Process for producing metallocenes

Abstract

The present invention relates to an improved process for preparing metallocenes of general formula (A) CR2L2MX2, as well as to intermediates useful in the synthesis of said metallocenes and their use as catalysts in the polymerization of olefins.

Description

[Technical Field]

[0001] The present invention relates to an improved process for preparing metallocenes of general formula (A) CR2L2MX2, as well as to intermediates useful in the synthesis of said metallocenes and their use as catalysts in the polymerization of olefins. [Background technology]

[0002] The polymerization of olefins, such as ethylene and propylene, to produce thermoplastics or norbornene-containing polymers often uses transition metal compounds, particularly metallocene compounds, as polymerization catalysts, which have been extensively improved and studied over the past several decades.

[0003] For example, metallocene compounds containing unsubstituted or alkyl-substituted indenyl or fluorenyl ligand systems are known (Patent Document 1).

[0004] As is generally known in the art, bridged and substituted bis-(1-indenyl) ligands are suitable as starting compounds in processes for producing metallocene catalysts for polymerizing olefins.

[0005] Patent Document 2 discloses 2,2-bisindenylpropane as a carbon-bridged, substituted biscyclopentadiene compound.

[0006] (Patent Document 3) and (Patent Document 4) discloses zirconium-based metallocenes (so-called zirconocenes) containing bridged indenyl derivatives as ligands.

[0007] Non-Patent Document 1 and Patent Document 5 disclose isopropylidene-bis-(1-indenyl)zirconium dichloride and isopropylidene-bis-(1-fluorenyl)zirconium dichloride. [ka]

[0008] However, there has been a long-standing interest in producing such bridged metallocene compounds in a more efficient manner and in high yields.

[0009] Patent Document 6 discloses a process for producing 2,2-bis(1-indenyl)propane. Indene was reacted with n-butyllithium, and then 1-isopropylindene was added to produce 2,2-bis(1-indenyl)propane. [ka]

[0010] 2,2-bis(1-indenyl)propane was further reacted with n-butyllithium, followed by the addition of a solution of zirconium chloride in dichloromethane to produce isopropylidene-bis(1-indenyl)zirconium dichloride. The orange precipitate was filtered, washed with dichloromethane, and dried. The yield of 2,2-bisindenylpropane was 39%.

[0011] Patent Document 7 discloses a process for producing 2,2-bis(1-indenyl)propane. Indene was added to a suspension of potassium hydroxide (KOH) and dimethoxyethane (DME), and acetone was added dropwise. The mixture thus obtained was treated with dilute phosphoric acid and diethyl ether. The organic phase was separated, washed, and dried over Na2SO4.

[0012] Patent Document 8 discloses a process for producing bridged metallocenes, such as rac-isopropylidene-bis(indenyl)zirconium dichloride. 2,2-Bis(indenyl)propane was dissolved in ether and treated with n-BuLi in pentane. The suspension was treated with triethylstannyl chloride, after which ZrCl4 was added to the separated organic phase.

[0013] Patent Document 9 discloses a process for producing 2,2-bisindenylpropane and isopropylidene-bis-(1-indenyl)zirconium dichloride. Indene was dissolved in toluene, and an aqueous solution of sodium hydroxide (NaOH) and a phase transfer catalyst, triethylbenzylammonium chloride (TEBA), was added. Then, acetone was added dropwise. The aqueous phase was separated and extracted twice with diethyl ether. Finally, the organic phase was dried over MgSO4, and the solvent was removed under vacuum. The yield of 2,2-bisindenylpropane was 85%. [ka]

[0014] In addition, Patent Document 10 disclosed that the use of a metallation step as the next step resulted in the isolated reaction product being obtained in 55% yield. 2,2-bisindenylpropane was reacted with n-butyllithium (BuLi) in diethyl ether. After adding hexane, the suspension was filtered and washed with pentane. The precipitate of the dilithium salt was dried and added to a suspension of ZrCl4 in dichloromethane.

[0015] However, the yield is insufficient for commercial purposes, and trace amounts of the phase transfer catalyst triethylbenzylammonium chloride and impurities remain in the reaction product, interfering with subsequent reactions.

[0016] Patent Document 11 discloses a process for producing 2,2-bisindenylpropane derivatives having a substituent at the 2-position via an isopropylidene-bis(2-bromo-1-indene) intermediate, as well as metallocenes thereof, such as isopropylidene-bis(2-methyl-1-indenyl)zirconium dichloride. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] British Patent No. A934,281 [Patent Document 2] US Patent No. A6,072,085 [Patent Document 3] European Patent Application Publication No. A0 485 823 [Patent Document 4] European Patent Application Publication No. A0 563 917 [Patent Document 5] European Patent Application Publication No. A0 511 665 [Patent Document 6] European Patent Application Publication No. A0 416 566 [Patent Document 7] European Patent Application Publication No. A0 722 949 [Patent Document 8] European Patent Application Publication No. A0 722 950 [Patent Document 9] European Patent No. B0 751 143 [Patent Document 10] European Patent Application Publication No. A0 751 143 [Patent Document 11] Japanese Patent No. 4108334 [Non-patent literature]

[0018] [Non-Patent Document 1] "Metalorganic Catalysts for Synthesis and Polymerization", 1999, page 462 (Walter Kaminsky) Summary of the Invention [Problem to be solved by the invention]

[0019] As noted above, much research has been done on metallocene compounds as catalysts for producing olefin polymers, and on processes for their production. Despite the advances described so far, there is still room for improvement in processes for producing metallocene catalysts. Specifically, having reproducible synthetic routes and processes is essential to establishing synthetic routes that can be easily scaled up.

[0020] A manufacturing process is sought that is reproducible and at the same time efficient in terms of conversion of starting materials, solvent and catalyst use, and number of synthetic steps (i.e., an economical process). [Means for solving the problem]

[0021] As outlined above, the object to be solved by the present invention can be seen as providing an improved process for the preparation of metallocenes of general formula (A) CR2L2MX2, such as isopropylidenebis-(1-indenyl)zirconium dichloride.

[0022] The present invention relates to a compound represented by general formula (A) CR2L2MX2(A) The present invention provides a process for preparing a metallocene of formula (I), which comprises the steps of: (a) A symmetric or asymmetric linear or cyclic ketone of general formula (B) (C=O)R2 and a ligand L are reacted with M of an alkali metal alkoxide. 1 OR 1 to form a compound of general formula (C) (b) reacting the compound (C) CR2L2 with a metal halide MX4 in the presence of a deprotonating agent; [In the formula, R is individually C1-C8 alkyl, cycloalkyl, or phenyl, preferably methyl, ethyl, propyl, or phenyl, more preferably methyl or phenyl; R 1 is C1~C 20 alkyl, preferably C1-C6 alkyl, more preferably methyl or ethyl; L is individually unsubstituted indenyl, substituted indenyl, unsubstituted benzoindenyl, substituted benzoindenyl, unsubstituted fluorenyl, or substituted fluorenyl, preferably unsubstituted indenyl, unsubstituted fluorenyl, or unsubstituted benzoindenyl, more preferably unsubstituted indenyl; M is zirconium, hafnium, titanium, or a lanthanide, preferably zirconium or hafnium, more preferably zirconium; M 1 is an alkali metal, preferably lithium, sodium, or potassium, more preferably sodium, and X is a halogen, preferably chlorine or bromine, more preferably chlorine. Includes:

[0023] Furthermore, the present invention provides the use of the metallocene of general formula (A) obtained according to the present invention as a catalyst in the polymerization of olefins.

[0024] These and further features and advantages of the present invention will become apparent from the following detailed description and claims. DETAILED DESCRIPTION OF THE INVENTION

[0025] Throughout this specification and claims or clauses, unless the context otherwise requires, the term "comprise" and its variations "comprises" or "comrising" should be understood to mean the inclusion of a stated integer (or step) or group of integers (or steps).

[0026] The present invention is directed to a process for producing metallocenes of general formula (A) CR2L2MX2, preferably isopropylidenebis-(1-indenyl)zirconium dichloride.

[0027] The present invention further provides the use of a metallocene of general formula (A) CR2L2MX2 above, preferably isopropylidenebis-(1-indenyl)zirconium dichloride, as a polymerization catalyst for olefins.

[0028] Reaction step (a): Preparation of compounds of general formula (C) A process for producing a metallocene of general formula (A) CR2L2MX2, such as isopropylidenebis-(1-indenyl)zirconium dichloride, comprises a first step (a) of reacting a symmetrical or unsymmetrical, linear or cyclic ketone of general formula (B) (C=O)R2 with a ligand L in the presence of sodium methoxide or sodium ethoxide to form a compound of general formula (C) CR2L2.

[0029] Ketone (B) (C=O)R2 The ketone of general formula (B) (C=O)R2 is a symmetrical or asymmetrical, linear or cyclic ketone, where R is individually C1-C8 alkyl, cycloalkyl, or phenyl, preferably methyl, ethyl, propyl, or phenyl, more preferably methyl or phenyl. R may combine to form a 3- to 7-membered cyclic ring.

[0030] In a preferred embodiment, the ketone (B) is acetone, benzophenone, acetobenzophenone, or cyclohexanone, more preferably acetone or benzophenone.

[0031] Ligand L Ligand L is individually unsubstituted indenyl, substituted indenyl, unsubstituted benzoindenyl, or substituted benzoindenyl, preferably unsubstituted indenyl, unsubstituted fluorenyl, or unsubstituted benzoindenyl, more preferably unsubstituted indenyl.

[0032] In the present invention, the term "substituted" refers to a C1-C 20 substituted with alkyl, or C 6 ~C 20 Aryl-substituted or substituted with 3-trimethylsilyl This means that

[0033] Suitable examples of substituted indenyl ligands are 4,5,6,7-tetrahydro-1-indene, 3-methylindene, 3-tert-butylindene, 3-trimethylsilylindene. 、4 -phenylindene , or 2-methyl-4,6-diisopropylindene is.

[0034] Suitable examples of substituted benzoindenyl ligands are 4,5-benzoindene, 2-methyl-4,5-benzoindene, or 2-Methyl-α-acenaphthiinde In be.

[0035] In a preferred embodiment of the present invention, only one type of ligand L is used in reaction step (a), not a mixture.

[0036] M of alkali metal alkoxide 1 OR 1 The first reaction step (a) of the present invention is to react an alkali metal alkoxide M 1 OR 1 where R 1 is C1~C 20 alkyl, preferably C1-C6 alkyl, more preferably methyl or ethyl, most preferably methyl; and M 1 is an alkali metal, preferably lithium, sodium, or potassium, more preferably sodium.

[0037] In a preferred embodiment, the reaction is carried out in the presence of an alkali metal methoxide or alkali metal ethoxide. In a more preferred embodiment, the reaction is carried out in the presence of sodium methoxide or sodium ethoxide. In a most preferred embodiment, the reaction is carried out in the presence of sodium methoxide.

[0038] In a preferred embodiment, the reaction of the first reaction step (a) involves the reaction of acetone with sodium methoxide and unsubstituted indene in dimethyl sulfoxide (DMSO), which can be summarized as follows: [ka]

[0039] In a preferred embodiment of the present invention, the compound of general formula (C) is 2,2-bisindenylpropane.

[0040] In the present invention, it has been found that by using sodium methoxide or sodium ethoxide as a base in the first reaction step, the formation of a compound of general formula (C) CR2L2, preferably the intermediate 2,2-bisindenylpropane, can be achieved in much higher yield and without the inclusion of side reaction products, such as indenyl sodium, oxidation reaction products of indenyl sodium, or polymerization reaction products, which are normally formed when an alkali metal hydroxide, such as sodium hydroxide or potassium hydroxide, is used as the base.

[0041] In particular, it was found that when sodium hydroxide was used, the yield of the intermediate 2,2-bisindenylpropane changed dramatically, and in some test reactions, the 2,2-bisindenylpropane reaction product may not even be formed at all. Furthermore, when sodium hydroxide was used, it was difficult and / or cumbersome to remove the by-products from the desired reaction product, i.e., 2,2-bisindenylpropane.

[0042] Furthermore, it has been found in the present invention that when dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) is used as a solvent in the reaction of a symmetrical or asymmetrical, linear or cyclic ketone with indene, it is possible to obtain a high reaction product yield, for example, greater than 60%, more preferably greater than 70%, of the isolated reaction product, 2,2-bisindenylpropane.

[0043] In an even more preferred embodiment, the reaction of symmetric or asymmetric, linear or cyclic ketone (B) with indene is carried out by adding symmetric or asymmetric, linear or cyclic ketone (B) to a reaction mixture comprising indene and dimethylformamide (DMF) or dimethyl sulfoxide (DMSO), preferably DMSO.

[0044] In an even more preferred embodiment, the reaction of the symmetric or asymmetric, linear or cyclic ketone (B) with the ligand L as described above is carried out at a temperature of 0 to 40°C, more preferably 0 to 25°C, and even more preferably 5 to 15°C, for a time period of 10 to 30 minutes.

[0045] In a preferred embodiment, the reaction mixture is further stirred at a temperature below 40° C. for 1 to 120 minutes.

[0046] After carrying out this reaction, the reaction mixture is typically quenched by workup, for example, by adding methyl tert-butyl ether (MTBE), water, and / or 10% NaCl solution, and the organic phase is separated by phase separation and washed with water. The organic phase is then typically dried, for example, by adding sodium sulfate (NaSO). The organic phase may then be subjected to a distillation step to purify the reaction product, 2,2-bisindenylpropane.

[0047] In a preferred embodiment, the reaction of step (a) is carried out without the use of any phase transfer catalyst.

[0048] As indicated above, in the present invention, a second reaction step ("metalation") is then carried out.

[0049] Reaction step (b): Preparation of metallocenes of general formula (A) CR2L2MX2 In the second step (b) of the process of the present invention, the compound CR2L2 of general formula (C) above is reacted with a metal halide MX4 in the presence of a deprotonating agent to form a metallocene of general formula (A) CR2L2MX2, preferably isopropylidenebis-(1-indenyl)zirconium dichloride.

[0050] Metal Halide MX4 X in the metal halide MX4 is a halogen, preferably fluoride, chloride, bromide, or iodide, more preferably chloride.

[0051] The metal halide MX4, M, is zirconium (Zr), hafnium (Hf), titanium (Ti), or a lanthanide such as neodymium.

[0052] The metal halide MX4 is preferably ZrF4, ZrCl4, ZrBr4, ZrI4, HfCl4, TiCl4, or NdCl3, more preferably ZrCl4.

[0053] Deprotonating Agent In the present invention, a typical deprotonating agent can be used. The deprotonating agent is preferably butyllithium (n-BuLi), sodium hydride (NaH), BEM, or BOMAG, more preferably n-BuLi. In a preferred embodiment, a deprotonating agent that is highly soluble in tetrahydrofuran (THF) is used.

[0054] In a preferred embodiment of the present invention, the second reaction step (b) is carried out using as a solvent tetrahydrofuran (THF), methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), methyl tetrahydrofuran, di-n-butyl ether, or diisopropyl ether (DIPE), more preferably a mixture of THF and hexane.

[0055] In a preferred embodiment of the present invention, the second step (b) is carried out using a solution of n-BuLi in hexane at a concentration of 80% or more, preferably 90% or more. Concentrations of n-BuLi less than 80%, such as the commercially available only 20%, are not preferred because they result in a large amount of hexane, which can cause LiCl to precipitate.

[0056] In a preferred embodiment, the ligand L is first dissolved in a solvent, preferably THF, MTBE, ETBE, TAME, or DIPE, and then the deprotonating agent and metal halide MX4 are added to the mixture. [ka]

[0057] The second reaction step (b) is usually carried out by adding MX4 to CR2L2 of compound (C) at a temperature of 0 to -20°C, more preferably -5 to -15°C, for a period of 15 minutes to 10 hours, more preferably 30 minutes to 5 hours.

[0058] Preferably, the second reaction step (b) is carried out by adding zirconium(IV) chloride to the intermediate dilithium salt of 2,2-bisindenylpropane at a temperature of 0 to −20° C., more preferably −5 to −15° C., for a period of 15 minutes to 10 hours, more preferably 30 minutes to 5 hours.

[0059] The inventors have found that by using THF as a solvent in the second reaction step, a high yield of the final reaction product can be obtained, because in the above case, the by-product LiCl formed in the second reaction step is soluble in THF and does not need to be removed in a further step, whereas the reaction product is insoluble and therefore precipitates.

[0060] As is known to those skilled in the art, the polymerization yield of olefins in the presence of a metallocene catalyst, such as isopropylidenebis-(1-indenyl)zirconium dichloride, depends on the purity of the metallocene catalyst. Surprisingly, when isopropylidenebis-(1-indenyl)zirconium dichloride obtained according to the process claimed in the present invention is used as a metallocene catalyst in the polymerization of olefins, it will be possible to obtain high polymerization yields.

[0061] In a preferred embodiment of the present invention, the metallocene of general formula (A) CR2L2MX2 is symmetrical.

[0062] In a further aspect of the present invention, the metallocene of general formula (A), preferably isopropylidenebis-(1-indenyl)zirconium dichloride, prepared according to the various processes of the present invention, is used as a catalyst in the polymerization of olefins. [Example]

[0063] Example 1: Reaction step (a): Synthesis of 2,2-bisindenylpropane All operations were carried out under an inert gas (argon) atmosphere. A 2-L double-walled reactor was charged with DMSO (100 mL), NaOMe (0.9 g, 0.02 mol), and indene (40 g, 0.33 mol) and stirred at 20 °C for 30 minutes. The reactor was cooled to 10 °C. Acetone (9.7 g, 0.17 mol) was then added within 15 minutes, while the reactor temperature was maintained below 20 °C (exothermic reaction). The reaction mixture was then stirred at 40 °C for 2 hours and at room temperature overnight, at which point the reaction was complete (determined by GC: 6,6-dimethylfulvene, less than 1%). At 10 °C, 100 g of water was added and stirred for 30 minutes. Then, methyl tert-butyl ether (MTBE; 236 g) was added to the reaction mixture. The mixture was stirred at room temperature for another 30 minutes.

[0064] The two phases were separated, the aqueous phase was extracted once more with MTBE, and the combined organic phases were washed neutral with saturated aqueous NaCl (2 × 100 mL). The organic phase was dried over NaSO, and then MTBE and unconverted indene were removed by vacuum distillation at a maximum temperature of 40 °C to near dryness. The resulting viscous suspension was filtered, and the crude product was washed with methanol, hexane, and MTBE. Upon drying, a brown, crystalline solid was obtained (27 g) with a purity of 98.4%. Additionally, the remaining mother liquor was subjected to the same isolation steps as above to obtain another 10 g of pure product. Total yield: 37 g, 81%. [ka]

[0065] Reaction step (b): Preparation of isopropylidenebis-(1-indenyl)zirconium dichloride All operations were carried out under an inert gas atmosphere. In a 2 L double-walled reactor, 2,2-bisindenylpropane (15.8 g, 0.056 mol, 98.6% purity) from reaction step (a) was dissolved in tetrahydrofuran (THF; 200 mL) at room temperature, and the mixture was cooled to -5 °C. Within 30 min, n-BuLi (90% solution in n-hexane, 8.06 g, 0.1120 mol) was added, while the reactor temperature remained below 7 °C. The solution was stirred at 0 °C for 60 min. The dilithium salt of the ligand precipitated. The suspension was warmed to room temperature and stirred at 25 °C for an additional 120 min. The solution was cooled again to 0 °C, and ZrCl4·2THF (21.15 g, 0.056 mol) was added. The addition was exothermic, with the temperature rising by approximately 10–20 K. The reaction mixture is warmed to 20°C and stirred overnight. After 120 minutes, a dark red product precipitates. The product is isolated by filtration and washed twice with THF and twice with hexane / THF to remove any remaining traces of LiCl. The product is dried in vacuo to give 16.6 g (0.038 mol, 67.8% yield) of fine orange-red crystals. [ka]

[0066] Example 2: Example 2 was carried out in the same manner as Example 1, except that the crosslinker was replaced with benzophenone (O=CPh; 15.2 g, 0.08 mol) and the amount of NaOMe was doubled, as seen in Table 1. The reaction product was dried in vacuo to give 35.5 g (0.064 mol, 80.1% yield) of fine orange-red crystals.

[0067] Example 3: Example 3 was carried out in the same manner as Example 1, except that DMF (dimethylformamide) was used as the solvent, as seen in Table 1. The reaction product was dried in vacuo to give 20.0 g (0.073 mol, 44.2%) of fine white crystals.

[0068] Example 4 (scale-up): A reactor having a volume of 1 cubic meter was conditioned with an inert gas atmosphere, and DMSO (120 kg, 1536 mol) and NaOMe (1.01 kg, 20 mol) were added to the reactor. While stirring the suspension, 42.4 kg of indene was added, and the reaction mixture was stirred at 20°C for 30 minutes. The mixture was cooled to 10°C, and acetone (10.6 kg, 180 mol) was added within 10 minutes. The reactor was further cooled to maintain a temperature below 40°C. Upon completion of the addition, the reaction mixture was heated to 40°C and stirred at that temperature for 1 hour. After sampling, the reaction mixture was cooled to 20°C and stirred at 20°C for 12 hours. 258 kg of MTBE was added to the reaction mixture, followed by 118 kg of 10% NaOH solution at 0°C. The temperature rose to approximately 20°C, and the resulting two-phase mixture was stirred for a minimum of 30 minutes. The two phases were separated, and the organic phase was washed again with 120 kg of MTBE. The combined organic phases were dried with Na2SO4 and injected back into the reactor. At 40 °C, approximately 85% of the MTBE was distilled off, and the same amount of heptane was added and distilled again. The resulting suspension was cooled to 20 °C, filtered through a pressure filter, and washed with methanol / heptane (1:1 mixture). The reaction product was dried in vacuo to give a brown powder with a purity of more than 96%, with a yield of 30 kg (110.1 mol, 59.4%).

[0069] [Table 1]

Claims

1. A process for preparing a metallocene of general formula (A), comprising: CR ２ L ２ MX ２ (A) (a) (C═O)R of general formula (B) ２ and a ligand L are reacted with an alkali metal alkoxide M １ OR １ in the presence of ２ L ２ forming a compound of formula (I); and (b) CR of the compound (C) ２ L ２ and metal halide MX ４ in the presence of a deprotonating agent, wherein the deprotonating agent is n-butyllithium in hexane at a concentration of 80% or greater; (In the formula, R is individually, C １ ~C ８ alkyl, cycloalkyl, or phenyl; R １ is C １ ~C ２０ is alkyl, L is individually unsubstituted indenyl, substituted indenyl, unsubstituted benzoindenyl, or substituted benzoindenyl; M is zirconium, hafnium, titanium, or a lanthanide; M １ is an alkali metal, and X is a halogen. The method includes the steps of: the alkali metal alkoxide is sodium methoxide or sodium ethoxide; The process wherein said reacting step (a) is carried out in the absence of any phase transfer catalyst.

2. 2. The process of claim 1, wherein the ketone (B) is a symmetrical ketone.

3. 3. The process of claim 1 or 2, wherein the ketone (B) is acetone, benzophenone, acetobenzophenone, or cyclohexanone.

4. The process of any one of claims 1 to 3, wherein the alkali metal alkoxide is sodium methoxide.

5. 5. The process of any one of claims 1 to 4, wherein the reacting step (a) is carried out in dimethylformamide or dimethylsulfoxide.

6. 6. The process of any one of claims 1 to 5, wherein the reaction (a) is carried out at a temperature of 0 to 40°C for a time period of 10 to 30 minutes.

7. 7. The process of any one of claims 1 to 6, wherein the reaction (b) is carried out in tetrahydrofuran, methyl tert-butyl ether, ethyl tert-butyl ether, tert-amyl methyl ether, or diisopropyl ether as a solvent, or in a mixture of tetrahydrofuran and hexane.

8. 8. The process of any one of claims 1 to 7, wherein the reaction (b) is carried out at a temperature of from -5 to -15°C for a time period of from 30 minutes to 5 hours.

9. (a) reacting acetone with unsubstituted indene in the presence of sodium methoxide to form 2,2-bisindenylpropane; and (b) 2,2-bisindenylpropane was reacted with ZrCl in the presence of n-BuLi. ４ reacting with The process according to any one of claims 1 to 7, comprising:

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