Integrated process for alkylation and redistribution of halosilanes
AssigneeDow Corning Corporation
InventorsKirk M. Chadwick, Roland L. Halm, Brian R. Keyes
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Abstract
An improved process for the preparation of multi-organic substituted silanes from the reaction of halides of silicon with an alkyl halide in the presence of a halogen-accepting metal is described. The improvement integrates a redistribution process into the alkylation process. The redistribution process involves an interaction between a multi-organic substituted silane and a halosilane with fewer organic substituents whereby an organic group from the multi-organic substituted silane is exchanged with a halogen group of the less organic substituted halosilane.
Claims28
A process for preparing multi-organic substituted silanes having the formula,
- R.sub.a R.sup.i.sub.b SiX.sub.(4-a-b),
- where each R is independently selected from the group consisting of methyl, ethyl, and n-propyl;
- each R.sup.i is independently selected from a group consisting of alkyl, substituted alkyl, alkenyl, aryl, and alkaryl groups;
- a has a value of 1, 2, 3, or 4, b has a value of 0, 1, 2, or 3 and the sum of a+b is 2, 3, or 4;
- and X is a halogen atom, the process comprising
- (A) contacting a halide of silicon, having the formula,
- R.sup.i.sub.b SiX.sub.(4-b),
- where R.sup.i, b, and X are defined above;
- with an alkyl halide, having the formula,
- RX;
- where R and X are defined above, in the presence of a metal which serves as a halogen acceptor;
- (B) reacting the halide of silicon with the alkyl halide in the presence of the metal at a temperature greater than 200.degree. C. to form an initial reaction mixture;
- and
- (C) contacting the initial reaction mixture with a redistribution catalyst;
- (D) isolating and separating the multi-organic substituted silane.
A process for preparing mono-alkylated silanes having the formula,
- RSiX.sub.3,
- where R is selected from the group consisting of methyl, ethyl, and n-propyl;
- and X is a halogen atom, the process comprising
- (A) contacting a halide of silicon, having the formula,
- SiX.sub.4,
- where X is defined above;
- with an alkyl halide having the formula,
- RX,
- where R and X are defined above, in the presence of a metal which serves as a halogen acceptor;
- (B) reacting the halide of silicon with the alkyl halide in the presence of the metal at a temperature greater than 200.degree. C. to form an initial reaction mixture;
- and
- (C) contacting the intial reaction mixture with a redistribution catalyst;
- (D) isolating and separating the mono-alkylated silane.
Dependencies are inferred from the claim text.