3, 3, 3-Trifluoropropyl(methyl)cyclosiloxanes
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The catalytic rearrangement of the cyclopentasiloxanes ΦmD5-m, where Φ represents a 3, 3, 3-trifluoropropyl(methyl)siloxane link and D a dimethylsiloxane link, and m=2–5 has been studied by the method described previously . The rate of rearrangement and the rate of formation of a linear polysiloxane rise with an increase in m from 2 to 4. The equilibrium concentration of the linear polysiloxane formed from ΦmD5-m and from ΦmD4-m (m=0–4)  is inversely proportional to the molar fraction of Φ links in the ring and rises with an increase in the total concentration of siloxane links in solution. Results have been obtained on the kinetics of the formation of the cyclosiloxanes ΦmDn (where m=0–5, n=0–5, and m+n=3-6) during the rearrangement of the cyclopentasiloxanes ΦmD5-m. It has been established that at equilibrium a mixture of cyclosiloxanes ΦmDn containing practically constant ratios of tetramers, pentamers, and hexamers (m+n=4, 5, and 6) is obtained, regardless of the composition and structure of the initial cyclosiloxane and of the conditions of rearrangement (polymerization). The cyclopentasiloxanes ΦmD5-m are less active in the process of rearrangement than the cyclotetrasiloxanes ΦmD4-m. The activity of the cyclosiloxanes in rearrangement in the presence of a base rises in the sequence D4≪ΦD3 ≈ Φ2D3<Φ3D2<Φ4D < Φ2D2 < Φ3D.
KeywordsPolymerization Methyl Organic Chemistry Molar Fraction Total Concentration
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