Silicon halogenosilanes

The alkyl- or aryl-halogenosilanes are prepared commercially by passing the vapour of an alkyl or an aryl halide over a heated intimate mixture of powdered silicon and either copper or silver. 

Three types of halogenosilanes (235, 236 and 237) with pentacoordinate silicon atom are considered. The first comprises anions of type 235, the second is a neutral species containing a Lewis base (D) (236) and the last is a cation formed and stabilized by a chelate ligand of a Lewis base character (237). 

The first observation of the formation of a silicone oil was reported more than 120 years ago [195], but it was just after the World War II that the first industrial applications started at General Electric and Dow Corning, mainly after the discovery of direct synthesis of organochlorosilanes from halogenosilanes by Rochow [196]. The structure of silicones was first recognized by Robinson and Kipping [197],... 

Most studies of halogenosilanes have been concerned with the methylsilanes (Section ll.C). The data that have been collected for the mixed silicon halides Y4 SiX (26,57) are presented graphically in Fig. 12. In contrast to the methylhalogenosilanes (Me4 SiF is shown in Fig. 12 for comparison), the sagging" pattern, which is apparently... 

This type of elimination reaction seems to be limited to halogenosilanes containing a silicon atom exhibiting a strong Lewis acidity. The analogous reaction of CP2M0H2 with several other chlorosilanes only yields the monochloro compound Cp2Mo(H)Cl. 

Functional silicon compounds R3SiX are also optically stable. Racemization is observed only in the presence of nucleophilic agents. Kinetic studies of the nucleophilically assisted racemizations of halogenosilanes, germanes, and stannanes have revealed that they involve two molecules of nucleophile in the rate-... 

Silicones with unsaturated double bonds can be produced as halogen silanes by acetylene addition to halogenosilanes ... 

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