Organosilicon chemistry. Part VII. Reactions of bis(trimethylsilyl)-mercury with perfluoro-olefins and -acetylenes
Bis(trimethylsilyl)mercury reacts readily with fluoro-olefins under u.v. irradiation to give products resulting from the replacement of one or more vinylic fluorine atoms by trimethylsilyl groups, together with mercury and fluorotrimethylsilane. Thus perfluorocyclobutene gives 1,3,3,4,4-pentafluoro-2-trimethylsilylcyclobutene and tetrafluoro-1,2-bis(trimethylsilyl)cyclobutene, tetrafluoroethylene gives trimethyltrifluorovinylsilane, and hexafluoropropene gives a mixture of trimethyl-cis- and -trans-1,2,3,3,3-pentafluoroprop-1-enylsilanes, each of which reacts with the mercurial to give a different 1,3,3,3-tetrafluoro-1,2-bis(trimethylsilyl)propene. Intermediate 1 : 1 adducts of the mercurial and fluoro-olefin have been intercepted in some reactions; they decompose readily by a β-elimination to give the observed products. Bis(trimethylsilyl)mercury reacts under irradiation with hexafluoro-but-2-yne to give hexafluoro-1,2-bis(trimethylsilyl)but-trans-2-ene, and with tetrafluoropropyne to give mainly the product of replacing the acetylenic fluorine atom by a trimethylsilyl group, together with a small amount of tetrafluoro-1,2-bis(trimethylsilyl)propene.