| 摘要 |
In making an organopolysiloxane by condensing a compound of the formula: <FORM:0943607/C3/1> wherein each R is a monovalent hydrocarbon radical (saturated or unsaturated) with or without halogen, hydroxyl, cyano, alkoxy or aryloxy substituents, R1 is H or an alkyl radical and n is at least 1, a fluorine-substituted aliphatic acid is used as the condensation catalyst. Catalysts specified are mono-, di-, tri- and chlorodifluoroacetic acids; 2-fluoropropanoic, 2-fluorobutanoic, 2,3-difluoropentanoic, fluoromalonic, perfluorosuccinic and perfluoroglutaric acids. The process, which may be effected in an inert organic liquid, is generally conducted at 25 DEG to 170 DEG C., and the by-produced water or water and alcohol is preferably continuously removed, the catalyst being removed from the end-product, if desired, as by washing with water. The linear products may be end-blocked by reaction with a trihydrocarbon halosilane. In a modification, alkoxysilanes RrSi(OR1)4-r, where r is 1, 2 or 3, and R1 and R are defined above, and in addition, R may be gamma hydroxypropyl, are co-condensed with the starting organosilicon compound to yield diorganosiloxanes containing functional radicals uniformly spaced throughout or at the ends of the siloxane chain. In a typical example (1) HO[(CH3)2SiO]20H was heated with CF3. COOH to yield a siloxane gum free of low molecular weight cyclics. The products may be cyclic siloxanes, siloxane gums or siloxane oils.
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