Organic compounds -- part of the class 532-570 series – Organic compounds – Boron containing
Reexamination Certificate
1997-10-21
2004-01-27
Vollano, Jean F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Boron containing
Reexamination Certificate
active
06683218
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for preparing a (fluoroaryl)borane compound, such as tris(fluoroaryl)borane and bis(fluoroaryl)boryl halide, serving, for example, as a useful cocatalyst for a metallocene catalyst (polymerization catalyst) used in a cation complex polymerization reaction, and to a process for preparing a tetrakis(fluoroaryl)borate derivative.
BACKGROUND OF THE INVENTION
A (fluoroaryl)borane compound, particularly, tris(pentafluorophenyl)borane, is a useful compound as a cocatalyst for promoting the activity of a metallocene catalyst (polymerization catalyst) used in a cation complex polymerization reaction, and recently, the metallocene catalyst has been receiving considerable attention as an olefin polymerization catalyst.
An example process of obtaining the above-mentioned tris(pentafluorophenyl)borane is disclosed in Proc. Chem. Soc., 1963 (July), 212. More specifically, pentafluorophenyl lithium produced by reacting bromopentafluorobenzene and n-butyl lithium (n-BuLi) is reacted with boron trichloride, and as a consequence, tris(pentafluorophenyl)borane is obtained. However, in this process, the reaction system must be cooled to −78° C. which makes this process almost inapplicable to industrial use.
To solve the above problem, a process using the Grignard reaction is disclosed in Z. Naturforsch., 20b, 5 (1965) as another example process of obtaining tris(pentafluorophenyl)borane. According to this process, for example, pentafluorophenyl magnesium bromide and boron trifluoride diethyl etherate are reacted with each other in a chain ether solvent. Thus, it is not necessary to cool the reaction system to −78° C., which makes this process advantageous over the above-mentioned reaction.
Further, Japanese Laid-open Patent Application No. 199871/1994 (Tokukaihei 6-199871) discloses a process of obtaining triarylborane by reacting a aryl magnesium halide derivative and boron halide in a chain ether solvent or a mixed solvent of the chain ether solvent and an aromatic hydrocarbon solvent. The above publication also discloses a process of separating and removing magnesium halide produced as a by-product from the target product, namely triarylborane.
A tetrakis(fluoroaryl)borate derivative is also a useful compound as the above cocatalyst. For example, Japanese Laid-open Patent Application No. 247980/1994 (Tokukaihei 6-247980) discloses a process of producing tetrakis(pentafluorophenyl)borate derivative as one kind of the tetrakis(fluoroaryl)borate derivative. More specifically, a process of reacting a pentafluorophenyl magnesium derivative and boron halide, such as boron trifluoride, or a boron compound, such as tris(pentafluorophenyl)borane is disclosed. When boron halide is used in the above process, magnesium halide is produced as a by-product together with the target product, namely, the tetrakis(pentafluorophenyl)borate derivative.
However, since the above conventional processes use the chain ether solvent having a relatively low boiling point, such as diethyl ether, the reaction system must be cooled. Thus, to produce the (fluoroaryl)borane compound for industrial use, a cooling apparatus or the like is indispensable. Moreover, diethyl ether is highly inflammable. In addition, in the above conventional processes, it is so difficult to control the reaction that a by-product, such as a quaternary compound of boron like a tetrakis(fluoroaryl)borate derivative, is produced. This makes it difficult to selectively obtain the (fluoroaryl)borane compound, such as tris(fluoroaryl)borane and bis(fluoroaryl)boryl halide. Furthermore, the chain ether solvent is generally expensive compared with a cyclic ether solvent.
Thus, the above conventional processes have a problem that they are not readily applied for industrial use, in other words, not only are the solvents hard to handle, but also the (fluoroaryl)borane compound, such as tris(fluoroaryl)borane and bis(fluoroaryl)boryl halide, from which magnesium halide produced as a by-product is separated and removed, can not be produced selectively in a simple manner at a low cost. Using a cyclic ether solvent in the above conventional processes triggers an unwanted side-reaction, such as a ring-opening polymerization of the cyclic ether solvent. In addition, using an aromatic hydrocarbon solvent alone in the above conventional processes reduces the yield of the (fluoroaryl)borane compound, such as tris(fluoroaryl)borane and bis(fluoroaryl)boryl halide.
On the other hand, when magnesium halide remains in the (fluoroaryl)borane compound or tetrakis(fluoroaryl)borate derivative used as the cocatalyst for the metallocene catalyst, the metallocene catalyst loses its activity considerably. Thus, when the above compound or derivative is used as the above cocatalyst, magnesium halide produced as a by-product must be separated and removed.
However, since the tetrakis(pentafluorophenyl)borate derivative and magnesium halide have almost the same solubility into solvents, they can not be isolated easily. In other words, in the above conventional process of producing the tetrakis(fluoroaryl)borate derivative, the by-product, namely magnesium halide, can not be separated and removed easily from the target product, namely the tetrakis(fluoroaryl)borate derivative. Thus, the above conventional process of producing the tetrakis(fluoroaryl)borate derivative has a problem that it can not produce the tetrakis(fluoroaryl)borate derivative from which the by-product, namely, magnesium halide, is separated and removed.
A process for preparing a fluoroaryl magnesium derivative which is an intermediate in the process of preparing the tetrakis(fluoroallyl)borate derivative is disclosed, for example, in J. Org. Chem., 29, 2385 (1964). More specifically, an alkyl magnesium derivative, such as ethyl magnesium bromide (EtMgBr), is dropped to a solution prepared by dissolving pentafluorobenzene into an ether solvent, such as tetrahydrofuran (THF), to trigger an EtMgBr-pentafluorobenzene reaction. Consequently, a pentafluorophenyl magnesium derivative is obtained as one kind of the fluoroaryl magnesium derivative. Japanese Laid-open Patent Application No. 247976/1994 (Tokukaihei 6-247976) discloses another producing process. In this process, the pentafluorophenyl magnesium derivative is obtained by dropping a solution prepared by dissolving pentafluorobenzene into an ether solvent to another solution prepared by mixing an alkyl magnesium derivative with the ether solvent.
In these processes, the pentafluorophenyl magnesium derivative is obtained through an exchange reaction, in which an alkyl group in the alkyl magnesium derivative is replaced with a pentafluorophenyl group.
However, to produce the tetrakis(pentafluorophenyl)borate derivative by the above conventional process, the alkyl magnesium derivative is produced in the first step, the above exchange reaction is carried out in the second step to obtain the pentafluorophenyl magnesium derivative, and the pentafluorophenyl magnesium derivative is reacted with a boron compound in the third step. In other words, since the alkyl magnesium derivative and pentafluorophenyl magnesium derivative are prepared separately before obtaining the tetrakis(pentafluorophenyl)borate derivative, the reaction takes place in three steps. Thus, there is a problem that the above conventional processes cannot produce the tetrakis(pentafluorophenyl)borate derivative effectively in a simple manner.
SUMMARY OF THE INVENTION
Therefore, it is a first object of the present invention to provide a producing process of a (fluoroaryl)borane compound, such as tris(fluoroaryl)borane and bis(fluoroaryl)boryl halide, from which magnesium halide produced as a by-product is separated and removed, selectively in a simple manner at a low cost.
The inventors of the present invention conducted a research diligently on a producing process of the (fluoroaryl)borane compound, and discovered that magnesium halide produced as a by-product with the (fluoroaryl)borane compound precipitates from the reaction
Katsumi Ikuyo
Mitsui Hitoshi
Yamamoto Naoko
Kubovcik & Kubovcik
Nippon Shokubai Co. , Ltd.
Vollano Jean F.
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