Method for selectively synthesizing racemic metallocene catalyst

Abstract

The invention relates to a method for selectively synthesizing a racemic metallocene catalyst, and belongs to the technical field of metallocene catalyst preparation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metallocene catalyst preparation, and particularly relates to a method for selectively synthesizing a racemic metallocene catalyst. BACKGROUND

[0002] Compared with traditional Ziegler-Natta catalysts, metallocene catalysts exhibit more superior properties in the field of olefin polymerization. Especially, metallocene catalysts based on group 4 greatly promote the development of the field of olefin polymerization in the past few decades. Ansameta-zirconium metal catalysts with C2 symmetry, especially silicon-bridged bis-metallocene zirconium metal catalysts, exhibit excellent properties in the synthesis of isotactic polypropylene. At the same time, research shows that this series of catalysts also have unique advantages in the field of POE polymerization. However, the industrialization of this series of catalysts is not smooth, and one of the important reasons is that: the bridged bis-indene zirconium catalysts only have racemic (rac-) isomers with C2 symmetry to achieve isotactic stereoscopic control when catalyzing the polymerization of prochiral α-olefins such as propylene; when catalyzing POE polymerization, the catalytic activity, α-olefin insertion rate and other key indicators of meso isomers are also obviously different from those of racemic isomers. During the polymerization process, only racemic isomers can be selected, otherwise it is difficult to obtain polymer products with commercial application value. However, during the synthesis of the catalyst, racemic (rac-) and meso- two diastereoisomers are inevitably produced. If a mixture of the two is used as a catalyst, the catalytic activity will be greatly reduced by 70%-80% (Angew. Chem. Int. Edit., 1985, 24(6): 507-508.). The experimental phenomenon that the use of a mixture of enantiomers as a catalyst leads to a significant reduction in activity can also be observed in POE polymerization.

[0003] Therefore, the separation of the two diastereoisomers is of great importance in the numerous applications of such complexes. Generally, the separation of racemic and meso isomers of bridged bis-indenyl zirconium complexes is mainly achieved by multiple recrystallization, but complete separation cannot be achieved by multiple recrystallization in many cases; in addition, even if pure products can be separated by tedious recrystallization, the yield is very low (usually less than 30%), and it is difficult to achieve large-scale synthesis (Organometallics 1994, 13(3), 954-963; Macromolecules 2018 51(20), 8073-8083). The existing synthesis method of rac-dimethylsilyl-bis(2-methyl-4-phenylindenyl)zirconium dichloride catalyst and its analogues has many shortcomings. Therefore, it is necessary to develop a synthesis method of metallocene catalyst which can efficiently and selectively obtain single racemic (rac-) product. SUMMARY

[0004] To improve the above technical problems, the present application provides a method for selectively synthesizing a racemic metallocene catalyst, comprising the following steps:

[0005]

[0006] Step S1: dispersing MX4 in an organic solvent, mixing with tetramethylpropylenediamine to obtain a guiding solution;

[0007] Step S2: dissolving compound a in an organic solvent, adding a lithium salt solution, and mixing to obtain a solution containing compound b;

[0008] Step S3: mixing the guiding solution with the solution containing compound b to obtain the racemic metallocene catalyst shown in formula (I) after reaction;

[0009] wherein M is selected from titanium, zirconium and hafnium;

[0010] X is selected from chlorine, bromine and iodine;

[0011] each R1, R2 and R3 is the same or different, and is independently selected from the following groups which are unsubstituted or optionally substituted by one, two or more R a substituted C 1-10 alkyl, C 6-10 aryl and 5-10 membered heteroaryl; each R a is the same or different, and is independently selected from H, halogen, C 1-10 alkyl and C

[0012] each R4 is the same or different, and is independently selected from C 1-10 alkyl and C

[0013] m is selected from 1, 2, 3 or 4.

[0014] According to an embodiment of the present application, each R1, R2, R3is the same or different, independently from each other, selected from the group consisting of C 1-6 alkyl, C 1-6 alkyl-C 6-10 aryl, halogenated C 6-10 aryl;

[0015] According to an embodiment of the present application, each R1, R2, R3is the same or different, independently from each other, selected from the group consisting of methyl, tert-butylphenyl, halogenated phenyl.

[0016] According to an embodiment of the present application, each R4is the same or different, independently from each other, selected from the group consisting of C 1-6 alkyl, such as methyl.

[0017] According to an embodiment of the present application, the compound a is selected from the group consisting of:

[0018] According to an embodiment of the present application, the compound a is selected from the group consisting of:

[0019]

[0020] According to an embodiment of the present application, the compound of formula (I) is selected from the group consisting of:

[0021] According to an embodiment of the present application, the compound of formula (I) is selected from the group consisting of:

[0022]

[0023] According to an embodiment of the present application, the organic solvent is selected from the group consisting of non-polar aprotic solvents, such as n-hexane, toluene.

[0024] According to an embodiment of the present application, MX4is selected from the group consisting of titanium tetrachloride, zirconium tetrachloride, hafnium tetrachloride.

[0025] According to an embodiment of the present application, the lithium salt is selected from the group consisting of n-butyllithium or tert-butyllithium.

[0026] According to an embodiment of the present application, the molar ratio of MX4to tetramethylpropylenediamine in step S1 is selected from the group consisting of 1 : (0.8-5), such as 1 : (1-3), like 1 : 1.2, 1 : 1.4, 1 : 1.5, 1 : 1.6, 1 : 1.8, 1 : 2.

[0027] According to an embodiment of the present application, the mass to volume ratio of MX4to organic solvent in step S1 is selected from the group consisting of 1 g : (2-15) mL, such as 1 g : (5-10) mL, like 1 g : 6 mL, 1 g : 8 mL.

[0028] According to an embodiment of the present application, the reaction temperature of step S1 is selected from 10-40℃, such as room temperature; the reaction time is selected from 1-10h, such as 2-8h.

[0029] According to an embodiment of the present application, the specific method of step S1 comprises: adding tetramethylpropylenediamine dropwise into the organic solvent of MX4, and obtaining a directing solution after mixing.

[0030] According to an embodiment of the present application, the mass-volume ratio of compound a to the organic solvent in step S2 is selected from 1g:(5-40)mL, such as 1g:(10-30)mL, for example, 1g:15mL, 1g:20mL, 1g:25mL.

[0031] According to an embodiment of the present application, the molar ratio of compound a to lithium salt in step S2 is selected from 1:(1-8), such as 1:(2-6), for example, 1:2, 1:3, 1:4, 1:5, 1:6.

[0032] According to an embodiment of the present application, the reaction temperature of step S2 is selected from -10-30℃, such as -5-10℃; the reaction time is selected from 2-24h, such as 10-18h.

[0033] According to an embodiment of the present application, the specific method of step S2 comprises: adding lithium salt solution dropwise into the organic solvent of compound a, and obtaining a solution containing compound b after mixing.

[0034] According to an embodiment of the present application, the molar ratio of MX4 in the directing solution to compound a in the solution containing compound b in step S3 is selected from 1:(0.5-2), such as 1:(0.6-1.5), for example, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2.

[0035] According to an embodiment of the present application, the reaction temperature of step S3 is selected from -10-30℃, such as -5-25℃; the reaction time is selected from 2-24h, such as 10-18h.

[0036] According to an embodiment of the present application, the method further comprises a step of post-treatment, which comprises: filtering after the reaction is completed, dissolving the filter cake in an organic solvent by heating, filtering again, removing the solvent in the mother liquor, and obtaining the racemic metallocene catalyst; the amount of the organic solvent is selected from 1g:(50-150)mL, such as 1g:(80-120)mL, for example, 1g:90mL, 1g:100mL, 1g:110mL, based on the weight of MX4, and the mass-volume ratio of MX4 to the organic solvent is selected from 1g:(50-150)mL, such as 1g:(80-120)mL, for example, 1g:90mL, 1g:100mL, 1g:110mL.

[0037] According to an embodiment of the present application, the method further comprises a step of further purification, comprising: adding an organic solvent to the racemic metallocene catalyst, and beating at 40-60°C (e.g. 50°C) for 10-40 min (e.g. 30 min), filtering while hot to obtain the purified racemic metallocene catalyst.

[0038] Advantages

[0039] The prior art process for synthesizing rac-dimethylsilyl-di(2-methyl-4-phenylindenyl)zirconium dichloride catalyst and its analogs has the disadvantage of high production cost and inoperability. The present application reacts tetramethylpropylenediamine auxiliary ligand with diindenylsilane to obtain racemic (rac-) product in a higher proportion. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 H NMR spectrum of the crude product of Example 1. 1 H NMR spectrum of the crude product of Example 1.

[0041] Figure 2 H NMR spectrum of the crude product of Example 2. 1 H NMR spectrum of the crude product of Example 2.

[0042] Figure 3 H NMR spectrum of the crude product of Example 3. 1 H NMR spectrum of the crude product of Example 3.

[0043] Figure 4 H NMR spectrum of the crude product of Comparative Example 1. 1 H NMR spectrum of the crude product of Comparative Example 1.

[0044] DEFINITIONS AND EXPLANATIONS OF TERMS

[0045] Unless otherwise indicated, the groups and terms defined in the specification and claims of this application, including the definitions of examples, illustrative examples, preferred definitions, definitions set forth in tables, definitions of specific compounds in examples, etc., can be combined and incorporated with each other in any manner. The group definitions and compound structures after such combination and incorporation should be understood to be within the scope of the specification and / or claims.

[0046] The term "C 1-10 "alkyl" means straight and branched chain alkyl groups having 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 carbon atoms, "C 1-8 "alkyl" means straight and branched chain alkyl groups having 1, 2, 3, 4, 5, 6, 7, or 8 carbon atoms, "C 1-6"Alkyl" denotes straight-chain and branched alkyl groups having 1, 2, 3, 4, 5 or 6 carbon atoms. Said alkyl groups are, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1 -methylbutyl, 1 -ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1 -dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1 -methylpentyl, 2-ethylbutyl, 1 -ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1 -dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl or 1,2-dimethylbutyl and the like or their isomers.

[0047] The term "C 6-10 "Aryl" is to be understood as preferably denoting an aromatic or partially aromatic monocyclic or bicyclic (e.g. fused ring) hydrocarbon ring having 6, 7, 8, 9, 10 carbon atoms, which can be a single aromatic ring or multiple aromatic rings that are fused together, in particular a ring having 6 carbon atoms ("C6-aryl"), such as phenyl; or a ring having 9 carbon atoms ("C9-aryl"), such as indanyl or indenyl, or a ring having 10 carbon atoms ("C10-aryl"), such as tetrahydronaphthyl, dihydronaphthyl or naphthyl. When the C 10 "Aryl" is to be understood as preferably denoting an aromatic or partially aromatic monocyclic or bicyclic (e.g. fused ring) hydrocarbon ring having 6, 7, 8, 9, 10 carbon atoms, which can be a single aromatic ring or multiple aromatic rings that are fused together, in particular a ring having 6 carbon atoms ("C6-aryl"), such as phenyl; or a ring having 9 carbon atoms ("C9-aryl"), such as indanyl or indenyl, or a ring having 10 carbon atoms ("C10-aryl"), such as tetrahydronaphthyl, dihydronaphthyl or naphthyl. When the C 6-10 "Aryl" is to be understood as preferably denoting an aromatic or partially aromatic monocyclic or bicyclic (e.g. fused ring) hydrocarbon ring having 6, 7, 8, 9, 10 carbon atoms, which can be a single aromatic ring or multiple aromatic rings that are fused together, in particular a ring having 6 carbon atoms ("C6-aryl"), such as phenyl; or a ring having 9 carbon atoms ("C9-aryl"), such as indanyl or indenyl, or a ring having 10 carbon atoms ("C10-aryl"), such as tetrahydronaphthyl, dihydronaphthyl or naphthyl. When the C

[0048] The term "5-10 membered heteroaryl" is to be understood as including monocyclic, bicyclic (e.g. fused ring) aromatic ring systems having 5, 6, 7, 8, 9, 10 ring atoms and containing 1-5 heteroatoms independently selected from N, O and S, in particular 5 or 6 or 9 or 10 carbon atoms and containing 1-5, preferably 1-3 heteroatoms each independently selected from N, O and S and, in addition, in each case can be benzo-fused. Non-limiting examples include indolizinyl, isoindolyl, indolyl, indazolyl, quinolinyl, isoquinolinyl, quinazolinyl, benzofuranyl, benzimidazolyl, benzothiazolyl. DETAILED DESCRIPTION

[0049] The technical solutions of the present disclosure will be further described in detail below in combination with specific examples. It should be understood that the following examples are only illustratively described and explained the present disclosure, and should not be interpreted as limiting the scope of protection of the present disclosure. Any technology realized based on the above description of the present disclosure is covered within the scope intended to be protected by the present disclosure.

[0050] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0051] Example 1:

[0052] In a glove box, 6.2 g of ZrCl4was added to a 1 L Schlenk flask, 40 mL of super dry toluene was added, and the mixture was stirred until homogeneous, forming a slurry. At room temperature, 5.2 g of tetramethylpropylenediamine was added dropwise, and the stirring was continued for 5 hours to form a solution of the zirconium tetrachloride complex, which was used as is. In a glove box, 10.98 g of dimethylbis(2-methyl-4-phenylindenyl)silane was added to a 500 mL Schlenk flask, 200 mL of super dry toluene was added, and the mixture was stirred until homogeneous. At 0 °C, 10.6 mL of n-BuLi solution was added dropwise, and the mixture was allowed to warm to room temperature and stirred for 12 hours to form a solution of the dilithium salt. The solution of the zirconium tetrachloride complex was cooled to 0 °C, and the solution of the dilithium salt was added dropwise to the solution of the zirconium tetrachloride complex. After the addition was complete, the mixture was allowed to warm to room temperature and stirred for 12 hours. The reaction was complete, and the mixture was filtered directly. The filter cake was dissolved in 600 mL of toluene by heating to reflux, and the mixture was filtered. The mother liquor was removed by evaporation to give a crude product, 7.60 g, in 45.6% yield. The1H NMR spectrum is shown in Figure 1. Figure 1 .

[0053] After the peaks of deuterated chloroform were calibrated, the peaks of rac- and meso- were 2.46 and 2.27, respectively. The ratio of rac- to meso- was 100:2 in Example 1, and the mixture was used in the polymerization without washing.

[0054] 1 H NMR (CDCI3): d (ppm) 7.63-7.70 (m, 6H), 7.35-7.46 (m, 8H), 7.11-7.15 (m, 2H), 6.97 (s, 2H), 2.27 (s, 6H), 1.36 (s, 6H).

[0055] Example 2:

[0056] In a glove box, 6.2 g of ZrCl4was added into a 1 L Schlenk flask, 40 mL of super dry toluene was added, and the mixture was stirred until it became a slurry. At room temperature, 4.64 g of tetramethylethylenediamine was added dropwise, and the mixture was stirred for 5 hours to obtain a solution of zirconium tetrachloride complex, which was used as received. In a glove box, 10.98 g of dimethylbis(2-methyl-4-phenylindenyl)silane was added into a 500 mL Schlenk flask, 200 mL of super dry toluene was added, and the mixture was stirred until it became a slurry. At 0 °C, 10.6 mL of n-BuLi solution was added dropwise, and the mixture was allowed to warm to room temperature and stirred for 12 hours to obtain a solution of dilithium salt. The solution of zirconium tetrachloride complex was cooled to 0 °C, and the solution of dilithium salt was added dropwise. After the addition was completed, the mixture was allowed to warm to room temperature and stirred for 12 hours. The reaction was completed, and the mixture was filtered directly. The filter cake was dissolved in 600 mL of toluene by heating to reflux, and the mixture was filtered. The mother liquor was removed directly to obtain the crude product, which was 8.86 g in total and had a yield of 53.2%. The nuclear magnetic resonance spectrum of the product is shown in FIG. 1. Figure 2 .

[0057] In Example 2, after the peaks of deuterated chloroform were calibrated, the ratio of rac- to meso- was 100:27. The crude product was washed with toluene, 100 mL of toluene was used to wash the crude product, and the temperature was increased to 50 °C and maintained for half an hour. The mixture was filtered while hot, and the filter cake was dried to obtain the single rac- product, which was 6.32 g in total and had a yield of 37.9%.

[0058] 1 H NMR (CDCI3): d (ppm) 7.63-7.70 (m, 6H), 7.35-7.46 (m, 8H), 7.11-7.15 (m, 2H), 6.97 (s, 2H), 2.27 (s, 6H), 1.36 (s, 6H).

[0059] Example 3:

[0060] In a glove box, 6.2 g of ZrCl4was added into a 1 L Schlenk flask, 40 mL of super dry toluene was added, and the mixture was stirred until it became a slurry. At room temperature, 10.2 g of N,N'-diphenyl-N,N'-dimethylpropylenediamine was added dropwise, and the mixture was stirred for 5 hours to obtain a zirconium tetrachloride complex solution. In a glove box, 10.98 g of dimethylbis(2-methyl-4-phenylindenyl)silane was added into a 500 mL Schlenk flask, 200 mL of super dry toluene was added, and the mixture was stirred until it became a slurry. At 0°C, 10.6 mL of n-BuLi solution was added dropwise, and the mixture was stirred at room temperature for 12 hours to obtain a dilithium salt solution. The zirconium tetrachloride complex solution was cooled to 0°C, and the obtained dilithium salt solution was added dropwise into the solution. After the addition was completed, the mixture was slowly warmed to room temperature and stirred for 12 hours. After the reaction was completed, the mixture was directly filtered, and the filter cake was dissolved in 600 mL of toluene by heating to reflux. The mixture was filtered, and the obtained mother liquor was directly dried to obtain a crude product, 9.78 g in total, with a yield of 58.7%. The nuclear magnetic resonance spectrum of the product is shown in FIG. 1. Figure 3 .

[0061] In Example 3, after the peaks of deuterated chloroform were calibrated, the ratio of rac- to meso- was 100:86. The crude product was washed with toluene, 300 mL of toluene was used to slurry the crude product, and the temperature was increased to 50°C and maintained for half an hour. The slurry was filtered while hot, and the filter cake was dried to obtain a single rac- product, 2.60 g in total, with a yield of 15.6%.

[0062] 1 H NMR (CDCI3): d (ppm) 7.63-7.70 (m, 6H), 7.35-7.46 (m, 8H), 7.11-7.15 (m, 2H), 6.97 (s, 2H), 2.27 (s, 6H), 1.36 (s, 6H).

[0063] Comparative Example 1

[0064] In a glove box, 6.2 g of ZrCl4 was added into a 100 mL Schlenk flask, 40 mL of super dry toluene was added, and stirred well to form a slurry. At room temperature, 6.33 g of pyridine was added dropwise, and stirred for 5 hours to form a solution of zirconium tetrachloride complex, which was used as a precursor. In a glove box, 10.98 g of dimethylbis(2-methyl-4-phenylindenyl)silane was added into a 500 mL Schlenk flask, 200 mL of super dry toluene was added, and stirred well. At 0°C, 10.6 mL of n-BuLi solution was added dropwise, and the temperature was allowed to return to room temperature after the addition was completed. The reaction was allowed to proceed for 12 hours to form a solution of dilithium salt. The solution of zirconium tetrachloride complex was cooled to 0°C, and the solution of dilithium salt was added dropwise into the solution. The temperature was allowed to return to room temperature slowly after the addition was completed, and stirred for 12 hours. After the reaction was completed, the product was directly filtered. The filter cake was dissolved in 600 mL of toluene at reflux, and filtered. The mother liquor was directly dried to obtain the crude product, which was 7.74 g in total, and the yield was 46.4%. The NMR spectrum of the product is shown in FIG. 1. Figure 4 .

[0065] In the comparative example 1, after the peaks of deuterated chloroform were calibrated, the ratio of rac-:meso- was 66:100.

[0066] Example 4:

[0067] In a glove box, 6.2 g of ZrCl4 was added into a 100 mL Schlenk flask, 40 mL of super dry toluene was added, and stirred well to form a slurry. At room temperature, 6.33 g of pyridine was added dropwise, and stirred for 5 hours to form a solution of zirconium tetrachloride complex, which was used as a precursor. In a glove box, 10.98 g of dimethylbis(2-methyl-4-phenylindenyl)silane was added into a 500 mL Schlenk flask, 200 mL of super dry toluene was added, and stirred well. At 0°C, 10.6 mL of n-BuLi solution was added dropwise, and the temperature was allowed to return to room temperature after the addition was completed. The reaction was allowed to proceed for 12 hours to form a solution of dilithium salt. The solution of zirconium tetrachloride complex was cooled to 0°C, and the solution of dilithium salt was added dropwise into the solution. The temperature was allowed to return to room temperature slowly after the addition was completed, and stirred for 12 hours. After the reaction was completed, the product was directly filtered. The filter cake was dissolved in 600 mL of toluene at reflux, and filtered. The mother liquor was directly dried to obtain the crude product, which was 7.74 g in total, and the yield was 46.4%. The NMR spectrum of the product is shown in FIG. 1.

[0068] 1H NMR (CDCI3): d (ppm) 7.60-7.68 (m, 10H), 7.24 (m, 2H), 7.12 (m, 2H), 6.87 (s, 2H), 2.27 (s, 6H), 1.46 (s, 36H), 1.36 (s, 6H).

[0069] Example 5:

[0070] In a glove box, 6.2 g of ZrCl4was added into a 1 L Schlenk flask, 40 mL of super dry toluene was added, and stirred well to be slurry. At room temperature, 5.2 g of tetramethylpropylenediamine was added dropwise, and stirred for 5 hours to be a zirconium tetrachloride directing complex solution. In a glove box, 13.4 g of dimethylbis(2-methyl-4-(4-fluorophenyl)indenyl)silane was added into a 500 mL Schlenk flask, 200 mL of super dry toluene was added, and stirred well. At 0 °C, 21.2 mL of n-BuLi solution was added dropwise, and after the addition was completed, it was returned to room temperature and reacted for 12 hours to be a dilithium salt solution. The zirconium tetrachloride directing complex solution was cooled to 0 °C, and the obtained dilithium salt solution was slowly added dropwise to the solution, and after the addition was completed, it was slowly returned to room temperature and stirred for 12 hours. After the reaction was completed, it was directly filtered, and the filter cake was dissolved again with 600 mL of toluene and filtered. The obtained mother liquor was directly dried to obtain a crude product, and the catalyst product was obtained without purification (rac-: meso- = 100:2, which can be directly used for polymerization reaction.), 8.39 g in total, with a yield of 47.5%.

[0071] 1 H NMR (CDCI3): d (ppm) 7.60-7.68 (m, 10H), 7.24 (m, 2H), 7.12 (m, 2H), 6.87 (s, 2H), 2.27 (s, 6H), 1.46 (s, 36H), 1.36 (s, 6H).

[0072] Example 6:

[0073] Into a polymerization reactor, 332 mL of n-hexane, 85 mL of 1-octene and 0.6 mmol of triisobutylaluminum (molar ratio of 600:1 to the catalyst) were introduced at room temperature. The polymerization reactor was heated to 120°C, while the ethylene pressure in the polymerization reactor was increased to 2.5 MPa. 1 μmol of rac-dimethylsilyl-di(2-methyl-4-phenylindenyl)zirconium dichloride catalyst and 2 μmol of triphenylcarbenium tetrakis(pentafluorophenyl)borate were dissolved in 30 mL of toluene to form an activated catalyst solution (total volume of the polymerization system was 450 mL, and the concentration of 1-octene was 1.22 mol / L). Then, the activated catalyst solution was quickly injected into the polymerization reactor to initiate the polymerization, and the ethylene gas switch was opened to supplement ethylene at any time, so that the pressure in the polymerization reactor was maintained at 2.5 MPa. The polymerization temperature was set to 120°C. After 30 minutes of reaction, the ethylene inlet switch and the reactor heating switch were turned off, the temperature was lowered to room temperature, and then the polymerization reactor was depressurized to atmospheric pressure before opening. The polymer was taken out and terminated with an acid-alcohol solution (ethanol:hydrochloric acid = 9:1). After filtration, the polymer was dried to a constant weight, which was the obtained product, a total of 67.2 g, and the catalyst activity was 134.4 x 10 6 g / mol.h.

[0074] The above illustrates the embodiments of the technical solutions of the present disclosure. It should be understood that the protection scope of the present disclosure is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principles of the present disclosure shall be included in the protection scope of the claims of the present application.

Claims

1. A method for selectively synthesizing a racemic metallocene catalyst, comprising the following steps: Step S1: dispersing MX4 in an organic solvent to obtain a directing solution after mixing with tetramethylpropylenediamine; Step S2: dissolving compound a in an organic solvent, adding a lithium salt solution, and mixing to obtain a solution containing compound b; Step S3: mixing the directing solution with the solution containing compound b to obtain the racemic metallocene catalyst of formula (I) after reaction; wherein M is selected from titanium, zirconium, hafnium; X is selected from chlorine, bromine, iodine; each R1, R2, R3is the same or different, independently of one another, selected from the group consisting of no substitution or optionally substituted with one, two, or more R a substituted C 1-10 alkyl, C 6-10 aryl, 5-10 membered heteroaryl; each R a is the same or different, independently of one another, selected from the group consisting of H, halogen, C 1-10 alkyl; each R4is the same or different, independently selected from C 1-10 alkyl; m is selected from 1, 2, 3 or 4.

2. The method of claim 1, wherein, each R1, R2, R3is the same or different, independently of each other, selected from the group consisting of C 1-6 alkyl, C 1-6 alkyl-C 6-10 aryl, haloC 6-10 aryl; Preferably, each R1, R2, R3 is the same or different, and is independently selected from methyl, tert-butyl phenyl, halogenated phenyl; Preferably, each R4is the same or different, independently selected from C 1-6 alkyl, for example methyl.

3. The method according to claim 1 or 2, characterized in that, The compound a is selected from: Preferably, compound a is selected from:

4. The method according to any one of claims 1 to 3, characterized in that, The compounds of formula (I) are selected from the group consisting of: Preferably, the structure of compound of formula (I) is selected from:

5. The method according to any one of claims 1 to 4, characterized in that, the organic solvent is selected from a non-polar aprotic solvent, such as n-hexane, toluene; Preferably, MX4 is selected from titanium tetrachloride, zirconium tetrachloride, hafnium tetrachloride; Preferably, the lithium salt is selected from n-butyllithium or tert-butyllithium.

6. The method according to any one of claims 1 to 5, characterized in that, The molar ratio of MX4 to tetramethylpropylenediamine in step S1 is selected from 1:(0.8-5), for example 1:(1-3); Preferably, the mass-volume ratio of MX4 to organic solvent in step S1 is selected from 1g:(2-15)mL, for example 1g:(5-10)mL; Preferably, the specific method of step S1 comprises: adding tetramethylpropylenediamine dropwise to the organic solvent of MX4, and mixing to obtain the directing solution.

7. The method according to any one of claims 1 to 6, characterized in that, The mass-volume ratio of compound a to organic solvent in step S2 is selected from 1g:(5-40)mL, for example 1g:(10-30)mL; Preferably, the molar ratio of compound a to lithium salt in step S2 is selected from 1:(1-8), for example 1:(2-6); Preferably, the specific method of step S2 comprises: adding a lithium salt solution dropwise to the organic solvent of compound a, and mixing to obtain a solution containing compound b.

8. The method according to any one of claims 1 to 7, characterized in that, The molar ratio of MX4 in the directing solution to compound a in the solution containing compound b in step S3 is selected from 1:(0.5-2), for example 1:(0.6-1.5).

9. The method according to any one of claims 1 to 8, characterized in that, The method further comprises a post-treatment step, which comprises: filtering after the reaction is completed, dissolving the filter cake in an organic solvent, filtering again, removing the solvent in the mother liquor, and obtaining the racemic metallocene catalyst; the amount of the organic solvent is selected from 1g:(50-150)mL, for example 1g:(80-120)mL, based on the weight of MX4, and the mass-volume ratio of MX4 to organic solvent is selected from 1g:(50-150)mL, for example 1g:(80-120)mL.

10. The method according to any one of claims 1 to 9, characterized in that, The method further comprises a purification step, which comprises: adding an organic solvent to the racemic metallocene catalyst, and beating at 40℃-60℃ for 10min-40min, filtering while hot to obtain the purified racemic metallocene catalyst.

Images