Halogenated alkylsilanes

The alkylation of halogen-substituted benzenes such as fluorobenzene and dichlorobenzenes with other (dichloroalkyl)silanes in the presence of aluminum chloride catalyst afforded isomeric mixtures of the corresponding (dihalogen-substituted phenyl)alkylsilanes in moderate yields (Eq. (13)). These results are summarized in Table Xll. 

The chemistry of silacyclopentanes resembles closely that of acyclic alkylsilanes. Strong bases are needed to cleave the silicon-carbon bond, while electrophilic attack occurs readily with halogens and strong acids, e.g. sulfuric. In addition, aluminum chloride will induce polymerization of silacyclopentanes unless one of the groups on silicon is carbofunctional (Scheme 154) (67MI12000). If this is chloromethyl, then ring expansion occurs (Scheme 155). 

Electrochemical synthesis of various cyclic alkylsilanes has been performed similarly113. It should be noted that 5-silaspiro[4,4]nonane is formed despite the high probability of polymer formation due to the high functionality of the silicon. Such high selectivity in the electrochemical ring closure seems to be due to the orientating effect of an electrode in the course of an irreversible reduction of a carbon-halogen bond in the monosilylated intermediate (equations 87 and 88). 

Surface modification can be achieved by binding of different substituted alkylsilanes at the surface. SAMs have been reported from alkyltrichlorosilanes with terminal groups of amine [552, 570], halogen [553-555, 572], alkyl (Ci 4,6-8,10,12,18) [556-558, 570-572],... 

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