Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
  • C07F17/00—Metallocenes

Definitions

• This invention relates to the purification of metallocenes, particularly metallocene halides such as dicyclopentadienyl Group 4 metal dihalides. More particularly, this invention relates to separation of such metallocenes from tarry oligomeric materials with which they are often associated during their synthesis.
• Metallocenes such as bridged and unbridged dicyclopentadienyl Group 4 metal dihalides are useful as components of olefin polymerization catalyst systems. As such, their purity is of considerable importance. Unfortunately, large scale processes for producing such metallocenes often coproduce significant amounts of hydrocarbonaceous tarry materials.
• tars result in part from oligomerization of exo-isomers of the metallocene ligand such as alkenyl-substituted cyclopentene hydrocarbons in the presence of Group 4 metal halides used in the synthesis process.
• metallocene ligand such as alkenyl-substituted cyclopentene hydrocarbons
• Group 4 metal halides used in the synthesis process.
• ligands such as 3-but-l-enylcyclopentene (an exo- isomer) and n-butylcyclopentadiene (an endo-isomer) can be formed in situ.
• the exo-isomer can be oligomerized to form an oligomer (dimers and trimers) of which the hydrocarbonaceous tarry material is comprised.
• the organic impurities that are readily removed by the process of U.S. Pat. No. 5,648,308 tend to be black-brown colored materials, and result primarily from overheating or hot-spot charring of the reaction mixture during synthesis of the metallocene.
• the quantity of such materials typically falls in the range of 1 to 10,000 parts by weight per million parts by weight of the metallocene product.
• the oligomers formed from exo-isomers of the metallocene ligand differ from the organic materials removed by process of U.S. Pat. No.
• the oligomers are formed differently (i.e., by Friedel-Crafts catalysis of the exo-isomers due to the presence of inadvertent excess of the Group 4 metal halide used in the synthesis of the metallocene); b) the oligomers are indifferent to and thus not absorbed by absorbent materials such as dried, porous silicas having low water and -OH group contents; c) in severe cases the oligomers can be formed in quantities in the range 20 to 60 wt% of the total metallocene product; and d) when the oligomers are formed, they can be, and often are, accompanied by formation of conventional small amounts of the organic materials that can be removed by the use of absorbent materials such as silica.
• the oligomers When isolated in the fluid state the oligomers not only can be in admixture with organic materials resulting primarily from overheating or hot-spot charring of the reaction mixture, but in addition the endo-isomer of the ligand as well as some exo-isomer of the ligand that has not been oligomerized.
• This invention is deemed to fulfill this need remarkably well.
• a two-stage extraction process is provided which is highly effective and economical, and moreover, facile in execution. Indeed, the two stages of the process can be carried out in the same extraction vessel. In addition, the process is capable of providing a product which satisfies purity specifications for polymerization catalyst applications.
• the process enables efficient separation of an unbridged or bridged dihalo Group 4 metallocene wherein the pair of hydrocarbyl groups containing the cyclopentadienyl moiety each contains, individually and independently, in the range of 5 to 18 carbon atoms, from a mixture comprising such metallocene and hydrocarbonaceous tarry material.
• R 1 and R 2 can be the same or different and are cyclopentadienyl, indenyl, fluorenyl, hydrocarbyl-substituted cyclopentadienyl, hydrocarbyl-substituted indenyl, or hydrocarbyl-substituted fluorenyl groups; (ii) each of R 1 and R 2 contains, individually and independently, in the range of 5 to 18 carbon atoms; (iii) at least one of R 1 and R is a hydrocarbyl-substituted cyclopentadienyl, hydrocarbyl-substituted indenyl, or hydrocarbyl- substituted fluorenyl group in which the substitution includes at least one primary alkyl substituent having at least 2 carbon atom
• hydrocarbonaceous tarry material means the oligomeric materials referred to above, whether or not such oligomeric materials are accompanied by organic materials resulting primarily from overheating or hot- spot charring of the reaction mixture, and/or the endo-isomer of the ligand and/or exo-isomer of the ligand that has not been oligomerized.
• hydrocarbonaceous tarry material is composed (comprises) at least oligomerized exo-isomer of the ligand, and can, and usually does further include organic materials resulting primarily from overheating or hot-spot charring of a small portion of the reaction mixture, which materials are typically dark-colored organic color bodies.
• organic materials resulting primarily from overheating or hot-spot charring of a small portion of the reaction mixture, which materials are typically dark-colored organic color bodies.
• Other materials that may or may not be present in hydrocarbonaceous tarry material include the endo-isomer of the ligand and/or a portion of the exo-isomer of the ligand that has not been oligomerized.
• the mixtures with which this invention is concerned comprise a metallocene of the above formula, hydrocarbonaceous tarry material, and optionally, but typically, a least a portion of the aromatic hydrocarbon solvent or diluent in which the metallocene was produced.
• the hydrocarbonaceous tarry material is not removed from the mixture by absorption with an absorbent material such as dry silica.
• the efficient separation made possible by this invention is accomplished by: a) mixing polar organic solvent and non-polar organic solvent with the foregoing mixture, these solvents being substantially incompatible with each other, so that after the mixing there are formed at least two separate phases comprising (i) a substantially polar phase comprising the unbridged or bridged metallocene and polar organic solvent, and (ii) a substantially non-polar phase comprising non-polar organic solvent, hydrocarbonaceous tarry material and some of the metallocene; b) separating the polar phase and the non-polar phase; and c) extracting the non-polar phase with fresh polar organic solvent to form another substantially polar phase comprising the metallocene and polar organic solvent.
• the metallocene can readily be recovered from the polar phases, for example by distilling off the polar solvent.
• the polar organic solvent and the non-polar organic solvent have boiling temperatures low enough to be distillable from the metallocene.
• any residual non-polar solvent associated with the polar solvent after the phase separation is removed during the distillation.
• the distillation is itself is typically performed at reduced pressures and is conducted at temperatures below the sublimation temperature and/or thermal decomposition temperature of the metallocene.
• the initial mixture of metallocene and hydrocarbonaceous tarry material is subjected to a pretreatment before the above two-stage extraction process.
• the mixture is treated with a dilute aqueous acid such as 10 to about 13 wt% aqueous hydrochloric acid, hydrobromic acid, or the like, and the mixture is stirred or otherwise agitated for about 0.5 to about 5 hours at one or more temperatures in the range of -10 to 25 °C, and preferably in the range of -10 to 10°C. Then the aqueous and organic phases are separated, for example by phase-cutting.
• a dilute aqueous acid such as 10 to about 13 wt% aqueous hydrochloric acid, hydrobromic acid, or the like
• the solvent or diluent of the initial mixture is predominately an aromatic solvent or diluent, it is possible, though not recommended, to replace the solvent with a predominately paraffinic solvent or diluent before conducting the treatment with dilute acid, to enhance precipitation of inorganic salt impurities such as zinc halide and iron halide
• the organic phase is then treated with an aqueous brine solution (preferably a saturated solution) and stirred or otherwise agitated for about 0.5 to about 5 hours at one or more temperatures in the range of 0 to 30 °C and preferably in the range of 10 to 25 °C.
• the phases are then separated, e.g., by phase-cutting.
• the organic phase is subjected to distillation at reduced pressure (up to 70-100°C and 1-100 mm of mercury pressure) to remove volatile organics and, azeotropically, the water.
• the resultant organic phase remaining after the distillation is then subjected to the two-stage extraction process of this invention referred to above.
• the pretreatment procedure removes inorganic impurities and certain soluble organic impurities from the initial mixture.
• the pretreatment serves to improve the color of the end product metallocene as recovered from the ensuing two-stage extraction process. It is preferred to conduct the above pretreatment procedure in an aromatic hydrocarbon solvent or diluent as this simplifies the operation and enables removal of the water as an azeotrope in the reduced pressure distillation.
• Another preferred embodiment in this invention involves use of a post-treatment procedure for further improving the color characteristics of the purified metallocene end product.
• the organic phase from the substantially polar phase comprising the metallocene and polar organic solvent formed in step c) above is replaced by a paraffinic solvent or diluent and the resultant mixture is passed through a column containing silica gel or other suitable absorbent material.
• Use of the pretreatment and post-treatment procedures constitutes a particularly preferred embodiment of this invention.
• the unbridged metallocenes have the formula R 1 R 2 MX 2 where (i) R 1 and R 2 can be the same or different and are cyclopentadienyl, indenyl, fluorenyl, hydrocarbyl-substituted cyclopentadienyl, hydrocarbyl-substituted indenyl, or hydrocarbyl-substituted fluorenyl groups; (ii) each of R 1 and R 2 contains, individually and independently, in the range of 5 to 18 carbon atoms; (iii) at least one of R 1 and R 2 is a hydrocarbyl-substituted cyclopentadienyl, hydrocarbyl-substituted indenyl, or hydrocarbyl-substituted fluorenyl group in which the hydrocarbyl substituent(s) can be, for example, alkyl, alkenyl, cycloalkyl, aryl and aralkyl, and in
• QR 1 R 2 MX 2 where M and X are as just described, and R 1 and R 2 are as described above except that they are linked or bridged together by means of a divalent linking group, Q, having a univalent bond attached directly to each of the cyclopentadienyl rings that constitute, or that form part of, R 1 and R 2 .
• Q include silylene (R 2 Si ⁇ ), phenylene (C 6 H 4 ⁇ ) or substituted phenylene, methylene (CH 2 ⁇ ) or substituted methylene, and ethylene (-CH 2 CH 2 -) or substituted ethylene bridges.
• the metallocene whether bridged or unbridged may contain 60 or more carbon atoms in the molecule, but typically will contain from 10 to about 40 carbon atoms in the molecule.
• the process of this invention is preferably applied to the unbridged metallocenes.
• metallocenes to which this invention is applicable include such compounds as: bis(n-butylcyclopentadienyl)zirconium dichloride; bis(diethylcyclopentadienyl)zirconium dichloride; bis(n-butylmethylcyclopentadienyl)zirconium dichloride; bis(n-propylcyclopentadienyl)zirconium dichloride; bis(methylethylcyclopentadienyl)zirconium dichloride;
• the origin of the initial mixture of metallocene and hydrocarbonaceous tarry material is of little importance, as the separation/purification procedure of this invention is deemed applicable to any mixture containing these two materials in a liquid organic medium.
• the initial mixture is a reaction product from a synthesis procedure for the formation of the dihalo Group IV metallocene. See for example, U.S. Pat. No.
• the hydrocarbonaceous tarry material is or comprises oligomeric or relatively low molecular polymeric material resulting from oligomerization/polymerization of exo-isomers of the metallocene ligand, such as bridged or unbridged cyclopentadiene hydrocarbons having a primary alkyl (or alkenyl) substituent of at least 2 carbon atoms in the presence of Group 4 metal halides used in the synthesis process.
• a tarry material containing silicon by virtue of use of a silyl- bridged metallocene ligand is included within the term "hydrocarbonaceous tarry material" as the material possesses the characteristics and exhibits in the practice of this invention the behavior of analogous completely hydrocarbonaceous tarry materials.
• Polar solvents for use in the process include suitable alcohols, nitriles, amides, and similar polar solvents which preferably are distillable liquids at temperatures of up to 100°C at pressures as low as 1 mm Hg.
• solvents examples include acetonitrile, propionitrile, n-butyronitrile, isobutyronitrile, methanol, N,N-dimethylformamide, and N,N-dimethyl- acetamide. Mixtures of different polar solvents can be used. Acetonitrile is a particularly preferred polar solvent.
• the non-polar solvent is typically an inert liquid hydrocarbon solvent which can be paraffinic or cycloparaffinic.
• Preferred are paraffinic hydrocarbons, especially those which can be distilled at temperatures of up to 100° C at pressures as low as 1 mm Hg.
• Examples include n-hexane, 2-methylpentane, 3-methylpentane, n-heptane, 2,2-dimethylpentane, 2,3-dimethyl- pentane, 2,4-dimethylpentane, 3,3-dimethylpentane, 3-ethylpentane, 2-methyl-hexane, 3-me- thylhexane, n-octane, 2-methylheptane, 4-methylheptane, 2,3-dimethyl-hexane, 2,4-dimethyl- hexane, 2,5-dimethylhexane, 3,4-dimethylhexane, 3-ethylhexane, 2,2,4-trimethylpentane, 3- ethyl-2-methylpentane, n-nonane, 2,6-dimethylheptane, n-decane, cyclohexane, methylcy- clopent
• mixtures of the same types of hydrocarbons e.g., mixed paraffinic hydrocarbons such as Isopar-C and Isopar-E
• mixtures of different types of these hydrocarbons i.e., a mixture of paraffins and cycloparaffins
• Preferred non-polar solvents are those which can be distilled at temperatures below 100°C and at a pressure as low as 1 mm Hg, such as Isopar-ETM.
• polar and non-polar solvents used in the process are selected so as to be substantially insoluble in each other.
• this is meant that at O°C to 50°C neither the polar solvent nor the non-polar solvent of the mixed solvents selected should be capable of dissolving more than about 15 weight percent of the other.
• the more incompatible the polar and non-polar solvents the better.
• a portion of a dark blue-green reaction product mixture (300 kg) containing bis(l- butyl-3-methylcyclopentadienyl)zirconium dichloride, toluene, some inorganic metal chloride salts, and approximately 150 kg of a hydrocarbonaceous tarry or oligomeric material is subjected to purification pursuant to this invention as follows: At 5-10°C with stirring, 100 grams of 11 wt% aqueous HCl is slowly added over a period of 30 minutes to 100 grams of the above dark green solution having a content of about 29 wt% of bis(l-butyl-3-methyl- cyclopentadienyl)zirconium dichloride, and about 15 wt% of tarry oligomeric material. The resulting mixture is stirred at 22 °C for one hour and allowed to stand at 22 °C for two hours.
• the organic and aqueous phases are then separated to remove 101 grams of aqueous phase.
• the two acetonitrile fractions are then combined, and the acetonitrile and some residual paraffinic solvent are removed therefrom by subjecting the combined fractions to distillation under reduced pressure (1-100 mm Hg, e.g., at least 28 inches of mercury) of vacuum up to a temperature of 70°C).
• reduced pressure (1-100 mm Hg, e.g., at least 28 inches of mercury) of vacuum up to a temperature of 70°C).
• yields of 27.5 to 29.1 grams of purified light-tan, solid bis(l-butyl-3-methylcyclopentadienyl)zirconium dichloride were recovered.
• the products were found by proton NMR to be 96-98% pure.
• the melting points of the products were 45 to 48°C.
• the yield of recovered product was in the range of 93-96%.
• Example 1 The procedure of Example 1 is repeated except that the combined acetonitrile fractions are mixed with another 50 grams of the paraffinic solvent to remove additional small quantities of tarry material and further improve product quality. To achieve a better phase separation between lower acetonitrile phase and the upper paraffinic phase, the mixture is allowed to stand for a period of 2-5 hours before decanting off the upper paraffinic layer. The acetonitrile fraction is then subjected to a final distillation as in Example 1.
• Examples 1 and 2 are repeated with the exception that the paraffinic solvent used in each case is hexane instead of the Isopar-ETM paraffinic solvent.
• a portion (1.25 grams) of a crude reaction product mixture from which toluene has been stripped off at reduced pressure at 50-70°C containing about 0.93-0.95 gram of bis(l- butyl-3-methylcyclopentadienyl)zirconium dichloride and about 0.30-0.32 gram of a hydrocarbonaceous tarry or oligomeric material is subjected to purification pursuant to this invention as follows: To this portion of the crude reaction product are added 4.40 grams of acetonitrile, and then 1.44 grams of Isopar-E with stirring. After standing for about 10 minutes at 22 °C, an upper Isopar-E layer and a lower acetonitrile layer form.
• the phases are separated to give about 2 grams of acetonitrile solution and about 1.59 grams of Isopar-E solution.
• the dark-brown Isopar-E/tar solution is again extracted with 2.0 grams of fresh acetonitrile at 22°C.
• the upper Isopar- ETM layer and the lower acetonitrile layer are phase-cut to give about 5.5 grams of acetonitrile solution and about 1.59 grams of Isopar-E solution.
• the combined orange acetonitrile solutions (7.5 grams) are washed with 0.5 gram of fresh Isopar- ETM at 22°C.
• Example 5 The procedure of Example 5 above is repeated except that the steps wherein the combined orange acetonitrile solutions (7.5 grams) are washed with 0.5 gram of fresh Isopar-
• the dark brown sample contained 27.1 wt% of bis(l-butyl-3-methylcyclo- pentadienyl)zirconium dichloride, 1.9 wt% gram of oligomeric material, in the range of 30 to 3000 ppm (wt/wt) of organic color body impurities, toluene solvent, and some inorganic metal chloride salts.
• the toluene was removed from a 10-gram sample of this reaction mixture by reduced pressure distillation, leaving 2.90 grams of solids containing 2.71 grams of bis(l-butyl- 3-methylcyclopentadienyl)zirconium dichloride, 0.19 gram of oligomeric material, in the range of 10 to 1000 ppm (wt/wt) of organic color body impurities, and some inorganic metal chloride salts.
• the sample thus contained 7 wt% of oligomeric material.
• the sample was dissolved in 17.30 grams of dry pentane.
• the resultant dark brown solution which contained some insoluble solids, was passed through a column packed with 0.30 gram of dried Grace 948 silica.
• the silica absorbed the dark brown organic color bodies from the solution. After rinsing the silica bed with 3.00 grams of dry pentane and combining the rinse liquid with the silica-treated solution, the silica bed remained dark brown in color, and the combined liquids were yellow-orange in color. The pentane was evaporated from the combined solution to yield 2.82 grams of solids. Proton NMR analysis indicated that these solids contained more than

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• 1999
  • 1999-03-11 WO PCT/US1999/005539 patent/WO1999052919A1/en not_active Application Discontinuation
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