Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Reexamination Certificate
2000-11-17
2001-08-07
Shaver, Paul F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
C556S435000
Reexamination Certificate
active
06271406
ABSTRACT:
TECHNICAL FIELD
The invention relates to a process for the preparation of halogenated 1,2-disilaethanes.
BACKGROUND ART
A large number of processes for the preparation of halogenated 1,2-disilaethanes are known. Thus, they are obtainable via hydrosilylation reactions. For example, the preparation of 1,2-bis(chlorodimethylsilyl)ethane is carried out via the hydrosilylation reaction between chlorodimethylsilane and chlorodimethylvinylsilane. The hydrosilylation reactions are described in U.S. Pat. Nos. 3,041,362, 3,497,539, 3,220,972, 3,674,739, DE-A 2 131 74 1 and the corresponding U.S. Pat. No. 3,798,252 (Wacker-Chemie GmbH, published on Mar. 19, 1974) and DE-A 2 131 742 (Wacker-Chemie GmbH, laid open on Dec. 28, 1972).
Further processes for the preparation of 1,2- bis(chlorodimethylsilyl)-ethane are chlorination reactions of bis(trimethylsilyl)ethane (Kumada et al., J. ORGANOMET. CHEM. 1967, 10(1), 111-119, and Ishikawa et al., J. ORGANOMET. CHEM. 1970, 23(1), 63-69). It is also known that halogenated 1,2-disilaethanes can be prepared by reacting disilanes with organyl chlorides or HCl (H. Sakurai et al., TETRAHEDRON LETT. 1966, 45, 5493-7). 1, 2-Bis(chlorodimethylsilyl)ethane is also obtainable via the hydrosilylation of dimethylmethoxyvinylsilane with chlorodimethylsilane (Suryanarayanan et al., J. ORGANOMET. CHEM. 1973, 55(1), 65-71).
DE-A 2 131 741 and the corresponding U.S. Pat. No. 3,798,252 (Wacker-Chemie GmbH, published on Mar. 19, 1974), DE-A2 131 742 (Wacker-Chemie GmbH, laid open on Dec. 28, 1972) and DE-A 2 001 303 (Wacker-Chemie GmbH, laid open on Jul. 22, 1971) describe halogenated 1,2-disilaethanes, such as 1,2-bis(chlorodimethylsilyl)ethane, as solvents in the preparation of alkenylsilanes, such as chlorodimethylvinylsilane.
DISCLOSURE OF THE INVENTION
It was an object of the present invention to provide a process for the preparation of halogenated 1,2-disilaethanes which is simple, the halogenated 1,2-disilaethanes being obtained in high yield and purity over a short reaction time. It was a further object to provide a particularly economical and environmentally friendly process for the preparation of halogenated 1,2-disilaethanes. These and other objects are achieved by the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The invention relates to a process for the preparation of halogenated 1,2-disilaethanes of the general formula
X
3−n
R
n
Si—CHR
1
CHR
1
—SiR
n
X
3−n
(I),
in which R may be identical or different and denotes a hydrogen atom or a monovalent optionally substituted hydrocarbon radical having 1 to 40 carbon atom(s) per radical, R
1
may be identical or different and denotes a hydrogen atom or a monovalent optionally substituted hydrocarbon radical having 1 to 40 carbon atom(s) per radical, X denotes a halogen atom, and n denotes 0, 1 or 2,
wherein halogenated 1,2-disilaethenes of the general formula
X
3−n
R
n
Si—CR
1
═CR
1
—SiR
n
X
3−n
(II),
in which R, R
1
, X and n have the meaning stated above therefor, are reacted with hydrogen in the presence of a hydrogenation catalyst.
Examples of hydrocarbon radicals R are alkyl radicals such as the methyl, ethyl, n-propyl, isopropyl, 1-n-butyl, 2-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, and tert-pentyl radicals, hexyl radicals such as the n-hexyl radical, heptyl radicals such as the n-heptyl radical, octyl radicals such as the n-octyl radical and isooctyl radicals such as the 2,2,2-trimethylpentyl radical, nonyl radicals such as the n-nonyl radical, decyl radicals such as the n-decyl radical, and octadecyl radicals such as the n-octadecyl radical; cycloalkyl radicals such as the cyclopentyl, cyclohexyl, cycloheptyl, and methylcyclohexyl radicals; alkenyl radicals such as the vinyl, allyl, 3-butenyl, 5-hexenyl, 1-propenyl and 1-pentenyl radicals; alkynyl radicals such as the ethynyl, propargyl, and 1-propynyl radicals; aryl radicals such as the phenyl, naphthyl, anthryl and phenanthryl radicals; alkaryl radicals, such as o-, m- and p-tosyl radicals, xylyl radicals, and ethylphenyl radicals; and aralkyl radicals such as the benzyl radical, the phenylethyl radical and the phenylnonyl radical.
Examples of substituted hydrocarbon radicals R are haloalkyl rad//icals such as the 3,3,3-trifluoro-n-propyl radical, the 2,2,2,2′,2′,2′-hexafluoroisopropyl radical, and the heptafluoroisopropyl radical; haloaryl radicals such as the o-, m- and p-chlorophenyl radicals; and hydrocarbon radicals substituted by amino, mercapto and ammonium groups and having 1 to 18 carbon atoms.
The radical R is preferably a hydrogen atom or a monovalent hydrocarbon radical having 1 to 18 carbon atom(s) per radical, the hydrogen atom, and the methyl and ethyl radicals being particularly preferred.
Examples of unsubstituted and substituted radicals R are all applicable also to radicals R
1
. The radical R
1
is preferably a hydrogen atom or a monovalent hydrocarbon radical having 1 to 18 carbon atom(s) per radical, the hydrogen atom and the methyl and ethyl radicals being particularly preferred.
Examples of X are fluorine, chlorine, bromine and iodine, chlorine being preferred.
Preferred examples for halogenated 1,2-disilaethanes of the formula (I) are:
1,2-bis(chlorodimethylsilyl)ethane,
1,2-bis(dichloromethylsilyl)ethane,
1,2-bis(trichlorosilyl)ethane,
1,2-bis(chlorodiethylsilyl)ethane,
1,2-bis(dichloroethylsilyl)ethane,
1-(chlorodimethylsilyl)-2-(dichloromethylsilyl)ethane,
1,2-bis(chlorodimethylsilyl)propane,
1,2-bis(chlorodimethylsilyl)butane and
2,3-bis(chlorodimethylsilyl)butane.
Particularly preferred 1,2-disilaethanes(I) are:
1,2-bis(chlorodimethylsilyl)ethane,
1,2-bis(dichloromethylsilyl)ethane, and
1,2-bis(trichlorosilyl)ethane.
Further examples of halogenated 1,2-disilaethanes of the formula (I) are the corresponding fluorine, bromine and iodine derivatives of the examples above, the corresponding bromine derivatives being preferred.
Preferred examples of the halogenated 1,2-disilaethenes of the formula (II) which are used in the process according to the invention are the cis and trans isomers of
1,2-bis(chlorodimethylsilyl)ethene,
1,2-bis(dichloromethylsilyl)ethene,
1,2-bis(trichloromethyl)ethene,
1,2-bis(chlorodiethylsilyl)ethene,
1,2-bis(dichloroethylsilyl)ethene,
1-(chlorodimethylsilyl)-2-(dichloromethylsilyl)ethene,
1,2-bis(chlorodimethylsilyl)prop-1-ene,
1,2-bis(chlorodimethylsilyl)but-1-ene, and
2,3-bis(chlorodimethylsilyl)but-2-ene.
Particularly preferred are the cis and trans isomers of
1,2-bis(chlorodimethylsilyl)ethene,
1,2-bis(dichloromethylsilyl)ethene, and
1,2-bis(trichlorosilyl)ethene.
Further examples of halogenated 1,2-disilaethenes of the formula (II) are the corresponding fluorine, bromine and iodine derivatives of the foregoing compounds, the corresponding bromine derivatives being preferred.
Halogenated 1,2-disilaethenes are preferably prepared by a hydrosilylation reaction between vinylsilanes and hydridosilanes and subsequent hydrogen abstraction. Halogenated 1,2-disilaethene are obtained as byproducts of 1,2-disilaethane preparation from vinylsilanes and hydridosilanes. In the process according to the invention, halogenated 1,2-disilaethenes of the formula (II) and hydrogen are reacted with one another preferably in a molar ratio (ratio of double bond in (II) to molecular H
2
) of from 1:0.6 to 1:10
10
, more preferably in a molar ratio of from 1:0.8 to 1:10
9
, and most preferably in a molar ratio of from 1:1 to 1:10
8
.
Preferably used hydrogenation-promoting catalysts are homogeneous catalysts, heterogeneous catalysts and catalysts for catalytic transfer hydrogenation, preferably heterogeneous catalysts and homogeneous catalysts, most preferably, heterogeneous catalysts.
Examples of heterogeneous catalysts, i.e. those which are present on supports, are metals of subgroup VIII of the Periodic Table, such as palladium, platinum, nickel, cobalt and iron; copper; mixtures of the above-mentioned metals; metal oxides of the above-mentioned metals, such as rhenium oxide, mixed metal oxides of the above-mention
Abele Bors C.
Winterfeld Jörn
Brooks & Kushman P.C.
Shaver Paul F.
Wacker-Chemie GmbH
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