The title compound, [(Me3Si)2N]2Si: (1), was prepared by the reduction of [(Me3Si)2N]2SiBr2 (2) with potassium graphite at -78 degrees C. Unlike the corresponding germanium and tin compounds, 1 is unstable, but it can be studied in solution at low temperatures. The 29Si NMR chemical shift of 1 measured at -20 degrees C was 223.9 ppm, in good agreement with a value obtained from model calculations of 233 ppm. Reaction of solutions of 1 with methanol or phenol gave the trapping products expected for the silylene, [(Me3Si)2N]2Si(H)OR (R = CH3, C6H5).
The hydrosilylation of cyclic alkenes and linear alkenes with trialkylsilanes in the presence
of Lewis acid catalysts under mild conditions gave the corresponding (trialkylsilyl)alkanes
in fair to good yields. The reaction of 1-methylcyclohexene with triethylsilane at −20 °C
gave cis-1-triethylsilyl-2-methylcyclohexane with regio- and stereoselectivity via a trans
hydrosilylation pathway. Cycloalkenes having an alkyl group at the double-bonded carbon
showed better reactivity than nonsubstituted compounds in the Lewis acid-catalyzed
hydrosilylation. The catalytic reactivity of Lewis acids decreases in the following order: AlBr3
> AlCl3 > HfCl4 > EtAlCl2 > ZrCl4 > TiCl4. When triorganochlorosilane was used as an
activator in the aluminum chloride-catalyzed reaction, the hydrosilylation rate drastically
increased. The results are consistent with a stepwise mechanism proceeding via the formation
of a trialkylsilylenium ion intermediate.
In this study, multi-walled carbon nanotubes (MWNTs) reinforced poly(methyl methacrylate) (PMMA) nanocomposites were prepared by in situ polymerization. Glycidyl methacrylate (GMA) grafted MWNTs (GMAMWNTs) were used to improve the compatibility between the MWNTs and the PMMA matrix. The physical and rheological properties of the PMMA nanocomposites with different GMA-MWNT contents were examined. The GMA-MWNTs were embedded homogeneously into the PMMA matrix by in situ polymerization. A uniform dispersion of GMA-MWNTs produced nanocomposites with enhanced physical properties. The maximum tensile strength was observed with the 2.0 wt% GMA-MWNT loading, and was 41% higher than that of pure PMMA. In addition, the viscosity of the nanocomposites was increased gradually by the addition of GMA-MWNTs. The storage (G') and loss modulus (G'') were increased significantly by increasing the GMA-MWNT content, which was attributed to the strong interaction between highly dispersed GMA-MWNTs and PMMA matrix.
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