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. Finally, protons are captured through a lithiation reagent and then react with zirconium chloride to obtain the metallocene complex, compared with some routes with complex initial raw materials or routes involved in 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] The application belongs to the technical field of catalyst preparation, and particularly relates to a metallocene complex and a preparation method thereof. BACKGROUND

[0002] The metallocene catalyst is defined as a main catalyst containing at least one cyclopentadienyl (Cp) or cyclopentadiene derivative in a ligand with a group IVB transition metal as an active center. Forty years ago, Kaminsky et al. discovered a metallocene / methylaluminoxane (MAO) catalyst system for olefin polymerization in the Hamburg laboratory. Such catalysts have only one metal active center (single-site catalysts), which introduces a new transition metal complex system for the polymerization of olefins, dienes and styrene.

[0003] Due to the fact that these single active center catalysts can control the microstructure of the polymer, such as the comonomer distribution, the stereoregularity and the regioselectivity of the polymer, chemists and engineers have always been highly interested in such metallocene catalysts. In 1980, Professors Kaminsky and Sinn found through a series of experimental studies that the presence of methylaluminoxane (MAO) in a dichlorobis-titanocene / trimethylaluminum system can greatly increase the activity of the catalyst system. Using this homogeneous catalyst system, the polydispersity and microstructure of the polymer can be adjusted by only changing the organic ligand around the group IV metal.

[0004] The single active center feature of the metallocene catalyst allows people to systematically analyze and study the mechanism of the catalyst catalyzing the polymerization of olefins, deepen the understanding of the process of the polymerization of olefins, and lay a solid foundation for future research on catalytic polymerization.

[0005] The current metallocene synthesis method has many defects, such as the starting material is too structurally complex (CN

[0006] 117164616A, CN 117467055 A) or involves controlled drugs (CN 117396489 A) which are not conducive to production scale-up, and the general method conditions are harsh (CN 117069771 A, CN 117069773 B), the operation is cumbersome (CN

[0007] 117396489A, CN 117467055 A), the purification method is high in cost and inconvenient (CN 117069771 A), the sensitive intermediate processing method has a risk of deterioration (US006046346A), and so on. SUMMARY

[0008] The present application aims to provide a metallocene complex and a preparation method thereof, wherein the preparation method has the advantages of mild reaction conditions, simple synthetic route and low cost, and is beneficial to industrial production.

[0009] The technical solution of the present application is as follows:

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

[0011] (1) a 2,5-pentanedione derivative shown in formula (a) is subjected to a hydroxy aldehyde condensation reaction in a solution of a base to obtain a cyclopentenone derivative shown in formula (b);

[0012] (2) the cyclopentenone derivative is reacted with a Grignard reagent, and then acidified to obtain a cyclopentadiene derivative shown in formula (c);

[0013] (3) the cyclopentadiene derivative is reacted with a lithiation reagent, and then with a zirconium chloride to form a metallocene complex shown in formula (d);

[0014] The structures of formula (a) to formula (d) are as follows:

[0015]

[0016] wherein R1 and R2 are independently selected from H, C1-C6 substituted or unsubstituted alkyl, C6-C10 substituted or unsubstituted aryl, and C6-C10 substituted or unsubstituted aralkyl; 12 wherein R1 and R2 are independently selected from H, C1-C6 substituted or unsubstituted alkyl, C6-C10 substituted or unsubstituted aryl, and C6-C10 substituted or unsubstituted aralkyl;

[0017] wherein step (3) is carried out in anhydrous and anaerobic environment, and the specific operation is as follows: under an inert atmosphere, the cyclopentadiene derivative is dissolved in a dry organic solvent, the lithiation reagent is added dropwise at -10-10°C, then the reaction is carried out at room temperature for 2-6h, after the reaction is completed, the system is in a gel state, anhydrous tetrahydrofuran is added to restore the system to a solution state, finally the zirconium chloride is added and the reaction is carried out at 28-32°C for 12-20h to obtain the metallocene complex, the lithiation reagent is alkyl lithium, and the molar equivalent ratio of the cyclopentadiene derivative, the lithiation reagent and the zirconium chloride is 1:1-2:0.5-1.

[0018] In the above steps, preferably, the molar equivalent ratio of the cyclopentadiene derivative, the lithiation reagent and the zirconium chloride is 1:1.1:0.5; and / or, the concentration of the cyclopentadiene derivative in the organic solvent is 0.1-0.5mol / L; and / or, the concentration of the lithiation reagent is 1-5mol / L, preferably 2-4mol / L; and / or, the lithiation reagent is n-butyl lithium.

[0019] Further preferably, step (3) further comprises the following operation: after the reaction is completed, the temperature is raised to 40°C, hot suction filtration is carried out, and then the metallocene complex is obtained after concentration, crystallization and recrystallization, wherein the temperature for crystallization is -20--5°C, and the temperature for recrystallization is -20--5°C.

[0020] In some possible implementation manners, the specific operation of step (1) is: mixing the aqueous solution of the first base with an organic solvent, heating to reflux under an inert atmosphere, then adding dropwise the 2,5-pentanedione derivative, and reacting for 2-8 hours to obtain the cyclopentenone derivative.

[0021] In the formula, 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.

[0022] In the above step, 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.

[0023] In some possible implementation manners, the specific operation of step (1) is: placing the aqueous solution of the second base, the 2,5-pentanedione derivative, and a phase transfer catalyst in an autoclave for reaction to obtain the cyclopentenone derivative.

[0024] In the formula, 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 to 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.

[0025] This embodiment uses only water as the solvent in the reaction process of step (1), avoids the problem of repeatedly performing the distillation under reduced pressure in the post-processing process and avoids the problem of part of the product being taken out by the organic solvent in the distillation under reduced pressure, improves the reaction yield, simplifies the post-processing steps, and effectively reduces the cost.

[0026] In the above step, 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 to 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 hours; and / or, the reaction temperature is 140°C.

[0027] Further preferably, step (1) further comprises the following operation: after the reaction is completed, adjusting to pH 1-6 by adding dilute hydrochloric acid, and then sequentially performing liquid separation, extraction, washing, drying, concentration, and reduced pressure distillation to obtain the purified cyclopentenone derivative.

[0028] In some possible embodiments, the specific operation of step (2) is as follows: under an inert atmosphere, the system temperature is reduced to -10-20℃, then the cyclopentenone derivative is mixed with the Grignard reagent, the system temperature is controlled to be not higher than 20℃ during the mixing process, after the addition is completed, the reaction is carried out at room temperature and monitored by TLC until completion, then the system temperature is reduced to -10-20℃, an aqueous acid solution is added dropwise under stirring, the system temperature is controlled to be not higher than 30℃ during the dropwise addition process, after the addition is completed, the reaction is carried out by increasing the temperature and monitored by liquid chromatography until completion, to obtain the cyclopentadiene derivative.

[0029] In the above steps, preferably, the molar equivalent ratio of the cyclopentenone derivative, the Grignard reagent, and the acid is 1:1.3:2.5; and / or, the concentration of the acid is 10wt%; and / or, the acid is an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, or an organic acid such as formic acid, acetic acid, propionic acid, trifluoroacetic acid, preferably an organic acid; and / or, the temperature of the temperature-increasing reaction is 35℃; and / or, the time of the temperature-increasing reaction is 2-28h.

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

[0031] Further preferably, step (2) further comprises the following operation: after the reaction is completed, the unreacted acid is neutralized by an alkaline aqueous solution, and then sequentially performing extraction, washing, drying, concentration, and reduced pressure distillation to obtain the purified cyclopentadiene derivative.

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

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

[0034] (1) The present application uses cheap and commercially available 2,5-hexanedione 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), the temperature for dropping the lithiating reagent is increased to -10-10℃ and the reaction is carried out at room temperature by optimizing the reaction conditions, which is more mild compared to the conditions in the prior art, i.e., dropping at -78℃ and reacting, effectively reducing the energy consumption and cost of the reaction, and significantly reducing the equipment requirements.

[0036] (3) The step (3) of first cooling the zirconium chloride and then adding it in batches to the previously cooled anhydrous tetrahydrofuran (THF) can effectively avoid the problem of material flushing caused by the severe heat release in the process of adding anhydrous THF and zirconium chloride in the prior art. In addition, compared with the technical solution of adding anhydrous THF to zirconium chloride, the feeding sequence of the present application can ensure that the heat generated during the feeding process can be quickly neutralized by the low-temperature anhydrous THF; when the preparation method is scaled up for industrial production, this process can still be effectively stirred.

[0037] (3) The purification of all intermediates and final products in the present application is carried out by distillation or crystallization, which is more convenient and cost-saving compared with the route involving column chromatography purification.

[0038] (4) In some possible embodiments, water is used as the reaction solvent in step (1), which can greatly reduce the cost and give the advantages of high reaction conversion rate, less impurities and simple work-up. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 NMR spectrum of bis(1-butyl-3-methylcyclopentadienyl)zirconium dichloride prepared in Example 1. DETAILED DESCRIPTION

[0040] The technical solutions of the present application are further described and explained by specific embodiments.

[0041] In the following examples, if not specifically stated, the water used can be one or more of distilled water, pure water, drinking water; the detection methods in the following examples, if not specifically stated, are conventional detection methods; the reagents in the following examples, if not specifically stated, are purchased from commercial channels.

[0042] The concentration referred to in the present application means the removal of solvents in the reaction system. In the following examples, the specific way of concentration is rotary evaporation, and the present application has no special requirements for the speed and time of rotary evaporation, as long as the solvents can be removed. If not specifically stated, the % in the present application means mass percent. The batch addition in the present application means that the reactants are added in at least two times, which aims to prevent the problem of material flushing caused by severe heat release, and there is no specific limitation on the number of batch addition.

[0043] Example 1

[0044] (1) Synthesis of 3-methyl-2-cyclopenten-1-one

[0045]

[0046] In a 250 mL three-necked flask, sodium hydroxide (25 g, 1 eq) was dissolved in water (150 mL), and after cooling to room temperature, dimethylsulfate (50 mL) was added under nitrogen. After heating to reflux, 2,5-hexanedione (70.7 g, 1 eq) was added dropwise. After the addition was completed, the reaction was maintained at reflux for 3 h. GC showed that the product was 76%. The system was cooled to room temperature, and the pH was adjusted to 5-6 with dilute hydrochloric acid. After stirring, the phases were separated, and the aqueous phase was extracted with DCM. The combined organic phases were washed with water once. The organic phase was dried over anhydrous sodium sulfate, and the crude product was obtained by rotary evaporation at 30°C. The crude product was distilled under reduced pressure to obtain 3-methyl-2-cyclopenten-l-one (34.24 g).

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

[0048]

[0049] In a three-necked flask, 3-methyl-2-cyclopenten-l-one (20 g, 1 eq) was added, and after nitrogen replacement, anhydrous THF (100 mL) was injected, and the temperature was lowered to -10°C. n-Butylmagnesium chloride Grignard reagent (2 M, 1.1 eq) 114 mL was added dropwise while controlling the internal temperature to be no higher than 10°C, and after the addition was completed, the system was transferred to room temperature for reaction. TLC was used to monitor the completion of the reaction.

[0050] Then the reaction solution was cooled to 0°C, and 25 wt% acetic acid solution (3.0 eq) 150 g was added dropwise under mechanical stirring. The system became turbid, and solids appeared. After the addition was completed, the solids dissolved, and the temperature of the system was controlled to be no higher than 5°C during the addition. After the addition was completed, the temperature was raised to 36°C, and the reaction was maintained for 15 h.

[0051] The phases were separated, and the aqueous phase was extracted with PE. The combined organic phases were washed with saturated sodium bicarbonate solution until no gas bubbles were generated. The phases were separated, and the organic phase was dried to remove the solvent to obtain the crude product 21.3 g. Distillation under reduced pressure yielded 3-butyl-l-methyl-l,3-cyclopentadiene 11.4 g as a yellow oil. Product: isomer = 75.9%: 20.1%.

[0052] (3) Synthesis of bis(l-butyl-3-methylcyclopentadienyl)zirconium dichloride

[0053]

[0054] Into a flask was placed 3-butyl-l-methyl-l,3-cyclopentadiene (9.3 g, 1 eq). Double-tube nitrogen was replaced, and then dissolved in n-hexane (500 mL) and replaced by nitrogen again. The system was cooled to 0 °C, and then n-butyllithium n-hexane solution (2.5 M, 30 mL, 1.1 eq) was added dropwise, and the internal temperature was controlled to have no obvious change. After the addition was completed, it was transferred to room temperature and reacted for 3 h. The system was in a gel state, and then stirred in anhydrous THF (15 mL), and the system returned to a solution state. Under the protection of nitrogen flow, zirconium chloride (8.0 g, 0.5 eq) was added, the whole system was brownish, and then stirred at 30 °C for 16 h, and the system turned brown. After being heated to 40 °C, it was hot-filtered, and the filter cake was washed with hot n-hexane. The obtained filtrate was concentrated, and then cooled to -20 °C to crystallize. It was filtered, the filter cake was dissolved in n-hexane again, and then the insoluble matter was filtered off, and then the filtrate was concentrated, and then cooled to -20 °C to recrystallize, and then the solid was washed with cold n-hexane to obtain white needle-shaped solid bis(l-butyl-3-methylcyclopentadienyl)zirconium dichloride 5.3 g. Yield 47.91%.

[0055] The product was subjected to hydrogen nuclear magnetic resonance detection, and the results are shown in Figure 1 1 H NMR (500 MHz, CDCI3) δ 6.10 (t, J = 2.3 Hz, 1 H), 6.01 - 5.95 (m, 1 H), 5.94 - 5.90 (m, 1 H), 2.65 - 2.55 (m, 1 H), 2.52 - 2.42 (m, 1 H), 2.22 (d, J = 2.5 Hz, 3 H), 1.59 - 1.41 (m, 2 H), 1.41 - 1.30 (m, 2 H), 0.93 (t, J = 7.3 Hz, 3 H).

[0056] Example 2

[0057] Example 2 only shows another preparation method of the cyclopentenone derivative provided in step (1), and the remaining steps please refer to Example 1.

[0058] (1) Synthesis of 3-methyl-2-cyclopenten-l-one

[0059]

[0060] ​A 500 mL autoclave was charged with water (400 mL), 2,5-hexanedione (20 g, 1 eq), tri-potassium phosphate trihydrate (1.4 g, 0.03 eq), and phase transfer catalyst tetrabutylammonium bromide (0.56 g, 0.01 eq), then sealed and heated to 140 °C for 2 h. GC monitoring showed that the starting material was completely consumed and the product was 95.7%. After the system was acidified with dilute hydrochloric acid to pH 5, DCM was used to extract (100 mL x 3), the combined organic phase was washed with saturated brine (200 mL x 2), and anhydrous sodium sulfate was used for drying. DCM was removed by rotary evaporation at 30 °C to obtain a crude product, which was distilled under reduced pressure to obtain a light yellow transparent oil, 3-methyl-2-cyclopenten-1-one 14.9 g, with a yield of 88%.

[0061] Example 3

[0062] Example 3 only shows another method for preparing bis(1-butyl-3-methylcyclopentadienyl)zirconium dichloride provided by step (3), and the remaining steps refer to Example 1.

[0063] (3) Synthesis of bis(1-butyl-3-methylcyclopentadienyl)zirconium dichloride

[0064]

[0065] A 500 mL autoclave was charged with water (400 mL), 2,5-hexanedione (20 g, 1 eq), tri-potassium phosphate trihydrate (1.4 g, 0.03 eq), and phase transfer catalyst tetrabutylammonium bromide (0.56 g, 0.01 eq), then sealed and heated to 140 °C for 2 h. GC monitoring showed that the starting material was completely consumed and the product was 95.7%. After the system was acidified with dilute hydrochloric acid to pH 5, DCM was used to extract (100 mL x 3), the combined organic phase was washed with saturated brine (200 mL x 2), and anhydrous sodium sulfate was used for drying. DCM was removed by rotary evaporation at 30 °C to obtain a crude product, which was distilled under reduced pressure to obtain a light yellow transparent oil, 3-methyl-2-cyclopenten-1-one 14.9 g, with a yield of 88%.

[0066] Comparative Example 1

[0067] Comparative Example 1 only shows the specific operation of mixing zirconium chloride with anhydrous THF in the prior art.

[0068] A 500 mL three-necked flask was subjected to multiple nitrogen replacement, then zirconium chloride (87 g) was quickly added under nitrogen protection, and the flask was subjected to nitrogen replacement again. After cooling in an ice bath, anhydrous THF (120 mL) was slowly injected. The exothermic reaction was violent, backflow occurred on the flask wall, a large amount of white mist appeared in the flask, and the zirconium chloride clumped, affecting stirring and causing solid to splash onto the flask wall.

[0069] Comparative Example 2

[0070] Comparative Example 2 only shows the specific operation of mixing zirconium chloride with anhydrous THF in the prior art.

[0071] A 250 mL three-necked flask was subjected to multiple nitrogen replacement, then anhydrous THF (80 mL) was injected, the flask was cooled in an ice bath, and zirconium chloride (25 g) was quickly added in batches under nitrogen protection. The reaction was violent, material was splashed, and a large amount of reactant was lost.

[0072] The above is only a preferred embodiment of the present application, and therefore cannot limit the scope of the present application. Equivalent changes and modifications made in accordance with the scope and content of the present patent should still be within the scope of the present 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 a lithium reagent 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, the cyclopentadiene derivative is dissolved in a dry organic solvent under an inert atmosphere, and a lithium-ionizing agent is added dropwise at -10 to 10°C. The reaction is then carried out at room temperature for 2 to 6 hours. After the reaction is completed, the system is in a gel state. Anhydrous tetrahydrofuran is added until the system returns to a solution state. Finally, zirconium chloride is added and the reaction is carried out at 28 to 32°C for 12 to 20 hours to obtain the metallocene complex. The lithium-ionizing agent is alkyllithium, and the molar equivalent ratio of the cyclopentadiene derivative, the lithium-ionizing agent, and the zirconium chloride is 1:1 to 2:0.5 to 1.

2. The preparation method according to claim 1, characterized in that, The concentration of the cyclopentadiene derivative in the organic solvent is 0.1–0.5 mol / L; And / or, the concentration of the lithium-ionizing agent is 1–5 mol / L; And / or, the lithiumizing agent is n-butyllithium.

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 temperature is raised to 40°C, filtered while hot, and then concentrated, crystallized and recrystallized to obtain the purified metallocene complex, wherein the crystallization temperature is -20 to -5°C and the recrystallization temperature is -20 to -5°C.

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 was lowered to -10 to 20°C, and then the cyclopentenone derivative was mixed with the Grignard reagent. During the mixing process, the system temperature was controlled to be no higher than 20°C. After the addition was completed, the reaction was carried out at room temperature and the reaction was monitored by TLC until completion. Then, the system temperature was lowered to -10 to 20°C, and an aqueous solution of acid was added dropwise with stirring. During the dropwise addition, the system temperature was controlled to be no higher than 30°C. After the addition was completed, the temperature was raised and the reaction was 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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