CN114507305A - Method for synthesizing zirconocene type olefin polymerization catalyst - Google Patents

Abstract

The method for synthesizing a zirconocene type olefin polymerization catalyst of the invention belongs to the technical field of organic and macromolecular material synthesis. 3-bromothiophene is reacted with a strong base, and then methylated with methyl iodide to obtain 2-methyl-3-bromothiophene; and then subjected to Friedel-Crafts acylation, Nazarov cyclization and Suzuki coupling The reaction obtains 2,5-dimethyl-3-phenyl-5,6-dihydrocyclopentane[1,2-b]thiophen-4-ketone; then through reduction and elimination to obtain 2,5-dimethyl ‑3‑phenyl‑6‑cyclopentene[1,2‑b]thiophene; finally, after silylation and coordination with zirconium salts, the target zirconocene type olefin polymerization catalyst is obtained. The synthesis conditions of the invention are relatively mild, the synthesis method has low cost and low energy consumption, and is helpful for realizing the industrialized production of the catalyst.

Description

A kind of synthetic method of zirconocene type olefin polymerization catalyst

technical field

The invention belongs to the technical field of metal organic and polymer material synthesis, in particular to a synthesis method of a zirconocene type olefin polymerization catalyst.

Background technique

Polypropylene is the fastest growing polyolefin resin in recent years, and the key factor for its rapid development lies in the rapid development of technologies related to polymerization catalysts. Catalyst plays a pivotal role in polypropylene production technology. The catalyst system affects the properties of polypropylene products (such as relative molecular mass and distribution, product morphology, random polymer content, etc.), conversion rate, production conditions (such as operating temperature) And the catalyst residue in the product has an important impact.

In the research and development of polypropylene catalysts, improving the catalytic activity and stereoselectivity of the catalyst and improving the production economy of the catalyst have always been the focus of research and development. Compared with traditional Z-N catalysts, metallocene catalysts have the characteristics of a single active center, which can more precisely control the relative molecular mass of the polymer and its distribution, crystal structure, and the insertion method of comonomers on the polymer molecular chain; By adjusting the structure of the ligands, the electron distribution around the metal center can be changed, which in turn affects the structure and mechanical properties of the polymer product. Metallocene polypropylene (mPP) produced by metallocene catalyst catalyzed polymerization has the advantages of narrow relative molecular mass distribution, low crystallinity, small crystallites, high transparency, excellent gloss, excellent impact strength and toughness. At the same time, mPP also has the characteristics of good radiation resistance and insulation, and good compatibility with other polymers. Therefore, in recent years, metallocene catalysts have been rapidly developed in the industrial production of polypropylene.

The use of metallocene catalysts to catalyze the production of propylene copolymers is another important application of metallocene catalysts in the field of olefin polymerization: metallocene catalysts can catalyze the synthesis of many propylene copolymers that are difficult to catalyze synthesis by Z-N catalysts, such as propylene-styrene random And block copolymers, copolymers of propylene and long-chain olefins, cyclic olefins, dienes, etc. Compared with traditional catalytic systems, when using metallocene catalysts to produce random copolymers, the randomness of comonomer insertion is very good, and it can be used to synthesize random copolymers with high comonomer content. material potential. Exon company used dual metallocene catalysts to synthesize bimodal propylene-ethylene copolymers in a single reactor. The disadvantage of the narrow processing temperature range of unimodal mPP resin is that it stretches more uniformly and is not easy to break during the production of BOPP film, and can produce polypropylene film with good performance at a lower processing temperature than traditional polypropylene.

ExxonMobil Corporation, LyondellBasell Corporation, Dow Chemical Corporation and iFan Corporation (now a Total Petrochemical Corporation) are leaders in the development of mPP catalysts and have now developed second generation mPP catalysts, and some companies have also begun to industrialize mPP based on the developed catalysts Production. However, due to the protection of intellectual property rights, the high cost of catalysts and the continuous improvement of traditional Z-N catalysts, the overall development of mPP is still slow and has not been widely used, but its development potential is huge.

my country has been developing metallocene catalysts and mPP since 1993, but today, domestic mPP is still in its infancy. In 2001, Arnold L.Rheingold et al. reported 6,6'-dimethylsilylbis(2,5-dimethyl-3-phenyl-thieno[2,3-b]cene)dichloro Synthesis of zirconium (J.Am.Chem.Soc. 2001,123,4763-4773), but this method uses polyphosphoric acid and phosphorus pentoxide as reagents, which is expensive, difficult to operate and produces a large amount of waste acid Emissions are not conducive to industrial production, but also run counter to my country's goal of achieving carbon peak carbon neutrality.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a synthesis method of a zirconocene type olefin polymerization catalyst in order to solve the problems of complex and harsh conditions, high cost and high energy consumption of the existing zirconocene type olefin polymerization catalyst synthesis method. The zirconocene type olefin polymerization catalyst of the present invention can efficiently solve the problem of isomeric regularity control in the production of metallocene polypropylene, and can catalyze the synthesis of polypropylene with high isomeric regularity.

The technical scheme of the present invention is as follows:

A kind of synthetic method of zirconocene type olefin polymerization catalyst, has the following steps:

Step 1: 3-bromothiophene is reacted with a strong base, and then methylated with methyl iodide to obtain 2-methyl-3-bromothiophene;

Step 2: 2-methyl-3-bromothiophene undergoes Friedel-Crafts acylation, Nazarov cyclization and Suzuki coupling to obtain 2,5-dimethyl-3-phenyl-5,6- Dihydrocyclopentane[1,2-b]thiophen-4-one;

Step 3: 2,5-dimethyl-3-phenyl-5,6-dihydrocyclopentane[1,2-b]thiophen-4-one is then reduced and eliminated to obtain 2,5-dimethyl -3-phenyl-6-cyclopenten[1,2-b]thiophene;

Step 4: After 2,5-dimethyl-3-phenyl-6-cyclopentene[1,2-b]thiophene is silylated and coordinated with a zirconium salt, the target zirconocene type olefin polymerization catalyst is obtained.

Described zirconocene type olefin polymerization catalyst structure is as follows:

Preferably, the strong base described in step 1 is selected from n-butyllithium, isobutyllithium, lithium diisopropylamide or lithium hexamethyldisilazide, sodium hexamethyldisilazide or potassium hexamethyldisilazide.

Preferably, the molar ratio of 3-bromothiophene, strong base and methyl iodide in step 1 is 1:(1～2):(1～2); the reaction temperature of the methylation reaction is -80～ At 100°C, the reaction time is 30 minutes to 7 days.

Preferably, the catalyst used in the Friedel-Crafts acylation reaction described in step 2 is selected from aluminum trichloride, aluminum tribromide, aluminum triiodide, tin tetrachloride, titanium tetrachloride or zinc chloride; use The acylating reagent is selected from methacryloyl chloride, methacrylic anhydride, methacrylic acid, sodium methacrylate or methyl methacrylate; the solvent used is selected from dichloromethane or dichloroethane; wherein 2-methyl methacrylate The molar ratio of -3-bromothiophene, acylating reagent and catalyst is 1:(1-5):(1-5); the reaction temperature is -80-100 DEG C, and the reaction time is 1-48 hours.

Preferably, the catalyst used in the Nazarov cyclization reaction described in step 2 is selected from perfluorosulfonic acid resin, solid acid catalyst, sulfuric acid, phosphoric acid or trifluoroacetic acid, and the molar mass ratio of raw material to catalyst is 1 mmol: (0.5 ~10g); the solvent used is selected from toluene, ethylbenzene or xylene; the reaction temperature is 0-200° C., and the reaction time is 1-48 hours.

Preferably, the catalyst used in the Suzuki coupling reaction in step 2 is selected from tetrakis(triphenylphosphine) palladium, tetrakis(triphenylphosphine) platinum, bis(triphenylphosphine) palladium dichloride, palladium carbon , palladium black or palladium-calcium carbonate; the base used is selected from potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide or potassium trimethylsiliconate; the phenylated reagent used is selected from phenylboronic acid, sodium phenylboronic acid, Phenylboronic acid anhydride or phenylboronic acid pinacol ester; the solvent used is selected from toluene, ethylbenzene or xylene; wherein the molar ratio of reaction raw materials to alkali, phenylation reagent and catalyst is 1:(1～5):(1 ～5): (0.0001～1); the reaction temperature is 100～200°C, and the reaction time is 10 minutes～48 hours.

Preferably, the reducing agent used in the reduction reaction in step 3 is selected from sodium borohydride, lithium aluminum hydride, borane-tetrahydrofuran or borane-dimethyl sulfide; wherein the molar ratio of raw materials to reducing agent is 1: (0.1 ~2); the reaction temperature is -50°C to 100°C, and the reaction time is 1 minute to 48 hours.

Preferably, the catalyst used in the elimination reaction described in step 3 is selected from p-toluenesulfonic acid monohydrate, p-toluenesulfonic acid pyridinium salt, pyridine hydrochloride, pyridine sulfate, camphorsulfonic acid, phenylboronic acid, sulfuric acid or hydrochloric acid The solvent used is selected from tetrahydrofuran, ethylene dichloride, 1,4-dioxane, toluene, xylene or ethylbenzene; wherein the raw material and catalyst mol ratio are (1～5): 1; the reaction temperature is-50 ~200°C, the reaction time is 10 minutes to 48 hours.

Preferably, the strong base reagent used in the silylation reaction in step 4 is selected from n-butyllithium, isobutyllithium, tert-butyllithium, methyllithium, diisopropylamide lithium, hexamethylidene Lithium hexamethyldisilazide, sodium hexamethyldisilazide or potassium hexamethyldisilazide; the silane reagent used is selected from dichlorodimethylsilane, dibromodimethylsilane or dimethylsilane Bis-trifluoromethanesulfonate; The solvent used is selected from ether, dichloromethane, dichloroethane, n-butyl ether or methyl tert-butyl ether; The molar ratio of raw material to strong base reagent and silane reagent is 1:( 1 to 5): (0.2 to 5); the reaction temperature is -80 to 100°C, and the reaction time is 1 minute to 48 hours.

Preferably, the strong base reagent used in the coordination reaction in step 4 is selected from n-butyllithium, isobutyllithium, tert-butyllithium, methyllithium, diisopropylamide lithium, hexamethylidene Lithium disilazide, sodium hexamethyldisilazide or potassium hexamethyldisilazide; the zirconium salt used is selected from anhydrous zirconium tetrachloride or bis(tetrahydrofuran) zirconium tetrachloride; the solvent used It is selected from diethyl ether, dichloromethane, dichloroethane, n-butyl ether or methyl tert-butyl ether; wherein the molar ratio of ligand to strong base reagent and zirconium salt is 1:(1～5):(0.2～5 ); the reaction temperature is 0 to 100°C, and the reaction time is 1 to 48 hours.

Beneficial effects:

The invention provides a method for synthesizing a zirconocene type olefin polymerization catalyst. In the method, 3-bromothiophene is reacted with a strong base, and then methylated with methyl iodide to obtain 2-methyl-3-bromothiophene; and then 2 -Methyl-3-bromothiophene undergoes Friedel-Crafts acylation, Nazarov cyclization and Suzuki coupling to obtain 2,5-dimethyl-3-phenyl-5,6-dihydrocyclopentane Alkyl[1,2-b]thiophen-4-one; after reduction and elimination, 2,5-dimethyl-3-phenyl-6-cyclopentene[1,2-b]thiophene was obtained; finally 2, 5-Dimethyl-3-phenyl-6-cyclopentene[1,2-b]thiophene reacts with a strong base reagent, undergoes silylation and then coordinates with zirconium salt to obtain the target zirconocene type olefin polymerization catalyst. Compared with the prior art, the synthesis process conditions are relatively mild, the synthesis method has low cost and low energy consumption, which is helpful for the industrialized production of catalysts, and provides a good and efficient solution for domestic research and development of this type of catalyst, especially for industrialization. Support; contribute to the development of new olefin polymers with special functions, especially the development of new polypropylene materials, new ethylene octene copolymer materials and other polymeric materials.

Description of drawings

Fig. 1 is 6,6'-dimethylsilyl bis(2,5-dimethyl-3-phenyl-thieno[2,3-b]cene) dichloride synthesized in Example 1 of the present invention Hydrogen NMR spectrum of zirconium.

Detailed ways

The present invention will be further described in detail below in conjunction with the examples, and the raw materials involved in the examples are all commercially available.

Example 1

Step 1. Synthesis of 2-methyl-3-bromothiophene

Diisopropylamine (56ml, 363mmol) was dissolved in 200ml of anhydrous tetrahydrofuran, cooled to -78°C, n-butyllithium (2.5M n-hexane solution, 140ml, 330mmol) was added, and after the addition was completed, continue at -78°C Stir for 15 minutes. To the solution containing lithium diisopropylamide (LDA) was added 3-bromothiophene (50 g, 307 mmol) dropwise. After the addition was completed, the reactant was moved into an ice bath, allowed to rise to 0°C naturally, and stirred for another 30 min. The reaction was cooled to -78°C and iodomethane (21 ml, 330 mmol) was slowly added dropwise. The reaction mixture was stirred at -78°C for an additional 30 min, then warmed to 0°C and stirred for 1 h. After the reaction was completed, it was quenched with saturated brine, and the layers were separated. The aqueous phase was extracted with dichloromethane, washed with water, separated, dried over magnesium sulfate, filtered, and the solvent was removed in vacuo. The residue was distilled under reduced pressure to obtain colorless oily liquid 2 (46.80 g, 86%). ¹ H NMR(400MHz,chloroform-d)δ7.07(d,J=5.4Hz,1H),6.90(d,J=5.4Hz,1H),2.41(s,3H).

Step 2. Synthesis of 2,5-dimethyl-3-phenyl-5,6-dihydrocyclopentane[1,2-b]thiophen-4-one

In a 1L three-necked flask, aluminum trichloride (56.4g, 423mmol) was suspended in 500ml of dry dichloromethane, protected by argon, and 2-methyl-3-bromothiophene (50g, 282mmol) was slowly added dropwise under ice-water bath cooling , and stirring for 5min after dripping. Then slowly add a solution of methacrylic anhydride (63 ml, 423 mmol) dissolved in 100 ml of dry dichloromethane, and stir for 30 min to obtain a dark black red solution. After the disappearance of starting material was monitored by TLC, it was slowly poured into ice water to quench. Separation, the aqueous phase was extracted with dichloromethane, the organic phases were combined, washed with water, separated, dried over magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain an orange-yellow oily liquid 3 (58.80 g, 85%), which could be used directly without purification. The next step is to synthesize.

Dissolve 3 in 250ml dichloroethane in a 500ml round-bottomed flask, add concentrated sulfuric acid (24ml, 1ml/mmol) dropwise under ice bath cooling, remove from the ice bath after dropping, naturally rise to room temperature and stir for 2h, TLC monitors the disappearance of raw materials . It was slowly poured into ice water to quench, and the solution was separated. The aqueous phase was washed with dichloroethane. The washings and the organic phase were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain a brown oily liquid 4, and 4 was passed through the column layer. It solidified into yellow needle-like crystals (45.92 g, 78%) after purification. ¹ H NMR (400MHz, Chloroform-d) δ3.15 (dd, J=17.4, 6.9Hz, 1H), 2.97 (pd, J=7.4, 2.6Hz, 1H), 2.50 (s, 3H), 2.49 (dd , J=17.3, 2.7Hz, 1H), 1.33(d, J=7.5Hz, 3H).

Potassium hydroxide (21.12g, 376mmol) and phenylboronic acid (45.62g, 374mmol) were dissolved in 200ml of water in a 1L round-bottomed flask, the compound 4 obtained in the previous step was dissolved in 200ml of dioxane, the two were mixed and stirred. Tetrakis (triphenylphosphine) palladium (0.14 g, 0.12 mmol) was added and heated under reflux for 3 h until the disappearance of the starting material was monitored by TLC. Cooling, separation, the aqueous phase was extracted with dichloromethane, the washing liquid and the organic phase were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain a brown oily liquid 5. After purification by column chromatography, 5 solidified into a beige solid (40.80 g, 90%). ¹ H NMR (400MHz, Chloroform-d) δ 7.47 (td, J=7.2, 6.3, 1.4Hz, 2H), 7.42-7.25 (m, 3H), 3.18 (dd, J=17.3, 6.8Hz, 1H) ,2.97(pd,J=7.4,2.7Hz,1H),2.54(s,3H),2.54(dd,J=17.3,2.7Hz,1H),1.33(d,J=7.5Hz,3H).

Step 3. Synthesis of 2,5-dimethyl-3-phenyl-6-cyclopenten[1,2-b]thiophene

Compound 5 (24.2 g, 100 mmol) was dissolved in 200 ml of anhydrous tetrahydrofuran in a 500 ml round-bottomed flask, and after cooling to 0°C in an ice-water bath, lithium aluminum hydride (3.81 g, 100 mmol) was slowly added. After the addition was completed, the ice-water bath was removed, and the temperature of the reaction flask was raised to room temperature, followed by stirring for 1 h, and the completion of the reaction was monitored by TLC. Slowly add dilute hydrochloric acid to quench, separate the layers, extract the aqueous phase with dichloromethane, combine the organic phases, wash with water, dry over magnesium sulfate, filter, and remove the solvent in vacuo to obtain a white solid 7. 7 is directly dissolved in 100 ml of toluene without purification, Add p-toluenesulfonic acid monohydrate (2 g, 10 mmol) and heat to reflux. After 1.5 hours, TLC monitored the disappearance of the raw materials, cooled, washed with water, separated, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain a brown oily liquid 7 (21.69 g, 96%), which was purified by column chromatography and solidified into off-white solid. ¹ H NMR (400MHz, Chloroform-d)δ7.42(d,J=5.3Hz,4H),7.37-7.27(m,1H),6.42(q,J=1.6Hz,1H), 3.13(d,J ＝1.4Hz, 2H), 2.50(s, 3H), 2.14(d, J＝1.6Hz, 3H).

Step 4. Synthesis of 6,6'-dimethylsilylbis(2,5-dimethyl-3-phenyl-thieno[2,3-b]locene) zirconium dichloride

In a 250ml round-bottom flask, compound 7 (11.35g, 50mmol) was dissolved in 65ml of dry tetrahydrofuran, cooled to -78°C under argon protection, and n-butyllithium (2.5M n-hexane solution, 20ml) was slowly added dropwise thereto. , 50 mmol), and the reaction was raised to room temperature for 12 h to obtain a dark red solution. The obtained lithium salt solution was cooled to -78°C again, dimethyldichlorosilane (3.55 g, 27.5 mmol) was added dropwise to it, and the solution was raised to room temperature for 12 h, and a large amount of white precipitates were precipitated. Filtered with suction, washed with ether, and dried to obtain compound 8 (18.5 g, 72%) as an off-white solid, and compound 8 was used in the next step without further purification.

Compound 8 (2.5 g, 4.9 mmol) was added to a 250 ml round-bottomed flask, 125 ml of dry diethyl ether was added, and the mixture was stirred. At this time, compound 8 was suspended in diethyl ether as a white suspension. Under the protection of argon at room temperature, n-butyllithium (2.5M n-hexane solution, 4 ml, 10 mmol) was slowly added dropwise, the solid was gradually dissolved into an orange-yellow clear solution with the dropwise addition, and the reaction was completed at room temperature for 12 h. The obtained lithium salt solution was moved into a glove box, anhydrous zirconium tetrachloride powder (0.58 g, 2.5 mmol) was added to it in batches, and a large amount of yellow turbidity was formed in the reactant along with the addition of zirconium salt, and the addition was sealed and stirred at room temperature for 12 h. Filtered with suction, washed with ether, and dried to obtain compound 9 (2.30 g, 70%) as a bright yellow solid. The H NMR spectrum is shown in Figure 1. ¹ H NMR (600MHz, Chloroform-d) δ 7.52-7.47 (m, 4H), 7.42 (dd, J=8.6, 6.9Hz, 4H), 7.31 (ddt, J=8.7, 7.2, 1.3Hz, 2H) , 6.60(s, 2H), 2.54(s, 6H), 2.33(s, 6H), 1.07(s, 6H).

Example 2

Step 1. Synthesis of 2-methyl-3-bromothiophene

Dissolve 3-bromothiophene (50g, 307mmol) in 200ml of anhydrous tetrahydrofuran, cool to -78°C, add lithium hexamethyldisilazide (2M tetrahydrofuran solution, 165ml, 330mmol), after the addition, - Stirring was continued for 15 min at 78°C. Then the reactant was moved into an ice-water bath, allowed to rise to 0°C naturally, and stirred for another 30 min. The reaction was cooled to -78°C and iodomethane (21 ml, 330 mmol) was slowly added dropwise. The reaction mixture was stirred at -78°C for an additional 30 min, then warmed to 0°C and stirred for 1 h. After the reaction was completed, it was quenched with saturated brine, and the layers were separated. The aqueous phase was extracted with dichloromethane, washed with water, separated, dried over magnesium sulfate, filtered, and the solvent was removed in vacuo. The residue was distilled under reduced pressure to obtain a colorless oily liquid (38.11 g, 70%).

Step 2. Synthesis of 2,5-dimethyl-3-phenyl-5,6-dihydrocyclopentane[1,2-b]thiophen-4-one

In a 1L three-necked flask, tin tetrachloride (110.20g, 423mmol) was dissolved in 500ml of dry dichloromethane, under argon protection, 2-methyl-3-bromothiophene (50g, 282mmol) was slowly added dropwise under ice-water bath cooling , and stirring for 5min after dripping. Then slowly add a solution of methacrylic anhydride (63 ml, 423 mmol) dissolved in 100 ml of dry dichloromethane, and stir for 30 min to obtain a dark black red solution. After the disappearance of starting material was monitored by TLC, it was slowly poured into ice water to quench. Separation, the aqueous phase was extracted with dichloromethane, the organic phases were combined, washed with water, separated, dried over magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain an orange-yellow oily liquid 3 (45.10 g, 65%), which could be used directly without purification. The next step is to synthesize.

Dissolve 3 in 250ml xylene in a 500ml round-bottomed flask, add perfluorosulfonic acid resin (18g, 10mmol/g), reflux at 135°C for 5h, and monitor the disappearance of raw materials by TLC. Suction filtration, the solid was washed with dichloromethane, the washings and the filtrate were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain a brown oily liquid 4. After purification by column chromatography, 4 was solidified into yellow needle-like crystals (36.22 g , 80%).

In a 1L round-bottom flask, potassium carbonate (41.46g, 300mmol) and phenylboronic acid (36.10g, 296mmol) were mixed in 200ml of xylene, the compound 4 obtained in the previous step was dissolved in 100ml of xylene, the two were mixed, and the mixture was stirred. Tetrakis (triphenylphosphine) palladium (0.21 g, 0.18 mmol) was added and heated to reflux for 5 h until the disappearance of the starting material was monitored by TLC. Cooling, separation, the aqueous phase was extracted with dichloromethane, the washings and the organic phase were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain a brown oily liquid 5. After purification by column chromatography, 5 solidified into a beige solid (41.02 g, 90%).

Step 3. Synthesis of 2,5-dimethyl-3-phenyl-6-cyclopenten[1,2-b]thiophene

Compound 5 (24.2 g, 100 mmol) was dissolved in 200 ml of anhydrous tetrahydrofuran in a 500 ml round-bottomed flask, and after cooling to 0°C in an ice-water bath, borane-tetrahydrofuran (1M tetrahydrofuran solution, 100 ml, 100 mmol) was slowly added. After the addition was completed, the ice-water bath was removed, and the temperature of the reaction flask was raised to room temperature, followed by stirring for 1 h, and the completion of the reaction was monitored by TLC. Dilute hydrochloric acid was slowly added to quench, and the layers were separated. The aqueous phase was extracted with dichloromethane. The organic phases were combined, washed with water, dried over magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain a white solid 7. 7 was directly dissolved in 100 ml of toluene without purification. Add pyridinium p-toluenesulfonate (2.5 g, 10 mmol) and heat to reflux. After 1.5 hours, TLC monitored the disappearance of the raw materials, cooled, washed with water, separated, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain a brown oily liquid 7 (20.41 g, 90%), which was purified by column chromatography and solidified into off-white solid.

Step 4. Synthesis of 6,6'-dimethylsilylbis(2,5-dimethyl-3-phenyl-thieno[2,3-b]locene) zirconium dichloride

In a 250ml round-bottomed flask, compound 7 (11.35g, 50mmol) was dissolved in 65ml of dry tetrahydrofuran, cooled to -78°C under argon protection, and methyllithium (1.6M ether solution, 31.3ml, 50mmol) was slowly added dropwise into it. ), and the reaction was raised to room temperature for 12 h to obtain a dark red solution. The obtained lithium salt solution was cooled to -78 °C again, dimethyldichlorosilane (3.55 g, 27.5 mmol) was added dropwise to it, and the solution was raised to room temperature for 12 h, and a large amount of white precipitates were precipitated. Filtered with suction, washed with ether, and dried to obtain compound 8 (19.77 g, 77%) as an off-white solid, and compound 8 was used in the next step without further purification.

Compound 8 (2.5 g, 4.9 mmol) was added to a 250 ml round-bottomed flask, 125 ml of dry diethyl ether was added, and the mixture was stirred. At this time, compound 8 was suspended in diethyl ether as a white suspension. Under the protection of argon at room temperature, methyl lithium (1.6M ether solution, 3.1 ml, 4.9 mmol) was slowly added dropwise into it, the solid was gradually dissolved into an orange-yellow clear solution with the dropwise addition, and the reaction was completed at room temperature for 12 h. The obtained lithium salt solution was moved into a glove box, anhydrous zirconium tetrachloride powder (0.58 g, 2.5 mmol) was added to it in batches, and a large amount of yellow turbidity was formed in the reactant along with the addition of zirconium salt, and the addition was sealed and stirred at room temperature for 12 h. Filtered with suction, washed with ether, and dried to obtain compound 9 (2.33 g, 71%) as a bright yellow solid.

Example 3

Step 1. Synthesis of 2-methyl-3-bromothiophene

Dissolve 3-bromothiophene (50g, 307mmol) in 200ml of anhydrous tetrahydrofuran, cool to -78°C, add sodium hexamethyldisilazide (2M tetrahydrofuran solution, 165ml, 330mmol), after the addition, - Stirring was continued for 15 min at 78°C. Then the reactant was moved into an ice-water bath, allowed to rise to 0°C naturally, and stirred for another 30 min. The reaction was cooled to -78°C and iodomethane (21 ml, 330 mmol) was slowly added dropwise. The reaction mixture was stirred at -78°C for an additional 30 min, then warmed to 0°C and stirred for 1 h. After the reaction was completed, it was quenched with saturated brine, and the layers were separated. The aqueous phase was extracted with dichloromethane, washed with water, separated, dried over magnesium sulfate, filtered, and the solvent was removed in vacuo. The residue was distilled under reduced pressure to obtain a colorless oily liquid (39.70 g, 73%).

Step 2. Synthesis of 2,5-dimethyl-3-phenyl-5,6-dihydrocyclopentane[1,2-b]thiophen-4-one

In a 1L three-necked flask, aluminum trichloride (56.4g, 423mmol) was suspended in 500ml of dry dichloromethane, under argon protection, methacryloyl chloride (41ml, 423mmol) was slowly added dropwise under ice-water bath cooling, and the dropping was completed and stirred for 5min . Then slowly drop 2-methyl-3-bromothiophene (50g, 282mmol) into 100ml of dry dichloromethane solution, and stir for 30min after dropping, to obtain a dark black red solution, control the temperature so that the temperature in the bottle is not high during the dropping process at 10°C. After the disappearance of starting material was monitored by TLC, it was slowly poured into ice water to quench. Separation, the aqueous phase was extracted with dichloromethane, the organic phases were combined, washed with water, separated, dried over magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain an orange-yellow oily liquid 3 (65.62 g, 95%), which could be used directly without purification. The next step is to synthesize.

In a 500ml round-bottomed flask, 3 was dissolved in 530ml of xylene, a solid acid catalyst (26g, 10mmol/g) was added, the mixture was refluxed at 135°C for 3h, and the disappearance of the raw materials was monitored by TLC. Suction filtration, the solid was washed with dichloromethane, the washings and the filtrate were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain a brown oily liquid 4. After purification by column chromatography, 4 was solidified into yellow needle-like crystals (54.51 g , 83%).

In a 1L round-bottomed flask, anhydrous sodium carbonate (46.63g, 440mmol) and phenylboronic acid (53.65g, 440mmol) were mixed in 250ml xylene, the compound 4 obtained in the previous step was dissolved in 250ml xylene, and the two were mixed, Tetrakis (triphenylphosphine) palladium (0.25 g, 0.22 mmol) was added under stirring, and the mixture was heated to reflux for 5 h until the disappearance of the starting material was monitored by TLC. Cooling, separation, the aqueous phase was extracted with dichloromethane, the washings and the organic phase were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain a brown oily liquid 5. After purification by column chromatography, 5 solidified into a beige solid (48.44 g, 90%).

Step 3. Synthesis of 2,5-dimethyl-3-phenyl-6-cyclopenten[1,2-b]thiophene

Compound 5 (24.22 g, 100 mmol) was dissolved in 200 ml of anhydrous methanol in a 500 ml round-bottomed flask, and after cooling to 0°C in an ice-water bath, sodium borohydride (3.8 g, 100 mmol) was slowly added. After the addition was completed, the ice-water bath was removed, and the temperature of the reaction flask was raised to room temperature, followed by stirring for 1 h, and the completion of the reaction was monitored by TLC. Dilute hydrochloric acid was slowly added to quench, dried over magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain white solid 7. Without purification, 7 was directly dissolved in 100 ml of toluene, added pyridinium p-toluenesulfonate (2.5 g, 10 mmol), and heated to reflux. . After 1.5 hours, TLC monitored the disappearance of the raw materials, cooled, washed with water, separated, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed in vacuo to obtain an orange-red oily liquid 7 (19.71 g, 87%), which was purified by column chromatography and solidified as Off-white solid.

Step 4. Synthesis of 6,6'-dimethylsilylbis(2,5-dimethyl-3-phenyl-thieno[2,3-b]locene) zirconium dichloride

In a 250ml round-bottomed flask, compound 7 (11.38g, 50mmol) was dissolved in 65ml of dry tetrahydrofuran, cooled to -78°C under argon protection, and methyllithium (1.6M ether solution, 31.3ml, 50mmol) was slowly added dropwise into it. ), and the reaction was raised to room temperature for 12 h to obtain a dark red solution. The obtained lithium salt solution was cooled to -78 °C again, dimethyldichlorosilane (3.55 g, 27.5 mmol) was added dropwise to it, and the solution was raised to room temperature for 12 h, and a large amount of white precipitates were precipitated. Filtered with suction, washed with ether, and dried to obtain compound 8 (19.77 g, 77%) as an off-white solid, and compound 8 was used in the next step without further purification.

Compound 8 (2.5 g, 4.9 mmol) was added to a 250 ml round-bottomed flask, 125 ml of dry diethyl ether was added, and the mixture was stirred. At this time, compound 8 was suspended in diethyl ether as a white suspension. Under the protection of argon at room temperature, lithium hexamethyldisilazide (2M tetrahydrofuran solution, 2.5 ml, 5.0 mmol) was slowly added dropwise into it, the solid was gradually dissolved into a dark yellow clear solution with the dropwise addition, and the reaction was completed at room temperature for 12 h. . The obtained lithium salt solution was moved into the glove box, bis(tetrahydrofuran) zirconium tetrachloride (0.94 g, 2.5 mmol) powder was added in batches, and the zirconium salt was added. Yellow turbidity began to form, and the solid content gradually increased. After the addition was completed, the mixture was sealed and stirred at room temperature for 12 h. Filtered with suction, washed with ether, and dried to obtain compound 9 (2.27 g, 66%) as a bright yellow solid.

Example 4

A 250 mL stainless steel autoclave was replaced three times with dry propylene gas, and then 80 mL of dry toluene and 1.5 mL of methylaluminoxane (MAO) (1M toluene solution) were added to it, and stirred under a propylene atmosphere. 1.34 g (1 mmol) of the catalyst prepared in Example 1 was weighed, dissolved in 20 mL of toluene, added to the reaction system under vigorous stirring, and the temperature was started. When the temperature rises to 50°C, propylene gas is charged into it, and the pressure in the kettle is kept at 1 MPa. After 10 minutes, the temperature is raised to 60°C for another 10 minutes, and then the temperature is raised to 70°C for 10 minutes, for a total of 30 minutes, and the polymerization reaction is completed. The propylene gas cylinder was closed to stop the reaction. The resulting polymer was filtered out, and the residual toluene on the surface was washed off with ethanol. After drying, 27.2 g of polypropylene was weighed to obtain a catalyst polymerization activity of 2.72×10 ⁷ g/mol/h. The obtained polypropylene product was analyzed by proton nuclear magnetic resonance spectroscopy, and its isotacticity was 99%.

Claims (10)

1. A method for synthesizing a zirconocene type olefin polymerization catalyst comprises the following steps:

the method comprises the following steps: reacting 3-bromothiophene with strong base, and performing methylation reaction on the 3-bromothiophene and iodomethane to obtain 2-methyl-3-bromothiophene;

step two: 2-methyl-3-bromothiophene is subjected to Friedel-crafts acylation reaction, Nazaro cyclization reaction and Suzuki coupling reaction to obtain 2, 5-dimethyl-3-phenyl-5, 6-dihydrocyclopentane [1,2-b ] thiophene-4-ketone;

step three: 2, 5-dimethyl-3-phenyl-5, 6-dihydrocyclopentane [1,2-b ] thiophene-4-ketone is reduced and eliminated to obtain 2, 5-dimethyl-3-phenyl-6-cyclopentene [1,2-b ] thiophene;

step four: the target zirconocene type olefin polymerization catalyst is obtained by carrying out silicatization and coordination with zirconium salt on 2, 5-dimethyl-3-phenyl-6-cyclopentene [1,2-b ] thiophene, and has the following structure:

2. the method of claim 1, wherein the strong base in step one is selected from n-butyllithium, isobutyllithium, diisopropyllithium, lithium hexamethyldisilazide, sodium hexamethyldisilazide or potassium hexamethyldisilazide.

3. The method for synthesizing a zirconocene type olefin polymerization catalyst according to claim 1, wherein the molar ratio of the 3-bromothiophene, the strong base and the methyl iodide in the first step is 1 (1-2) to (1-2); the reaction temperature of the methylation reaction is-80-100 ℃, and the reaction time is 30 minutes-7 days.

4. The process for synthesizing a catalyst for the polymerization of olefins of the zirconocene type according to claim 1, wherein the catalyst used in the friedel-crafts acylation reaction in the second step is selected from the group consisting of aluminum trichloride, aluminum tribromide, aluminum triiodide, tin tetrachloride, titanium tetrachloride and zinc chloride; the acylating agent used is selected from methacryloyl chloride, methacrylic anhydride, methacrylic acid, sodium methacrylate or methyl methacrylate; the solvent used is selected from dichloromethane or dichloroethane; wherein the molar ratio of the 2-methyl-3-bromothiophene to the acylation reagent to the catalyst is 1 (1-5) to 1-5; the reaction temperature is-80 to 100 ℃, and the reaction time is 1 to 48 hours.

5. The method for synthesizing a zirconocene type olefin polymerization catalyst according to claim 1, wherein the catalyst used in the Nazaloff cyclization reaction in the second step is selected from perfluorosulfonic acid resin, solid acid catalyst, sulfuric acid, phosphoric acid or trifluoroacetic acid, and the molar mass ratio of the raw material to the catalyst is 1mmol (0.5-10 g); the solvent used is selected from toluene, ethylbenzene or xylene; the reaction temperature is 0-200 ℃, and the reaction time is 1-48 hours.

6. The method for synthesizing a zirconocene-type olefin polymerization catalyst according to claim 1, wherein the catalyst used in the Suzuki coupling reaction in step two is selected from tetrakis (triphenylphosphine) palladium, tetrakis (triphenylphosphine) platinum, bis (triphenylphosphine) palladium dichloride, palladium on carbon, palladium black, or palladium-calcium carbonate; the alkali is selected from potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide or potassium trimethylsilanolate; the phenylating agent used is selected from phenylboronic acid, sodium phenylboronate, phenylboronic anhydride or pinacol ester of phenylboronic acid; the solvent used is selected from toluene, ethylbenzene or xylene; wherein the molar ratio of the reaction raw materials to the alkali, the phenylating reagent and the catalyst is 1 (1-5) to 1-5 to 0.0001-1; the reaction temperature is 100-200 ℃, and the reaction time is 10 minutes-48 hours.

7. The method for synthesizing a zirconocene-type olefin polymerization catalyst according to claim 1, wherein the reducing agent used in the reduction reaction in step three is selected from sodium borohydride, lithium aluminum hydride, borane-tetrahydrofuran, or borane-dimethyl sulfide; wherein the molar ratio of the raw material to the reducing agent is 1 (0.1-2); the reaction temperature is-50 ℃ to 100 ℃, and the reaction time is 1 minute to 48 hours.

8. The process for synthesizing a catalyst for the polymerization of olefins of the zirconocene type according to claim 1, wherein the catalyst used in the elimination reaction in step three is selected from the group consisting of p-toluenesulfonic acid monohydrate, p-toluenesulfonic acid pyridinium salt, pyridine hydrochloride, pyridine sulfate, camphorsulfonic acid, phenylboronic acid, sulfuric acid and hydrochloric acid; the solvent used is selected from tetrahydrofuran, dichloroethane, 1, 4-dioxane, toluene, xylene or ethylbenzene; wherein the molar ratio of the raw material to the catalyst is (1-5) to 1; the reaction temperature is-50 to 200 ℃, and the reaction time is 10 minutes to 48 hours.

9. The method of claim 1, wherein the strong basic reagent used in the silylation reaction in the step four is selected from n-butyllithium, isobutyllithium, tert-butyllithium, methyllithium, diisopropylaminium, hexamethyldisilazane, sodium hexamethyldisilazane, and potassium hexamethyldisilazane; the silane reagent used is selected from dichlorodimethylsilane, dibromodimethylsilane or dimethylsilane bistrifluoromethanesulfonate; the solvent used is selected from diethyl ether, dichloromethane, dichloroethane, n-butyl ether or methyl tert-butyl ether; wherein the molar ratio of the raw material to the strong alkali reagent to the silane reagent is 1 (1-5) to 0.2-5; the reaction temperature is-80-100 ℃, and the reaction time is 1 minute-48 hours.

10. The method of claim 1, wherein the strong basic reagent used in the coordination reaction in step four is selected from n-butyllithium, isobutyllithium, tert-butyllithium, methyllithium, diisopropylaminolithium, hexamethyldisilazane, sodium hexamethyldisilazane, and potassium hexamethyldisilazane; the zirconium salt used is selected from anhydrous zirconium tetrachloride or bis (tetrahydrofuran) zirconium tetrachloride; the solvent used is selected from diethyl ether, dichloromethane, dichloroethane, n-butyl ether or methyl tert-butyl ether; wherein the molar ratio of the ligand to the strong alkali reagent to the zirconium salt is 1 (1-5) to 0.2-5; the reaction temperature is 0-100 ℃, and the reaction time is 1-48 hours.

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