U.S. patent application number 12/091780 was filed with the patent office on 2008-11-20 for process for hydrosilylation.
This patent application is currently assigned to WACKER CHEMIE AG. Invention is credited to Frank Baumann, Gilbert Geisberger.
Application Number | 20080287699 12/091780 |
Document ID | / |
Family ID | 37814115 |
Filed Date | 2008-11-20 |
United States Patent
Application |
20080287699 |
Kind Code |
A1 |
Geisberger; Gilbert ; et
al. |
November 20, 2008 |
Process for Hydrosilylation
Abstract
Compounds containing unsaturated carbon-carbon bonds are
hydrosilylated with H-silanes or H-siloxanes in the presence of a
noble metal catalyst, wherein the water content of the reaction
mixture is less than 500 ppm and the noble metal catalyst is
supplied as a liquid, and is present in an amount of not more than
50 ppm.
Inventors: |
Geisberger; Gilbert;
(Altoetting, DE) ; Baumann; Frank; (Tittmoning,
DE) |
Correspondence
Address: |
BROOKS KUSHMAN P.C.
1000 TOWN CENTER, TWENTY-SECOND FLOOR
SOUTHFIELD
MI
48075
US
|
Assignee: |
WACKER CHEMIE AG
Munich
DE
|
Family ID: |
37814115 |
Appl. No.: |
12/091780 |
Filed: |
October 13, 2006 |
PCT Filed: |
October 13, 2006 |
PCT NO: |
PCT/EP2006/067394 |
371 Date: |
April 28, 2008 |
Current U.S.
Class: |
556/479 |
Current CPC
Class: |
C08K 9/06 20130101; C08L
83/08 20130101; C08K 5/34 20130101; C08K 9/06 20130101; C08K 5/5415
20130101 |
Class at
Publication: |
556/479 |
International
Class: |
C07F 7/08 20060101
C07F007/08 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 27, 2005 |
DE |
10 2005 051 587.9 |
Claims
1.-12. (canceled)
13. A process for hydrosilylating compounds (A) containing
carbon-carbon double bonds or carbon-carbon triple bonds with
organosilicon compounds (B) having silicon-bonded hydrogen by
catalysis with a compound or complex of a noble metal of transition
group VIII as a catalyst (C), comprising desiccating starting
materials with a desiccant selected from the group consisting of
calcium chloride, magnesium sulfate, sodium sulfate, metals,
molecular sieves or H-free chlorosilanes, such that the water
content of the reaction mixture is not more than 500 ppm and the
catalyst is added in liquid form to the reaction mixture, with the
proviso that the noble metal concentration is not more than 50 ppm
based on the entire reaction composition.
14. The process of claim 13, wherein the noble metal catalyst
concentration is from 5 to 25 ppm based on the entire reaction
composition.
15. The process of claim 13, wherein the water content of the
reaction mixture is not more than 100 ppm.
16. The process of claim 14, wherein the water content of the
reaction mixture is not more than 100 ppm.
17. The process of claim 13, wherein the catalyst (C) comprises one
or more compounds or complexes of a noble metal selected from the
group consisting of platinum, ruthenium, iridium, rhodium and
palladium.
18. The process of claim 13, wherein the catalyst (C) used
comprises at least one platinum-olefin complex or
platinum-divinyltetramethyldisiloxane complex.
19. The process of claim 13, wherein the process is carried out at
a temperature of from 60 to 140.degree. C.
20. The process of claim 13, wherein the process is carried out at
a pressure of from 1 to 20 bar.
21. The process of claim 13, wherein organosilicon compounds with
silicon-bonded hydrogen (B) comprise compounds containing units of
the formula (II) R.sup.2.sub.cH.sub.dSiO.sub.(4-c-d)/2 (II) where
R.sup.2 are identical or different monovalent radicals selected
from the group consisting of --F, --Cl, --Br, --CN, --SCN, --NCO,
alkoxy radicals, and SiC-bonded, substituted or unsubstituted
hydrocarbon radicals optionally interrupted by oxygen atoms or a
--C(O)-- group, c is 0, 1, 2 or 3 and d is 0, 1 or 2, with the
proviso that the sum of c+d is .ltoreq. and at least one Si-bonded
hydrogen atom per molecule is present.
22. The process of claim 13, wherein organosilicon compounds having
silicon-bonded hydrogen (B) comprise silanes of the formula (III)
R.sup.3.sub.eH.sub.fSi (III) where R.sup.3 are identical or
different monovalent radicals selected from the group consisting of
--F, --Cl, --Br, --CN, --SCN, --NCO, alkoxy radicals, and
Si--C-bonded, substituted or unsubstituted hydrocarbon radicals
optionally interrupted by oxygen atoms or the --C(O)-- group, e is
1, 2 or 3 and f is 1, 2 or 3, with the proviso that the sum of
e+f=4.
23. The process of claim 13, wherein the desiccant comprises
silicon tetrachloride.
24. A process for hydrosilylating compounds (A) containing
carbon-carbon double bonds or carbon-carbon triple bonds with
organosilicon compounds (B) having silicon-bonded hydrogen by
catalysis with a compound or complex of a noble metal of transition
group VIII as a catalyst (C), comprising desiccating starting
materials (A) and/or (B), and desiccating the such that the water
content of the reaction mixture is not more than 500 ppm and the
catalyst is added in liquid form to the reaction mixture, with the
proviso that the noble metal concentration is not more than 50 ppm
based on the entire reaction composition.
Description
[0001] The invention relates to a process for hydrosilylating
H-silanes and linear, cyclic or branched H-siloxanes with compounds
containing carbon-carbon double bonds or carbon-carbon triple bonds
with catalysis with noble metal, wherein, to improve the catalytic
activity, the water content of the reaction mixture is not more
than 1000 ppm and the catalyst is added to the reaction mixture in
liquid form.
[0002] In Chemie Ingenieur Technik (1999), 71 (5), 490-493, A. Behr
et al. describe the hydrosilylation of alkoxysilane with anhydrous
hexachloroplatinic acid. The catalyst used was dried under high
vacuum at 260.degree. C. The metering of a solid catalyst has a
disadvantageous effect, since this places a high level of technical
complexity on the process control and metering precision. The
drying method used is additionally uneconomic and impracticable on
the industrial scale. The process described also works with very
high platinum concentrations, the lowest platinum concentration
being 50 ppm. The dried catalyst is a hygroscopic solid, which
makes storage and handling difficult in industrial processes.
[0003] The European patent EP 0 693 492 B1 describes the
hydrosilylation of dimethylchlorosilane (HM2) with allyl
methacrylate in the presence of a noble metal catalyst selected
from compounds or metals of transition group VIII of the Periodic
Table, the water content in the allyl methacrylate being not more
than 200 ppm. The allyl methacrylate is dried by means of a
molecular sieve or by azeotropic distillation with a
water-immiscible solvent. The resulting
methacryloyloxypropyldimethylchlorosilane is purified by means of
distillation in the presence of a polymerization inhibitor. The
process is notable for a low fraction of the undesired
.alpha.-methylpropionyl-oxypropyldimethylchlorosilane by-product
and the reduction in gelling during the final distillation.
[0004] In Polymer Preprints (1989), 30 (1), 133-134, L. Lestel
discloses the hydrosilylation of polydimethylsiloxane with
diallyl-terminated polyethylene oxide in the presence of platinum
catalysts selected from the group consisting of dried H2PtCl6
powder, hexachloroplatinic acid dissolved in 1-octanol and
1,2-divinyl-1,1,2,2-tetramethyldisiloxane-platinum complex
dissolved in xylene. In the production of membranes consisting of
the block copolymers described, bubble formation as a result of
hydrogen formed is attributed to the presence of water traces. This
is demonstrated with reference to the reaction of
pentamethyldisiloxane with water with hydrogen elimination to give
the silanol which itself reacts further to give
decamethyltetrasiloxane with release of water.
[0005] The International patent application WO2004/56907 A2
describes hydrophilic siloxane copolymers prepared by means of
hydrosilylation of organopolysiloxanes which have at least one
silicon-bonded hydrogen atom per molecule with alkenyl polyethers
and subsequent reaction with diisocyanates, with the proviso that
the water content of the organopolysiloxane and alkenyl polyether
raw materials is less than 2000 ppm. The water content is kept
below 2000 ppm owing to the side reaction of the water with the
diisocyanates, in order to suppress foam formation in the second
reaction step.
[0006] The German patent DE 101 33 008 C1 discloses a process for
adding silicon-bonded hydrogen onto aliphatic carbon-carbon
multiple bonds in the presence of platinum catalysts, in which
addition of peracids maintains or enhances the catalytic activity
of the platinum catalyst. As a result of their oxidizing action,
they can reactivate an inhibited state of the platinum catalyst in
the continuous and batchwise hydrosilylation and act as a
coactivator or cocatalyst. The disadvantage of this process is the
additional addition of an additive in order to maintain the
catalytic activity.
[0007] It is therefore an object of the present invention to
provide a process usable on the industrial scale for
hydrosilylating silicon-bonded hydrogen onto carbon-carbon multiple
bonds, which enables simple addition of the noble metal catalyst
used and ensures a uniformly high or relatively high activity of
the catalyst without addition of further assistants.
[0008] The object underlying this invention is solved,
surprisingly, by keeping the water content of the hydrosilylation
composition below 1000 ppm and metering the catalyst in liquid
form.
[0009] The invention therefore provides a process for
hydrosilylating compounds (A) containing carbon-carbon double bonds
or carbon-carbon triple bonds with organosilicon compounds having
silicon-bonded hydrogen (B) by means of a compound or of a complex
of a noble metal of transition group VIII as a catalyst (C),
wherein, to improve the catalytic activity, the water content of
the reaction mixture is not more than 1000 ppm and the catalyst is
added in liquid form to the reaction mixture, with the proviso that
the noble metal concentration is not more than 50 ppm, preferably
25 ppm, based on the entire reaction composition.
[0010] The water content in the reaction mixture of the process
according to the invention is preferably from 0.05 to 500 ppm, more
preferably from 0.1 to 100 ppm.
[0011] The liquid metering of the catalyst and the maximum water
content of 1000 ppm in the reaction mixture give rise to a higher
catalytic activity which necessitates a smaller amount of noble
metal used. A simultaneous result is shorter plant occupation
times. The liquid metering is industrially particularly simple to
realize and very precise. This gives rise to safer process control,
since fewer variations in the exothermic reaction occur.
[0012] The compound (A) used in accordance with the invention may
comprise silicon-free organic compounds having aliphatically
unsaturated groups, and also organosilicon compounds with
aliphatically unsaturated groups.
[0013] Examples of organic compounds which can be used as component
(A) in the process according to the invention are all types of
olefins, such as 1-alkenes, 1-alkynes, vinylcyclohexane,
2,3-dimethyl-1,3-butadiene, 7-methyl-3-methylene-1,6-octadiene,
2-methyl-1,3-butadiene, 1,5-hexadiene, 1,7-octadiene,
4,7-methylene-4,7,8,9-tetrahydroindene, cyclopentene,
methylcyclopentadiene, 5-vinyl-2-norbornene,
bicyclo[2.2.1]hepta-2,5-diene, 1,3-diisopropenylbenzene,
vinyl-containing polybutadiene, 1,4-divinylcyclohexane,
1,3,5-triallylbenzene, 1,3,5-trivinylbenzene,
1,2,4-trivinylcyclohexane, 1,3,5-triisopropenylbenzene,
1,4-divinylbenzene, 3-methyl-1,5-heptadiene,
3-phenyl-1,5-hexadiene, 3-vinyl-1,5-hexadiene and
4,5-dimethyl-4,5-diethyl-1,7-octadiene, diallyl ether,
diallylamine, diallyl carbonate, N,N'-diallylurea, triallylamine,
tris(2-methylallyl)amine, 2,4,6-triallyloxy-1,3,5-triazine,
triallyl-s-triazine-2,4,6(1H,3H,5H)-trione, diallylmalonic esters,
allyl alcohols, allyl glycols, allyl glycidyl ether and
allylsuccinic anhydride.
[0014] In principle, the process according to the invention is also
suitable for converting acrylates, for example
N,N'-methylenebis(acrylamide), 1,1,1-tris(hydroxymethyl)propane
triacrylate, 1,1,1-tris(hydroxymethyl)propane trimethacrylate,
tripropylene glycol diacrylate, polyethylene glycol diacrylate,
polyethylene glycol dimethacrylate or poly-(propylene glycol)
methacrylate.
[0015] In addition, aliphatically unsaturated organosilicon
compounds can be used as constituent (A) in the process according
to the invention.
[0016] If organosilicon compounds which have SiC-bonded radicals
with aliphatic carbon-carbon multiple bonds are used as constituent
(A), they are preferably those composed of units of the formula
R.sub.aR.sup.1.sub.bSiO.sub.(4-a-b)/2 (I),
where [0017] R may be the same or different and is an organic
radical free of aliphatic carbon-carbon multiple bonds, [0018]
R.sup.1 may be the same or different and is a monovalent,
optionally substituted, SiC-bonded hydrocarbon radical having an
aliphatic carbon-carbon multiple bond, [0019] a is 0, 1, 2 or 3 and
[0020] b is 0, 1 or 2, with the proviso that the sum of a+b is
.ltoreq.4.
[0021] The organosilicon compounds (A) used in accordance with the
invention may be either silanes, i.e. compounds of the formula (I)
where a+b=4, or siloxanes, i.e. compounds containing units of the
formula (I) where a+b.ltoreq.3.
[0022] The R radical includes the monovalent radicals --F, --Cl,
--Br, --CN, --SCN, --NCO, alkoxy radicals and SiC-bonded,
optionally substituted hydrocarbon radicals which may be
interrupted by oxygen atoms or the --C(O)-- group.
[0023] Examples of R radicals are alkyl radicals, for example the
methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl,
n-pentyl, isopentyl, neopentyl, tert-pentyl radical, hexyl
radicals, for example the n-hexyl radical, heptyl radicals, for
example the n-heptyl radical, octyl radicals, for example the
n-octyl radical and isooctyl radicals, for example the
2,2,4-trimethylpentyl radical, nonyl radicals, for example the
n-nonyl radical, decyl radicals, for example the n-decyl radical,
dodecyl radicals, for example the n-dodecyl radical, and octadecyl
radicals, for example the n-octadecyl radical, cycloalkyl radicals,
for example cyclopentyl, cyclohexyl, cycloheptyl and
methylcyclohexyl radicals, aryl radicals, for example the phenyl,
naphthyl, anthryl and phenanthryl radical, alkaryl radicals, for
example o-, m-, p-tolyl radicals, xylyl radicals and ethylphenyl
radicals, and aralkyl radicals such as the benzyl radical, and the
.alpha.- and the .beta.-phenylethyl radical.
[0024] Examples of substituted R radicals are haloalkyl radicals
such as the 3,3,3-trifluoro-n-propyl radical, the
2,2,2,2',2',2'-hexafluoroisopropyl radical and the
heptafluoroisopropyl radical, and also haloaryl radicals such as
the o-, m- and p-chlorophenyl radical.
[0025] The R radical is preferably a monovalent SiC-bonded,
optionally substituted hydrocarbon radical which is free of
aliphatic carbon-carbon multiple bonds and has from 1 to 18 carbon
atoms, more preferably a monovalent SiC-bonded hydrocarbon radical
which is free of aliphatic carbon-carbon multiple bonds and has
from 1 to 6 carbon atoms, in particular the methyl or phenyl
radical.
[0026] The R.sup.1 radical may be any groups obtainable by an
addition reaction (hydrosilylation) with an SiH-functional
compound.
[0027] If the R.sup.1 radical is SiC-bonded, substituted
hydrocarbon radicals, preferred substituents are halogen atoms,
cyano radicals, alkoxy groups and siloxy groups.
[0028] The R.sup.1 radical is preferably alkenyl and alkynyl groups
having from 2 to 16 carbon atoms, such as vinyl, allyl, methallyl,
1-propenyl, 5-hexenyl, ethynyl, butadienyl, hexadienyl,
cyclopentenyl, cyclopentadienyl, cyclohexenyl,
vinylcyclohexylethyl, divinylcyclohexylethyl, norbornenyl,
vinylphenyl and styryl radicals, particular preference being given
to vinyl, allyl and hexenyl radicals.
[0029] Preferred components (A) are all terminal olefins and all
allylic, vinylic and alkynic systems, particular preference being
given to allylic systems.
[0030] The organosilicon compounds (B) used may be all
hydrogen-functional organosilicon compounds which have also been
used before in hydrosilylation reactions.
[0031] The organosilicon compounds (B) having Si-bonded hydrogen
atoms used are preferably those which contain units of the
formula
R.sup.2.sub.cH.sub.dSiO.sub.(4-c-d)/2 (II)
where R.sup.2 may be the same or different and is as defined above
for R, c is 0, 1, 2 or 3 and d is 0, 1 or 2, with the proviso that
the sum of c+d is .ltoreq.4 and at least one Si-bonded hydrogen
atom is present per molecule.
[0032] The R.sup.2 radicals are preferably selected from the group
comprising the monohydric radicals --F, --Cl, --Br, --CN, --SCN,
--NCO and SiC-bonded, optionally substituted hydrocarbon radicals,
for example alkyl radicals, for example the methyl, ethyl,
n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl,
isopentyl, neopentyl, tert-pentyl radical, hexyl radicals, for
example the n-hexyl radical, heptyl radicals, for example the
n-heptyl radical, octyl radicals, for example the n-octyl radical
and isooctyl radicals, for example the 2,2,4-trimethylpentyl
radical, nonyl radicals, for example the n-nonyl radical, decyl
radicals, for example the n-decyl radical, dodecyl radicals, for
example the n-dodecyl radical, and octadecyl radicals, for example
the n-octadecyl radical, cycloalkyl radicals, for example
cyclopentyl, cyclohexyl, cycloheptyl and methylcyclohexyl radicals,
aryl radicals, for example the phenyl, naphthyl, anthryl and
phenanthryl radical, alkaryl radicals, for example o-, m-, p-tolyl
radicals, xylyl radicals and ethylphenyl radicals, and aralkyl
radicals such as the benzyl radical, and the .alpha.- and the
.beta.-phenylethyl radical.
[0033] The organosilicon compounds (B) used in accordance with the
invention may either be silanes, i.e. compounds of the formula (II)
where c+d=4, or siloxanes, i.e. compounds containing units of the
formula (II) where c+d.ltoreq.3. The organosilicon compounds used
in accordance with the invention are preferably
organopolysiloxanes, especially those which consist of units of the
formula (II).
[0034] The organosilicon compound (B) used in accordance with the
invention preferably contains Si-bonded hydrogen in the range from
0.02 to 1.7 percent by weight, based on the total weight of the
organosilicon compound (B).
[0035] The molecular weight of constituent (B) in the case of
siloxane may vary within wide limits, for instance between 10.sup.2
and 10.sup.6 g/mol. For example, constituent (B) may be a
relatively low molecular weight SiH-functional oligosiloxane such
as tetramethyldisiloxane, but also a high molecular weight
polydimethylsiloxane possessing pendant or terminal SiH groups or a
silicone resin having SiH groups. The structure of the molecules
forming constituent (B) is also not fixed; in particular, the
structure of a relatively high molecular weight, i.e. oligomeric or
polymeric, SiH-containing siloxane may be linear, cyclic, branched
or else resin-like, network-like.
[0036] In the process according to the invention, constituent (B)
is preferably used in such an amount that the molar ratio of
aliphatically unsaturated groups of constituent (A) to SiH groups
of constituent (B) is between 0.1 and 20 and, for siloxanes,
preferably between 1.0 and 5.0.
[0037] The components (A) and (B) used in accordance with the
invention are commercial products or preparable by processes common
in chemistry.
[0038] In the process according to the invention, the component (C)
used may be all catalysts which have also been used before for the
addition of Si-bonded hydrogen to aliphatically unsaturated
compounds. Examples of such catalysts are compounds or complexes of
the group of the noble metals comprising platinum, ruthenium,
iridium, rhodium and palladium, for example platinum halides,
platinum-olefin complexes, platinum-alcohol complexes,
platinum-alkoxide complexes, platinum-ether complexes,
platinum-aldehyde complexes, platinum-ketone complexes, including
reaction products of H.sub.2PtCl.sub.6.6H.sub.2O and cyclohexanone,
platinum-vinylsiloxane complexes, especially
platinum-divinyltetramethyldisiloxane complexes with or without a
content of detectable inorganically bonded halogen,
bis(.gamma.-picoline)platinum dichloride,
trimethylenedipyridineplatinum dichloride,
dicyclopentadieneplatinum dichloride,
dimethylsulfoxyethyleneplatinum(II) dichloride and reaction
products of platinum tetrachloride with olefin and primary amine or
secondary amine or primary and secondary amine, for example the
reaction product of platinum tetrachloride dissolved in 1-octene
with sec-butylamine. In a further preferred embodiment of the
process according to the invention, complexes of iridium with
cyclooctadienes, for example
.mu.-dichlorobis(cyclooctadiene)diiridium(I), are used.
[0039] The catalyst (C) is preferably compounds or complexes of
platinum, preferably platinum chlorides and platinum complexes,
especially platinum-olefin complexes and more preferably
platinum-divinyltetramethyldisiloxane complexes.
[0040] In the process according to the invention, catalyst (C) is
used in amounts of from 1 to 50 ppm by weight, calculated as
elemental noble metal and based on the total weight of component
(A) and (B) present in the compositions. Preference is given to
using from 5 to 25 ppm by weight.
[0041] In a likewise preferred embodiment, silanes of the general
formula (III)
R.sup.3.sub.eH.sub.fSi (III)
are reacted, where R.sup.3 may be the same or different and is as
defined above for R, e is 1, 2 or 3 and f is 1, 2 or 3, with the
proviso that the sum of e+f=4.
[0042] Examples of R.sup.3 radicals are in particular --F, --Cl,
--Br, --CN, --SCN, --NCO and the SiC-bonded, optionally substituted
alkyl and aryl radicals specified for the R radical, and also
halogen-substituted aryl radicals, preference being given to
methyl, propyl, phenyl and halogenated phenyl radicals and
particular preference to the methyl radical and halogenated phenyl
radicals.
[0043] The process according to the invention can be carried out in
the presence or absence of organic solvent (D).
[0044] Examples of organic solvents (D) are all solvents which have
also been usable before in hydrosilylation reactions, such as
toluene, xylene, isopropanol, acetone, isophorone and glycols.
[0045] If organic solvents (D) are used, they are preferably
toluene, isopropanol and glycols, and more preferably toluene.
[0046] If organic solvents (D) are used in the process according to
the invention, the amounts are preferably from 5 to 60% by weight,
more preferably from 5 to 40% by weight, based in each case on the
total weight of the reaction mixture.
[0047] In the process according to the invention, apart from
components (A) to (D), it is also possible to use all further
substances (E) which have also been used before in hydrosilylation
reactions.
[0048] In the process according to the invention, preference is
given to not using any further substances in addition to components
(A) to (E).
[0049] The components (A) to (E) used in accordance with the
invention may each be a single type of such a component or a
mixture of at least two different types of such a component.
[0050] In the process according to the invention, the components
used may be mixed with one another by any known processes. In the
process according to the invention, preference is given to either
initially charging all reagents apart from catalyst (C) and then
starting the reaction by adding the catalyst, or to initially
charging all reagents apart from the Si--H-- containing compounds
(B) and then metering in the Si--H-- containing compounds.
[0051] The process according to the invention can be carried out
continuously or batchwise.
[0052] In the process according to the invention, Si-bonded
hydrogen can be added onto aliphatic multiple bonds under the same
conditions as in the hydrosilylation reactions known to date.
[0053] The temperatures are preferably from 20 to 200.degree. C.,
more preferably from 60 to 140.degree. C., and the pressure from 1
to 20 bar. However, it is also possible to employ higher or lower
temperatures and pressures.
[0054] The organosilicon compounds prepared in the process
according to the invention may be used for all purposes for which
modified organosilicon compounds have also been used before.
[0055] The process according to the invention has the advantage
that a significant catalyst reduction can be achieved, since the
catalytic activity of the original catalyst can be significantly
increased and prolonged.
[0056] In addition, the process according to the invention has the
advantage that a catalyst reduction can also achieve secondary
effects, such as improved color qualities and lower proportion of
toxic heavy metals in the hydrosilylation product, especially in
the case of polysiloxanes.
[0057] The water content of not more than 1000 ppm in the reaction
mixture can be achieved by the use of starting compounds with
correspondingly low water contents or the pretreatment of the
starting compounds used and of the catalyst, for example with a
suitable desiccant.
[0058] Examples of suitable desiccants are calcium chloride,
magnesium sulfate, sodium sulfate, metals or molecular sieve.
Unsuitable desiccants for the H-siloxanes are, for example,
potassium hydroxide, sodium hydroxide or acidic alumina, which lead
to the reaction with SiH or equilibration reactions. In the case of
H-containing chlorosilanes, particular preference is given to the
preliminary blending of the catalyst in H-free chlorosilane as a
desiccant, for example silicon tetrachloride.
[0059] The time up to the exothermic temperature jump after the
start of the hydrosilylation reaction can be considered as a
measure of the catalytic activity. For this purpose, the
SiH-containing and olefinic component are mixed and, after addition
of the catalyst, the temperature increase which sets in is
monitored.
[0060] A further measure of the catalytic activity in the case of
inhomogeneous starting mixtures is the time until, for example, a
clear mixture is present in the case of polyether/silicone
mixtures.
EXAMPLES
1.) Chlorosilane
A) Comparative Example Without "Drying" (Noninventive)
[0061] A 100 ml glass flask is initially charged with 29 g (0.13
mol) of hexadecene at room temperature which are mixed with 19.0 g
(0.14 mol) of trichlorosilane. The reaction mixture is admixed with
0.05 g of a platinum catalyst solution (4% by weight of platinum)
in dodecene. After approx. 5 minutes, the reaction mixture exhibits
a high temperature rise and attains the temperature maximum after
12 minutes. The reaction is complete after 15 minutes.
B) Inventive Example
[0062] Drying: 10 g of a platinum catalyst solution are admixed
with 2% by weight of tetrachlorosilane at room temperature and
stirred for 15 minutes.
[0063] A 100 ml glass flask is initially charged with 29 g (0.13
mol) of hexadecene at room temperature which are mixed with 19.0 g
(0.14 mol) of trichlorosilane. The reaction mixture is admixed with
0.05 g of a dried platinum catalyst solution (4% by weight of
platinum) in dodecene. After approx. 3 minutes, the reaction
mixture exhibits a high temperature rise and attains the
temperature maximum after 8 minutes. The reaction is complete after
10 minutes.
2.) Glycol-Functional Silicone Oil
A) Comparative Example
Hydrosilylation with >1000 ppm of H2O in the Reaction Mixture
(Noninventive)
[0064] 800 g of an .alpha.,.omega.-dihydropolydimethylsiloxane with
0.055% by weight of Si-bonded hydrogen and a water content of 55
ppm by weight are mixed with 1407 g of an allyl alcohol
ethoxylate/propyloxylate of the formula
H.sub.2C.dbd.CH--CH.sub.2--(OCH.sub.2CH.sub.2).sub.a[OCH.sub.2CH(CH.sub.-
3)].sub.b--OH,
with an a:b ratio=1.0, a water content of 1619 ppm by weight and an
iodine number of 14.3 (the iodine number refers to the number which
specifies the amount of iodine in grams consumed in the addition to
the aliphatic multiple bond per 100 grams of material to be
analyzed used).
[0065] The reaction mixture is heated to 95.degree. C. and admixed
at reaction temperature with 2.20 g of a 1.25% solution of
hexachloroplatinic acid in dimethoxyethane.
[0066] The reaction mixture heats up by 6.degree. C. and is
homogeneous 15 minutes after the start of the reaction.
B) Inventive Example
[0067] The preceding example is repeated except, for comparison, by
using a polyether which has been dried beforehand under high vacuum
at 100.degree. C. for 2 hours. As a result, the water content of
the polyether is 127 ppm by weight.
[0068] The reaction mixture heats up by 8.degree. C. and is
homogeneous as early as 12 min after the start of the reaction.
3.) Carbinol-Functional Silicone Oil
A) Comparative Example
Hydrosilylation with >1000 ppm of H2O in the Reaction Mixture
(Noninventive)
[0069] 100 g of allyl alcohol, 113 ml of toluene and 1 g of
anhydrous sodium carbonate are initially charged in a three-neck
flask and heated to 90.degree. C. After addition of 2.0 ml of the
platinum catalyst solution (1.25% solution of hexachloroplatinic
acid in dimethoxyethane), 585 g of an
.alpha.,.omega.-dihydropolydimethylsiloxane with 0.22% by weight of
Si-bonded hydrogen are metered in continuously, so that the
reaction temperature is from 90 to 110.degree. C. The metering time
is 1.5 hours. The reaction mixture is kept at 105.degree. C. for a
further hour and then cooled to room temperature. The hydrogen
number is determined as a measure of the reaction progress. The
hydrogen number is 55 (target value <10), and so another 2.0 ml
of the catalyst solution (1.25% solution of hexachloroplatinic acid
in dimethoxyethane) are added and the reaction mixture is heated to
105.degree. C. for a further 1.5 hours. The hydrogen number of the
brown reaction solution is 8 and the water content 1285 ppm. On a
rotary evaporator, the low boilers are distilled off at 112.degree.
C./0.5 hour/vacuum <1 mbar. The residue is filtered to obtain a
carbinol-functional silicone oil with the following properties:
Hazen color number (DIN ISO 6271): 54; water content: 794 ppm.
B) Inventive Example
[0070] The preceding example is repeated except, for comparison, by
using an .alpha.,.omega.-dihydropolydimethylsiloxane which has been
baked out beforehand under high vacuum at 90.degree. C. for 1 hour.
There is no need for a second addition of the platinum catalyst
solution, since the first value of the hydrogen number measurement
is 9. The resulting carbinol-functional silicone oil has the
following properties: Hazen color number (DIN ISO 6271): 6; water
content: 390 ppm.
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