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3, 3, 3-Trifluoropropyl(methyl)cyclosiloxanes
Authors:Yu. A. Yuzhelevskii  E. G. Kagan  V. N. Frolov  A. L. Klebanskii
Affiliation:(1) Lebedev All-Union Scientific Research Institute for Synthetic Rubber, Leningrad
Abstract:The influence of the number of 3, 3, 3-trifluoropropyl(methyl)siloxane links (PHgr/PHgr) in the cyclotetrasiloxanes PHgrmD4-m, where D represents the dimethylsiloxane link and m=0–4, on the rearrangement of these compounds in acetone solution under the action of sodium siloxanolate has been studied. The rearrangement takes place with the formation of a linear polysiloxane the degradation of which yields, in addition to the initial ring, cyclosiloxanes with a different structure. The rate of rearrangement of PHgrmD4-m and of the formation of a linear polysiloxane rises with an increase in m from 0 to 3. The equilibrium concentration of the linear polysiloxane formed from PHgrmD4-m is inversely proportional to m. Results have been obtained on the kinetics of the formation of the cyclosiloxanes PHgrmDn, where m=0–5, n=0–5, and m+n=3–6, in the rearrangement of the rings PHgrD3, PHgr2D2, PHgr3D, and PHgr4. The reactivity of the siloxane links rises in the sequence sim (CH3)2Si-O-Si(CH3)2 sim<sim (CF3CH2CH2)-(CH3) Si-O-Si(CH3)2 sim<(CF3CH2CH2) (CH3)Si-O-Si(CH3) (CH2CH2CF3) sim. Because of the negative inductive effect transferred through the siloxane links, the 3, 3, 3-trifluoropropyl groups strongly activate the siloxane ring with respect to nucleophiiic reagents.For part I, see [3].
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