Silane organic group

Figure 25.4 Silane organic group effect on flexural strength of a silica/polyester composite.

Alkylation and arylation of organosilanes occur readily with alkyl and aryl alkaU metal compounds. Yields from these reactions are good but are iafluenced by steric requirements on both silane and metal compounds. There is Httie iaductive effect by the organic groups attached to siUcon, as measured by the yield of products (126,127). These reactions proceed more readily ia tetrahydrofuran and ethyl ether than ia ligroin or petroleum ether, where R and are alkyl or aryl and M is Li, Na, or K. 

One organic group is readily transferred from tetraorganosilanes (and some other silanes) to palladium ). Tetramethylsilane, lithium tetrachloropalladate(II) and styrene at 120 C in acetonitrile solution form 1 -phenyl- 1-propene in 65% yield along with ca. 1.5% 2-phenyl-1-propene.33 Trimethylphenylsil-ane transfers phenyl and with styrene under the above conditions gives fra/w-stilbene in 94% yield.33 Similar vinyl substitution reactions have been achieved with potassium ( )-alkenyl pentafluorosili-cates.34... 

Isocyclic silanes are only known in the form of derivatives. Unsubstituted cyclic hydrosilicons have not been investigated, though SisHio was recently prepared (see p. 6). The best known derivatives are those with the simple organic groups like methyl or phenyl. Derivatives with other groups are rare. 

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