Y-Silicon effect

A remarkably high rate accelaation by a y-sUyl group was found for the acyclic primary sulphonate 241, which is 218(X) times more reactive than its silicon-free analogue. In this case a 1,2-migration of Me3SiCH2 occurs after the rate-limiting formation of the carbocation 243, yielding the more stable tetiary carbocation 244 (equation 38). For the secondary sulphonate 242 a smaller kinetic y-silicon effect was detected . ... 

In the adamantyl framework the y-silicon effect was studied by Grob and coworkCTs . The first-y-trimethylsilyl substituent (cf 245) enhances the solvolysis rate of 1-bromoadamantane 246 by a factor of only 8.6 and the second trimethylsUyl group in... 

Y. Watanahe, Effects of annealing on oxygen depth profiles and chemical etching rates of thermally grown silicon oxides, J. Electrochem. Soc. 145(4), 1306, 1998. 

N. Hirosaki, Y. Okamoto, M. Ando, F. Munakata and Y. Akimune, Effect of Grain Growth on the Thermal Conductivity of Silicon Nitride , Journal of the Ceramic Society of Japan, 104, 1996, 50 54. 

T. Ogasawara and Y. Mabuchi, Effect of Humidity and Cyclic Loading Condition on Fatigue behavior of Silicon Nitride , J. Ceram. Soc. Jap., Int. Edition, 101, 1993, 1122-1127. 

An impressive example for the demonstration of the transition metal effect on the reactivity of SiH-units with respect to oxygen insertion is given by the bis(ferrio)-siloxane 9a, containing a metal-substituted as well as a metal-firee silicon atom. Due to the influence of the neighboring transition metal fragments the a-silicon differs considerably both in chemical and spectroscopic properties from the normal y-silicon. As a consequence, the reaction with dimethyldioxirane leads to the exclusive formation of the bis(ferrio)-disiloxanol 11, isolated in excellent yield (Eq. 2) [12]. The y-SiH moiety remains unaffected even when an excess of dimethyldioxirane is employed. 

Kim H-S, Zouzounis EC, Xie Y (2002) Effective method for stress reduction in thick porous silicon films. Appl Phys Lett 80 2287-2289... 

M.J. Wang, M.D. Morris, Y. Kutsovsky. Effect of fumed silica surface area on silicone rubber reinforcement Kautsch. Gummi, Kunstst., 61 (3), 107-117,2008. 

Zhou, X. G., Yu, H. J., Huang, B. Y. (2007). Effect of Silicon Carbide Interlayers on the Mechanical Behavior of T800-HB-Fiber-Reinforced Silicon Carbide-Matrix Composites. Key Engineering Materials, 368-372,1844-1846. doi 10.4028/www. scientific.net/KEM.368-372.1844. 

Chung PM-Y, Kawaji M (2004) The effect of channel diameter on adiabatic two-phase flow characteristics in micro-channels. Int J Multiphase Flow 30 735-761 Colgan E (2005) A practical implementation of silicon microchannel coolers for high power chips. 

Kubo, Y., Sakurai, Y., Tanaka, Y., Nakamura, T., Kawata, H. and Shiotani, N. (1997) Effects of self-interaction correction on Compton profiles of diamond and silicon, J. Phys. Soc. Jpn., 66, Till 2780. 

The softening effect of silicones results from their lubrication behaviour that affects both the surface and the interior of the fibre. The behaviour of polysiloxanes of the 10.230 type can be varied by adjusting the average values of x and y and the range of chain lengths present. Further variations are possible by varying the R groups. In view of the technical and... 

The reader will no doubt have realized that the y-hetero rearrangement is well-known, being none other than the familiar neighboring group effect. The a-hetero rearrangement is known for all of the elements mentioned but boron, aluminum, and silicon. Perhaps a suitably constituted boron compound would rearrange to a zwitterionic product as follows ... 

Cui, Y. Zhong, Z. Wang, D. Wang, W. U. Lieber, C. M. 2003. High performance silicon nanowire field effect transistors. Nano Lett. 3 149-152. 

---