Use of organometallic flurorenyl compounds.

Abstract: Fluorenyl-containing metallocenes are disclosed along with methods for making the metallocenes. Also disclosed are methods for using the metallocenes as polymerization catalysts. In addition, polymers resulting from such polymerizations are disclosed.

Description: This invention relates to a method for polymerizing olefins using organometallic compounds containing at least one fluorenyl ligand. Background of the Invention Since the discovery of ferrocene in 1951, a number of metallocenes have been prepared by the combination of compounds having cyclopentadienyl structure with various transition metals. The term "cyclopentadienyl structure" as used herein refers to the following structure. The term "cyclopentadiene-type compounds" as used herein refers to compounds containing the cyclopentadiene structure. Examples include unsubstituted cyclopentadiene, unsubstituted indene, unsubstituted fluorene, and substituted varieties of such compounds. Also included is tetrahydro indene. Many of the cyclopentadiene-type metallocenes have been found useful in catalyst systems for the polymerization of olefins. It has been noted in the art that variations in the chemical structure of such cyclopentadienyl-type metallocenes can have significant effects upon the suitability of the metallocene as a polymerization catalyst. For example, the size and substitutions on cyclopentadienyl-type ligands has been found to affect the activity of the catalyst, the stereoselectivity of the catalyst, the stability of the catalyst, and other properties of the resulting polymer; however, the effect of various substituents is still largely an empirical matter, that is, experiments must be conducted in order to determine just what effect a particular variation will have upon a particular type of cyclopentadienyl-type metallocene. Some examples of some cyclopentadienyl-type metallocenes are disclosed in U.S. Patent Nos. 4,530,914; 4,808,561; and 4,892,851. EP-A-0 426 645 relates to the production of copolymers of propylene and olefins having from 2 to 10 carbon atoms in which the microstructure of the site chains is highly syndiotactic. EP-A-0 423 101 discloses metallocene compounds suitable for producing hemiisotactic polypropylene. In EP-A-0 421 209 a process for producing a polyolefin using a specific metallocene-containing catalyst is disclosed. EP-A-0 387 691 and EP-A-0 387 690 are directed to processes for preparing syndiotactic polyolefin using a specific metallocene-containing catalyst. The article of Journal of Organometallic Chemistry, 401(1991) C5 - C9 of Herrmann et al. describes di-anions of the general type [(C 5 H 4 )CHR(Cp')] 2- (R = Me, t Bu; Cp' = C 5 H 4 , C 9 H 6 , C 13 H 8 ) which react with MCl 4 (M = Ti, Zr) in solution to give the complexes [(C 5 H 4 )CHR(Cp')]MCl 2 which complexes were characterized by 1 H and 13 C NMR spectroscopy. EP-A-0 351 392 discloses a specific metallocene catalyst and its use for producing syndiotactic polyolefins. A process for the preparation of metallocenes is described in WO-A-9 106 551, which process comprises the reaction of a transition metal salt and powder of the solid reaction product of the ligand with an alkyl-lithium in a non-polar hydrocarbon liquid, to recover a solid mixture of lithium salt and metallocene. The metallocene thus obtained can be used for the polymerization of olefins. EP-A-0 427 697 is concerned with a catalyst system comprising a neutral metallocene compound, an aluminum alkyl and a Lewis acid, which catalyst system can be used for the polymerization of olefins, primarily propylene. EP-A-0 320 762 discloses a process for preparing specific chiral stereorigid metallocene compounds of titanium, zirconium, and hafnium. While there are references in the prior art which have envisioned metallocenes containing fluorenyl groups, only a very limited number of fluorenyl-containing metallocenes have actually been prepared prior to the present invention. The Journal of Organometallic Chemistry, Vol. 113, pages 331-339 (1976), discloses preparing bis-fluorenyl zirconium dichloride and bis-fluorenyl zirconium dimethyl. U.S. Patent 4,892,851 and the New Journal of Chemistry, Vol. 14, pages 499-503, dated 1990, each disclose preparing a metallocene from the ligand 1,1-dimethylmethylene-1-(fluorenyl)-1-(cyclopentadienyl). The New Journal of Chemistry article also discloses preparing a similar compound in which the cyclopentadienyl radical has a methyl substituent in the number 3 position. The term fluorenyl as used herein refers to 9-fluorenyl unless indicated otherwise. An object of the present invention is to provide processes for the polymerization of olefins using fluorenyl-type metallocene catalyst systems. Summary of the Invention In accordance with the present invention, there is provided a process for the polymerization of ethylene or a mixture of ethylene and up to 12 mole-% of a higher molecular weight olefin, as defined in claim 1. Description of the Drawing Figure 1 is the 13 C NMR spectrum of a polymer produced by polymerizing 4-methyl-1-pentene using (1-fluorenyl-1-cyclopentadienyl methane)zirconium dichloride as a catalyst. Detailed Description of the Invention The metallocenes used in accordance with the present invention involve metallocenes in which a fluorenyl radical, either substituted or unsubstituted, is bonded to another cyclopentadienyl-type radical being an indenyl, tetrahydroindenyl, or fluorenyl radical by a bridging structure R". These metallocenes are referred to herein as bridged metallocenes. Methods for preparing fluorenyl-containing cyclopentadiene-type compounds which can be used in making the metallocenes are disclosed in the aforementioned U.S. Patent application Serial No. 697,363. The metal, Me is selected from the Group IVB, and VB metals of the Periodic Table. The currently preferred metals include titanium, zirconium, hafnium, and vanadium. The R" can be selected from any suitable bridging structure. Typical examples include hydrocarbyl and heteroatom containing alkylene radicals, germanium, silicon, phosphorus, boron, aluminum, tin, oxygen, nitrogen, and the like. The R" bridge when hydrocarbyl can be aromatic in nature, such as a phenyl substituted alkylene; however, the currently preferred modes employ aliphatic alkylene bridges. The currently most preferred bridges are hydrocarbyl or heteroatom containing alkylene radical having 1 to 6 carbon atoms. In an especially preferred embodiment k is equal to the valence of Me minus 2. The substituents R are each independently selected from hydrocarbyl radicals having 1 to 20 carbon atoms. In a particularly preferred embodiment, the hydrocarbyl radicals R are alkyl radicals. More preferably the alkyl R radicals have 1 to 5 carbon atoms. Each Q is a hydrocarbyl radical such as, for example, aryl, alkyl, alkenyl, alkaryl, or arylalkyl radical having from 1 to 20 carbon atoms, hydrocarbyloxy radicals having 1 to 20 carbon atoms, or halogen. Exemplary Q hydrocarbyl radicals include methyl, ethyl, propyl, butyl, amyl, isoamyl, hexyl, isobutyl, heptyl, octyl, nonyl, decyl, cetyl, 2-ethylhexyl, phenyl, and the like. Exemplary halogen atoms include chlorine, bromine, fluorine, and iodine and of these halogen atoms, chlorine is currently preferred. Exemplary hydrocarboxy radicals include methoxy, ethoxy, propoxy, butoxy, amyloxy, and the like. Illustrative, but non-limiting examples of metallocenes containing bridged fluorenyl ligands include for example (1,1-difluorenylmethane)zirconium dichloride, (1,2-difluorenyl)ethane zirconium dichloride, (1,3-difluorenylpropane)zirconium dichloride, (1,2-difluorenylethane)hafnium dichloride, (1,3-difluorenylpropane) hafnium dichloride, (1-fluorenyl-2-methyl-2-fluorenylethane)zirconium dichloride, dimethylsilyldifluorenyl zirconium dichloride, (1,2-di(1-methyl fluorenyl)ethane)zirconium dichloride, (1,2-di(1-methyl fluorenyl) ethane) hafnium dichloride, (1,2-di(2-ethyl fluorenyl)ethane)zirconium dichloride, (1,2-di(2-t-methyl fluorenyl)ethane)zirconium dichloride, (1,2-di(2-t-butyl fluorenyl)ethane)hafnium dichloride, (1,2-di(1-t-butyl fluorenyl)ethane) zirconium dichloride, (1,2-di(4-methyl fluorenyl) ethane) zirconium dichloride, (1,2-di(4-methyl fluorenyl)ethane) hafnium dichloride, (1,2-di(4-t-butyl fluorenyl)ethane) zirconium dichloride, (1-fluorenyl-2-indenyl ethane)zirconium dichloride, (1-fluorenyl-2-indenyl ethane)hafnium dichloride, (1-fluorenyl-2-methyl-2-indenyl ethane)zirconium dichloride, (1-fluorenyl-2-methyl-2-indenyl ethane)hafnium dichloride, (bis-fluorenylmethane)vanadium dichloride, (1,2-difluorenyl ethane)vanadium dichloride, (1-(1-methyl fluorenyl)-2-(4-methyl fluorenyl)ethane)zirconium dichloride, (1-(2,7-di-t-butyl fluorenyl)-2-(fluorenyl)ethane)zirconium dichloride, (1,2-di(2,7-di-t-butyl-4-methyl fluorenyl)ethane)zirconium dichloride, (1,2-di-(1-methyl-4-methyl fluorenyl)ethane) zirconium dichloride, and the like. Particularly preferred metallocene species used according to the invention include bridged metallocenes containing at least one substituted fluorenyl radical, i.e., there is at least one FlR n wherein n is 1 to 7. The metallocenes used according to the invention as well as related metallocenes can be prepared by reacting an alkali metal salt of the bridged fluorenyl compounds with a suitable transition metal compound in a suitable solvent under suitable reaction conditions. The term transition metal compound as used herein includes compounds of the formula MeQ k wherein Me, Q, and k are as defined above. Some non-limiting examples include zirconium tetrachloride, hafnium tetrachloride, cyclopentadienyl zirconium trichloride, fluorenyl zirconium trichloride, 3-methylcyclopentadienyl zirconium trichloride, indenyl zirconium trichloride, 4-methyl fluorenyl zirconium trichloride, and the like. In an especially preferred embodiment bridged fluorenyl compounds of the formula (FIR n )R"(CpR m ) are used wherein F1, R, R", and m are as defined above, and where n is 1 to 7, most preferably 1 to 4. Metallocenes in which Q is other than a halogen can be readily prepared by reacting the halide form of the metallocene with an alkali metal salt of the hydrocarbyl or hydrocarbyloxy radical under conditions as have been used in the past for forming such ligands in prior art metallocenes. See, for example, the aforemention J. Organomet. Chem. 113, 331-339 (1976). Another approach involves reacting a compound of the formula MeQ k wherein at least one Q is hydrocarbyl or hydrocarbyloxy with the alkali metal salt of the bridged fluorenyl compound. One embodiment of the present invention involves carrying out the reaction of the fluorenyl-containing salt and the transition metal compound in the presence of a liquid diluent which is non-halogenated and non-coordinating toward the transition metal compound. Examples of such suitable liquid include hydrocarbons such as toluene, pentane, or hexane as well as non-cyclic ether compounds such as diethylether. It has been found that the use of such non-halogenated non-coordinating solvents generally allows one to obtain large amounts of substantially pure metallocenes and in a more stable form; and also often allows the reaction to be conducted under higher temperature conditions, than when THF is used as the diluent. In an especially preferred embodiment the fluorenyl-containing salt used as a ligand is also prepared in a liquid diluent that is non-halogenated and non-coordinating toward the transition metal. The formation of the alkali metal salt of the bridged fluorenyl compound can be formed using generally any technique known in the art. For example, such can be prepared by reacting an alkali metal alkyl with the cyclopentadienyl type compounds, the bridged compounds having two cyclopentadienyl-type radicals per molecule. The molar ratio of the alkali metal alkyl to the cyclopentadienyl type radicals present can vary, generally however, the ratio would be in the range of 0.5/1 to 1.5/1, still more preferably about 1/1. Typically, the alkali metal of the alkali metal alkyl would be selected from sodium, potassium, and lithium, and the alkyl group would have 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms. Preferably if the fluorenyl salt is formed using tetrahydrofuran (THF) as the liquid solvent, the salt is isolated and substantially all of the THF is removed before the salt is contacted with the transition metal halide. The molar ratio of the bridged fluorenyl compound to the transition metal compound can vary over a wide range depending upon the results desired. Typically, however, the molar ratio of the bridged fluorenyl compound to the transition metal compound is about 1 to 1. The resulting metallocene can be recovered and purified using conventional techniques known in the art such as filtration, extraction, crystallization, and re-crystallization. It is generally desirable to recover the metallocene in a form that is free of any substantial amount of by-product impurities. Accordingly, recrystallization and fractional crystallization to obtain relatively pure metallocens is desirable. Dichloromethane has been found to be particularly useful for such recrystallizations. As a general rule, it has been found that the metallocenes based on unbridged fluorenyl compounds are less stable than the metallocene compounds formed from bridged fluorenyl compounds. Since the stability of the various metallocenes varies, it is generally desirable to use the metallocenes soon after their preparation or at least to store the metallocene under conditions favoring their stability. For example the metallocenes can generally be stored at low temperature, i.e. below 0°C in the absence of oxygen or water. The resulting fluorenyl containing metallocenes can be used in combination with a suitable co-catalyst for the polymerization of ethylene or a mixture of ethylene and up to 12 mole-% of a higher molecular weight olefin. In such processes the metallocene or the co-catalyst can be employed on a solid insoluble particulate support. Examples of suitable co-catalysts include generally any of those organometallic co-catalysts which have in the past been employed in conjunction with transition metal containing olefin polymerization catalysts. Some typical examples include organometallic compounds of metals of Groups IA, IIA, and IIIB of the Periodic Table. Examples of such compounds have included organometallic halide compounds, organometallic hydrides and even metal hydrides. Some specific examples include triethyl aluminum, tri-isobutyl aluminum, diethyl aluminum chloride, diethyl aluminum hydride, and the like. The currently most preferred co-catalyst is an aluminoxane. Such compounds include those compounds having repeating units of the formula where R is an alkyl group generally having 1 to 5 carbon atoms. Aluminoxanes, also sometimes referred to as poly(hydrocarbyl aluminum oxides) are well known in the art and are generally prepared by reacting an organo hydrocarbylaluminum compound with water. Such preparation techniques are disclosed in U.S. 3,242,099 and 4,808,561. The currently preferred co-catalysts are prepared either from trimethylaluminum or triethylaluminum, sometimes referred to as poly(methyl aluminum oxide) and poly(ethyl aluminum oxide), respectively. It is also within the scope of the invention to use an aluminoxane in combination with a trialkylaluminum, such as disclosed in U.S. Patent No. 4,794,096. The fluorenyl-containing metallocenes in combination with the aluminoxane co-catalyst can be used to polymerize ethylene or a mixture of ethylene and up to 12 mole-% of a higher molecular weight olefin. Generally such polymerizations would be carried out in a homogeneous system in which the catalyst and co-catalyst were soluble; however, it is within the scope of the present invention to carry out the polymerizations in the presence of supported forms of the catalyst and/or co-catalyst in a slurry or gas phase polymerization. It is within the scope of the invention to use a mixture of two or more fluorenyl-containing metallocenes or a mixture of an fluorenyl-containing metallocene with one or more other cyclopentadienyl-type metallocenes. The fluorenyl-containing metallocenes when used with aluminoxane are particularly useful for the polymerization of ethylene. The catalysts are also particularly useful for preparing copolymers of ethylene and generally a minor amount, i.e. no more than 12 mole percent, more typically less than 10 mole percent, of a higher molecular weight olefin. Preferably, the higher molecular weight olefin is selected among propylene, butene-1, pentene-1, 3-methylbutene-1, hexene-1, 4-methylpentene-1, 3-ethylbutene-1, heptene-1, octene-1, decene-1, 4,4-dimethyl-1-pentene, 4,4-diethyl-1-hexene, 3,4-dimethyl-1-hexene and mixtures thereof. The polymerizations can be carried out under a wide range of conditions depending upon the particular metallocene employed, and the results desired. Examples of typical conditions under which the metallocenes can be used in the polymerization of olefins include conditions such as disclosed in U.S. Patents 3,242,099; 4,892,851; and 4,530,914. It is considered that generally any of the polymerization procedures used in the prior art with any transition metal based catalyst systems can be employed with the present fluorenyl-containing metallocenes. Generally the molar ratio of the aluminum in the aluminoxane to the transition metal in the metallocene would be in the range of 0.1:1 to 10 5 :1 and more preferably 5:1 to 10 6 :1. As a general rule, the polymerizations would be carried out in the presence of liquid diluents which do not have an adverse affect upon the catalyst system. Examples of such liquid diluents include butane, isobutane, pentane, hexane, heptane, octane, cyclohexane, methylcyclohexane, toluene, xylene, and the like. The polymerization temperature can vary over a wide range, temperatures typically would be in the range of -60°C to 280°C, more preferably in the range of 20°C to 160°C. Typically the pressure would be in the range of from 1 to 500 atmospheres or greater. The polymers produced with the process of this invention have a wide range of uses that will be apparent to those skilled in the art from the physical properties of the respective polymer. Some of the catalysts are useful for preparing syndiotactic polymers. The term syndiotatic polymer as used herein is intended to include those polymers having segments of more than 10 monomeric repeating units in which the alkyl group of each successive monomeric unit is on the opposite side of the plane of the polymer. Generally, the polymer segments having such syndiotactic microstructure are formed of at least 40 monomeric repeating units in which the position of the alkyl group relative to the plane of the polymer alternates from one monomeric unit to the next monomeric unit. A further understanding of the present invention, its various aspects, objects and advantages will be provided by the following examples. Examples Example I Preparation of 1-methyl fluorene Two different reaction schemes have been used to prepare 1-methyl fluorene from fluoranthene. The reaction schemes can be illustrated by the following flow diagram. Both schemes involve the use of 1-carboxylic acid fluorenone as a starting material. To prepare the 1-carboxylic acid fluorenone, i.e. formula 1, 20.2 g (0.1 mol) of fluoranthene was dissolved in 150 ml of acetic acid at 90°C. At that temperature 200 ml of 30% aqueous H 2 O 2 , was then added gradually. Then the reaction mixture was stirred for another 3 hours at that temperature. At the beginning of the reaction, a light yellow precipitate was formed that disappeared after some time. Then the reaction mixture was cooled to 0°C in an ice bath. An orange precipitate was formed and filtered off. The filtrate was poured into cold diluted aqueous HCl. An orange yellow precipitate was formed which was washed twice with H 2 O and then dissolved in an aqueous NH 3 solution in order to remove the unreacted fluoranthene. Then the mixture was filtered. When the filtrate was neutralized with HCl, an orange precipitate was formed. The precipitate, 1-carboxylic acid fluorenone, was filtered off and dried. The amount produced was 13.4 g. Scheme I About 0.76 g (0.02 mmol) of LiAlH 4 was suspended in a mixture of 75 ml of diethylether and 25 ml of tetrahydrofuran (dried over LiAlH 4 ). The mixture was cooled to 0°C in an ice bath. Then 1.35 g (0.01 mmol) of AlCl 3 was added in small portions and the mixture was stirred at room temperature for 15 min. Then 4.2 g (0.02 mmol) of the carboxylic acid fluorenone dissolved in 400 ml of tetrahydrofuran was added via a dropping funnel while the reaction mixture was heated to reflux. Stirring was maintained for an additional 30 min. Then the reaction mixture was cooled to room temperature and the unreacted LiAlH 4 was destroyed with an aqueous solution of HCl. The organic phase was removed in vacuo. The solid, i.e. 1-hydroxymethyl fluorenone (formula 2), was recovered in the amount of 3.2 g. The raw 1-hydroxymethyl fluorenone can be used without further purification. 2 g of palladium on carbon catalyst containing about 10 weight percent Pd was weighed into a flask and 4.2 g (0.02 mmol) of the recovered 1-methanol fluorenone was dissolved in 250 ml tetrahydrofuran and added to the flask. The hydrogenation was conducted at room temperature with a slight overpressure of H 2 until 1350 ml of H 2 was consumed. The reaction mixture was filtered and the solvent of the filtrate was removed in vacuo. The creme colored residue was extracted with pentane, the solution was filtered over silica, and the solvent removed in vacuo. The resulting product, 1-methyl fluorene, was a colorless solid and formed in quantitative yield. Scheme II In the second route, the 1-carboxylic acid fluorenone is reduced using the palladium carbon catalyst in the same manner as described for converting the 1-hydroxymethyl fluorenone to 1-methyl fluorene. A quantitative yield of 1-carboxylic acid fluorene, i.e. formula 3, was obtained. The volume of hydrogen consumed was 960 ml. This product was then reduced to 1-hydroxymethyl fluorene, i.e. formula 4, by using the LiAlH 4 and AlCl 3 as described for the production of the 1-hydroxymethyl fluorenone. The 1-hydroxymethyl fluorene was then reduced using the palladium carbon catalyst and hydrogen to yield 1-methyl fluorene. Example II Preparation of 1-tert-butyl fluorene About 2 g (0.01 mmol) of 1-carboxylic acid fluorene was suspended in 50 ml of toluene. Then 4.6 ml AlMe 3 was added to the solution and the reaction mixture was refluxed for 10 hours. Upon heating, the reaction mixture formed a homogeneous solution. The reaction mixture was cooled to room temperature and then poured into ice cooled diluted aqueous HCl. The organic layer was separated, washed with H 2 O, and dried over Na 2 SO 4 . Then the solvent was removed in vacuo. The colorless residue was extracted with pentane, the solution filtered over silica, and the solvent removed in vacuo. The yield of 1-tert-butyl fluorene, formula 6, was quantitative. Example III Preparation of 2-ethyl fluorene In this reaction, 2-acetyl fluorene, i.e. formula 7, was converted into 2-ethyl fluorene by hydrogenation. The hydrogenation reaction was analogous to the reaction used to convert the compound of formula 6 to the compound of formula 5. The H 2 volume used was 970 ml. After the removal of the solvent in vacuo, a creme colored solid was obtained. It was dissolved in pentane and the solution was filtered over silica. Pentane was removed in vacuo. The yield of 2-ethyl fluorene was quantitative. Example IV Preparation of 2-tert-butyl fluorene In this reaction 2-acetyl fluorene was reacted with trimethyl aluminum. The methylation was analogous to the conversion of compound 3 to compound 6 described in Example II. However, in this case, only a two-fold excess of AlMe 3 was necessary. The 2-tert-butyl fluorene was formed as a white solid in quantitative yield. Example V Preparation of 4-methyl fluorene Two different reaction schemes have been used to prepare 4-methyl fluorene, i.e. formula 15. The schemes can be summarized as follows. Both schemes require 4-carboxylic acid fluorenone, formula 11, as a starting material. This compound was produced from phenanthrene using a procedure similar to that disclosed in J. Org. Chem. 21 , 243 (1956) except that no acetic anhydride was used. Instead, hydrogen peroxide and acetic acid were used to obtain a 67% yield of 2,2'-dicarboxylic acid biphenyl, i.e. formula 10. The biphenyl product of formula 10 was then oxidized using sulfuric acid in the manner taught in J. Am. Chem. Soc. 64 , 2845 (1942) to obtain an 82% yield of 4-carboxylic acid fluorenone, i.e. formula 11. Scheme 1 The compound of formula 11 was reduced using LiAlH 4 and AlCl 3 in the same manner as in Example I. The reaction produced an 80% yield of 4-hydroxymethyl fluorenone, i.e. formula 14, which was then reduced using hydrogen and the palladium carbon catalyst previously described. A quantitative yield of 4-methyl fluorene resulted. Scheme 2 The compound of formula 11 was reduced using hydrogen and the palladium carbon catalyst described previously. The reaction produced a quantitative yield of 4-carboxylic acid fluorene, i.e. formula 12. Reduction of this acid with LiAlH 4 and AlCl 3 resulted in an 80% yield of 4-hydroxymethyl fluorene, i.e. formula 13. This product was then reduced using hydrogen and the palladium carbon catalyst to produce a quantitative yield of 4-methyl fluorene. Example VI Preparation of 4-tert-butyl fluorene 4-carboxylic acid fluorene was reacted with trimethylaluminum generally as described in Example II to produce a 60% yield of 4-tert-butyl fluorene. Example VII Preparation of 2,7-bis(tert-butyl)-4-methyl fluorene 2,7-bis(tert-butyl)-4-methylene chloride fluorene was reduced using hydrogen and the palladium carbon catalyst to obtain a quantitative yield of 2,7-bis(tert-butyl)-4-methyl fluorene. Example VIII Preparation of 1,2-bis(9-fluorenyl)ethane About 8.3 g (0.05 mol) of fluorene was dissolved in 150 ml of tetrahydrofuran. Then 31.8 ml (0.05 m) of butyl lithium (1.6 molar in hexane) was added dropwise to this solution. After one hour, 2.3 ml (0.25 m) of dibromoethane in 25 ml of tetrahydrofuran was added. The solution was stirred for 3 hours. The yellow solution was washed with 50 ml of an aqueous NH 4 Cl solution (5 g NH 4 Cl/50 ml H 2 O), then washed with 50 ml of water and then the organic phase was dried over Na 2 SO 4 . Then the solvent was removed in vacuo. The light yellow residue was washed twice with 25 ml of pentane. The resulting product was white. The yield was 12.5 g, i.e. a yield of about 70%, based on the moles of fluorene reacted. The product was confirmed through 1 H NMR, 13 C NHR, mass spectroscopy, and gas chromatography. Example IX Preparation of 1-bromo-2-(fluorenyl)ethane In this reaction, 8.3 g (0,05 mol) of fluorene was dissolved in 150 ml of tetrahydrofuran. Then 31.8 ml (0.05 m) of butyl lithium (1.6 molar in hexane) was added dropwise to this solution. After one hour, this solution was added gradually to a stirred solution of 9 ml (0.1 m) of dibromoethane in 300 ml of pentane within 2 hours. Then the reaction mixture was treated with 50 ml of an aqueous NH 4 Cl solution, and then washed with 50 ml of water. The organic phase was dried over Na 2 SO 4 . Then the solvent was removed in vacuo. The yellow residue was dissolved in pentane. The pentane solution was filtered over silica. The solution was concentrated to about 20% of the original volume and then the product was crystallized at -30°C. A yield of 10.88 g of 1-bromo-2-(fluorenyl)ethane was obtained. The product was characterized through 1 H NMR, 13 C NMR, and Mass spectroscopy. Example X A number of fluorenyl-containing metallocenes were prepared using either diethyl ether or toluene as a solvent. Metallocenes referred to herein as bridged metallocenes are metallocenes in which a fluorenyl radical ligand and other cyclopentadienyl-type ligands are bound to a metal but not to each other. When diethyl ether was used as a solvent, about 1 millimole of the respective bridged or unbridged fluorenyl compound was dissolved in 200 milliliters of ether. Then 1.6 molar methyllithium in diethyl ether was added to the solution to provide 1 millimole of methyllithium for each millimole of cyclopentadienyl-type radical. (An exception would be in the case in which it was desired to produce a mono-valent salt of a bridged fluorenyl compound. In such a case then only about 0.5 millimole of methyl lithium would be used for each millimole of cyclopentadienyl-type radicals.) The reaction mixture was stirred until no additional methane gas was evolved. This was done at room temperature. Next the transition metal halide was added in small portions to the solution of the fluorenyl salt. The amount of transition metal was about 0.5 millimoles when the fluorenyl compound was a monovalent salt and about 1 millimole when the fluorenyl compound was a divalent salt. The resulting solution was typically stirred for an additional 30 minutes and then concentrated to about 50 milliliters and filtered. The orange to red-colored solids remaining on the filter plate were dissolved in dichloromethane and the resulting solution was concentrated and recrystallized, generally at about -78°C. In the runs prepared using toluene as the solvent, about 1 millimole of the bridged or unbridged fluorenyl compound was mixed in 250 milliliters of toluene. This was combined with methyllithium (1.6 molar in diethyl ether) in an amount sufficient to provide 1 millimole of methyllithium for the unbridged compounds and 2 millimoles of the methyllithium for the bridged fluorenyl compounds. (Again the exception discussed in the previous paragraph also applies.) Then the reaction mixture was heated at reflux until no more methane gas was being released. The solution was then allowed to cool to room temperature. The transition metal halide was then slowly added to the solution. Again, about 0.5 millimoles of transition metal compound was employed with the divalent fluorenyl salts and about 1 millimole was employed with the monovalent fluorenyl salts. The suspension was then stirred for about 30 minutes. The solution was then concentrated to about 50 to 75 milliliters and filtered. The orange to red solids on the filter plate were dissolved in dichloromethane and the resulting solution was concentrated and cooled to -78°C to obtain the metallocene as a solid precipitate. Procedures of those general types have been used to prepare the following metallocenes: (1,2-difluorenyl ethane) zirconium dichloride; (1-fluorenyl-2-indenyl ethane) zirconium dichloride and hafnium dichloride; (1-fluorenyl-1-cyclopentadienyl methane)zirconium dichloride; (1-fluorenyl-1-cyclopentadienyl methane)zirconium trichloride, (1,2-di(2-tert butyl fluorenyl) ethane) zirconium dichloride and hafnium dichloride; (1,2-di(2-methyl fluorenyl)ethane) zirconium dichloride; (1,2-difluorenyl ethane) hafnium dichloride; bis (2,7-tert butyl-4-methyl fluorenyl)zirconium dichloride; (1,3-difluorenyl propane) zirconium dichloride and hafnium dichloride; (1-fluorenyl-2-methyl-2-fluorenyl ethane) zirconium dichloride; dimethyl silyl difluorenyl zirconium dichloride; (1,2-di(1-methyl fluorenyl)ethane) zirconium dichloride; (1,2-di(1-tert butyl fluorenyl)ethane) zirconium dichloride and hafnium dichloride; (1,2-di(2-ethyl fluorenyl)ethane) zirconium dichloride and hafnium dichloride; (1,2-di(4-tert butyl fluorenyl)ethane) zirconium dichloride; (1-fluorenyl-2-cyclopentadienyl ethane) zirconium dichloride; (1-fluorenyl-2-(3-methylcyclopentadienyl) ethane) zirconium dichloride; (1-fluorenyl-3-indenyl propane) zirconium dichloride; (1-fluorenyl-2-methyl-2-cyclopentadienyl ethane) zirconium dichloride; (1-fluorenyl-2-methyl-2-indenyl ethane) zirconium dichloride; (1-fluorenyl-2-methyl-2-(3-methylcyclopentadienyl)ethane) zirconium dichloride; (1-(1-methyl fluorenyl)-2-(4-methyl fluorenyl)ethane) zirconium dichloride; (1-(1-tert butyl fluorenyl)-2-(4-tert butyl fluorenyl) ethane) zirconium dichloride; bis (2,7-di-tert butyl-4-methyl fluorenyl) zirconium dichloride; (1,2-difluorenyl ethane) vanadium dichloride, (1,1-difluorenyl methane) vanadium dichloride, bis(1-methyl fluorenyl) zirconium dichloride; bis (1-methyl fluorenyl) hafnium dichloride; bis(2-ethyl fluorenyl)zirconium dichloride; bis (4-methyl fluorenyl) zirconium dichloride, and bis (4-methyl fluorenyl) hafnium dichloride. Use of Fluorenyl Metallocenes A number of fluorenyl-containing metallocenes were prepared and evaluated for their effectiveness as catalysts for the polymerization of olefins. The specific metallocenes evaluated are referred to in the following tables as follows: Catalyst A (1,2-difluorenyl ethane) zirconium dichloride B (1-fluorenyl-2-indenyl ethane) zirconium dichloride C (1-fluorenyl-1-cyclopentadienyl methane) zirconium dichloride D (1,2-di(2-tert-butyl fluorenyl)ethane) zirconium dichloride E bis (2,7-tert-butyl-4-methyl fluorenyl) zirconium dichloride F (1-fluorenyl-1-cyclopentadienyl methane) zirconium trichloride G bis (1-methyl-4-methyl fluorenyl)zirconium dichloride H (1-fluorenyl-2-methyl-2-indenyl ethane) zirconium dichloride I (1,2-difluorenyl ethane) hafnium dichloride The polymerizations were carried out in an autoclave type reactor using methylaluminoxane as a cocatalyst. The source of the methylaluminoxane varied. In some runs a 30 weight percent toluene solution obtained from Schering was used. In other runs a 10 weight percent toluene solution of the methylaluminoxane obtained from Ethyl Corp was used. In a dry box under substantially inert conditions the solid metallocene was added to a serum vial and then a known quantity of the metallocene solution was added to the vial. The gram atom ratio of the aluminum in the aluminoxane to the metal in the metallocene was about 2200 to 1. Some of the resulting catalyst system solutions were used in more than one polymerization. Accordingly, all the catalyst system solutions were not used immediately after preparation. For optimum results it is considered desirable to use the catalyst system soon after preparation. The catalyst system solution was added to the polymerization reactor which had been suitably prepared for the particular polymerization to be conducted. Typically for the polymerization of propylene the reactor contained liquid propylene as the reaction diluent. For polymerizations of ethylene or 4-methyl-1-pentene liquid isobutane diluent was employed. After the catalyst was charged then monomer and hydrogen, if employed, was added at room temperature. The reaction was then allowed to proceed for a period of time at which the reactor was cooled in an attempt to maintain a selected reaction temperature. In most cases after the polymerization was complete the diluent was flashed off and the polymer solids recovered and characterized. In some cases where the polymer was of low molecular weight or substantially all in solution the liquid would be drained and the unreacted monomer, comonomer, and/or diluent removed by evaporation. Various characteristics of the polymer and the polymerization were characterized. Examples of characteristics determined in various cases include density in grams/ml (ASTM D1505-68); Melt Flow Index (MI) in grams of polymer/10 minutes (ASTM D1238-65T, Condition L); High Load Melt Index in grams of polymer/10 minutes 190°C (ASTM D1238, Condition E); Melt Index in grams of polymer/10 minutes 190°C (ASTM D1238, Condition E); heptane insolubles determined by the weight percent of insoluble polymer remaining after extraction with boiling heptane; melting point in degrees centigrade by Differential Scanning Calorimetry; molecular weights by size exclusion chromatography, i.e. weight average molecular weight referred to herein as Mw and number average molecular weight referred to herein as Mn; heterogenity index determined by dividing Mw by Mn. The (SEC) size exclusion chromatography was conducted using a linear column capable of resolving the wide range of molecular weights generally observed in polyolefins, such as polyethylene. The SEC used a 1,2,4-trichlorobenzene solution of the polymer at 140°C. The intrinsic viscosity was calculated from the SEC using the Mark-Houwink-Sakrada constants, i.e. k•HW a in deciliters/gram, referred to in the following tables as IV. Unless indicated otherwise the conditions employed for characterizing the various properties were the same for each polymer evaluated. In some cases infrared and 13 C NMR spectra were taken of the polymer. The NMR spectra were conducted on a 1,2,4-trichlorobenzene solution of the polymer. The base standard in the NMR spectra was 0 ppm based on tetramethylsilane. Example XI Ethylene Polymerization With (1,2 difluorenylethane) zirconium dichloride A number of polymerization runs were conducted to evaluate the effectiveness of (1,2-difluorenylethane) zirconium dichloride as a catalyst for the polymerization of ethylene both alone and with a comonomer. The various polymerization variables and the results are summarized in the following Table. The value reported for comonomer when used in all the following tables refers to grams of the comonomer. Also yield is in grams. PC 2 and PH 2 are the partial pressures of ethylene and hydrogen in MPa (psi). Time is in minutes. The table demonstrates that the fluorenyl-containing metallocene is capable of producing polymers of ethylene having a wide range of properties. In the absence of hydrogen the polymer was a very high molecular weight material as evidenced by the low HLMI, i.e. High Load Melt Index. The data further demonstrates that copolymerization of ethylene and hexene can result in lower density polymers. Example XII Ethylene Polymerization with Various Bridged Fluorenyl Metallocenes A number of ethylene polymerizations were also conducted using other bridged metallocenes. The various polymerization variables and the results are summarized in the following Table. Runs 4 and 5 from the previous Table are included for comparison. The Table demonstrates that (1-fluorenyl-2-indenyl ethane) zirconium dichloride, i.e Catalyst B, and Catalyst C, i.e (1-fluorenyl-1-cyclopentadienyl methane) zirconium dichloride are also suitable for the polymerization of ethylene. Catalyst C gave a higher molecular weight material as indicated by the HLMI values. Run 14 (Comparative Run) demonstrates that Catalyst C is also capable of producing a copolymer of ethylene and hexene. The particular copolymer produced in this run is particularly unusual in that it contained 12.4 mole percent comonomer and showed a relative comonomer dispersity of 105.9. The mole percent comonomer and relative comonomer dispersity were determined from NMR spectroscopy using the technique disclosed in U.S. 4,522,987, Such a polymer can be referred to as a low density super random copolymer, i.e. a polymer having a super random distribution of the comonomer. Example XIII (Comparative Example) Propylene Polymerization With Various Fluorenyl Metallocenes A number of polymerizations of propylene were conducted using various fluorenyl-containing metallocenes. The reaction variables and the results are summarized in the following Table. Table III demonstrates that Catalyst C, i.e. (1-fluorenyl-1-cyclopentadienyl methane) zirconium dichloride, can be used to produce a polymer from propylene. The data in runs 15-17 shows that the polypropylene is highly crystalline as demonstrated by the heptane insolubles values. It is believed that the polymer contains high levels of syndiotactic molecular structure. Run 20 demonstrates that Catalyst D, i.e. (1,2-di(2-tert butyl fluorenyl)ethane) zirconium dichloride can be used to produce a crystalline polypropylene. Run 21 demonstrates that Catalyst E, i.e. the unbridged metallocene bis(2,7-di-tert-butyl-4-methyl fluorenyl) zirconium dichloride, produced only a small amount of solid polypropylene at 60°C. Run 22 shows that Catalyst E was not particularly effective at all at 0°C. Run 23 and 24 employed a non-sandwich bonded metallocene, i.e. a metallocene in which only one of the cyclopentadienyl-type radicals was bonded to the transition metal. The catalyst produced only about 3 to 5 grams grams of solid polymer along with about 45 to 55 grams of low molecular weight propylene soluble polymer. Unless indicated otherwise by the formula or other means, all the bridged metallocenes referred to herein are sandwich bonded. Run 25 employed an unbridged metallocene, i.e. bis(1-methyl-4-methyl fluorenyl) zirconium dichloride. It yielded 41 grams of a solid polypropylene. It would therefore appear that Catalyst G is somewhat more active than Catalyst E. Run 26 employed the bridged metallocene (1-fluorenyl -2-indenyl ethane) zirconium dichloride. Although this catalyst yielded 460 grams of solid polymer 94.4 weight percent of the polymer was a low molecular weight xylene soluble polymer. Similarly, the bridged metallocene (1-fluorenyl-2-methyl-2-indenyl ethane) zirconium dichloride in Run 27 yielded 82 grams of solid, 88 weight percent of which was low molecular weight xylene soluble material. Runs 28 and 29 employed bridged metallocenes based on 1,2-difluorenyl ethane. Both the zirconium and the hafnium metallocenes yielded solid polypropylene. Example XIV (Comparative Example) Catalyst C, i.e. (1-fluorenyl-1-cyclopentadienyl methane) zirconium dichloride, was evaluated as a catalyst for the polymerization of 4-methyl-1-pentene. The amount of the metallocene employed was 5 mg. The polymerization was conducted in the presence of hydrogen with the differential pressure of the hydrogen being 25. The polymerization temperature was 120°C and the length of the polymerization was 2 hours. The polymerization resulted in the production of 96.7 grams of a solid having a weight average molecular weight of 33,330; a heterogenity index of 1.8; and a calculated intrinsic viscosity of 0.12. About 92 weight percent of the solid was insoluble in boiling heptane. The polymer had a melting point of 197.9°C. A 13 C NMR spectrum was taken of the polymer as recovered, i.e. without heptane solubles removed, and it indicated that the polymer contained a substantial amount of syndiotactic functionality. A copy of the 13 C NMR spectrum is provided in Figure 1. Significant peaks were observed at about 22.8, 24.8, 26, 31.8, 42.8, 43.1, 46.1, and 46.2 ppm. The intensity of the peak at 43.1 ppm is greater than 0.5 of the total peak intensities in the range of 42.0 and 43.5 ppm. The peak at about 46.2 ppm had a greater intensity than any peak between the major peaks at 46.1 and 43.1 ppm. Further, the peak at about 42.8 ppm had a greater intensity than any peak between the major peaks at 46.1 and 43.1 ppm. These peak locations are relative to a peak of zero ppm for tetramethylsilane. Example XV (Comparative Example) Under conditions substantially as used in Example XIII (Comparative Example), a run was carried out attempting to polymerize 4-methyl-1-pentene with Catalyst A, i.e. the bridged catalyst (1,2-difluorenyl ethane) zirconium dichloride. In this case 7 mg of the catalyst was employed and 180 grams of solid atactic wax-like polymer was obtained. A similar run was conducted substituting the unbridged metallocene, bis(2-methylfluorenyl) zirconium dichloride for Catalyst A in the polymerization of 4-methyl-1-pentene. In this run 5 mg of the metallocene was used and 9.7 grams of solid polymer was recovered. Two samples of the polymer were subjected to heptane extraction. The extraction gave heptane insoluble values of 54.8 and 68.8. The catalyst was thus not as active as either the bridged Catalyst mentioned in the preceding paragraph or bridged Catalyst A.

Claims: A process for polymerizing ethylene or a mixture of ethylene and up to 12 mole-% of a higher molecular weight olefin comprising contacting ethylene or a mixture of ethylene and up to 12 mole-% of a higher molecular weight olefin with a catalyst system comprising a metallocene of the general formula (I): R"(FlR n )(CpR m )MeQ k wherein Fl is a fluorenyl radical, Cp is an indenyl, tetrahydroindenyl, or fluorenyl radical, each R is the same or different and is an organo radical having 1 to 20 carbon atoms, R" is a structural bridge linking (FlR n ) and (CpR m ), Me is a metal selected from IVB and VB metals of the Periodic Table, each Q is the same or different and is selected from hydrocarbyl or hydrocarbyloxy radicals having 1 to 20 carbon atoms and halogen, k is a number sufficient to fill out the remaining valences of Me, n is a number in the range of 0 to 7, and m is a number in the range of 0 to 7. The process according to claim 1, wherein (CpR m ) and (FlR n ) are different. The process according to claim 1 or 2, wherein R" is the divalent methylene radical --CH 2 --. The process according to claim 1 or 2, wherein R" has the formula II = wherein each R' is hydrogen or at least one of R' is hydrocarbyl having from 1 to 7 carbon atoms, preferably an aliphatic hydrocarbyl. The process according to claim 4, wherein said R' is an alkyl radical. The process according to claim 5, wherein said alkyl radical is the methyl radical. The process according to claim 4, wherein all R' are H, Me is Zr, Q is Cl, k is 2, n is 0, and CpR m is either an indenyl or a 2-methylindenyl radical. The process according to any of the preceding claims, wherein R" is a hydrocarbyl or a heteroatom-containing alkylene radical having 1 to 6 carbon atoms. The process according to any of the preceding claims, wherein n is a number in the range of 1 to 4 and/or m is a number in the range of 1 to 4. The process according to any of the preceding claims, wherein Me is selected from Ti, Zr, and Hf. The process according to claim 10, wherein Me is Zr. The process according to claim 10, wherein Me is Hf. The process according to any of the preceding claims, wherein (CpR m ) is selected from fluorenyl and indenyl. The process according to any of the preceding claims, wherein (FlR n ) is selected from fluorenyl (n=0), 1-tert-butyl fluorenyl, 2-ethyl fluorenyl, 2-tert-butyl fluorenyl, 4-tert-buryl fluorenyl, 4-methyl fluorenyl, 2,7-di-tert-butyl fluorenyl, and 2,7-di-tert-butyl-4-methyl fluorenyl. The process according to any of the preceding claims, wherein Q is halogen, preferably chlorine. The process according to claim 1, wherein the metallocene is selected from (1,1-difluorenylmethane)zirconium dichloride, (1,2-difluorenyl ethane) zirconium dichloride, (1,3-difluorenylpropane) zirconium dichloride, (1,2-difluorenylethane) hafnium dichloride, (1,3-difluorenylpropane) hafnium dichloride, (1-fluorenyl-2-methyl-2-fluorenylethane)zirconium dichloride, dimethylsilyldifluorenyl zirconium dichloride, (1,2-di(1-methyl fluorenyl)ethane)zirconium dichloride, (1,2-di(1-methyl fluorenyl)ethane) hafnium dichloride, (1,2-di-(2-ethyl fluorenyl)ethane)zirconium dichloride, (1,2-di(2-tert-butyl fluorenyl)ethane)zirconium dichloride, (1,2-di(2-tert-butyl fluorenyl)ethane)hafnium dichloride, (1,2-di(1-tert-butyl fluorenyl) ethane) zirconium dichloride, (1,2-di(4-methyl fluorenyl) ethane) zirconium dichloride, (1,2-di(4-methyl fluorenyl)ethane) hafnium dichloride, (1,2-di(4-tert-butyl fluorenyl)ethane) zirconium dichloride, (1-fluorenyl-2-indenyl ethane)zirconium dichloride, (1-fluorenyl-2-indenyl ethane)hafnium dichloride, (1-fluorenyl-2-methyl-2-indenyl ethane) zirconium dichloride, (1-fluorenyl-2-methyl-2-indenyl ethane) hafnium dichloride, (bis-fluorenylmethane)vanadium dichloride, (1,2-difluorenyl ethane)vanadium dichloride, (1-(1-methyl fluorenyl)-2-(4-methyl fluorenyl)ethane)zirconium dichloride, (1-(2,7-di-tert-butyl fluorenyl)-2-(fluorenyl)ethane)zirconium dichloride, (1,2-di(2,7-di-tert-butyl-4-methyl fluorenyl)ethane) zirconium dichloride, and (1,2-di-(1-methyl-4-methyl fluorenyl)ethane) zirconium dichloride. The process of any of the preceding claims, wherein the fluorenyl-containing metallocene is obtainable by a method comprising the step of reacting an alkali metal salt of at least one fluorenyl-containing compound with a transition metal compound of the formula MeQ r in the presence of a non-halogenated solvent for the fluorenyl salt which solvent is non-coordinating with the transition metal compound, wherein the reaction is carried out in the absence of THF, Me and Q being defined as in claim 1, and r being a number corresponding to the valence of Me. The process according to claim 17, wherein said solvent is selected from toluene and pentane. The process according to claim 17, wherein said solvent is selected from hexane and diethylether. The process according to any of claims 7 to 19, wherein said alkali metal salt of said fluorenyl-containing compound has been formed by reacting an alkali metal alkyl with a fluorenyl-containing compound in the presence of a non-halogenated solvent for the fluorenyl salt which is non-coordinating with the transition metal compound. The process according to any of the preceding claims, wherein the higher molecular weight olefin is selected among propylene, butene-1, pentene-1, 3-methylbutene-1, hexene-1, 4-methylpentene-1,3-ethylbutene-1, heptene-1, octene-1, decene-1, 4,4-dimethyl-1-pentene, 4,4-diethyl-1-hexene, 3,4-dimethyl-1-hexene and mixtures thereof. The process according to any of the preceding claims, wherein an alkyl aluminoxane is used as a co-catalyst.

Inventors: ALT HELMUT G PROF DR, GEERTS ROLF LEONARD, HAWLEY GIL R, HSIEH ERIC TSU-YIN, MCDANIEL MAX PAUL, PALACKAL SYRIAC JOSPEH DR, PATSIDIS KONSTANTINOS, SMITH PAUL DAVID, WELCH MARVIN BRUCE, ALT, HELMUT G., PROF.DR., GEERTS, ROLF LEONARD, HAWLEY, GIL R., HSIEH, ERIC TSU-YIN, MCDANIEL, MAX PAUL, PALACKAL, SYRIAC JOSPEH, DR., PATSIDIS, KONSTANTINOS, SMITH, PAUL DAVID, WELCH, MARVIN BRUCE
Applicants: PHILLIPS PETROLEUM CO, PHILLIPS PETROLEUM COMPANY
Application year: 1992
Main classification: C08F4
IPC codes: C07C13, B01J31, C07C51, C08F10, C08F210, C08F4, C08F110, C07F17