Hydrosilylation reactions of methylhydridesiloxane to styrene and alpha-methylstyrene

摘要

The hydrosilylation reaction of alpha,omega-bis(trimethylsiloxy)methylhydridesiloxane to styrene and a-methylstyrene in the presence of the catalyst platinum hydrochloric acid (a 0.1M solution in tetrahydrofuran) at a 1:35 ratio of initial compounds at various temperatures (80-90 degrees C) was investigated, and methylsiloxane oligomers with aryl-substituted groups in the side chain were obtained. Complete hydrosilylation of all active Si-H groups did not take place. The hydrosilylation reaction order, activation energies. and rate constants were determined. The synthesized oligomers were characterized by H-1, C-13, and IR spectral data. For the full characterization of the hydride addition of methylhydridesiloxane to styrene by the quantum-chemical half-empiric Austin Model 1 (AM1) method for all initial, intermediate, and final products, in the modeling of the hydrosilylation reaction of methyldimethoxysilane to styrene, the heats of formation, energy changes of the system depending on the change of distance between C-Si bonds, and the charge values on the atoms, dipole moments, and bond orders were calculated. The synthesized oligomers were characterized by gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis, and wide-angle X-ray diffraction. (c) 2006 Wiley Periodicals, Inc.