| 摘要 |
A method for the production of 1,2-siloxa-alkane compounds comprises the reaction of a silane (A) of formula RaSi(O-CH2-CH = CH2)4-a where a is 0, 1, 2 or 3, with a silane (B), HSiRbX3-b where b is 0, 1 or 2, and R is a saturated hydrocarbon group in the presence of a catalyst promoting the addition of olefinically unsaturated compounds to Si-H groups. Temperatures above 50 DEG C., preferably between 80 DEG and 90 DEG C., are suitable. An autoclave may be necessary. The silanes (A) and (B) may be represented by single compound, e.g. R12Si(H)OCH2CH = CH2 carrying both an Si-H group and an alkenoxy group, the remaining substituents, (R1), being halogen, or alkoxy, allyloxy or hydrocarbon groups. In this case the reaction is performed by dripping reactant plus catalyst into a heated vessel. The products may be cyclic monomers <FORM:1036089/C3/1> or cyclic or linear polymers of unit -SiR2-(CH2)3-O-The latter decompose on heating into the monomers, while the monomers slowly polymerize at room temperature. In solution a state of equilibrium is established. Examples describe the reactions of trimethyl allyloxy silane with methyldichlorosilane and with triethoxysilane, using H2PtCl6 in alcohol, and Pt on carbon, respectively, to give 1-chloro-1-methyl- and 1,1-diethoxy-1,2-siloxacyclopentane, on distillation from baths at 250-350 DEG C. With silicochloroform, using H2PtCl6 and triethylene diamine, a polymer of 1,1-dichloro-1,2-siloxacyclopentane was obtained which was not distilled. A further example describes the cyclization of methyl allyloxy chlorosilane prepared from allyl alcohol and methyldichlorsilane. |
