Patent GB-684638-A (GB)
Title: Improvements in and relating to methods of preparing organohalogenosilanes
IPC: C07F7/12
Filed: 1950-08-09
Abstract: Organohalogenosilanes are prepared by heating in the presence of a catalyst selected from the halides of aluminium, boron and zinc, a hydrocarbon and one or more halogenodisilanes of the general formula Si2Xn(R)6-n, where R represents a monovalent hydrocarbon radical, X is a halogen and n is an integer equal to from 1 to 6.  Specified catalysts are aluminium trichloride and tribromide, boron trichloride and trifluoride and zinc chloride and fluoride.  Hydrocarbons mentioned are aliphatic hydrocarbons such as the saturated hydrocarbons methane, ethane, propane, butane, isobutane, pentane, 2-ethylhexane and decane, unsaturated hydrocarbons such as ethylene, propylene, octene-1, butadiene and acetylene, saturated and unsaturated cycloaliphatic hydrocarbons such as cyclopentane, cyclohexane, cyclopentene, cyclohexene and cyclopentadiene, hydrocarbon-substituted aromatic compounds such as toluene, xylene, ethylbenzene, the diisopropylbenzenes, styrene and diphenyl, aromatic hydrocarbons such as benzene, naphthalene and anthracene, and other hydrocarbons such as p-menthane, p-menthene and dipentene.  The halogenodisilanes may contain in addition to one halogen atom attached to a silicon atom (e.g. chlorine, bromine or fluorine), other inorganic or organic substituents attached to the silicon atoms, e.g. hydrogen, other halogen atoms or organic radicals such as saturated and unsaturated aliphatic radicals, aromatic radicals, hydrocarbon-substituted aromatic radicals, aromatic substituted aliphatic radicals and cycloaliphatic radicals corresponding to those listed above.  Specific disilanes referred to are hexachlorodisilane, hexabromodisilane, 1,2-dimethyl - 1,1,2,2 - tetrafluorodisilane,2, 2 - dimethyl - 1,1,1,2 - tetrachloro - disilane, methylpentachlorodisilane and methylhalogeno - disilanes which are obtained by the process of Specification 575,667, and comprising large amounts of the isomeric dimethyltetrachlorodisilanes, i.e.2, 2-dimethyl-1,1,1,2-tetrachlorodisilane and 1,2-dimethyl-1,1,2,2-tetrachlorodisilane, and of the isomeric trimethyltrichlorodisilanes as well as small amounts of hexachlorodisilane, methylpentachlorodisilane and the isomeric tetramethyldichlorodisilanes.  Other disilanes referred to are of the above general formula Si2Xn(R)6-n, wherein R is an alkyl radical, e.g. methyl, ethyl, propyl, butyl, isobutyl, amyl or decyl radical, an aryl radical, e.g. phenyl, naphthyl or anthracyl radical, an alkaryl radical, e.g. tolyl or xylyl radical, an aralkyl radical, e.g. benzyl or phenylethyl, and other saturated and unsaturated aliphatic and cycloaliphatic radicals, e.g. vinyl, allyl, butadienyl, propinyl, cyclohexanyl, cyclohexenyl or cyclopentanyl radical.  The reaction may be carried out in the presence of silicon tetrachloride. The preferred reaction temperature is of the order of from about 250 DEG  C. to below the decomposition point of the hydrocarbon, e.g. from 250 DEG  to 700 DEG  C. or from 300 DEG  to 600 DEG  C.  In the examples, hexachlorodisilane is reacted with benzene in the presence of aluminium chloride and in the presence of aluminium chloride phenyltrichlorosilane, a mixture of methylchlorodisilanes obtained by the process of Specification 575,667 and referred to above is reacted with benzene and aluminium chloride to give phenyltrichlorosilane and methyl phenyldichlorosilane, and hexachlorodisilane is reacted in the presence of boron trichloride with methane to give methylchlorosilanes containing mostly methyltrichlorosilane, with cyclohexane to give cyclohexyltrichlorosilane, with toluene to give isomeric tolyltrichlorosilanes, and with cyclohexene to give a product which is hydrolysed to give an organo-siloxane.