Process for preparing unsaturated organosilicon compounds

Details Process for preparing unsaturated organosilicon compounds Process for preparing unsaturated organosilicon compounds

2002-04-10

2004-11-09

Shaver, Paul F. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Silicon containing

C556S437000

Reexamination Certificate

active

06815554

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for preparing unsaturated organosilicon compounds containing organic carbonyloxy groups in the presence of phosphonium salts as phase transfer catalysts.
2. Background Art
Silicon compounds containing unsaturated organic carbonyloxy functions, e.g. 3-methacryloxypropyltrimethoxysilane, are widely employed as bonding agents between inorganic and organic materials, e.g. in sizes for glass fibers, or as crosslinkers in organic polymers.
Various methods of preparing such compounds are known. Thus, for example, DE 2851456 C2 describes the hydrosilylation of chlorosilanes containing SiH bonds by means of unsaturated organic molecules such as allyl methacrylate in the presence of metal catalysts to form chlorosilanes containing corresponding unsaturated organic functional groups. The disadvantage of this process is the fact that the subsequent alcoholysis step necessary to obtain the corresponding alkoxy-functionalized silanes generally cannot be carried out continuously due to the high tendency of the unsaturated organic functionality to polymerize.
Apart from the foregoing process, the direct reaction of an alkoxysilane containing SiH bonds with unsaturated organic molecules in the presence of metal catalysts is also known, e.g. from DE 38 32 621 C1. However, this process has the serious disadvantage that the alkoxysilanes necessary for carrying out the process present safety risks due to high toxicity and a tendency to decompose.
In EP 242 627 A2 and EP 437 653 B1, unsaturated organosilicon compounds are obtained by a nucleophilic substitution reaction between a metal or ammonium salt of an unsaturated organic acid and a haloorganofunctionalized silane. The unsaturated organic acid salts may be obtained in various ways. In the process described in EP 242 627 A2, the unsaturated organic acid is reacted with a tertiary amine to provide the ammonium salt which can be immediately reacted in the same reaction vessel with the haloorganosilicon compound. However, a significant disadvantage of this process is the low reactivity of the ammonium salts of unsaturated organic acids, which thus requires very long reaction times and the attendant serious risk of polymerization of the product.
Two alternative methods are described in EP 437 653 B1. In one process, the isolated sodium or potassium salt of the unsaturated organic acid is used. This has the disadvantage that this salt must be synthesized in a dedicated process and then dried in costly fashion. Alternatively, the metal salt of the unsaturated organic acid may be obtained by reaction of the corresponding metal alkoxide with the unsaturated organic acid, in the corresponding alcohol. After addition of the haloorganofunctionalized silicon compound and removal of the alcohol by distillation, further reaction can then be carried out in the same reaction vessel. This process has the disadvantage that the metal alkoxides used are generally corrosive, highly reactive, and very expensive. Moreover, large amounts of the respective and sometimes toxic alcohol are required as solvent, which significantly reduces the attractiveness of this process.
SUMMARY OF THE INVENTION
The present invention provides an economical route to unsaturated organosilicon compounds containing carbonyloxy groups by reacting a haloalkylsilane with a salt of an unsaturated carboxylic acid in the presence of a phase transfer catalyst.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
The invention provides a process for preparing unsaturated organosilanes containing organic carbonyloxy groups having the formula
(R
1
O)
3−n
R
2
n
Si—X—OC(O)C(R
3
)═CR
3
2
  (I),
where
R
1
may be identical or different and are each a monovalent, substituted or unsubstituted hydrocarbon radical which has from 1 to 10 carbon atoms optionally interrupted by oxygen atoms, R
2
may be identical or different and are each a monovalent, SiC-bonded, substituted or unsubstituted hydrocarbon radical which has from 1 to 10 carbon atoms optionally interrupted by oxygen atoms, or a sil(oxan)yl radical, X is a divalent, substituted or unsubstituted hydrocarbon radical which has from 1 to 40 carbon atoms optionally interrupted by oxygen atoms, R
3
may be identical or different and are each a hydrogen atom or a monovalent, substituted or unsubstituted hydrocarbon radical which has from 1 to 40 carbon atoms optionally interrupted by oxygen atoms, and n is 0, 1, 2 or 3;
by reacting haloorganofunctional silicon compounds of the formula
(R
1
O)
3−n
R
2
n
Si—X—Y  (II),
where R
1
, R
2
, X and n are as defined above and Y is a halogen atom, with a salt of an unsaturated organic carboxylic acid of the formula
M
+
[
−
OC(O)C(R
3
)═CR
3
2
]o  (III),
where R
3
is as defined above, M is an alkali metal or alkaline earth metal and o can be 1 or 2 depending on the valence of M, in the presence of a phosphonium salt as a phase transfer catalyst.
Examples of radicals R
1
include the radicals listed for radical R
3
which have from 1 to 10 carbon atoms. R
1
is preferably a hydrocarbon radical which has from 1 to 10 carbon atoms, optionally interrupted by oxygen atoms, and which may additionally bear nitrogen, sulfur or phosphorus substituents, most preferably a methyl, ethyl, 2-methoxyethyl, phenyl or isopropyl radical, in particular, an ethyl or methyl radical.
Examples of radical R
2
include the radicals listed for radical R
3
which have from 1 to 10 carbon atoms, and sil(oxan)yl radicals of the formula (V) R
3
Si—(OSiR
2
)
p
, where R may be identical or different and are each as defined for R
1
, p is 0 or an integer from 1 to 100, with the proviso that the radicals R may be bound to the silicon atom either directly, i.e. SiC-bonded, or via oxygen.
The radical R
2
is preferably a hydrocarbon radical which has from 1 to 10 carbon atoms, optionally interrupted by oxygen atoms, and which may also bear nitrogen, sulfur or phosphorus substituents, or a sil(oxan)yl radical of the formula (V), particularly preferably a phenyl, ethyl, methyl or pentamethoxydisiloxyl radical, in particular a methyl or ethyl radical.
Examples of radical X are alkylene radicals such as the methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, tert-butylene, n-pentylene, isopentylene, neopentylene and tert-pentylene radicals; hexylene radicals such as n-hexylene radicals; heptylene radicals such as the n-heptylene radical; octylene radicals such as the n-octylene radical, and isooctylene radicals such as the 2,2,4-trimethylpentylene radical; nonylene radicals such as the n-nonylene radical; decylene radicals such as the n-decylene radical; dodecylene radicals such as the n-dodecylene radical; octadecylene radicals such as the n-octadecylene radical; alkenylene radicals such as the vinylene and n-propenylene radicals; arylene radicals such as the phenylene, phenylmethylene, phenylethylene, 1-phenylpropylene and 2-phenylpropylene radicals, and also (poly)alkylenoxy groups of the formula (VI) —(CH
2
)
q
(OZ)
m
—, where m is an integer from 1 to 100, q is an integer from 1 to 6 and Z is an ethylene, n-propylene, isopropylene, n-butylene or isobutylene radical.
X is preferably a divalent hydrocarbon radical which has from 1 to 10 carbon atoms, optionally interrupted by oxygen atoms and which may be substituted by nitrogen, sulfur or phosphorus, particularly preferably an n-propylene, isopropylene, n-butylene, isobutylene, methylene, ethylene or p-phenylene radical, in particular a methylene or n-propylene radical.
Examples of substituted or unsubstituted hydrocarbon radicals R
3
are alkyl radicals such as the methyl, ethyl, n-propyl, isopropyl, 1-n-butyl, 2-n-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 2,2,4-trimethylpentyl radical; nonyl radicals such as

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