Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Reexamination Certificate
2000-02-23
2001-01-16
Nazario-Gonzalez, Porfirio (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
C556S053000, C502S107000, C502S117000, C526S160000, C526S943000
Reexamination Certificate
active
06175025
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for synthesizing metallocene compounds which can be effectively used as a catalyst for organic synthesis, a polymerization catalyst, a catalyst for hydrogenation of a low-molecular weight compound or high-molecular weight compound, etc.
BACKGROUND ART
Metallocene compounds are useful as catalysts and various metallocene compounds have been known.
Several synthesizing processes are known as processes for preparing a useful metallocene compound. However, in substituting the halogens of metallocene dihalide with a substituent, if the substituent has a high molecular weight, makes the substituted product bulky, or is an aromatic compound, etc., there have been problems that an exchange reaction of the halogen does not proceed sufficiently, resulting in a reduced yield and that a large amount of by-products are produced which makes post-treatment difficult.
For example, a conventionally known process for synthesizing an aryl metallocene compound is to react a metallocene dihalide with an aryl alkali metal compound at room temperature or at the reflux temperature of a solvent employed for the reaction (as described in L. Summers et al., J. Am. Chem. Soc., 77, p.3604, (1955), M. D. Rausch et al., J. Organometall. Chem., 10, p.127 (1967), etc.). However, since the above-described process is accompanied with the side reaction such as reduction of the metal atom of a metallocene, a target product cannot be obtained in a high yield. In order to obtain a high-purity aryl metallocene compound, an additional step for purification such as recrystallization is necessary, which is not economical.
On the other hand, known is a process for synthesizing a diaryl metallocene compound by reacting a metallocene dihalide (e.g., metallocene dichloride) with an aryl alkali metal (e.g., an aryl lithium) in a polar solvent at 0° C. or lower (as described in JP-B-2-34360, JP-B-63-60027 and JP-B-63-60028: the term “JP-B” as used herein means an “examined published Japanese patent publication”). This process requires the use of an expensive and highly dangerous chemical such as an alkali metal or diethyl ether. The alkali metal is very dangerous in handling because it ignites by the water content in the air. In addition, the alkali metal must be used in an amount not less than 2 times the theoretical amount, which necessarily leads to a cost increase. Since the target aryl metallocene compound is an industrially useful catalyst for preparation or hydrogenation of a high-molecular weight compound having a high stereoregularity, there is a strong demand for the development of its preparation process which is safe and inexpensive, which facilitates post-treatment and which permits preparation in a high yield.
In addition, known is a process for preparing a mono-substituted metallocene compound by reacting a metallocene dihalide with an alkyl Grignard reagent (as described, for example, in W. P. Long et al., J. Am. Chem. Soc., 82, p.1953 (1960), H. C. Beachell et al., Inorg. Chem., 4, p.1133 (1965), etc.). A preparation process of a di-substituted metallocene compound is however not described in the above documents.
A process for synthesizing a di-substituted dimethyl metallocene compound by reacting a metallocene dihalide with a methyl Grignard reagent at 25° C. in a solvent of THF is also known (as described in T. S. Piper et al., J. Inorg. Nucl. Chem., 3, p.104 (1956), etc.). The yield brought by this process is, however, 1% and is markedly low. It is reported in WO97/09336 that a di-substituted dimethyl metallocene compound can be obtained in a good yield by reacting a metallocene dihalide with a methyl Grignard reagent at −5° C. for 10 minutes or −5° C. for 1 hour.
A process for preparing a di-substituted metallocene compound having a substituent other than a methyl group by using a Grignard reagent has not yet known and a process for preparing such a di-substituted metallocene compound at a high purity in a high yield sufficient for industrial production is desired.
An object of the present invention is therefore to solve the above-described problems upon synthesis of a metallocene compound and to provide a process for safely and easily synthesizing, at a low cost and in a high yield, a di-substituted metallocene compound substituted with an aryl, benzyl or diaryl phosphinomethylene group.
DISCLOSURE OF THE INVENTION
As a result of various investigations, the present inventors have surprisingly found that the above-described di-substituted metallocene compound can be synthesized in a high yield by reacting a metallocene dihalide with a Grignard reagent under specified reaction conditions. Thus, the present invention was completed.
That is, the present invention relates to the following processes.
(1) A process for synthesizing a di-substituted metallocene compound, which comprises reacting a metallocene dihalide with a compound represented by formula (I): RMgX (wherein R represents an aryl, benzyl or diaryl phosphinomethylene group which may have a substituent, and X represents a halogen element) to produce a di-substituted metallocene compound.
(2) The process for synthesizing a metallocene compound according to the above (1), wherein the reaction is effected under conditions which do not cause a side reaction.
(3) The process for synthesizing a metallocene compound according to the above (1), wherein the compound of formula (I) is added dropwise to a solution containing the metallocene dihalide at a temperature lower than 25° C. but not lower than −30° C. over 3 to 20 hours.
(4) The process for synthesizing a metallocene compound according to the above (3), wherein the compound of formula (I) is added dropwise at a temperature ranging from 15° C. to −25° C. over 5 to 15 hours.
(5) The process for synthesizing a metallocene compound according to any one of the above (1) to (4), wherein the compound of formula (1) in a molar amount of 0.9 to 1.5 times the theoretical amount with respect to the metallocene dihalide is reacted with the solution containing the metallocene dihalide.
(6) The process for synthesizing a metallocene compound according to any one of the above (1) to (4), wherein the solvent of the solution containing the metallocene dihalide is at least one of a linear ether and a cyclic hydrocarbon.
(7) The process for synthesizing a metallocene compound according to the above (1) to (4), wherein the metal atom of the metallocene dihalide is Ti, Zr or Hf.
In the present invention, a metallocene dihalide is reacted with a Grignard reagent under specified conditions, which makes it possible to substitute the halogens of the metallocene dihalide with substituents such an aryl, benzyl or diaryl phosphinomethylene group without using an alkali metal compound which is a cause for the drawback of the conventional process and to prepare a highly-pure di-substituted metallocene compound in a high yield without an economical burden due to a large amount of a loss caused by cumbersome operations such as recrystallization or by purification.
Moreover, in the present invention, better results can be obtained by specifying the reaction solvent.
Furthermore, it is preferred that the metal of the metallocene halide is a specific metal as defined above, because the resulting di-substituted metallocene compound has higher usefulness
BEST MODES FOR CARRYING OUT THE INVENTION
In the present invention, the metallocene compound can be obtained by reacting a metallocene dihalide with a compound represented by formula (I) (hereinafter sometime referred to as “Grignard reagent”) under the conditions not causing a side reaction. The term “metallocene dihalide” as used herein means a compound in which two molecules of a cyclopentadiene ring or of a substituted cyclopentadiene ring and two halogen atoms are coordinated per center metal. The term “di-substituted metallocene compound” as used herein means a metallocene compound in which each of the two halogen atoms of a metallocene dihalide have been substituted with R of formula (I). In the
Kitagawa Yuichi
Kubo Tomoya
Otaka Koji
Takeichi Eiji
Asahi Kasei Kogyo Kabushiki Kaisha
Nazario-Gonzalez Porfirio
Pennie & Edmonds LLP
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