The Reaction of Olefins and Chlorohydrosilanes

Development of Fluoro-Silicone Elastomers

“…Its use in plastics and elastomers to give materials with superior properties is well known: the chemical resistance of polychlorotrifluoroethylene is second only to that of Teflon, and rubber-like materials containing chlorotrifluoroethylene (such as Kel-F Elastomer manufactured by the M. W. Kellogg Co.) are resistant to oxidizing agents such as fuming nitric acid and do not swell appreciably in organic fuels. Chlorotrifluoroethylene has also been found to 4 ake part in free radical reactions better than the perfluoroZ5lefins with the possible exception of tetrafluoroethylene.…”

“…The preparation of a silicone rubber involves several steps which are: 1) the preparation of the monomer (such as (CH 3 )}SiCI 2 ); 2) the hydrolysis to silicone units, CH 3 CH 3 I I -0i -0-Si -0-…”

“…However, the preparation of fluoro-alkylsilanes by this method seems to offer a number of difficulties. For example, no silane of the type RfCH 2 SiX 3 has yet been made because of the apparent inability of compounds such as CF 3 The reaction of the Grignard reagent with silicon tetrachloride gave tetrakis-(3, 3,4,4, 5, 5, 5-heptafluoropentyl)-silane (10% yield), the tris compound (47% yield), the bis compound (25% yield) and heptafluoropentyltrichlorosilane (20% yield). It can be seen that the formation of undesired, highly alkylated silanes used up a considerable portion of the fluoro Grignard reagent (16).…”

“…A communication appeared in 1947 describing the thermal addition of silanes to various olefins (4). For example, n-propylmethyldichlorosilane was prepared in 72% yield by heating propylene and rnethyldichlorosilane overnight at 3000.…”

“…However, because of the diverse claims and experimental procedures described, it is difficult to get a general idea of the scope or mechanism of the reaction. For instance, patents have been issued which describe as catalyst peroxides (3,11), aluminum chloride (8), platinum on charcoal (27), and in some cases, reaction has been shown to proceed without any of these substances (20).…”