U.S. patent application number 09/901891 was filed with the patent office on 2002-02-07 for preparation of vinylsilanes.
Invention is credited to Friedrich, Holger, Henkelmann, Jochem, Preiss, Thomas.
Application Number | 20020016422 09/901891 |
Document ID | / |
Family ID | 7649319 |
Filed Date | 2002-02-07 |
United States Patent
Application |
20020016422 |
Kind Code |
A1 |
Preiss, Thomas ; et
al. |
February 7, 2002 |
Preparation of vinylsilanes
Abstract
In the process for the preparation of vinylsilanes by reacting
acetylenic hydrocarbons with silanes which have at least one
silicon-bonded hydrogen atom in the liquid phase in the presence of
a catalyst, the silane is added to the liquid phase. In particular,
the reaction is carried out at superatmospheric pressure, and the
spent acetylenic hydrocarbon is replenished during the reaction
while maintaining a pressure which is constant during the entire
reaction.
Inventors: |
Preiss, Thomas; (Weisenheim
am Sand, DE) ; Friedrich, Holger; (Bobenheim-Roxheim,
DE) ; Henkelmann, Jochem; (Mannheim, DE) |
Correspondence
Address: |
Herbert B. Keil
KEIL & WEINKAUF
1101 Connecticut Ave., N.W.
Washington
DC
20036
US
|
Family ID: |
7649319 |
Appl. No.: |
09/901891 |
Filed: |
July 11, 2001 |
Current U.S.
Class: |
526/95 ; 526/279;
526/285 |
Current CPC
Class: |
C07F 7/14 20130101; C07F
7/1876 20130101 |
Class at
Publication: |
526/95 ; 526/279;
526/285 |
International
Class: |
C08F 004/06; C08F
004/42; C08F 030/08; C08F 038/00; C08F 138/00; C08F 238/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 18, 2000 |
DE |
10034894.7 |
Claims
We claim
1. A process for the preparation of vinylsilanes by reacting
acetylenic hydrocarbons with silanes which have at least one
silicon-bonded hydrogen atom in the liquid phase in the presence of
a catalyst, wherein the silane is added to the liquid phase
containing the acetylenic hydrocarbon and the catalyst.
2. A process as claimed in claim 1, wherein an acetylenic
hydrocarbon of the formula R.sup.1C.ident.CH, where R.sup.1 is
alkyl of 1 to 4 carbon atoms or hydrogen, is used.
3. A process as claimed in claim 2, wherein acetylene (R.sup.1
.dbd.H) is used.
4. A process as claimed in claim 1, wherein silanes of the formula
HSiR.sup.2.sub.nX.sub.3-n, where R.sup.2 is alkyl or halogenated
alkyl, X is a halide or alkoxy and n is from 0 to 3, are used.
5. A process as claimed in claim 4, wherein a silane of the formula
2where R.sup.3, R.sup.3' and R.sup.3'', independently of one
another, are alkyl, aryl or alkenyl, is used.
6. A process as claimed in claim 1, wherein the reaction is carried
out at superatmospheric pressure.
7. A process as claimed in claim 6, wherein the pressure is from 15
to 25 bar.
8. A process as claimed in claim 6, wherein the consumed acetylenic
hydrocarbon is replenished during the reaction while maintaining a
pressure which is constant during the entire reaction.
9. A process as claimed in claim 1, wherein the catalyst is a
homogeneously dissolved catalyst.
10. A process as claimed in claim 9, wherein a catalyst of the
formula Pt(0)L.sub.m, where m is from 2 to 4 and L is any desired
suitable ligand, is used.
Description
[0001] The present invention relates to a process for the
preparation of vinylsilanes.
[0002] Vinylsilanes are industrially useful products which are
used, for example, as adhesion promoters and as comonomers in
moisture-curable polyolefins.
[0003] The synthesis of vinylsilanes by reacting acetylenic
hydrocarbons with silicon compounds which contain at least one
hydrogen atom (hydrosilylation) is known from the literature.
[0004] However, the yields of the desired vinylsilanes are
frequently moderate in the processes known from the literature,
since the reaction results in undesirable byproducts, in particular
coupling products, which are formed by further hydrosilylation of
the desired vinylsilanes.
[0005] U.S. Pat. No. 2,823,218 relates to a process for reacting
silicon compounds which have a silicon-hydrogen bond with
aliphatically unsaturated compounds, improved yields of the
corresponding products and reduced yields of the byproducts being
obtained at low reaction temperatures. The reaction is carried out
by adding a mixture of a silicon compound and an aliphatically
unsaturated hydrocarbon to an inert solvent containing
chloroplatinic acid as a catalyst. In example 21, the reaction of
acetylene with triacetoxysilane is disclosed. Acetylene is added to
a mixture of triacetoxysilane and chloroplatinic acid in
isopropanol. The product obtained is vinyltriacetoxy-silane.
However, no yield is stated.
[0006] U.S. Pat. No. 2,637,738 relates to the reaction of silanes
with unsaturated aliphatic compounds, such as acetylene and
ethylene. The catalyst, platinum on active carbon, and the
corresponding silane are initially taken and are reacted with
acetylene or ethylene, preferably under superatmospheric pressure.
According to Table 1, in which the results of the investigation of
the reaction of acetylene with trichlorosilane are presented, 75%
of the desired vinyl compound and 25% of the undesired coupling
product are obtained with the use of 5% of platinum on powdered
active carbon as a catalyst.
[0007] U.S. Pat. No. 5,565,596 relates to the reaction of silanes,
in particular di- or trichlorosilanes, with alkynes over a platinum
catalyst. In order to reduce the formation of bissilylated adducts
of the alkynes, a catalyst modifier is added. The reaction is
carried out after addition of the silane as a mixture with the
alkyne to an inert solvent containing the platinum catalyst and the
catalyst modifier. In the examples, the weight ratio of the desired
vinylsilane to bissilylated derivatives is stated. The absolute
yield of the desired vinylsilane is not stated in the examples.
[0008] EP-A 0 409 141 relates to the preparation of alkenylsilanes
by reacting a gaseous acetylenic hydrocarbon with a gaseous silane
which has a silicon-hydrogen bond in the presence of a
hydrosilylation catalyst. The yield of desired alkenylsilane is
said to be maximized and the yield of undesired byproducts is said
to be minimized. At the same time, the dangers which occur when
working with gaseous acetylenic hydrocarbons are said to be
reduced. The reaction is carried out by feeding a gaseous mixture
containing an acetylenic hydrocarbon and a silane to a reaction
medium in the form of a dilute, mobile liquid film. This liquid
film contains the desired alkenylsilane prepared during the
reaction and a dissolved hydrosilylation catalyst and, if required,
an organic solvent. The ratio of the acetylenic hydrocarbon to the
silane is >1 and the reaction pressure is from atmospheric
pressure to 2 atm. Table 1 shows the ratios of desired vinylsilane
to undesired coupling product. However, an absolute yield of
vinylsilane is not stated.
[0009] The problems associated with the formation of coupling
products in the reaction of silanes which have at least one
silicon-hydrogen bond with acetylenic hydrocarbons is thus known
from the prior art. According to the prior art, the reaction is
carried out either by adding a mixture of silane and unsaturated
hydrocarbon to a solution containing a catalyst or by adding a
gaseous acetylenic hydrocarbon to a mixture of silane, catalyst
and, if required, solvent.
[0010] It is an object of the present invention to provide a
process for the preparation of vinylsilanes, in which a very high
conversion with high selectivities is to be achieved in combination
with a very high space-time yield.
[0011] We have found that this object is achieved by a process for
the preparation of vinylsilanes by reacting acetylenic hydrocarbons
with silanes which have at least one silicon-bonded hydrogen atom
in the liquid phase in the presence of a catalyst.
[0012] In the novel process, the silane is added to the liquid
phase containing the acetylenic hydrocarbon and the catalyst.
[0013] This process differs from the processes known from the prior
art in that the silane is added to a mixture of acetylenic
hydrocarbon and catalyst. As a result of the controlled addition of
the silane, an exact temperature program in the reactor is ensured.
Furthermore, it is possible in this way to prevent a local excess
of silane and to avoid coupling products.
[0014] An acetylenic hydrocarbon of the formula R.sup.1C.ident.CH,
where R.sup.1 is alkyl of 1 to 4 carbon atoms or hydrogen, is
preferably used. A gaseous acetylenic hydrocarbon is thus
preferably used. The gaseous acetylenic hydrocarbon acetylene
(R.sup.1.dbd.H) is particularly preferred.
[0015] Preferred silanes are those of the formula
HSiR.sup.2.sub.nX.sub.3-- n, where R.sup.2 is alkyl or halogenated
alkyl, X is a halide or alkoxy and n is from 0 to 3. R.sup.2 is
preferably alkyl or halogenated alkyl of 1 to 6, preferably 1 to 3,
carbon atoms. X is preferably chloride or alkoxy OR.sup.3, where
R.sup.3 can be alkyl or aryl. R.sup.3 is preferably a C.sub.1- to
C.sub.6-alkyl or a C.sub.6- to C.sub.12-aryl radical. R.sup.3 is
particularly preferably C.sub.1- to C.sub.3-alkyl, very
particularly preferably methyl. If X is a halide, n is preferably
from 0 to 2. If X is alkoxy, n is preferably from 0 to 1,
particularly preferably 0. Accordingly, trialkoxysilanes of the
formula 1
[0016] where R.sup.3, R.sup.3' and R.sup.3'', independently of one
another, have the meanings stated for R.sup.3, are very
particularly preferably used.
[0017] In a preferred embodiment, the novel process is carried out
at superatmospheric pressure. The pressure is in general from 5 to
30, preferably from 15 to 25, particularly preferably from 15 to
20, bar. The reaction is preferably carried out at constant
pressure, the gaseous acetylenic hydrocarbon being replenished at
the rate at which it is consumed, so that a constant pressure is
maintained.
[0018] The catalyst used in the novel process is preferably a
homogeneously dissolved catalyst. Suitable catalysts are those
selected from Pt or Pd catalysts. A homogeneously dissolved
platinum catalyst is particularly preferably used. A catalyst of
the formula Pt(0)L.sub.m, where m is from 2 to 4 and L is any
desired suitable ligand, for example tetramethyldivinyl-disiloxane,
is very particularly preferably used.
Tetramethyldidivinylsiloxaneplatinum is very particularly
preferably used as the catalyst. By operating under
superatmospheric pressure in a homogeneously catalyzed reaction, it
is possible to achieve high space-time yields which in general are
from 50 to 2 000 g/lh, depending on the corresponding product.
[0019] The homogeneous catalyst is generally used in a
concentration of from 1 to 1 000 ppm, preferably from 1 to 100 ppm,
particularly preferably from 1 to 40 ppm, based on the silane
used.
[0020] The reaction is preferably carried out in an inert
high-boiling solvent, selected from aliphatic and aromatic
hydrocarbons and mixtures of different hydrocarbons and
high-boiling esters and ethers. High-boiling aromatic hydrocarbons,
such as xylene, are particularly preferred.
[0021] In a preferred embodiment of the novel process, a silane is
reacted with a gaseous acetylenic hydrocarbon, preferably
acetylene. An inert high-boiling solvent, for example xylene, is
initially taken and a platinum catalyst is homogeneously dissolved
therein. The gaseous acetylenic hydrocarbon is added until a
pressure of 20 bar (18 bar partial pressure of the acetylenic
hydrocarbon) is reached. The silane to be reacted is then pumped
in. The duration for which the silane is pumped in is dependent on
the batch size and on the reactor geometry. In this reaction, the
gaseous acetylenic hydrocarbon is replenished at the rate at which
it is consumed, so that the reaction is carried out at constant
pressure.
[0022] The hydrosilylation of acetylenic hydrocarbons can thus be
carried out under mild reaction conditions at low temperatures. In
general, temperatures of from 0 to 80.degree. C., preferably from 0
to 60.degree. C., particularly preferably from 0 to 40.degree. C.,
are customary.
[0023] The novel process is preferably carried out in such a way
that the temperature variation in the reactor during the reaction
after heating up to the reaction temperature is in general not more
than 10.degree. C., preferably not more than 5.degree. C.,
particularly preferably not more than 2.degree. C.
[0024] By means of this procedure, high selectivities of in general
from 90 to >99%, preferably from 95 to >99%, particularly
preferably from 98 to >99%, are obtained. Undesired byproducts
and secondary reactions are avoided or suppressed by means of this
procedure.
[0025] The yield of vinylsilane is in general from 89 to 99.9%,
preferably from 94 to 99.5%, based on the silane used.
[0026] The novel process can be carried out in all reactors
suitable for this reaction. The process is preferably carried out
in a tubular reactor, stirred reactor or loop reactor. A reaction
in a loop reactor is particularly preferred.
[0027] The examples which follow additionally illustrate the
invention.
EXAMPLES
COMPARATIVE EXAMPLE
[0028] 600 g of xylene, 200 g of trimethoxysilane and 1 g of
tetramethyldivinyldisiloxaneplatinum solution in xylene (150 ppm)
were initially taken in a 2.5 1 autoclave. The reactor was then
provided with an inert atmosphere by means of 2 bar nitrogen and
was heated to 40.degree. C. while stirring. After the reaction
temperature had been reached, the pressure was increased to 20 bar
by forcing in acetylene. In the course of one hour, the internal
temperature increased to 50.degree. C. and was then reduced to
40.degree. C. by cooling. After 2 hours at 20 bar, the autoclave
was cooled to room temperature and let down. Starting material was
no longer detectable in the reaction discharge. The yield of
trimethoxyvinylsilane was 47.7%. 1,2-(Trimethoxy)ethylsilane and
1,1-(trimethoxy)ethylsilane were detectable as byproducts.
Example
(According to the Invention)
[0029] 647 g of xylene and 0.1 g of
tetramethyldivinyl-disiloxaneplatinum solution in xylene (20 ppm)
were initially taken in a 2.5 1 autoclave. The reactor was then
provided with an inert atmosphere by means of 2 bar nitrogen and
the pressure was increased to 20 bar by forcing in acetylene. In
the course of 30 minutes, 140 g of trimethoxysilane were pumped in.
During this time, the reactor pressure was kept at 20 bar with
acetylene. After 2 hours at 20 bar and 40.degree. C., the autoclave
was cooled to room temperature and let down. Starting material was
no longer detectable in the reaction discharge. The yield of
trimethoxyvinylsilane was 99.3%.
* * * * *