Reactions of Ph(ClCH2)SiH2 with fluoride ion sources: Formation of fluorine-terminated siloxanes

✍ Scribed by Jean L. Huhmann; Joyce Y. Corey

• Book ID: 102846554
• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 954 KB
• Volume: 4
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/hc.520040214

✦ Synopsis

The fluoride ion-induced rearrangement of Ph (ClCH,)SiH, was expected to provide either Ph-MeSiHF (migration of hydride) or (PhCH2)SiH2F (migration of phenyl). However, when B u $ I f F -(commercial TBAF) is added to Ph(ClCH2)SiH2, a mixture of fluorine-terminated siloxanes, FPh-MeSiO(PhMeSiO)&MePhF, is obtained. The presence of the Me group suggests a rapid anion-induced migration of hydride to produce PhMeSiHF which reacts further with water present in TBAF samples. When the reaction mixture is cooled to 0°C or is monitored at the ,early stage of the reaction, the major products are PhMeSiF,, PhMeSi(OH)F, Ph-MeSi(OH),, and FPhMeSiOSiMePhF which are proposed as the building blocks for the siloxanes. When dried CsF in CH3CN is used, the major products are PhMeSiF, and PhMeSiH, which are assumed to form from the fluoride ion-induced disproportionation of PhMeSiHF. The reaction chemistry is rationalized in terms of hypewalent intermediates. The fluoride ioninduced reaction:; of PhMeSiH, and PhMeSiCl, are also described and compared to those of Ph (ClCH2)S iH2.