Heretofore, it was known that organosilanes could be converted by the redistribution reaction of silanes. For example, organosilanes can be converted by reacting at least one silane (A) of the formula: EQU R.sub.a SiCl.sub.4-a
with at least one silane (B) which differs from (A) and which corresponds to the general formula: EQU R.sub.b SiCl.sub.4-b
where R represents the same or different hydrocarbon radicals having from 1 to 10 carbon atoms which are free of aliphatic unsaturation and a is 2, 3 or 4 and b is 0, 1, 2 or 3. Also Noll, "Chemie und Technologie der Silicone", Weinheim, 1968, discloses at pages 51 and 52 that this type of reaction can be enhanced in the presence of catalysts. In this regard, U.S. Pat. No. 2,786,861 discloses a mixture of aluminum chloride and a silane having at least one Si-bonded hydrogen atom as being a suitable catalyst for the redistribution reaction. British Pat. No. 851,868 discloses that organoaluminum compounds having the general formula: EQU R.sub.c.sup.1 AlY.sub.3-c
may be used to convert organosilanes by the redistribution reaction, in which R.sup.1 represents the same or different alkyl radicals having from 1 to 4 carbon atoms, Y represents halogen, hydrogen and hydrocarbon radicals having from 1 to 10 carbon atoms which are free of aliphatic unsaturation and are bonded to the aluminum atom via oxygen; and c is 1, 2 or 3. The processes known heretofore have several disadvantages. For example, the disadvantages of using aluminum chloride is described in British Pat. No. 851,868. Also British Pat. No. 915,479 discloses that hydrogen chloride exerts an undesirable influence on the redistribution reaction of silanes in the presence of a silane having Si-bonded hydrogen and aluminum chloride. German Patent Application No. 2,132,335 discloses a process for converting silanes which requires pressures above atmospheric pressure.
In comparison to the processes known heretofore, the process of this invention has several advantages. For example, the redistribution reaction can be carried out at atmospheric pressure. Also, the process can be carried out at low temperatures and in the presence of smaller quantities of aluminum compounds. Moreover, the disadvantages described in British Pat. No. 851,868 in using aluminum chloride are avoided in the present process. Furthermore contrary to the teachings of British Pat. No. 915,479, applicants have found that the presence of hydrogen halide in the present process does not exert an undesirable influence on the redistribution reaction of silanes.
Therefore it is an object of this invention to provide an improved process for preparing organosilanes. Another object of this invention is to provide an improved process for preparing organosilanes at atmospheric pressure. Still another object of this invention is to provide an improved process for preparing organosilanes at low temperatures and in the presence of smaller quantities of aluminum compounds. A further object of this invention is to provide an improved process for preparing organosilanes in the presence of hydrogen halides.
USPTO Backgrounds
USPTO Backgrounds