Mild route to convert SiH compounds to their alkoxy analogues

Alkoxysilanes, particularly ethoxysilanes, are widely used as cross-linkers for the moisture-induced, room-temperature vulcanization (RTV) of silicones. Karstedt's platinum catalyst is shown to be effective at converting commercially available small hydrosiloxanes containing 1−8 SiH groups, and higher molecular weight telechelic and pendant hydrosiloxane polymers, into the corresponding alkoxy compounds. Kinetic studies demonstrated that relatively high concentrations of platinum-500 ppm- were required for practical reaction rates to be realized. As with other silyl ether-forming processes, steric hindrance at both carbon (alcohol) and silicon centers retard the reaction progress. This alternative use of the platinum catalyst, employed widely in the silicone industry, permits the ready formation of small molecule and polymeric RTV alkoxysiloxane cross-linkers that can be used to tailor network structures.