Electrochemical activation of diorganyl dialkoxysilanes for siloxane backbone extension
作者:Robert Keyrouz、Viatcheslav Jouikov
DOI:10.1039/b300620b
日期:——
The reaction of diorganyl dialkoxysilanes PhRSi(OAlk)2
(R = Ph, vinyl, OMe; Alk = Me, Et) with electrochemically reduced forms of oxygen provides reactive intermediates that insert into hexamethyldisiloxane or permethyl cyclosiloxanes, D3 and D4, to give siloxane products with one additional PhRSiO fragment; the process is thought to occur with the intermediacy of diorganylsilanones.
Embodiments of the invention are directed to the preparation of a discrete cyclosiloxane or a discrete mixture of cyclosiloxanes where a dihydroxysilane or dihydroxysiloxane condenses with a dihydrosilane or dihydroxysiloxane in the presence of a Lewis acid catalyst in a reaction phase including a solvent. The introduction of the dihydroxysilane or dihydroxysiloxane and dihydrosilane or dihydroxysiloxane is controlled such that the cyclocondensation occurs in a reaction phase that is dilute in the SiH and SiOH functionality permitting the isolation of the monocyclocondensation adduct in high yield with little higher molecular weight condensation products. In one embodiment of the invention 1,1-diphenyl-3,3,5,5-tetramethylcyclotrisiloxane is prepared in very high yield.