Silane fluoro -, derivatives

However, the reaction rate is also increased by using silanes with R groups such as fluoro or alkoxy instead of alkyl. In fact, there are only a few successful examples of coupling reactions using trimethylsilane derivatives. 

High molecular weight perfluorinated tertiary alcohols can be prepared by the reaction of (perfluoroalkyl)- and (perfluorooxaalkyl)trimethylsilanes with fluoro ketones (vide supra). The reaction has been extended to carbonyl compounds other than ketones acid fluorides gave ketones, but no reaction was observed with esters. a-Oxo esters react with trimethyl(tri-fluoromcthyl)silane with fluoride initiation in tetrahydrofuran /(./(. -trifluoro lactic acid derivatives are produced in good yields in one step. 

The reaction (equation 59) between lithium amides and SiCLi affords Al-substituted silanes. The crystal stmctures of (55 X = F, Cl) clearly shows the intramolecular coordination of an aromatic nitrogen atom. As would be expected, the Si N a bonds are rather shorter (1.732 and 1.737 A) than the N — Si distances (1.969 and 1.9484 A for the fluoro and chloro derivatives, respectively). ... 

Chlorosilanes are also converted to siloxanes by reactions not involving hydrolysis. Most are highly exothermic, and appropriate measures for heat dissipation are recommended for safety. Thus chlorosilanes can be converted to siloxanes by reaction with DMSO or with NajCOj or ZnO in suitable solvents such as ethyl acetate or dioxane. Siloxanes can also be obtained by the reaction of alcohols with chlorosilanes, but this is really a kind of hydrolysis in which the water is generated in situ as a by-product of the formation of alkyl chloride from the alcohol and HCl. Siloxanes can of course be prepared from the reaction of HjO with many other kinds of hydrolyzable silanes (e.g., sulfato, iodo, bromo, fluoro, alkoxy, aryloxy, acyloxy, amino, amido, ketoximo) but such intermediates are themselves derived from chlorosilane precursors. Acetoxysilanes undergo thermolysis to yield siloxane bonds. 

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