Patent GB-657442-A (GB)
Title: A process for the manufacture of tertiary butyl silicon compounds
IPC: C07F7/12
Filed: 1949-02-10
Abstract: Polymeric siloxanes are obtained by hydrolysing tertiary-butyl organo silicon compounds of the general formula t-(C4H9)nRmSiX4-m-n, where m is 1 or 2, n is 1 or 2, n+m is 2 or 3, R is a phenyl or an alkyl radical other than a tertiary alkyl radical and X is a halogen or an alkoxy radical, and condensing the resulting silanols.  The tertiary-butyl organo silicon compounds may be hydrolysed and condensed with each other and with other hydrolysable silanes to form co-polymers.  The Specification as open to inspection under Sect. 91 refers to the above process employing tertiary-butyl organo silicon compounds of the general formula t-(C4H9)nRmSiX4-m-n, where m is an integer from 0 to 2, n is 1 or 2, R is a phenyl radical or an alkyl radical other than the tertiary-butyl radical and X is a halogen atom or an alkoxy radical.  This subject-matter does not appear in the Specification as accepted.ALSO:Tertiary-butyl silanes of the general formula <FORM:0657442/IV (b)/1> wherein m is 1 or 2, n is 1 or 2, n+m is 2 or 3, R is a phenyl radical or an alkyl radical other than a tertiary alkyl radical and X is a halogen or an alkoxy radical, are prepared by mixing t-butyl lithium with a silane of the formula RmSiX4-m in the liquid phase.  The product obtained may be of the formula t-(C+Hg RSiX2.  The reactant may be trichloromethylsilane, trichlorophenylsilane, dichlorodimethylsilane or dichlorodiphenylsilane or the corresponding ethoxy compounds. The tertiarybutyl silanes thus produced may be reacted with Grignard reagents in order to introduce additional hydrocarbon groups into the silanes e.g. t-butyl-trimethylsilane may be formed.  The tertiary-butyl chlorosilanes may be reacted with liquid ammonia or the t-butyl radical may be chlorinated. Silanols are obtained by hydrolysing the tertiary-butyl silanes of the above general formula. In the examples the following compounds are prepared: t-butyldichloro phenyl silane t-butyldichloromethyl silane and the corresponding silanols, t-butylchlorodimethyl silane and the corresponding silanol and t-butylhexadecyldichloro silane.  Tertiary-butyl lithium is prepared by rolling lithium into thin sheets in a mineral oil bath, cut into small pieces and add to pentane which has been rendered free from unsaturated compounds by agitation with concentrated sulphuric acid.  A solution of t-butyl chloride in pentane is then added and the mixture heated. Petroleum ether or liquid aliphatic hydrocarbons free from unsaturation are alternative solvents.  Lithium sand obtained by cooling a dispersion of molten lithium in mineral oil may also be used.  The Specification as open to inspection under Sect. 91 refers to the preparation of compounds of the general formula t-(C + Hg)nRmSiX4-m-n, where m is an interger from 0 to 2, n is 1 or 2, R is a phenyl radical or an alkyl radical other than the tertiary-butyl radical and X is a halogen atom or an alkoxy radical.  Silicon tetrachloride is given as an additional reactant.  The silanols derived from compounds of the above general formula are referred to. Additional compounds prepared are t-butyltrichlorosilane (can be converted to t-butyltrimethylsilane with methyl magnesium bromide or to (chloro-t-butyl)-trichlorosilane with peroxide catalysed chlorination with sulphuryl chloride), di-t-butyldichlorosilane (can be converted to diamino-di-t-butylsilane with liquid ammonia) and t-butyltriethoxysilane and the corresponding silanols.  This subject-matter does not appear in the Specification as accepted.