (the substituent becomes R2 in the rigid skeleton bridged cyclopentadiene-fluorene metal compound after the above reaction);

[0033] The structural formula of the ketone compound b is:

[0034] or

[0035] The strong base is one or more of sodium methoxide, sodium ethoxide, butyl lithium, methyl lithium, phenyl lithium, sodium hydroxide, and potassium hydroxide; preferably, the strong base is sodium methoxide, sodium ethoxide, or butyl lithium.

[0036] When preparing the above-mentioned compound a, the preparation of fulvene compounds, and the preparation of metallocene-fluorene compounds from the two, any one or both of them can be carried out under an inert atmosphere selected from argon, helium, nitrogen, and a mixture of the above gases.

[0037] When preparing the above-mentioned compound a, the preparation of the fulvene compound, and the preparation of the metallocene-fluorene compound from the two, any one or both of them can be carried out under the condition of using an organic medium, and the organic medium is selected from one or more of pentane, hexane, cyclohexane, tetrahydrofuran, ether, benzene, toluene, xylene, chloroform, dichloromethane and petroleum ether.

[0038] The process of preparing the rigid skeleton bridged cyclopentadienyl-fluorene metal compound according to the present invention is simpler and has a higher yield than the prior art.

[0039] The present invention also provides a catalyst, comprising the rigid skeleton bridged cyclopentadienyl-fluorene metal compound as described above.

[0040] The present invention also provides a method for preparing the catalyst as described above, which includes the method for preparing the rigid skeleton bridged cyclopentadienyl-fluorene metal compound as described above. In practice, the prepared rigid skeleton bridged cyclopentadienyl-fluorene metal compound can be further mixed with alkyl aluminum and a carrier, etc., for catalyzing olefin polymerization.

[0041] The present invention also provides the use of the catalyst as described above or the catalyst prepared by the method for preparing the catalyst as described above in olefin polymerization.

[0042] The present invention provides a rigid skeleton bridged cyclopentadienyl-fluorene metal compound and a preparation method thereof. The rigid skeleton structure in the rigid skeleton bridged cyclopentadienyl-fluorene metal compound is beneficial to the stability of the metal center, effectively preventing its deactivation reaction, so that it has higher high temperature resistance and life; during catalytic polymerization, it is also beneficial to protect the active center and inhibit chain transfer reaction, thereby preparing a polymer with a higher molecular weight. At the same time, the present invention introduces an alkoxy alkoxy group with electron donating ability on the fluorene ring, which plays a synergistic role with the rigid skeleton structure, greatly improving the stability of the active center of the compound after the activation of the co-catalyst, and still maintaining activity for a long time. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0045] Example 1

[0046] A method for preparing a rigid skeleton bridged cyclopentadiene-fluorene metal compound, the process is as follows:

[0047] Preparation of compound a: Add 2,7-dihydroxyfluorene (19.8 g, 100 mmol) to a 500 ml round-bottom flask, add 200 ml tetrahydrofuran as a solvent, add potassium carbonate (30.36 g, 220 mmol) and react for 30 min, add 2-bromoethyl methyl ether (29.2 g, 210 mmol) dropwise and react at room temperature for 6 h, filter to remove excess potassium carbonate, remove the solvent tetrahydrofuran and excess 2-bromoethyl methyl ether in vacuo to obtain a white solid, wash with 20 ml cold methanol and dry in vacuo to obtain 29.1 g of white 2,7-di(methoxyethoxy)fluorene, with a yield of 92.6%. The structural formula of the 2,7-di(methoxyethoxy)fluorene is as follows:

[0048]

[0049] The 2,7-bis(methoxyethoxy)fluorene is characterized by 1 HNMR (300MHz, CDCl3) δ is: 7.96-7.98 (d, J=7.8Hz, 2H), 7.17-7.18 (d, J=7.9Hz, 2H), 7.0 (m, 2 H), 3.87 (m, 2H), 3.77-3.79 (t, J = 7.3Hz, 4H), 4.31-4.33 (t, J = 7.6, 1.3Hz, 4H), 3.41 (m, 6H).

[0050] Preparation of fulvene compounds: Add fluorenone (90.1 g, 500 mmol), sodium methoxide (32.4 g, 600 mmol) and methanol (450 mL) to a 1000 ml round-bottom flask. Add butyl cyclopentadiene (122 g, 1000 mmol) dropwise, and stir the mixture to obtain an orange precipitate. After stirring the reaction for 12 hours, filter the orange precipitate, wash it with 50 mL of cold methanol and vacuum dry it for 8 hours to obtain 107 g of fulvene, with a yield of 75.4%. The structural formula of the fulvene compound is as follows:

[0051]

[0052] The fulvene compounds are characterized by 1HNMR (300MHz, CDCl3) δ is: 7.94-7.95 (d, J=7.4Hz, 2H), 7.57-7.58 (d, J=7.3 Hz,2H),7.47-7.49(t,J=7.2Hz,2H),7.37-7.39(t,J=7.4,2H),6.59-6.62( dd,J=5.1Hz,1.4Hz,1H),6.40-6.42(dd,J=5.1Hz,1.4Hz,1H),6.12(m,1H) ,2.55-2.60(t,J=7.2Hz,2H),1.29-1.38(t,4H),0.93-0.95(t,J=7.1,3H).

[0053] Under nitrogen atmosphere, the above-prepared 2,7-di(methoxyethoxy)fluorene (3.14 g, 10 mmol) was added to a 100 ml round-bottom flask, 30 ml of anhydrous tetrahydrofuran was added and the temperature was lowered to 0°C, 2.4 M n-butyl lithium hexane solution (4.2 ml, 10.1 mmol) was gradually added dropwise, the temperature was gradually raised to room temperature and reacted for 3 h to prepare substituted fluorenyl lithium;

[0054] Under nitrogen atmosphere, the fulvene compound (2.84 g, 10 mmol) prepared above was dissolved in 20 ml tetrahydrofuran, and added to the substituted fluorenyl lithium solution to react for 6 h to obtain a mixed solution, which can be directly used for the next step of synthesis, that is, 2.4 M n-butyl lithium hexane solution (4.2 ml, 10.1 mmol) was added to the mixed solution at 0 ° C, reacted at room temperature for 4 h, and then zirconium tetrachloride (2.33 g, 10 mmol) was added to react at room temperature for 24 h, filtered and the filter cake was washed with 10 ml n-hexane. The filter cake was dissolved in 10 ml dichloromethane, and 10 ml n-hexane was slowly added as a poor solvent for recrystallization, and placed in a refrigerator. After 24 h, a large amount of crystals precipitated, filtered and the filter cake was washed with 3×5 ml n-hexane, and the filter cake was vacuum dried to obtain 3.54 g of compound Zr1, with a yield of 45.0%.

[0055] The structural formula of the compound is as follows:

[0056]

[0057] The compound 1HNMR (300MHz, CDCl3) δ is: 8.19 (d, J = 8.0Hz, 1H), 7.94 (d, J = 7.4Hz, 4H), 7.78 (m, 2H), 7.57 (d, J =7.3Hz,2H),7.47(t,J=7.2Hz,2H),7.37(t,J=7.4,2H),7.11-7.28(d,2H),6.28(m,1H),6.24 (m,1H),5.87-5.93(t,J=2.7Hz,1H),4.21-4.25(t,J=7.6,1.3Hz,4H),3.92-3.95(t,J=7.2Hz ,4H),3.51(m,6H),2.55-2.60(t,J=7.2Hz,2H),1.29-1.38(t,4H),0.94-0.96(t,J=7.1,3H).

[0058] Example 2

[0059] A method for preparing a rigid skeleton bridged cyclopentadiene-fluorene metal compound, the process is as follows:

[0060] Preparation of fulvene compounds: Add fluorenone (90.1g, 500mmol), sodium methoxide (32.4g, 600mmol) and methanol (450mL) to a 1000ml round-bottom flask. Add butylcyclopentadiene (120g, 1000mmol) dropwise, and stir the mixture to obtain an orange precipitate. After stirring the reaction for 10h, filter the orange precipitate, wash it with 50mL of cold methanol and vacuum dry it for 8 hours to obtain 96.6g of fulvene, with a yield of 68.5%. The structural formula of the fulvene compound is as follows:

[0061]

[0062] The fulvene compounds are characterized by 1 HNMR (300MHz, CDCl3) δ is: 7.94-7.95 (d, J=7.4Hz, 2H), 7.57-7.58 (d, J=7.3Hz, 2H),7.47-7.49(t,J=7.2Hz,2H),7.37-7.39(t,J=7.4,2H),6.6-6.63(dd,J=5. 1Hz,1.4Hz,1H),6.40-6.42,(dd,J=5.1Hz,1.4Hz,1H),6.12(m,1H),5.82-5.98 (m,1H),4.94-5.16(m,2H),2.55-2.60(t,J=7.2Hz,2H),2.33(t,J=7.2Hz,2H).

[0063] Under nitrogen atmosphere, 2,7-di(methoxyethoxy)fluorene (3.14 g, 10 mmol) prepared in Example 1 was added into a 100 ml round-bottom flask, 30 ml of anhydrous tetrahydrofuran was added and the temperature was lowered to 0° C. Then, a 2.4 M hexane solution of n-butyl lithium (4.2 ml, 10.1 mmol) was gradually added dropwise, the temperature was gradually raised to room temperature and reacted for 3 h to prepare substituted fluorenyl lithium;

[0064] Under nitrogen atmosphere, the fulvene compound (2.82g, 10mmol) prepared above was dissolved in 20ml tetrahydrofuran, and added to the substituted fluorenyl lithium solution to react for 4h to obtain a mixed solution, which can be directly used for the next step of synthesis, that is, 2.4M n-butyl lithium hexane solution (4.2ml, 10.1mmol) was added to the above mixed solution at 0°C, reacted at room temperature for 4h, and then zirconium tetrachloride (2.33g, 10mmol) was added to react at room temperature for 12h, filtered and the filter cake was washed with 10ml n-hexane. The filter cake was dissolved in 10ml dichloromethane, and 10ml n-hexane was slowly added as a poor solvent for recrystallization, and placed in a refrigerator. After 24h, a large amount of crystals precipitated, filtered and the filter cake was washed with 3×5ml n-hexane, and the filter cake was vacuum dried to obtain 3.54g of compound Zr2, with a yield of 45.0%.

[0065] The structural formula of the compound is as follows:

[0066]

[0067] The compound 1 HNMR (300MHz, CDCl3) δ is: 8.08 (d, J = 8.0 Hz, 1H), 7.90 (d, J = 7.4 Hz, 4H), 7.68 (m, 2H), 7.5 4(d,J=7.3Hz,2H),7.46(t,J=7.2Hz,2H),7.36(t,J=7.4,2H),7.10-7.2(d,2H),6.28(m, 1H),6.28(m,1H),5.82-5.9(t,J=2.7Hz,1H),4.2-4.26(t,J=7.8,1.3Hz,4H),3.92-3.97 (t,J=7.2Hz,4H),3.51(m,6H),2.54-2.68(t,J=7.2Hz,2H),2.31-2.36(t,J=7.6Hz,2H).

[0068] Example 3

[0069] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0070]

[0071] The preparation method of the above-mentioned compound is basically the same as that in Example 1, except that butylcyclopentadiene in the preparation of fulvene compounds is replaced by allylcyclopentadiene; the yield of the obtained fulvene compounds is 65.2%, and the yield of the rigid skeleton bridged cyclopentadiene-fluorene metal compound Zr3 is 57.1%.

[0072] Example 4

[0073] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0074]

[0075] The preparation method of the above-mentioned compound is basically the same as that of Example 1, except that the 2-bromoethyl methyl ether in the preparation of compound a is replaced by chloromethyl methyl ether; wherein the yield of the obtained compound a is 89.5%, and the yield of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr4 is 48.2%.

[0076] Example 5

[0077] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0078]

[0079] The preparation method of the above-mentioned compound is basically the same as that of Example 2, except that the 2-bromoethyl methyl ether in the preparation of compound a is replaced by chloromethyl methyl ether; wherein the yield of the obtained compound a is 89.5%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr5 is 51.4%.

[0080] Example 6

[0081] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0082]

[0083] The preparation method of the above-mentioned compound is basically the same as that in Example 3, except that the 2-bromoethyl methyl ether in the preparation of compound a is replaced by chloromethyl methyl ether; wherein the yield of the obtained compound a is 89.5%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr6 is 43.8%.

[0084] Example 7

[0085] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0086]

[0087] The preparation method of the above-mentioned compound is basically the same as that in Example 1, except that the 2-bromoethyl methyl ether in the preparation of compound a is replaced by 1-bromo-3-methoxypropane; wherein the yield of the obtained compound a is 88.7%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr7 is 46.8%.

[0088] Example 8

[0089] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0090]

[0091] The preparation method of the above-mentioned compound is basically the same as that in Example 2, except that the 2-bromoethyl methyl ether in the preparation of compound a is replaced by 1-bromo-3-methoxypropane; wherein the yield of the obtained compound a is 88.7%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr8 is 48.5%.

[0092] Example 9

[0093] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0094]

[0095] The preparation method of the above-mentioned compound is basically the same as that in Example 3, except that the 2-bromoethyl methyl ether in the preparation of compound a is replaced by 1-bromo-3-methoxypropane; wherein the yield of the obtained compound a is 88.7%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr9 is 42.7%.

[0096] Example 10

[0097] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0098]

[0099] The preparation method of the above-mentioned compound is basically the same as that of Example 4, except that the fluorenone in the preparation of the fulvene compound is replaced by 2,7-di-tert-butyl-9H-fluorene-9-one, and the butylcyclopentadiene is replaced by methylcyclopentadiene; wherein the yield of the obtained fulvene compound is 76.4%, and the yield when synthesizing the rigid skeleton bridged cyclopentene-fluorene metal compound Zr10 is 53.8%.

[0100] Embodiment 11

[0101] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0102]

[0103] The preparation method of the above-mentioned compound is basically the same as that of Example 10, except that methylcyclopentadiene is replaced by ethylcyclopentadiene; the yield of the obtained fulvene compound is 78.2%, and the yield of the rigid skeleton bridged cyclopentadiene-fluorene metal compound Zr11 is 47.8%.

[0104] Example 12

[0105] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0106]

[0107] The preparation method of the above-mentioned compound is basically the same as that of Example 10, except that methylcyclopentadiene is replaced by n-propylcyclopentadiene; the yield of the obtained fulvene compound is 69.5%, and the yield of the rigid skeleton bridged cyclopentadiene-fluorene metal compound Zr12 is 44.7%.

[0108] Embodiment 13

[0109] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0110]

[0111] The preparation method of the above-mentioned compound is basically the same as that of Example 10, except that methylcyclopentadiene is replaced by butylcyclopentadiene; the yield of the obtained fulvene compound is 67.2%, and the yield of the rigid skeleton bridged cyclopentadiene-fluorene metal compound Zr13 is 44.2%.

[0112] Embodiment 14

[0113] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0114]

[0115] The preparation method of the above-mentioned compound is basically the same as that of Example 10, except that methylcyclopentadiene is replaced by butylcyclopentadiene; the yield of the obtained fulvene compound is 71.2%, and the yield of the rigid skeleton bridged cyclopentadiene-fluorene metal compound Zr14 is 42.9%.

[0116] Embodiment 15

[0117] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0118]

[0119] The preparation method of the above-mentioned compound is basically the same as that of Example 10, except that methylcyclopentadiene is replaced by n-propylcyclopentadiene; the yield of the obtained fulvene compound is 76.5%, and the yield of the rigid skeleton bridged cyclopentadiene-fluorene metal compound Zr15 is 46.0%.

[0120] Example 16

[0121] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0122]

[0123] The preparation method of the above-mentioned compound is basically the same as that of Example 5, except that the fluorenone in the preparation of the fulvene compound is replaced by xanthone; wherein the yield of the obtained fulvene compound is 72.1%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr16 is 47.2%.

[0124] Embodiment 17

[0125] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0126]

[0127] The preparation method of the above-mentioned compound is basically the same as that of Example 2, except that the fluorenone in the preparation of the fulvene compound is replaced by xanthone; wherein the yield of the obtained fulvene compound is 72.1%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr17 is 48.5%.

[0128] Embodiment 18

[0129] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0130]

[0131] The preparation method of the above-mentioned compound is basically the same as that of Example 8, except that the fluorenone in the preparation of the fulvene compound is replaced by xanthone; wherein the yield of the obtained fulvene compound is 72.1%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr18 is 51.2%.

[0132] Embodiment 19

[0133] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0134]

[0135] The preparation method of the above-mentioned compound is basically the same as that of Example 16, except that xanthone in the preparation of fulvene compounds is replaced by thioxanthone; wherein the yield of the obtained fulvene compounds is 81.4%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr19 is 54.1%.

[0136] Embodiment 20

[0137] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0138]

[0139] The preparation method of the above-mentioned compound is basically the same as that of Example 17, except that xanthone in the preparation of fulvene compounds is replaced by thioxanthone; wherein the yield of the obtained fulvene compounds is 81.4%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr20 is 56.1%.

[0140] Embodiment 21

[0141] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0142]

[0143] The preparation method of the above-mentioned compounds is basically the same as that of Example 18, with the main difference being that xanthone in the preparation of fulvene compounds is replaced by thioxanthone; wherein the yield of the obtained fulvene compounds is 81.4%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr19 is 57.4%.

[0144] Embodiment 22

[0145] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0146]

[0147] The preparation method of the above-mentioned compound is basically the same as that of Example 16, except that the xanthone in the preparation of the fulvene compound is replaced by 10,10-dimethylanthraquinone; wherein the yield of the preparation of the fulvene compound is 64.7%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadiene-fluorene metal compound Zr22 is 41.8%.

[0148] Embodiment 23

[0149] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0150]

[0151] The preparation method of the above-mentioned compound is basically the same as that of Example 17, except that the xanthone in the preparation of the fulvene compound is replaced by 10,10-dimethylanthraquinone; wherein the yield of the preparation of the fulvene compound is 64.7%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr23 is 43.3%.

[0152] Embodiment 24

[0153] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0154]

[0155] The preparation method of the above-mentioned compound is basically the same as that of Example 18, except that the xanthone in the preparation of the fulvene compound is replaced by 10,10-dimethylanthraquinone; wherein the yield of the preparation of the fulvene compound is 64.7%, and the yield of the synthesis of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound Zr24 is 46.2%.

[0156] Embodiment 25

[0157] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0158]

[0159] The preparation method of the above compound is basically the same as that of Example 1, except that zirconium tetrachloride is replaced by hafnium tetrachloride; wherein the yield of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound is 51.6%.

[0160] Embodiment 26

[0161] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0162]

[0163] The preparation method of the above compound is basically the same as that of Example 2, except that zirconium tetrachloride is replaced by hafnium tetrachloride; wherein the yield of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound is 54.3%.

[0164] Embodiment 27

[0165] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0166]

[0167] The preparation method of the above compound is basically the same as that of Example 14, except that zirconium tetrachloride is replaced by hafnium tetrachloride; wherein the yield of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound is 47.8%.

[0168] Embodiment 28

[0169] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0170]

[0171] The preparation method of the above compound is basically the same as that of Example 17, except that zirconium tetrachloride is replaced by hafnium tetrachloride; wherein the yield of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound is 46.1%.

[0172] Embodiment 29

[0173] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0174]

[0175] The preparation method of the above compound is basically the same as that of Example 20, except that zirconium tetrachloride is replaced by hafnium tetrachloride; wherein the yield of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound is 54.5%.

[0176] Embodiment 30

[0177] A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, the structural formula of which is:

[0178]

[0179] The preparation method of the above compound is basically the same as that of Example 23, except that zirconium tetrachloride is replaced by hafnium tetrachloride; wherein the yield of the rigid skeleton bridged cyclopentadienyl-fluorene metal compound is 44.7%.

[0180] Comparative Example 1

[0181] A metallocene-fluorene compound, the structural formula of which is:

[0182]

[0183] The preparation method of the above-mentioned compound is basically the same as that in Example 1, except that the fluorenone in the preparation of the fulvene compound is replaced by benzophenone; wherein the yield of the fulvene compound is 78.3%, and the yield of the diphenylmethylene bridged carbonyl-fluorene metal compound is 46.5%.

[0184] Comparative Example 2

[0185] A metallocene-fluorene compound, the structural formula of which is:

[0186]

[0187] The preparation method of the above-mentioned compound is basically the same as that of Example 1, except that 2-bromoethyl methyl ether in the preparation of compound a is replaced by iodomethane; wherein the yield of the obtained compound 2,7-dimethoxyfluorene is 94.5%, and the yield of the metallocene-fluorene compound is 57.4%.

[0188] Application Examples 1 to 25

[0189] An olefin polymerization method, the process of which is:

[0190] A solution of a cyclopentadienyl metal compound was prepared by dissolving (3.0 ± 0.1) mg of the corresponding cyclopentadienyl metal compound in 20 mL of toluene. Under an isobutane purge, 1 mL of triethylaluminum hexane solution (1.0 mol / L), approximately 300 mg of activated silica gel, and 1 mL of triethylaluminum hexane solution (1.0 mol / L) were added through the feed port. 955 and metallocene solution were fed into the cold reactor. The reactor was closed and 3L of isobutane was added. The reactor was quickly heated to an operating temperature of 95±2°C, and then ethylene was introduced into the reactor to maintain the reactor pressure at a target pressure of 4.5MPa. Throughout the experiment, the reactor was maintained at a desired temperature by an automated heating-cooling system. After the reactor was vented, purged and cooled, the resulting polymer product was dried at 60°C under reduced pressure. The difference between the application examples is only that the metallocene-fluorene metal compounds used are different, and the structures of the obtained polymers are shown in the following table:

[0191]

[0192]

[0193]

[0194] From the data in the table above, it can be seen that the comparison between Comparative Example 1 and Example 1 and its application examples shows that the number average molecular weight of the polyethylene obtained in Application Example 1 is 150% higher than that in Comparative Example 1, and the molecular weight distribution is narrower. The difference is that although the two benzene rings in the zirconocene metal compound have greater rigidity, the two benzene rings maintain a similar parallel structure, forming a larger coordination space at the metal center. After the zirconocene metal compound Zr1 is prepared by replacing benzophenone with fluorenone, the linker presents a structure similar to a large plane, which compresses the coordination space of the metal center, which is conducive to inhibiting the chain transfer reaction, thereby increasing the molecular weight. In general, for coordination polymerization, the more active species, the wider the molecular weight distribution. It is precisely because the steric hindrance of the active center is greater, the chain transfer reaction is weakened, the environment of the active center is more stable, and the active species are relatively single that the molecular weight distribution of the polyethylene obtained by catalysis in Example 1 is narrower than that in Comparative Example 1. The catalyst activity is within four hours, and the activity in Comparative Example 1 decreases significantly. The catalyst activity of Comparative Example 1 is almost lost after two hours, and the polymer obtained in four hours is only 9.6% more than the polymer in two hours. This indicates that under the action of the co-initiator, the thermal stability of the active center formed by the compound in Example 1 is significantly higher than that of the active center formed by the compound in Comparative Example 1, and the long-term maintenance of the catalytic activity is conducive to improving industrial production efficiency and reducing production costs. This is because the rigid skeleton increases the steric hindrance of the metal center and prevents the bimolecular deactivation of the active center, thereby maintaining high activity within 4 hours.

[0195] Compared with Example 1 and Comparative Example 2, the molecular weight of the polyethylene obtained in Application Example 1 increased by 50%, but the molecular weight distribution became significantly smaller. This is because the methoxy group is replaced by the methoxyethoxy group, and the steric hindrance of the substituent group is significantly increased, and the electron supply capacity is also significantly increased. The electron-donating methoxyethoxy group may coordinate with the active center, which is beneficial to stabilize the active center and reduce the chain transfer reaction, thereby increasing the molecular weight. In Application Example 1, the methoxyethoxy group with stronger electron supply capacity can stabilize the active center of the catalyst. On the one hand, its steric hindrance is greater than that of the methoxy group, which prevents the deactivation of the bimolecular to a certain extent, thereby extending the life of the catalyst and maintaining activity for a longer time.

[0196] It can be seen from Application Examples 1-9 and Comparative Example 2 that the molecular weight of the polymer prepared by the obtained compound when catalyzing ethylene polymerization when the 2,7-substituents on the fluorene ring are methoxy, methoxymethoxy, methoxyethoxy and methoxypropoxy groups has a significant increase trend. Comparing Application Example 1 with Application Examples 2 and 3, the molecular weight of polyethylene prepared by Zr2 and Zr3 containing double bonds under the action of cocatalysts is higher. Application Examples 10-15 can also verify that the molecular weight of the polymer obtained by the cyclopentadienyl-substituted cyclopentadienyl-containing cyclopentadienyl-cyclopentadienyl-substituted ...

[0197] The difference between Application Examples 16-24 and Application Example 2 is that the rigid skeletons and alkoxy groups of the cyclopentadienyl-fluorene zirconium metal compounds are different. These rigid skeleton-bridged cyclopentadienyl-fluorene zirconium compounds all show good catalytic stability, but their activity is lower than that of Application Example 2.

[0198] Examples 25-30 synthesized a series of rigid skeleton bridged hafnium cyclopentadienyl-fluorene compounds, which showed higher activity in catalyzing ethylene polymerization under the action of a co-catalyst compared with rigid skeleton bridged hafnium cyclopentadienyl-fluorene compounds of the same structure. The reason may be that the hafnium atomic radius is larger and the coordination space of the active center is larger, which is conducive to the rapid coordination polymerization of ethylene. It can be seen from the polymerization activity data of application examples 25-30 that these hafnium catalysts also maintained a high activity within 4 hours, but the activity decreased faster than that of zirconium catalysts of the same structure.

[0199] Among the rigid skeleton bridged cyclopentadiene-fluorene metal compounds provided by the present invention, in addition to the above-mentioned examples, other rigid skeleton bridged cyclopentadiene-fluorene metal compounds with similar structures can be prepared according to the above-mentioned method in combination with basic knowledge in the field.

[0200] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rigid skeleton bridged cyclopentadienyl-fluorene metal compound, characterized in that: Its general structural formula is shown in Formula I: Among them, linker is or R1 is independently selected from an ether group containing at least one oxygen atom and 2 to 20 carbon atoms; R2 is a C1 to C18 hydrocarbon group; M is Zr or Hf; Each X is independently selected from chlorine, bromine or iodine.

2. The rigid skeleton bridged cyclopentadiene-fluorene metal compound according to claim 1, characterized in that: R1 is methoxymethyl, ethoxymethyl, propyloxymethyl, methoxyethoxymethyl, methoxyethyl, methoxyethoxyethyl, ethoxyethyl, ethoxyethoxyethyl, methoxypropyl, ethoxypropyl, methoxybutyl or methoxypentyl; preferably, R1 is methoxymethyl, ethoxymethyl, methoxyethyl, methoxyethoxyethyl, ethoxyethyl, methoxypropyl, methoxybutyl or methoxypentyl; more preferably, R1 is methoxymethyl, methoxyethyl, methoxyethoxyethyl, methoxypropyl or methoxybutyl.

3. The rigid skeleton bridged cyclopentadiene-fluorene metal compound according to claim 1 or 2, characterized in that: R2 is a C1 to C8 hydrocarbon group; preferably, R2 is methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, 2-pentyl, 3-pentyl, 2-methyl-1-butyl, 3-methyl-1-butyl, hexyl, heptyl, octyl, nonyl, decyl, vinyl, allyl, allylbutyl, allylpentyl, allylhexyl, allylheptyl, allyloctyl or allylnonyl.

4. The rigid skeleton bridged cyclopentadiene-fluorene metal compound according to claim 3, characterized in that: R2 is a C1 to C5 hydrocarbon group; preferably, R2 is methyl, ethyl, n-propyl, isopropyl, n-butyl, allyl, butylene or pentyl; preferably, R2 is n-butyl, allyl, butylene or pentyl.

5. The rigid skeleton bridged cyclopentadienyl-fluorene metal compound according to any one of claims 1 to 4, characterized in that: X is chlorine.

6. The rigid skeleton bridged cyclopentadienyl-fluorene metal compound according to any one of claims 1 to 5, characterized in that: Selected from one of the following compounds:

7. The method for preparing the rigid skeleton bridged cyclopentadiene-fluorene metal compound according to any one of claims 1 to 6, characterized in that: include: First, compound a is reacted with organic lithium to prepare substituted fluorenyl lithium; The fulvene compound is reacted with the substituted fluorene lithium to obtain a mixed solution; organic lithium is then added to the mixed solution, and finally MX4 is added to react to generate the rigid skeleton-bridged metallocene-fluorene compound; The structural formula of the compound a is: Wherein, R1 is independently selected from an ether group containing at least one oxygen atom and 2 to 20 carbon atoms; The structural formula of the fulvene compound is: or Wherein, R2 is a C1 to C18 hydrocarbon group; Preferably, the organic lithium is one or more of n-butyl lithium, sec-butyl lithium, tert-butyl lithium, methyl lithium, and phenyl lithium, and the preferred alkyl lithium is n-butyl lithium; Preferably, the MX4 is a zirconium or hafnium halide, more preferably zirconium tetrachloride or hafnium tetrachloride.

8. The method for preparing the rigid skeleton bridged cyclopentadiene-fluorene metal compound according to claim 7, characterized in that: The preparation process of the compound a comprises: reacting 2,7-dihydroxyfluorene with a monohalogenated ether compound under the action of a base to obtain; The base is one or more of sodium methoxide, sodium ethoxide, butyl lithium, methyl lithium, phenyl lithium, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate or cesium carbonate, preferably one or more of lithium carbonate, sodium carbonate, potassium carbonate or cesium carbonate, preferably potassium carbonate; The monohalogenated ether compound is one or more of chloromethyl methyl ether, 1-chloromethyl ethyl ether, 1-chloromethyl propyl ether, 2-methoxyethoxymethyl chloride, 1-bromo-2-methoxyethane, 1-(2-chloroethoxy)-2-methoxyethane, 2-ethoxyethyl bromide, 2-(2-ethoxyethoxy)ethyl bromide, 1-bromo-3-methoxypropane, 1-bromo-3-ethoxypropane, 1-bromo-4-methoxybutane and 1-bromo-5-methoxypentane.

9. The method for preparing the rigid skeleton bridged cyclopentadiene-fluorene metal compound according to claim 8, characterized in that: The preparation process of the fulvene compound comprises: reacting monosubstituted cyclopentadiene with a ketone compound b under the action of a strong base to obtain; The substituent on the monosubstituted cyclopentadiene is a C1 to C18 hydrocarbon group; The structural formula of the ketone compound b is: or The strong base is one or more of sodium methoxide, sodium ethoxide, butyl lithium, methyl lithium, phenyl lithium, sodium hydroxide, and potassium hydroxide; preferably, the strong base is sodium methoxide, sodium ethoxide, or butyl lithium.

10. A catalyst, characterized in that The invention comprises the rigid skeleton bridged cyclopentadienyl-fluorene metal compound as described in claims 1 to 6.

11. The method for preparing the catalyst according to claim 10, characterized in that: The invention comprises a method for preparing the rigid skeleton bridged cyclopentadienyl-fluorene metal compound as described in claims 7 to 9.

12. Use of the catalyst according to claim 10 or the catalyst prepared by the preparation method of the catalyst according to claim 11 in olefin polymerization.

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