CLEAVAGE OF POLY(DIORGANOSILOXANES) BY TRIMETHYLALUMINUM

The interaction of AlMe3 at elevated temperatures with poly(diorganosiloxanes), (RMeSiO)x (R = Me, n-C18H37, –CH2CH2CF3, Ph), leads to rupture of the silicon–oxygen framework and yields the dimeric aluminum siloxides [Me2Al(OSiMe2R)]2. The molecular structure of [Me2Al(OSiMe2Ph)]2 has been confirmed by X-ray crystallography. The compound [Me2Al(OSiMe2Ph)]2 crystallizes in the monoclinic space group P21/n with unit cell dimensions a = 7.970 (3) Å, b = 24.563 (10) Å, c = 13.322 (4) Å, β = 105.05 (3)°, Z = 4, 2754 observed data, R = 0.0478, and Rw = 0.0639. At ambient temperatures the cyclic trisiloxane (Me2SiO)3 forms a highly fluxional 1:1 Lewis acid-base adduct with AlMe3. © 1990, American Chemical Society. All rights reserved.