Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Reexamination Certificate
2000-05-16
2001-07-10
Shaver, Paul F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
Reexamination Certificate
active
06258970
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a method for enhancing the formation and recovery of dialkyldihalosilane from alkylhalosilane crude. More particularly, the present invention relates to a direct method for methylchlorosilane manufacture by maintaining a low weight ratio of zinc with respect to copper while using phosphorus as a catalyst for enhancing dimethyldichlorosilane formation.
The Rochow Direct Method Process for making methylchlorosilanes by effecting reaction between powdered silicon and methyl chloride in the presence of a copper catalyst is shown by U.S. Pat. No. 2,380,995. As taught by Rochow in Chemistry of the Silicones, Second Edition, (1951), John Wiley and Sons, New York, pp. 79-80, dimethyldichlorosilane is the source of dimethylsiloxy, or “Di” units when hydrolyzed, and is basic for the manufacture of high molecular weight polymers. It has been long recognized, as shown by Rochow et al.,
J. Am. Chem. Soc.,
63, 798 (1941) that in addition to copper, key metallic promoters, such as zinc and tin, also can enhance the formation of dimethyldichlorosilane during direct method methylchlorosilane crude production.
T. Margaria et al., WO/95/01303, (1994) have further described the use of phosphorus as a promoter for dimethyldichlorosilane formation in the direct method. Copper phosphide has been cited by Halm et al., in U.S. Pat. No. 4,762,940 (1990), as a useful source of phosphorus for improving dimethyldichlorosilane selectivity in direct method procedures. As shown in U.S. Pat. No. 5,059,343, Halm et al., also investigated the effects of using phosphorus to improve dimethyldichlorosilane selectivity in direct method operations in combination with copper, tin and zinc. Even though significant advances have been made with respect to procedures for improving the yields of dimethyldichlorosilane in direct method methylchlorosilane manufacture, further techniques are constantly being sought.
SUMMARY OF THE INVENTION
A method is provided for promoting the formation of dialkyldihalosilane during direct method alkylhalosilane production. The method comprises effecting reaction between alkylhalide and powdered silicon in the presence of a catalyst comprising copper (Cu), silicon (Si), zinc (Zn), and phosphorus (P), where there is maintained during alkylhalosilane formation a reaction mixture comprising, by weight, an average proportion of copper in a range between about 1% and about 5% based on the weight of silicon;
a sufficient amount of zinc to provide a Cu/Zn weight ratio having a value in a range between about 25 and about 250;
and a proportion of phosphorus in a range between about 100 ppm and about 1000 ppm, based on the weight of reaction mixture.
REFERENCES:
patent: 2380995 (1945-08-01), Rochow
patent: 4500724 (1985-02-01), Ward et al.
patent: 4602101 (1986-07-01), Halm et al.
patent: 4762940 (1988-08-01), Halm et al.
patent: 4898960 (1990-02-01), Dosaj et al.
patent: 4946978 (1990-08-01), Halm et al.
patent: 5059343 (1991-10-01), Halm et al.
patent: 5059706 (1991-10-01), Degen et al.
patent: 5281739 (1994-01-01), Halm et al.
patent: 5596119 (1997-01-01), Halm et al.
patent: 5847181 (1998-12-01), Nakanishi et al.
patent: 5874604 (1999-02-01), Steiner et al.
patent: 6005130 (1999-12-01), Lewis et al.
patent: 9501303 (1995-01-01), None
“Polymeric Methyl Silicon Oxides” by E. G. Rochow and W.F. Gilliam, Journal of the American Chemical Society, 63 798 (1941).
International Search Report.
Bablin John Matthew
DeMoulpied David Cheney
Lewis Larry Neil
Ward, III William Jessup
Bennett Bernadette M.
General Electric Company
Johnson Noreen C.
Shaver Paul F.
LandOfFree
Method for promoting dialkyldihalosilane formation during... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for promoting dialkyldihalosilane formation during..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for promoting dialkyldihalosilane formation during... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2555825