- Preparation of cyclic oligosiloxane
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Cyclic oligosiloxane is prepared through disproportionation reaction of organopolysiloxane in the presence of a catalyst. Cyclic oligpsiloxane of high purity can be produced in high yields by using a catalyst having formula (4): wherein M is Al, Ti, Zr, Sn or Zn, p is the valence of M, and R4 is a monovalent hydrocarbon group or the like.
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Page/Page column 7-8
(2008/06/13)
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- PROCESS FOR PREPARING CYCLIC ORGANOHYDROGENSILOXANES
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A process for preparing cyclic organohydrogensiloxanes comprises: (A) contacting a silane of the formula RHSiCl2, where R is selected from alkyl radicals having 1 to 12 carbon atoms and aryl radicals, with water to form a hydrolyzate comprising cyclic organohydrogensiloxanes and linear organohydrogensiloxanes, and (B) contacting the hydrolyzate with an acidic rearrangement catalyst in the presence of an inert liquid diluent to increase the ratio of the cyclic organohydrogensiloxanes to linear organohydrogensiloxanes in the hydrolyzate. The acidic rearrangement catalyst is an organic compound containing a strong acid group, for example a sulphonic acid, which is dissolved in the inert diluent present.
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Page/Page column 6; 7
(2008/06/13)
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