Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Reexamination Certificate
2000-05-22
2001-02-06
Nazario-Gonzalez, Porfirio (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
C556S012000, C556S028000, C556S053000, C502S103000, C502S117000, C526S160000, C526S943000
Reexamination Certificate
active
06184402
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for the preparation of metallocene complexes containing cyclopentadienyl rings as a ligand which are utilizable for the polymerization of olefins or the like.
BACKGROUND ART
It is known that in the polymerization of olefins, especially propylene, any of the a tactic polypropylene, isotactic polypropylene and syndiotactic polypropylene can be produced by choosing a ligand of a metallocene complex among uniform catalysts (a metallocene complex/aluminoxane) for polymerization of olefins (Makromol. Chem. Rapid. Commun. 1983, 4, 417-421; Angew. Chem., Int. Engl. 1985, 24, 507-508; J. Am. Chem. Soc. 1988, 110, 6255-6256; etc.)
Depending on the positions of substituents at the time of synthesis, metallocene complexes may permit the existence of stereoisomers. In the event a mixture of complex isomers formed on synthesis is straightforwardly used for polymerization of olefins where different olefin polymers are produced according to the different nature of the isomers, the resultant polymer will become a mixture of two different polymers. In case a uniform polymer is to be produced, therefore, the mixture of polymers has to be separated. Especially, a C
2
symmetrical crosslinking type metallocene complex tends to form a racemic form and a meso form of isomers in a ratio of 1:1 on its synthesis. On polymerization of propylene, the use of the racemic form permits the production of isotactic polypropylene while the use of the meso form permits the production of atactic polypropylene. Hence, the meso form has to be eliminated in case of producing isotactic polypropylene alone. Separation of the recemic form and the meso form is usually carried out by extraction with a solvent and recrystallization. For obtaining a highly pure racemic form, however, repeating of the separation operations was necessary so that efficiency of the production was extremely low.
In Japanese Laid-open Patent Appln. No.Hei. 10-67793, there is disclosed that a method of changing the racemic/meso ratio wherein unnecessary isomer is decomposed with a decomposing agent such as acidic hydrogen atom or a reactive halogen atom. This method pertains to changing of the racemic/meso ratio by decomposing either one of the isomers, and more precisely, the racemic form is decomposed with ethylene-bis(4,7-dimethylindenyl)zirconium dichloride to obtain the pure meso form.
A number of references are known concerning the reaction for converting a metallocene complex into a &mgr;-oxo-complex, for example, Inorganic Chemistry 15, No. 9, 1976 disclosing that dimethylhafnocene is brought into contact with water in the air to form &mgr;-oxo-bis(methylhafnocene) and Comprehensive Organometallic Chemistry 3, 1982, 572-576 disclosing that a metaflocene dihalide is converted into a &mgr;-oxo-complex in the presence of water and a base.
PROBLEMS TO BE SOLVED BY THE INVENTION
It is an object of the present invention to provide a process for preparing metallocene complexes wherein stereoisomers of metallocene complexes formed on synthesis can easily be resolved into their isomers.
DISCLOSURE OF THE INVENTION
As a result of extensive research made to achieve the aforesaid object, it has now been found by the inventors that a reaction for replacing a substituent on the central metal of a metallocene complex by M—O bond differs in reactivity according to the isomer, and a part or all of a specific isomer can be converted into a complex having M—O bond and that the complex having M—O bond is significantly different in solubility from the original metallocene complex so that the complex having M—O bond can easily be separated according to an ordinary separation method, e.g. extraction or recrystallization while purity of unreacted isomer can efficiently be increased. The present invention has been accomplished on the basis of the above finding.
Especially for an isomeric mixture of the racemic form and the meso form of a bridged metllocene complex, a reaction for forming a &mgr;-oxo-complex is carried out whereby the meso form is preferentially converted into the &mgr;-oxo-complex. Thus, the purity of the racemic form can easily be increased by separating the &mgr;-oxo-complex thereform. If the total amount of the meso form is converted into the &mgr;-oxo-complex, the racemic form will be obtained in a higher purity.
In accordance with the present invention, there is provided a process for the preparation of metallocene complexes which comprises converting a part of an isomeric mixture of a metallocene complex represented by the formula (1):
wherein M stands for a transition metal belonging Group III, IV, V, VI Lantanoid or Actinoid of the Periodic Table, n stands for an integer of 1 or 2, Y stands for carbon, silicon, germanium or tin, X's may be the same or different and each independently stands for a halogen atom, a halogenoid atomic group, a hydrocarbon group having 1-20 carbon atoms which may contain a silicon, germanium, oxygen, sulfur, or nitrogen, or a monocyclic or polycyclic heteroaromatic group which may contain a hetero atom or atoms selected from the group consisting of oxygen atoms, sulfur atoms and nitrogen atoms in the 5-membered or 6-membered ring or rings thereof and which may be substituted on the ring or rings thereof by other substituents, R1, R2, R3, R4, R5, R6, R7, R8, R9 and R10 may be the same or different and each stands for hydrogen, an alkyl group having 1-20 carbon atoms, a cycloalkyl group having 3-20 carbon atoms, an alkenyl group with 2-20 carbon atoms, an aryl group having 6-20 carbon atoms, an alkylaryl group having 7-20 carbon atoms, or an aralkyl group having 7-20 carbon atoms with the proviso that these groups may contain a silicon, germanium, oxygen, sulfur, or nitrogen, or a monocyclic or polycyclic heteroaromatic group which may contain a hetero atom or atoms selected from the group consisting of oxygen atoms, sulfur atoms and nitrogen atoms in the 5-membered or 6-membered ring or rings thereof and which may be substiututed on the ring or rings by other substituents with the proviso that the adjacent substituents on the cyclopentadienyl groups may form together a cyclic structure having 5-8 carbon atoms and the cyclic structure may be an aromatic ring, and that R9 and R10 may form together with Y a cyclic structure having 4-8 atoms and which may contain oxygen, sulfur and nitrogen, into a complex containing M—O bond, and then separating it.
According to the present invention, there is also provided a process for the preparation of metallocene complexes which comprises converting a part of an isomeric mixture of a metallocene complex represented by the formula (2):
wherein M stands for titanium, zirconium or hafnium, n stands for an integer of 1 or 2, Y stands for carbon, silicon or germanium, X's may be the same or different and each independently stands for a halogen atom, a halogenoid atomic group, a hydrocarbon group having 1-20 carbon atoms which may contain a silicon, germanium, oxygen, sulfur, or nitrogen, R2 and R7 may be the same or different and each stands for an alkyl group having 1-20 carbon atoms, a cycloalkyl group having 3-20 carbon atoms, an alkenyl group having 2-20 carbon atoms, an aryl group having 6-20 carbon atoms, an alkylaryl group having 7-20 carbon atoms, or an aralkyl group having 7-20 carbon atoms which may include silicon, germanium, oxygen, sulfur and nitrogen, R1, R4, R5, and R8 may be the same or different and each stands for hydrogen, an alkyl group having 1-20 carbon atoms, a cycloalkyl group having 3-20 carbon atoms, an alkenyl group having 2-20 carbon atoms, an aryl group having 6-20 carbon atoms, an alkylaryl group having 7-20 carbon atoms, an aralkyl group having 7-20 carbon atoms which may include silicon, germanium, oxygen, sulfur, and nitrogen, or a monocyclic or polycyclic heteroaromatic group which may contain a hetero atom or atoms selected from the group consisting of oxygen atoms, sulfur atoms and nitrogen atoms in the 5-membered or 6-membered ring or rings thereof and which may be substitut
Harada Masato
Koyama Mina
Mitani Seiki
Nakano Masato
Saito Jun
Chisso Corporation
Leydig , Voit & Mayer, Ltd.
Nazario-Gonzalez Porfirio
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