Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Utility Patent
2000-01-28
2001-01-02
Shaver, Paul F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
Utility Patent
active
06169196
ABSTRACT:
TECHNICAL FIELD
The invention relates to a process for the preparation of di- and trialkylsilanes with bulky alkyl radicals by hydrosilylation of hydrogen-containing silanes with alkenes in the presence of a transition metal catalyst and an activator.
BACKGROUND ART
Dialkyldialkoxysilanes with bulky alkyl radicals on the silicon are now sought after, for example, by almost all major producers of polypropylene for their latest generation Ziegler catalysts. Silanes with short-chain, branched alkyl and cycloalkyl groups are in particular demand. These silanes must be employed in a high purity. Until a short time ago, these silanes were produced industrially exclusively from chlorosilanes or alkoxysilanes by the expensive organometallic route, that is to say employing large amounts of both solvents, and metals such as sodium or magnesium. Accordingly it was necessary to dispose of large amounts of metal-containing by-products.
Alkyl- or dialkylsilanes which, in addition to hydrogen bonded directly to silicon, contain chlorine atoms and/or alkoxy radicals, satisfactorily hydrosilylate linear alkenes having a terminal double bond, so-called &agr;-olefins, only in the presence of noble metal catalysts. Thus, for example, the hydrosilylation of silanes such as dichlorosilane, which contain 2 hydrogen atoms bonded directly to silicon, with branched or cyclic alkenes containing at least 3 carbons, leads only to a monoalkylchlorosilane, even if alkene is present in excess.
U.S. Pat. No. 5,663,400 describes a hydrosilylation process for the preparation of di- and trialkylsilanes with bulky alkyl radicals wherein the hydrosilylation of hydrogen-containing silanes takes place with bulky alkenes in the presence of a transition metal catalyst and activators. Hydrocarbons which contain aldehyde, keto or epoxide groups or halogen atoms as functional groups are employed as activators. Many different by-products, some of which are difficult to separate, are formed in this process. As a result, it is difficult to obtain highly pure products.
DISCLOSURE OF INVENTION
An object of the present invention is to provide a process for the preparation of di- and trialkylsilanes in which at least one alkyl radical is branched or cyclic or contains at least 3 carbons, and preferably the silanes also contain chlorine atoms and/or alkoxy radicals, during which process only few by-products, by-products which are easy to separate, are formed.
REFERENCES:
patent: 4469881 (1984-09-01), Arkles
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patent: 5082962 (1992-01-01), Schilling
patent: 5663400 (1997-09-01), Reitmeier et al.
patent: 0 602 922 (1994-06-01), None
Geisberger Gilbert
Lindner Tassilo
Reitmeier Rudolf
Brooks & Kushman P.C.
Shaver Paul F.
Wacker-Chemie GmbH
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