Metallocene complex and preparation method thereof

Abstract

The invention discloses a metallocene complex and a preparation method thereof.The preparation method comprises the steps that a 2, 5-pentanedione derivative which is cheap and commercially available serves as a starting raw material, a cyclopentenone derivative is generated through alkali catalytic intramolecular cyclization, then the cyclopentenone derivative reacts with a Grignard reagent to generate a cyclopentadiene derivative, and the metallocene complex is obtained. And finally, protons are captured through sodium hydride and then react with zirconium chloride to obtain the metallocene complex, compared with some routes with complex initial raw materials or routes related to medicine control, reagents involved in the reaction process are commercially available cheap raw materials, the reaction conditions are mild, the method is suitable for industrial production, and the method further has the amplified production potential.

Description

Technical Field

[0001] This application belongs to the field of catalyst preparation technology, specifically relating to a metallocene complex and its preparation method. Background Technology

[0002] Metallocene catalysts are defined as catalysts with a group IVB transition metal as the active center and at least one cyclopentadienyl (Cp) or cyclopentadiene derivative as the main catalyst. Forty years ago, Kaminsky et al. discovered the metallocene / methylaluminoxane (MAO) catalytic system for olefin polymerization in the Hamburg laboratory. This type of catalyst has only one metal active center (single-center catalyst), introducing a new transition metal complex system for the polymerization of olefins, dienes, and styrene.

[0003] Given that these single-active-site catalysts can control the microstructure of polymers, such as the distribution of comonomers, the stereoregularity of polymers, and regioselectivity, chemists and engineers have long been extremely interested in this type of metallocene catalyst. In 1980, Professors Kaminsky and Sinn, through a series of experimental studies, discovered that the presence of methylaluminoxane (MAO) in the dichlorodichlorocathocyanin / trimethylaluminum system could greatly increase the activity of the catalytic system. Using this homogeneous catalytic system, the polydispersity and microstructure of polymers could be tuned by simply changing the organic ligands surrounding the Group IV metal.

[0004] The single active site characteristic of metallocene catalysts allows for systematic analysis and research on the mechanism of catalytic olefin polymerization, deepening our understanding of the olefin polymerization process and laying a solid foundation for future research on catalytic polymerization.

[0005] Current metallocene synthesis methods have many drawbacks. For example, starting materials with overly complex structures (CN117164616A, CN117467055A) or involving controlled substances (CN117396489A) are not conducive to production scale-up. Furthermore, the general methods have harsh conditions (CN117069771A, CN117069773B), are cumbersome to operate (CN117396489A, CN117467055A), have high and inconvenient purification methods (CN117069771A), and pose a risk of deterioration when handling sensitive intermediates (US006046346A), etc. Summary of the Invention

[0006] The purpose of this application is to provide a metallocene complex and its preparation method, wherein the preparation method has the advantages of mild reaction conditions, simple synthetic route and low cost, which is conducive to industrial production.

[0007] The technical solution of this application is as follows:

[0008] A method for preparing a metallocene complex includes the following steps:

[0009] (1) The 2,5-pentanedione derivative shown in formula (a) is given by aldol condensation in an alkaline solution to obtain the cyclopentenone derivative shown in formula (b).

[0010] (2) The cyclopentenone derivative is reacted with Grignard reagent and then acidified to obtain the cyclopentadiene derivative shown in formula (c).

[0011] (3) The cyclopentadiene derivative reacts with sodium hydride and then with zirconium chloride to form a metallocene complex as shown in formula (d);

[0012] The structures of equations (a) to (d) are as follows:

[0013]

[0014] Among them, R1 and R2 are independently selected from H, C1 to C1, respectively. 12 Substituted or unsubstituted alkyl groups;

[0015] Step (3) is carried out in an anhydrous and oxygen-free environment. The specific operation is as follows: after washing sodium hydride with an organic solvent, anhydrous tetrahydrofuran and cyclopentadiene derivative are sequentially injected into sodium hydride under an inert atmosphere. After the addition is completed, the temperature is raised to 30-45°C, and then the reaction is carried out until the system is converted into a dark red suspension. After solid-liquid separation, an intermediate solution is obtained. Anhydrous tetrahydrofuran is cooled to -25 to -35°C, and zirconium chloride is added in batches to the cooled anhydrous tetrahydrofuran to prepare a zirconium chloride system. The intermediate solution is added to the zirconium chloride system. After the addition is completed, the reaction is carried out at 30-45°C for 10-12 hours to obtain a metallocene complex. The molar equivalent ratio of cyclopentadiene derivative, sodium hydride and zirconium chloride is 1:1-5:0.5-1.

[0016] In the above steps, preferably, the molar equivalent ratio of cyclopentadiene derivative, sodium hydride and zirconium chloride is 1:1.1:0.5; and / or, zirconium chloride is cooled to -30°C; and / or, the organic solvent in step (3) is n-hexane.

[0017] More preferably, step (3) further includes the following operations: after the reaction is completed, the reaction solution is mixed with an organic solvent and then filtered. The filtrate is concentrated, redissolved, filtered, crystallized and recrystallized to obtain the product. The crystallization temperature is -20 to -5℃ and the recrystallization temperature is -20 to -5℃.

[0018] More preferably, step (3) further includes the following operation: after injecting anhydrous THF into sodium hydride, the reaction system is purged with nitrogen again. This operation can further ensure that there is no residual air in the system.

[0019] More preferably, the addition of the cyclopentadiene derivative in step (3) is performed by adding the cyclopentadiene derivative dropwise to the system under ice bath conditions. This operation can further prevent the system from releasing a large amount of hydrogen gas due to an excessively fast reaction rate during the addition of the cyclopentadiene derivative.

[0020] More preferably, the operation to remove the precipitate in step (3) is to let it stand and take the supernatant, or to transfer the dark red suspension to a constant pressure dropping funnel with quartz glass wool. The latter can effectively prevent the residual sodium hydride solid in the intermediate solution from entering the zirconium chloride system through filtration.

[0021] In some possible implementations, the specific operation of step (1) is as follows: the aqueous solution of the first base is mixed with an organic solvent, heated to reflux under an inert atmosphere, and then 2,5-pentanedione derivative is added dropwise. The reaction is carried out for 2 to 8 hours to obtain cyclopentenone derivative.

[0022] The first base is an alkali metal hydroxide, an inorganic salt, or an alkali metal salt of a C1-C4 alcohol. The molar equivalent ratio of the 2,5-pentanedione derivative to the first base is 1:0.1-1.5. The organic solvent is an aprotic solvent. The volume ratio of the aqueous solution of the first base to the organic solvent is 1:0.3-2.5.

[0023] In the above steps, preferably, the first base is sodium hydroxide, potassium hydroxide, sodium methoxide, sodium ethoxide, sodium tert-butoxide, or potassium tert-butoxide; and / or, the molar equivalent ratio of the 2,5-pentanedione derivative to the base is 1:1; and / or, the organic solvent is dibromomethane, toluene, n-hexane, cyclohexane, or n-heptane; and / or, the reaction time is 4 hours.

[0024] In some possible implementations, step (1) specifically involves placing an aqueous solution of the second base, a 2,5-pentanedione derivative, and a phase transfer catalyst in a high-pressure reactor to react and obtain a cyclopentenone derivative.

[0025] The second base is an alkali metal hydroxide, an inorganic salt, or an alkali metal salt of a C1-C4 alcohol. The molar equivalent ratio of the 2,5-pentanedione derivative, the second base, and the catalyst is 1:0.01-0.1:0.01-0.1. The mass ratio of the second base to water is 1:20-50. The reaction time is 0.5-3 hours, and the reaction temperature is 120-180℃.

[0026] In the above steps, preferably, the phase transfer catalyst is tetrabutylammonium bromide or tetrabutylammonium iodide, and the second base is sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, tripotassium phosphate, sodium methoxide, sodium ethoxide, sodium tert-butoxide or potassium tert-butoxide; and / or, the molar equivalent ratio of the 2,5-pentanedione derivative, the second base and the catalyst is 1:0.03:0.01; and / or, the mass ratio of the second base to water is 1:20; and / or, the reaction time is 2 h; and / or, the reaction temperature is 140 °C.

[0027] More preferably, step (1) further includes the following operation: after the reaction is completed, dilute hydrochloric acid is added to adjust the pH to 1-6, and the product is then subjected to separation, extraction, washing, drying, concentration and vacuum distillation to obtain the purified cyclopentenone derivative.

[0028] In some possible implementations, step (2) is specifically performed as follows: under an inert atmosphere, the system temperature is lowered to -10 to 20°C, and then the cyclopentenone derivative is mixed with Grignard reagent. During the mixing process, the system temperature is controlled not to exceed 20°C. After the addition is completed, the reaction is carried out at room temperature and the reaction is monitored by TLC until completion. Then, the system temperature is lowered to -10 to 20°C, and an aqueous solution of acid is added dropwise with stirring. During the dropwise addition, the system temperature is controlled not to exceed 30°C. After the addition is completed, the temperature is raised to carry out the reaction and the reaction is monitored by liquid chromatography until completion to obtain the cyclopentadiene derivative.

[0029] The concentration of Grignard reagent is 1.0–2.5 mol / L, the concentration of acid is 5–30 wt%, the molar equivalent ratio of cyclopentenone derivative, Grignard reagent and acid is 1:1–15:2–5, the temperature of the reaction is 30–45 °C, and the reaction of cyclopentenone derivative and Grignard reagent is carried out in an anhydrous and oxygen-free environment.

[0030] In the above steps, preferably, the molar equivalent ratio of the cyclopentenone derivative, Grignard reagent, and acid is 1:1.3:2.5; and / or, the concentration of the acid is 10 wt%; and / or, the acid is an inorganic acid such as hydrochloric acid, sulfuric acid, or nitric acid, or an organic acid such as formic acid, acetic acid, propionic acid, or trifluoroacetic acid, preferably an organic acid; and / or, the temperature of the heating reaction is 35°C; and / or, the heating reaction time is 2–28 h.

[0031] More preferably, step (2) further includes the following operations: after the reaction is complete, the unreacted acid is neutralized with an alkaline aqueous solution, and then the product is successively extracted, washed, dried, concentrated and distilled under reduced pressure to obtain the purified cyclopentadiene derivative.

[0032] A metallocene complex was prepared by the above-described preparation method.

[0033] This application has at least the following beneficial effects:

[0034] (1) This application uses 2,5-hexanedione, which is inexpensive and commercially available, as a starting material to construct a substituted cyclopentadiene ring, which has greater potential for scale-up production compared to some routes with complex starting materials or routes involving controlled drugs.

[0035] (2) In step (3), cooling zirconium chloride before adding it in batches to pre-cooled anhydrous tetrahydrofuran (THF) effectively avoids the problem of material overflow caused by the violent exothermic reaction during the addition of anhydrous THF and zirconium chloride in the prior art. In addition, compared with the technical solution of adding anhydrous THF to zirconium chloride, the addition sequence of this application can ensure that the heat generated during the addition process can be quickly neutralized by the low-temperature anhydrous THF; when the preparation method is scaled up industrially, the process can still be effectively stirred.

[0036] (3) All intermediates and final products in this application are purified by distillation or crystallization, which is more convenient and cost-effective than the route involving column chromatography purification.

[0037] (4) In some possible implementations, step (1) uses water as the reaction solvent to avoid the problem of repeated vacuum distillation in the post-processing and to avoid the problem of some products being carried out by organic solvents during vacuum distillation. This reduces impurities in the product, improves the reaction conversion rate, simplifies the post-processing steps, and effectively reduces costs. Attached Figure Description

[0038] Figure 1 The NMR spectrum is that of bis(1-butyl-3-methylcyclopentadienyl)zirconia prepared in Example 1. Detailed Implementation

[0039] The technical solution of this application will be further explained and described below through specific embodiments.

[0040] In the following embodiments, unless otherwise specified, the water used may be one or more of distilled water, purified water, and drinking water; the detection methods in the following embodiments are conventional detection methods unless otherwise specified; the reagents in the following embodiments are commercially available unless otherwise specified.

[0041] Concentration as used in this application refers to the removal of solvent from the reaction system. In the following embodiments, the specific method of concentration is rotary evaporation. This application has no special requirements for the rotation speed and time of rotary evaporation, as long as the solvent can be removed. Unless otherwise specified, % in this application refers to mass percentage. Partial addition in this application refers to adding the reactants in at least two batches. The purpose is to prevent the problem of material overflow caused by violent exothermic reactions. There is no specific limit to the number of batch additions.

[0042] Example 1

[0043] (1) Synthesis of 3-methyl-2-cyclopenten-1-one (cyclopentenone derivative)

[0044]

[0045] 2,5-Hexanedione (2,5-pentanedione derivative, 240 g, 1 eq) was placed in a constant-pressure dropping funnel. Sodium hydroxide (primary base, 85.7 g, 1 eq) was dissolved in 500 mL of water. After slight cooling, 400 mL of dibromomethane, an organic solvent, was added. The mixture was purged with nitrogen and then heated to reflux. 2,5-Hexanedione was added dropwise to the sodium hydroxide system, and the reaction was maintained at this temperature for 4 h. GC analysis showed that 4.9% of the starting material and 85% of the product remained.

[0046] The system was cooled to room temperature, and the pH was adjusted to 5-6 with dilute hydrochloric acid. The mixture was separated, and the aqueous phase was sequentially extracted with dichloromethane (DCM) (100 mL × 3), washed with saturated brine, and dried over anhydrous sodium sulfate. Most of the DCM was removed by rotary evaporation at 37°C. Finally, multiple vacuum distillations yielded 149.63 g of product. GC analysis showed that the purity of 3-methyl-2-cyclopenten-1-one in the product was 99.7%, with a yield of 74.11%.

[0047] (2) Synthesis of 3-butyl-1-methyl-1,3-cyclopentadiene (cyclopentadiene derivative)

[0048]

[0049] Dissolve 100 g of 3-methyl-2-cyclopenten-1-one in 50 mL of anhydrous THF and place the solution in a constant pressure dropping funnel.

[0050] Take 675 mL of n-butylmagnesium chloride (Grignard reagent, 2 M, 1.3 eq) into a three-necked flask, purge with nitrogen, and cool the system to 0 °C. Slowly add 3-methyl-2-cyclopenten-1-one dropwise, controlling the system temperature not to exceed 10 °C during the addition. After the addition is complete, transfer to room temperature and monitor the reaction until it is complete using TLC.

[0051] The system was cooled to 0°C, and a 10% aqueous solution of acetic acid (2.5 eq) was added dropwise under mechanical stirring, with the system temperature controlled not to exceed 10°C during the addition. The system initially showed a solid, which then dissolved. After the addition was complete, the temperature was raised to 36°C and the reaction proceeded for 27 hours. Heating was stopped, and the mixture was neutralized with a saturated sodium bicarbonate aqueous solution until no more bubbles were produced. THF was recovered by rotary evaporation, and the mixture was separated. The aqueous phase was extracted with PE, and the organic phases were combined, washed with saturated brine, and dried to obtain the crude product. Vacuum distillation yielded 81.1 g of a pale yellow oil, with a yield of 58.36%.

[0052] (3) Synthesis of bis(1-butyl-3-methylcyclopentadienyl)zirconia (metallocene complex)

[0053]

[0054] Take 81.1 g of 3-methyl-1-butylcyclopentadiene (1 eq) and place it in a constant pressure dropping funnel.

[0055] Sodium hydride (26.2 g 60% mineral oil dispersion, 1.1 eq) was placed in a three-necked flask, washed with the organic solvent n-hexane, and then purged with nitrogen. Anhydrous tetrahydrofuran (180 mL) was added to the three-necked flask, and the mixture was purged with nitrogen again. 3-Methyl-1-butylcyclopentadiene was added dropwise at room temperature. After the addition was complete, the temperature was raised to 45 °C, and the reaction was stirred for 12 h until the system turned deep red. Stirring and heating were stopped, and the solid was allowed to precipitate. The supernatant was collected to obtain the intermediate solution.

[0056] Separately, 120 mL of anhydrous THF was placed in a dry three-necked flask purged with nitrogen and cooled to -25 °C. Zirconium chloride (87 g, 0.63 eq) was added in three batches to a solid powder feeder. After addition, the mixture was heated to room temperature and stirred for 1 h. The intermediate solution was transferred to the zirconium chloride system using a double needle; the zirconium chloride system turned brown. After addition, the mixture was reacted at 45 °C for 12 h. The reaction solution was added to 500 mL of hexane and stirred, then filtered. The filter cake was washed with hexane, and the washings were combined with the filtrate. The filtrate was concentrated to dryness, and then 500 mL of hexane was added again with stirring and filtered. The filtrate was cooled at -20 °C to crystallize. The precipitated solid was filtered to obtain a crude product. The crude product was dissolved in 300 mL of hexane and recrystallized at -20 °C to obtain 44.19 g of white solid bis(1-butyl-3-methylcyclopentadienyl)zirconium dichloride, with a yield of 34.32%.

[0057] The product was analyzed by hydrogen nuclear magnetic resonance, and the results are as follows: Figure 1 As shown,

[0058] 1 HNMR (500MHz, CDCl3) δ6.10 (s, 1H), 5.97 (dt, J = 4.7, 2.5Hz, 1H), 5.92 (dd, J = 4.9, 2.4Hz, 1H), 2.60 (ddd, J = 14.7, 10. 6,5.5Hz,1H),2.53–2.42(m,1H),2.22(d,J=2.4Hz,3H),1.58–1.42(m,2H),1.41–1.30(m,2H),0.93(t,J=7.3Hz,3H).

[0059] Example 2

[0060] (1) Synthesis of 3-methyl-2-cyclopenten-1-one

[0061] In a three-necked flask, sodium hydroxide (85.7 g, 1 eq) was dissolved in water (520 mL). After cooling to room temperature, dibromomethane (260 mL) was added, followed by nitrogen purging. The mixture was heated to reflux, and 2,5-hexanedione (240 g, 1 eq) was added dropwise. After the addition was complete, the reaction was maintained at this temperature for 2 hours. GC analysis showed that the starting material had completely reacted. The system was cooled to room temperature, and the pH was adjusted to 2–3 with dilute hydrochloric acid. After stirring and separation, the aqueous phase was sequentially extracted with DCM. The combined organic phases were washed with saturated brine (500 mL × 2). The solution was dried over anhydrous sodium sulfate and concentrated to obtain 287 g of crude product. Multiple vacuum distillations yielded 134 g of the product, with a yield of 66.38%.

[0062] (2) Synthesis of 3-butyl-1-methyl-1,3-cyclopentadiene

[0063] Add 135 mL of 2 M butyl magnesium chloride (1.3 eq) and 20 g of 3-methyl-2-cyclopenten-1-one (1 eq) dissolved in 100 mL of anhydrous THF to a three-necked flask and place the solution in a constant-pressure dropping funnel. After purging with nitrogen, cool the three-necked flask to -5 °C, and then add 3-methyl-2-cyclopenten-1-one dropwise, controlling the temperature of the system to not exceed 10 °C during the addition. After the addition is complete, transfer the solution to room temperature and monitor the reaction by TLC until completion.

[0064] The reaction solution was cooled to -5°C, and a 10% acetic acid solution (4.0 eq) was added dropwise with mechanical stirring. The system became turbid, and a solid appeared, which dissolved after the addition was complete. The system temperature was controlled to not exceed 10°C throughout the process. After the addition was complete, the temperature was raised to 36°C and the reaction was allowed to proceed for 26 hours.

[0065] After the reaction was complete, the liquid-liquid phase was separated. The aqueous phase was extracted with PE, and the organic phases were combined. The mixture was washed with saturated sodium bicarbonate solution until no more bubbles were generated. The liquid-liquid phase was separated again, and then the organic phase was dried and desoluble to obtain 27.3 g of crude product. Vacuum distillation yielded 18.26 g of a yellow oily substance. The product 3-butyl-1-methyl-1,3-cyclopentadiene:isomer ratio was determined to be 71.9%:26.7%.

[0066] (3) Synthesis of bis(1-butyl-3-methylcyclopentadienyl)zirconia

[0067] Add 6.4 g of sodium hydride (60% mineral oil dispersion, 1.1 eq) to a three-necked flask, wash with hexane (50 mL × 2), purge with nitrogen in a double-row tube, and then add anhydrous THF (45 mL) to the flask and stir. Place 20 g (1 eq) of 3-butyl-1-methylcyclopentadiene in a constant-pressure dropping funnel and add it dropwise to the three-necked flask under ice bath conditions. After the addition is complete, heat to 45 °C and stir for 24 h. The system becomes a red suspension. Stop stirring and heating, allow the precipitate to stand, and allow the system temperature to drop to room temperature. Transfer the upper red liquid using a double needle and add it to a zirconium chloride system (0.5 eq, 50 mL anhydrous THF). After the addition is complete, heat to 45 °C and stir; the system turns brownish-yellow. After 12 h of reaction, it turns dark green.

[0068] The system was added dropwise to 200 mL of n-hexane with stirring, filtered, the filter cake was washed with n-hexane, and the filtrate was concentrated to obtain a black oily substance. This oily substance was then added dropwise to another 200 mL of n-hexane, resulting in a black viscous substance. The mixture was filtered, the filtrate was concentrated to dryness, and then dissolved in approximately 150 mL of n-hexane. Crystallization occurred upon cooling. A large amount of solid precipitated, yielding 13.8 g of crude product. Recrystallization yielded 8.3 g of white needle-like solid bis(1-butyl-3-methylcyclopentadienyl)zirconium dichloride, with a yield of 26.14%.

[0069] Example 3

[0070] (1) Synthesis of 3-methyl-2-cyclopenten-1-one

[0071]

[0072] In a 500 mL reactor, 400 mL of an aqueous solution of tripotassium phosphate trihydrate (containing 1.4 g of the second base, tripotassium phosphate trihydrate, 0.03 eq), 2,5-hexanedione (20 g, 1 eq), and the phase transfer catalyst tetrabutylammonium bromide (0.56 g, 0.01 eq) were added, and the mixture was sealed and heated to 140 °C for 2 h. GC monitoring showed that the reaction proceeds were complete, and the product yield was 95.7%. The system was acidified with dilute hydrochloric acid to a pH of 3–4, then extracted with DCM (100 mL × 3). The organic phases were combined and washed with saturated brine (200 mL × 2). The mixture was dried over anhydrous sodium sulfate, and the DCM was removed by rotary evaporation at 30 °C to obtain the crude product. Finally, the crude product was distilled under reduced pressure to obtain 14.9 g of a light yellow transparent oil, with a yield of 88%.

[0073] (2) Synthesis of 3-butyl-1-methyl-1,3-cyclopentadiene

[0074]

[0075] Add 135 mL of 2 M butyl magnesium chloride (1.3 eq) and 20 g of 3-methyl-2-cyclopenten-1-one (1 eq) to a three-necked flask in a constant-pressure dropping funnel. After purging with nitrogen, cool to -8 °C and add 3-methyl-2-cyclopenten-1-one dropwise, keeping the system temperature below 10 °C during the addition process. After the addition is complete, transfer to room temperature and monitor the reaction until completion by TLC.

[0076] The reaction solution was cooled to -5°C, and a 10% acetic acid solution (2.5 eq) was added dropwise with mechanical stirring. The system became turbid, and a solid appeared. The solid dissolved after the addition was complete. During the addition, the system temperature was controlled not to exceed 10°C. After the addition was complete, the temperature was raised to 36°C and the reaction was allowed to proceed for 28 hours.

[0077] After the reaction was complete, the mixture was separated. The aqueous phase was extracted with PE, and the organic phases were combined and washed with saturated sodium bicarbonate solution until no more bubbles were generated. The mixture was separated, the organic phase was dried, and solvent was removed to obtain the crude product. The crude product was distilled under reduced pressure to give 18.4 g of a light yellow transparent oil. The product was 3-butyl-1-methyl-1,3-cyclopentadiene:isomer = 72.5%:26.3%.

[0078] (3) Synthesis of bis(1-butyl-3-methylcyclopentadienyl)zirconia

[0079]

[0080] Sodium hydride (9.5 g, 60% mineral oil dispersion, 1.1 eq) was added to a three-necked flask and washed with n-hexane (50 mL × 2). 29.2 g (1 eq) of 3-butyl-1-methylcyclopentadiene was added to a constant-pressure dropping funnel, purged with nitrogen using a double-row tube, and anhydrous THF (90 mL) was added to the flask with stirring. 3-Butyl-1-methylcyclopentadiene was added dropwise under ice bath conditions. After the addition was complete, the temperature was raised to 45 °C and the reaction was stirred for 12 h. The system became a red suspension; stirring was then stopped, and the mixture was allowed to cool to room temperature.

[0081] Take another dry three-necked flask, purge it with nitrogen, and then quickly add zirconium chloride (25 g, 0.5 eq) into a solid powder feeder under nitrogen purging, immediately purging with nitrogen again. Inject anhydrous THF (60 mL) into the three-necked flask and cool to -30°C. Add zirconium chloride in batches; the system will heat up. After the addition is complete, heat to 40°C and stir for 0.5 h.

[0082] The upper red liquid layer of the 3-butyl-1-methylcyclopentadiene system was transferred using a double needle to a constant-pressure dropping funnel lined with quartz glass wool, and then added dropwise to the zirconium chloride system. After the addition was complete, the temperature was raised to 45°C and stirred, and the system turned brownish-yellow. After reacting for 12 hours, it turned dark green.

[0083] 400 mL of n-hexane was added dropwise with stirring, and the mixture was filtered. The filter cake was washed with n-hexane, and the filtrate was concentrated to obtain a black oily substance. Another 200 mL of n-hexane was added to redissolve the oil. The mixture was then filtered again, and the filtrate was cooled at -20°C to allow crystallization. A large amount of solid precipitated, yielding 14.5 g of crude product. Recrystallization gave 12.2 g of white needle-like solid, with a yield of 26.32%.

[0084] Example 4

[0085] (1) Synthesis of 3-methyl-2-cyclopenten-1-one

[0086] In a 50L sealed reactor, water (8.5kg), 2,5-hexanedione (425g, 1eq), tripotassium phosphate trihydrate (24g, 0.024eq), and tetrabutylammonium iodide (12g, 0.01eq) were added, and the reactor was sealed. The temperature was raised to 110℃ within 2 hours, and the reaction was carried out for 7 hours. GC monitoring showed that the reactants were basically completely reacted, and the product yield was 91.5%. The system was acidified with 10wt% dilute hydrochloric acid (80mL), and then DCM (2kg) was added. The mixture was stirred and discharged. After separation, the aqueous phase was extracted with DCM (0.5kg × 3). The organic phases were combined, washed with saturated brine (4kg), and dried over anhydrous sodium sulfate. The DCM was removed by rotary evaporation at 30℃ to obtain 493g of crude product. Vacuum distillation yielded 262.5g of a light yellow transparent oil, with a yield of 72.44% and a purity of 99.2%.

[0087] (2) Synthesis of 3-butyl-1-methyl-1,3-cyclopentadiene

[0088] After purging a 500L reactor with nitrogen, 2M 180L butyl magnesium chloride and 30kg of 3-methyl-2-cyclopenten-1-one were added to the nitrogen-purged reactor. The reactor was cooled to 10℃, and 3-methyl-2-cyclopenten-1-one was added dropwise over 4.5 hours, maintaining the internal temperature between 10 and 20℃. After the addition was complete, the reactor was transferred to room temperature and reacted for 2 hours. The reaction was monitored by TLC until completion. An aqueous acetic acid solution (39.3kg acetic acid dissolved in 160kg water) was added dropwise over 5 hours with stirring. The system became turbid, and a solid appeared; the solid dissolved after the addition was complete. The internal temperature was maintained between 15 and 25℃ throughout the process. After the addition was complete, the system was heated to 30℃ and reacted for 2 hours.

[0089] After separation, the organic phases were extracted with PE in the aqueous phase and then combined. The mixture was washed with saturated sodium bicarbonate solution until no more bubbles were produced. The organic phase was then separated, dried, and dissolved to obtain the crude product. Vacuum distillation yielded 29.6 kg of a pale yellow, transparent oil, with a product:isomer ratio of 78%:22%. The yield was 69.64%.

[0090] (3) Synthesis of bis(1-butyl-3-methylcyclopentadienyl)zirconia

[0091] After purging with nitrogen in a 100L high- and low-temperature reactor, 7.5 kg of sodium hydride (60% mineral oil dispersion) was added, followed by washing with 15 L of n-hexane. 15 kg of 3-butyl-1-methylcyclopentadiene was then added to the nitrogen-purged reactor, and 35 L of anhydrous THF was added dropwise. The addition of 3-butyl-1-methylcyclopentadiene was completed within 1 hour. After the addition was complete, the temperature was raised to 55°C and the reaction was stirred for 48 hours. The system turned into a red suspension; stirring was then stopped, and the mixture was allowed to cool to room temperature.

[0092] A separate 100L high-low temperature reactor was selected. After purging with nitrogen, 30L of anhydrous tetrahydrofuran was added, and the reactor temperature was lowered to -30℃. Under nitrogen protection, 13kg of zirconium chloride was added to the tetrahydrofuran in batches over 2.5 hours. After the addition was complete, the mixture was allowed to react at room temperature for 2 hours. The system was a grayish-white suspension. The zirconium chloride system was cooled to -20℃, and under nitrogen protection, the supernatant of the sodium hydride system was transferred to the zirconium chloride system, maintaining the internal temperature below 0℃. After the addition was complete, the mixture was heated to 45℃ and reacted for 8 hours. The solvent was removed, and the residue was dissolved in 60L of n-hexane and stirred for 2 hours. The mixture was then discharged, allowed to stand for 4 hours, centrifuged, and filtered. The filtrate was concentrated to dryness, and then dissolved in another 60L of n-hexane. The insoluble matter was filtered off using a plate and frame organic filter membrane, and the filtrate crystallized at -20℃. A large amount of solid precipitated out. The crude product was obtained by filtration and recrystallization, yielding 7.5kg of product, with a yield of 31.52%.

[0093] Comparative Example 1

[0094] Comparative Example 1 only shows the specific operation of mixing zirconium chloride with anhydrous THF in the prior art.

[0095] Take a 500mL three-necked flask, purge with nitrogen several times, then quickly add zirconium chloride (87g) under nitrogen purging, followed by another nitrogen purging. After cooling in an ice bath, slowly inject anhydrous THF (120mL). The exothermic reaction is intense, reflux occurs on the flask wall, a large amount of white mist appears inside the flask, zirconium chloride clumps, affecting stirring and solids splash onto the flask wall.

[0096] Comparative Example 2

[0097] Comparative Example 2 only shows the specific operation of mixing zirconium chloride with anhydrous THF in the prior art.

[0098] Take a 250mL three-necked flask, purge with nitrogen several times, inject anhydrous THF (80mL), cool in an ice bath, and rapidly add zirconium chloride (25g) in batches under nitrogen protection. The reaction is violent, resulting in a surge of reactants and a large loss of reactants.

[0099] The above description is merely a preferred embodiment of this application, and therefore cannot be used to limit the scope of this application. All equivalent changes and modifications made in accordance with the patent scope and specification of this application should still fall within the scope of this application.

Claims

1. A method for preparing a metallocene complex, characterized in that, Includes the following steps: (1) The 2,5-pentanedione derivative shown in formula (a) is given by aldol condensation in an alkaline solution to obtain the cyclopentenone derivative shown in formula (b). (2) The cyclopentenone derivative is reacted with a Grignard reagent and then acidified to obtain a cyclopentadiene derivative as shown in formula (c). (3) The cyclopentadiene derivative reacts with sodium hydride and then with zirconium chloride to form a metallocene complex as shown in formula (d); The structures of equations (a) to (d) are as follows: Among them, R1 and R2 are independently selected from H, C1 to C1, respectively. 12 Substituted or unsubstituted alkyl groups; Step (3) is carried out in an anhydrous and oxygen-free environment. Specifically, sodium hydride is washed with an organic solvent, and anhydrous tetrahydrofuran and the cyclopentadiene derivative are sequentially injected into the sodium hydride under an inert atmosphere. After the addition is complete, the temperature is raised to 30-45°C, and the reaction continues until the system is converted into a dark red suspension. After solid-liquid separation, an intermediate solution is obtained. Anhydrous tetrahydrofuran is cooled to -25 to -35°C, and zirconium chloride is added in batches to the cooled anhydrous tetrahydrofuran to prepare a zirconium chloride system. The intermediate solution is added to the zirconium chloride system. After the addition is complete, the reaction is carried out at 30-45°C for 10-12 hours to obtain the metallocene complex. The molar equivalent ratio of the cyclopentadiene derivative, the sodium hydride, and the zirconium chloride is 1:1-5:0.5-1.

2. The preparation method according to claim 1, characterized in that, The molar equivalent ratio of the cyclopentadiene derivative, the sodium hydride, and the zirconium chloride is 1:1.1:0.5; And / or, the zirconium chloride is cooled to -30°C; And / or, the organic solvent in step (3) is n-hexane.

3. The preparation method according to claim 1 or 2, characterized in that, Step (3) also includes the following operations: after the reaction is completed, the reaction solution is mixed with an organic solvent and then filtered. The filtrate is concentrated, redissolved, filtered, crystallized and recrystallized to obtain the product. The crystallization temperature is -20 to -5℃ and the recrystallization temperature is -20 to -5℃.

4. The preparation method according to claim 1, characterized in that, The specific operation of step (1) is as follows: the aqueous solution of the first base is mixed with an organic solvent, heated to reflux under an inert atmosphere, and then the 2,5-pentanedione derivative is added dropwise. The reaction is carried out for 2 to 8 hours to obtain the cyclopentenone derivative. Wherein, the first base is an alkali metal hydroxide, an inorganic salt, or an alkali metal salt of a C1-C4 alcohol; the molar equivalent ratio of the 2,5-pentanedione derivative to the first base is 1:0.1-1.5; the organic solvent is an aprotic solvent; and the volume ratio of the aqueous solution of the first base to the organic solvent is 1:0.3-2.

5.

5. The preparation method according to claim 1, characterized in that, The specific operation of step (1) is as follows: the aqueous solution of the second base, the 2,5-pentanedione derivative and the phase transfer catalyst are placed in a high-pressure reactor for reaction to obtain the cyclopentenone derivative; Wherein, the second base is an alkali metal hydroxide, an inorganic salt, or an alkali metal salt of a C1-C4 alcohol; the molar equivalent ratio of the 2,5-pentanedione derivative, the second base, and the catalyst is 1:0.01-0.1:0.01-0.1; the mass ratio of the second base to water is 1:20-50; the reaction time is 0.5-3 hours; and the reaction temperature is 120-180°C.

6. The preparation method according to claim 5, characterized in that, The phase transfer catalyst is tetrabutylammonium bromide or tetrabutylammonium iodide.

7. The preparation method according to claim 4 or 5, characterized in that, Step (1) further includes the following operation: after the reaction is completed, dilute hydrochloric acid is added to adjust the pH to 1-6, and the product is then subjected to separation, extraction, washing, drying, concentration and vacuum distillation to obtain the purified cyclopentenone derivative.

8. The preparation method according to claim 1, characterized in that, The specific operation of step (2) is as follows: under an inert atmosphere, the system temperature is lowered to -10 to 20°C, and then the cyclopentenone derivative is mixed with the Grignard reagent. During the mixing process, the system temperature is controlled to be no higher than 20°C. After the addition is completed, the reaction is carried out at room temperature and the reaction is monitored by TLC until completion. Then, the system temperature is lowered to -10 to 20°C, and an aqueous solution of acid is added dropwise with stirring. During the dropwise addition, the system temperature is controlled to be no higher than 30°C. After the addition is completed, the temperature is raised and the reaction is monitored by liquid chromatography until completion to obtain the cyclopentadiene derivative. The concentration of the Grignard reagent is 1.0–2.5 mol / L, the concentration of the acid is 5–30 wt%, the molar equivalent ratio of the cyclopentenone derivative, the Grignard reagent, and the acid is 1:1–15:2–5, the temperature of the heating reaction is 30–45 °C, and the reaction of the cyclopentenone derivative and the Grignard reagent is carried out in an anhydrous and oxygen-free environment.

9. The preparation method according to claim 8, characterized in that, Step (2) further includes the following operations: after the reaction is completed, the unreacted acid is neutralized with an alkaline aqueous solution, and then the cyclopentadiene derivative is obtained by extraction, washing, drying, concentration and vacuum distillation in sequence.

10. A metallocene complex, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 9.

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