Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Reexamination Certificate
2000-11-22
2001-09-04
Shaver, Paul F. (Department: 1754)
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
Reexamination Certificate
active
06284907
ABSTRACT:
TECHNICAL FIELD
The invention relates to a process for the preparation of 1,3-dihalo-1,1,3,3-tetra(organyl)disiloxanes.
BACKGROUND ART
1,3-dihalo-1,1,3,3-tetra(organyl)disiloxanes are used not only in the preparation of specific polysiloxanes but increasingly as protective group reagents in organic synthesis. Probably the most thoroughly investigated and most widely used disiloxanes of this class of substances are 1,3-dichloro-1,1,3,3-tetramethyldisiloxane and 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane.
These compounds can be prepared in principle by chlorinating 1,3-dihydro-1,1,3,3-tetra(organyl)disiloxanes. However, the chlorination processes described in the literature are generally unsuitable for scaling up to industrial production and also frequently have further disadvantages.
Thus, although the chlorination is possible in principle using elemental chlorine in the presence of a catalyst, for example according to JP-A-02145591, the substitution often takes place not only selectively at the desired silicon-bonded hydrogen but also at the organyl radicals. Purification of the desired molecule is often difficult and expensive.
The chlorination of 1,3-dihydro-1,1,3,3-tetramethyldisiloxane with copper(II) chloride in the presence of copper(I) iodide is described in EP-A-557 762 or the corresponding U.S. Pat. No. 5,258,535. Substantial disadvantages of this process are that at least one (mole) equivalent of copper(II) chloride is required per H—Cl exchange, and that considerable amounts of copper salts have to be handled, especially on an industrial scale. In addition, a solvent is required for the reaction.
Use of allyl chlorides is disclosed in DE-A-351 8605, of chlorohydrocarbons in JP-A-58004792, of acid chlorides in H. X. Zang et al., Synth. Commun. 17 (1987) 1299-1307, and of hypochlorites in R. Chawla et al., Synth. Commun. 29 (1999) 3499-3501, all generally in the presence of a specific catalyst for the chlorination of 1,3-dihydro-1,1,3,3-tetra(organyl)disiloxanes. Owing to the toxicological properties of these chlorinating agents, however, industrial use is problematic. Moreover, byproducts which have to be separated from the desired product by distillation are generated in these chlorination reactions.
DISCLOSURE OF INVENTION
The object of the invention is to provide a simple and in particular economical process for the preparation of 1,3-dihalo-1,1,3,3-tetra(organyl)disiloxanes in the presence of a catalyst selected from transition metals of the 8th subgroup of the periodic table of the elements, compounds of transition metals of the 8th subgroup, and complexes of transition metals of the 8th subgroup.
DETAILED DESCRIPTION OF THE INVENTION
The invention relates to a process for the preparation of 1,3-dihalo-1,1,3,3-tetra(organyl)disiloxanes of the general formula
XR
2
Si—O—SiR
2
X (1)
by reacting hydrogen halide with 1,3-dihydro-1,1,3,3-tetra(organyl)disiloxanes of the general formula
HR
2
Si—O—SiR
2
H (2),
in which
R are identical or different and denote C
1-20
hydrocarbon radicals optionally substituted by fluorine or chlorine atoms, and
X are identical or different and denote a halogen atom, in the presence of a catalyst selected from transition metals of the 8th subgroup of the periodic table of the elements, compounds of transition metals of the 8th subgroup and complexes of transition metals of the 8th subgroup.
Examples of hydrocarbon radicals R are alkyl radicals such as the methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, thexyl, n-hexyl, n-heptyl, n-octyl, and octadecyl radicals; cycloalkyl radicals such as the cyclopentyl, cyclohexyl, and methylcyclohexyl radicals; and aralkyl radicals, such as the benzyl, phenylethyl, phenylnonyl, 2-phenylpropyl, and fluorenyl radicals.
Examples of substituted hydrocarbon radicals R are the 3,3,3-trifluoropropyl, the 3,3,4,4,5,5,6,6,6-nonafluorohexyl and the 2,3,4,5,6-pentafluorophenyl radicals and the chloromethyl and 3-chloropropyl radicals.
Preferred radicals R are alkyl and cycloalkyl radicals having 1 to 10 carbon atoms, the methyl, ethyl, isopropyl, tert-butyl, cyclopentyl and cyclohexyl radicals being particularly preferred.
X is preferably fluorine, chlorine or bromine, chlorine being particularly preferred.
The tetravalency of the silicon atom is applicable in all formulae.
The 1,3-dihalo-1,1,3,3-tetra(organyl)disiloxanes of the general formula (1) which are prepared by the process according to the invention as well as the 1,3-dihydro-1,1,3,3-tetra(organyl)disiloxanes of the general formula (2) which are used as starting materials according to the invention are organosilicon compounds which are liquid or solid at room temperature and 1013 hPa.
Preferred examples of the disiloxanes of the general formula (1) which are prepared by the process according to the invention are
1,3-dichloro-1,1,3,3-tetramethyldisiloxane,
1,3-dichloro-1,1,3,3-tetraethyldisiloxane,
1,3-dichloro-1,1,3,3-tetra-n-propyldisiloxane,
1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane,
1,3-dichloro-1,1,3,3-tetra-n-butyldisiloxane,
1,3-dichloro-1,1,3,3-tetraisobutyldisiloxane,
1,3-dichloro-1,1,3,3-tetra-sec-butyldisiloxane,
1,3-dichloro-1,1,3,3-tetra-tert-butyldisiloxane,
1,3-dichloro-1,1,3,3-tetracyclopentyldisiloxane,
1,3-dichloro-1,1,3,3-tetracyclohexyldisiloxane,
1,3-dichloro-1,3-diethyl-1,3dimethyldisiloxane,
1,3-dichloro-1,3-dimethyl-1,3-di-n-propyldisiloxane,
1,3-dichloro-1,3-dimethyl-1,3-diisopropyldisiloxane,
1,3-dichloro-1,3-di-n-butyl-1,3-dimethyldisiloxane,
1,3-dichloro-1,3-diisobuty-1,3-dimethyldisiloxane,
1,3-dichloro-1,3-di-sec-butyl-1,3-dirnethyldisiloxane,
1,3-dichloro-1,3-di-tert-butyl-1,3-dimethyldisiloxane,
1,3-dichloro-1,3-dicyclopentyl-1,3-dimethyldisiloxane,
1,3-dichloro-1,3-dicyclohexyl-1,3-dimethyldisiloxane,
1,3-dichloro-1,3-diethyl-1,3-di-n-propyldisiloxane,
1,3-dichloro-1,3-diethyl-1,3-diisopropyldisiloxane,
1,3-dichloro-1,3-di-n-butyl-1,3-diethyldisiloxane,
1,3-dichloro-1,3-diisobutyl-1,3-diethyldisiloxane,
1,3-dichloro-1,3-di-sec-butyl-1,3-diethyldisiloxane,
1,3-dichloro-1,3-di-tert-butyl-1,3-diethyldisiloxane,
1,3-dichloro-1,3-dicyclopentyl-1,3-diethyldisiloxane, and
1,3-dichloro-1,3-dicyclohexyl-1,3-diethyldisiloxane.
Preferred dihalotetra(organyl)siloxanes are
1,3-dichloro-1,1,3,3-tetramethyldisiloxane,
1,3-dichloro-1,1,3,3-tetra-isopropyldisiloxane,
1,3-dichloro-1,1,3,3-tetra-n-butyldisiloxane,
1,3-dichloro-1,1,3,3-tetra-sec-butyldisiloxane,
1,3-dichloro-1,1,3,3-tetra-tert-butyldisiloxane,
1,3-dichloro-1,1,3,3-tetracyclohexyldisiloxane,
1,3-dichloro-1,3-dimethyl-1,3-diisopropyldisiloxane,
1,3-dichloro-1,3-di-n-butyl-1,3-dimethyldisiloxane,
1,3-dichloro-1,3-di-sec-butyl-1,3-dimethyldisiloxane,
1,3-dichloro-1,3-di-tert-butyl-1,3-dimethyldisiloxane, and
1,3-dichloro-1,3-dicyclohexyl-1,3-dimethylsiloxane.
The disiloxanes of the general fornula (2) used in the process according to the invention are preferably
1,3-dihydro-1,1,3,3-tetramethyldisiloxane,
1,3-dihydro-1,1,3,3-tetraethyldisiloxane,
1,3-dihydro-1,1,3,3-tetra-n-propyldisiloxane,
1,3-dihydro-1,1,3,3-tetraisopropyldisiloxane,
1,3-dihydro-1,1,3,3-tetra-n-butyldisiloxane,
1,3-dihydro-1,1,3,3-tetraisobutyldisiloxane,
1,3-dihydro-1,1,3,3-tetra-sec-butyldisiloxane,
1,3-dihydro-1,1,3,3-tetra-tert-butyldisiloxane,
1,3-dihydro-1,1,3,3-tetracyclopentyldisiloxane,
1,3-dihydro-1,1,3,3-tetracyclohexyldisiloxane,
1,3-dihydro-1,3-diethyl-1,3-dimethyldisiloxane,
1,3-dihydro-1,3-dimethyl-1,3-di-n-propyldisiloxane,
1,3-dihydro-1,3-dimethyl-1,3-diisopropyldisiloxane,
1,3-dihydro-1,3-di-n-butyl-1,3-dimethyldisiloxane,
1,3-dihydro-1,3-diisobutyl-1,3-dimethyldisiloxane,
1,3-dihydro-1,3-di-sec-butyl-1,3-dimethyldisiloxane,
1,3-dihydro-1,3-di-tert-butyl-1,3-dimethyldisiloxane,
1,3-dihydro-1,3-dicyclopentyl-1,3-dimethyldisiloxane,
1,3-dihydro-1,3-dicyclohexyl-1,3-dimethyldisiloxane,
1,3-dihydro-1,3-diethyl-1,3-di-n-propyldisiloxane,
1,3-dihydro-1,3-diethyl-1,3-diisopropyldisiloxane,
1,3-dihydro-1,3-di-n-butyl-1,3-diethyldisiloxane,
1,3-dihydro-1,3-diisobutyl-1,3-diethyldisiloxane,
1,3-dihydro-1,3-di-sec-butyl-1,3-diethyldisiloxane,
1,3-dihydro-
Abele Bors C.
Winterfeld Jörn
Brooks & Kushman P.C.
Shaver Paul F.
Wacker-Chemie GmbH
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