Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Reexamination Certificate
2000-05-19
2001-01-23
Shaver, Paul F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
Reexamination Certificate
active
06177585
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is a hydrosilation process comprising contacting a silicon hydride with an unsaturated reactant in the presence of a supported bimetallic catalyst comprising an active hydrosilating metal such as platinum in elemental or compound form, and a surface segregating metal such as copper in elemental or compound form on a support.
It is known in the art to produce organosilicon compounds by reacting a silicon hydride containing compound with an unsaturated organic compound in the presence of a catalyst. This reaction is commonly referred to as hydrosilation or hydrosilylation. Typically the catalyst is monometallic platinum metal on a carbon support, a platinum compound generally in a solvent, or a platinum complex. The present invention uses a bimetallic catalyst such as platinum-copper, to increase the hydrosilation rate, total conversion product selectivity and increase process efficiency, while decreasing processing cost, compared to monometallic catalysts used for hydrosilations. Speier et al., U.S. Pat. No. 2,823,218, teaches a method for the production of organosilicon compounds by reacting Si—H with a compound containing aliphatic carbon atoms linked by multiple bonds in the presence of chloroplatinic acid. Lamoreaux, U.S. Pat. No. 3,220,972, teaches a similar process, however the catalyst is a reaction product of chloroplatinic acid.
Wagner et al., U.S. Pat. No. 2,851,473, disclose a process for the production of organosilicon compounds comprising reacting an unsaturated organic compound with a platinum-gamma alumina catalyst.
One of the major problems known in the art with hydrosilation reactions is the de-activation of the catalyst prior to the completion of the reaction. One method for reactivation of the catalyst has been to expose the reaction mixture to oxygen. For example, Onopchenko et al., U.S. Pat. No. 4,578,497, teaches the use of an oxygenated platinum containing catalyst for use in hydrosilating alkylsilanes. Kleyer et al., EP Patent Application No. 0533170A1, discloses a method for controlling a hydrosilation reaction by controlling the solution concentration of oxygen in the reaction mixture, relative to the platinum present in the reaction mixture.
SUMMARY OF INVENTION
The present invention is a hydrosilation process comprising contacting a silicon hydride with an unsaturated reactant in the presence of a supported bimetallic catalyst comprising an active hydrosilating metal such as platinum in elemental or compound form, and a surface segregating metal such as copper in elemental or compound form on a support.
DETAILED DESCRIPTION OF INVENTION
The present invention is a hydrosilation process comprising contacting a silicon hydride with an unsaturated reactant in the presence of a supported bimetallic catalyst comprising an active hydrosilating metal such as platinum in elemental or compound form, and a surface segregating metal such as copper in elemental or compound form on a support. The hydrosilation process comprises:
(A) contacting a silicon hydride described by formula R
1
a
H
b
SiX
4−a−b
where each R
1
is independently selected from the group consisting of alkyls comprising one to about 20 carbon atoms, cycloalkyls comprising about four to 12 carbon atoms, and aryls; each X is a halogen; a=0 to 3, b=1 to 3, and a+b=1 to 4; and
(B) an unsaturated reactant selected from the group consisting of
(i) substituted and unsubstituted unsaturated hydrocarbon compounds,
(ii) silicon compounds comprising substituted or unsubstituted unsaturated hydrocarbon substituents, and
(iii) mixtures of (i) and (ii);
in the presence of a supported bimetallic catalyst comprising an active hydrosilating metal in elemental or compound form and a surface segregating metal in elemental or compound form on a support, at a temperature of from about 0° C. to 350° C., the active hydrosilating metal being different from the surface segregating metal.
The contacting of the silicon hydride with the unsaturated reactant can be effected in standard reactors for conducting hydrosilation processes. The process may be run as a continuous, semi-continuous, or batch process.
Silicon hydrides useful in the present process are described by formula R
1
a
H
b
SiX
4−a−b
where each R
1
is independently selected from the group consisting of alkyls comprising one to about 20 carbon atoms, cycloalkyls comprising about four to 12 carbon atoms, and aryls; a=0 to 3, b=1 to 3, and a+b=1 to 4. R
1
can be a substituted or unsubstituted alkyl, cycloalkyl, or aryl as described. It is preferred that each R
1
be independently selected from the group consisting of alkyls comprising one to about six carbon atoms. Even more preferred is when each R
1
is methyl. Each X is a halogen and preferably X is chlorine. Examples, of silicon hydrides described by formula R
1
a
H
b
SiX
4−a−b
which may be useful in the present process include trimethylsilane, dimethylsilane, triethylsilane, dichlorosilane, trichlorosilane, methyldichlorosilane, dimethylchlorosilane, ethyldichlorosilane, cyclopentlydichlorosilane, methylphenylchlorosilane and (3,3,3-trifluoropropyl)dichlorosilane. Preferably, the silicon hydride is selected from a group consisting of dimethylchlorosilane, methyldichlorosilane, trichlorosilane and dichlorosilane.
The silicon hydride may contain siloxanes described by formula
R
2
m
SiO(−R
2
2
SiO)−(R
2
2
SiO)
o
−SiR
2
m
,
where R
2
independently selected from the group consisting of hydrogen, alkyls comprising one to about 20 carbon atoms, cycloalkyls comprising about four to 12 carbon atoms and aryls; m=0 to 3, n=0 to 100 and o=0 to 100. An example of a siloxane is bis-trimethylsiloxymethylhydridosilane.
The silicon hydride is contacted with an unsaturated reactant selected from the group consisting of (i) substituted and unsubstituted unsaturated hydrocarbon compounds, (ii) silicon compounds comprising substituted and unsubstituted unsaturated hydrocarbon substituents, and (iii) mixtures of (i) and (ii). For purpose of this invention, “unsaturated” means that the compound contains at least one carbon-carbon double bond or one carbon-carbon triple bond.
Specific examples of the unsaturated reactants useful in the process include unsubstituted cycloalkene compounds comprising at least four carbon atoms, substituted cycloalkene compounds comprising at least four carbon atoms, linear alkene compounds comprising two to about 30 carbon atoms, such as acetylene, ethylene, propene, butene, 1-octene, 1-dodecene, and 1-octadecene and branched alkene compounds comprising four to about 30 carbon atoms, such as isobutene, amylene, 2-methyl heptene and mixtures of two or more of any of the above.
The substituted and unsubstituted cycloalkene compounds useful in the process are those containing one or more unsaturated carbon-carbonbonds in the ring. The unsubstituted cycloalkene compounds may be, for example, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclopentadiene, 1,3-cyclohexadiene, and 1,3,5-cycloheptatriene. Substituted unsaturated compounds useful in the present invention may be, for example, 3-methylcyclopentene, 3-chlorocyclobutene, 4-phenylcyclohexene, and 3-methylcyclopentadiene. The preferred cycloalkene compounds are cyclohexene and cyclopentene, with cyclohexene being the most preferred.
Other unsaturated hydrocarbon compounds useful in the process are linear and branched alkene compounds including, for example, compounds with terminal unsaturation such as 1-hexene, 1,5-hexadiene, 1,4-hexadiene and compounds with internal unsaturation such as trans-2-hexene, 2-methyl-2-butene, 2,3-dimethyl-2-butene and unsaturated aryl containing compounds such as styrene and alpha-methylstyrene.
The unsaturated reactants may also comprise halogen, oxygen in the form of acids, anhydrides, esters, and ethers, and nitrogen. Two or more of the above described unsaturated hydrocarbon compounds may be used in the present proc
Chen Wei
Dinh Paul Charles
Tzou Ming-Shin
Dow Corning Corporation
Fletcher Melvin D.
Shaver Paul F.
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