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KMID : 1059519990430010042
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Journal of the Korean Chemical Society
1999 Volume.43 No. 1 p.42 ~ p.51
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Syntheses of Disubstituted Polysilanes(II):Sonochemical Study
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Lee Gyu-Hwan
Jeon Tae-Ha
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Abstract
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Polysilanes with stericafly bulky substituents, -[2-(R1R2-phenyl)propyl]Si[R3]-, such as poly(2-phenylpropyl)(n-hexyl)silane [R1=R2=H, R3=n-hexyl] were prepared by Wurtz-type coupling reactions with Na using a sonochemical method. The high-intensity ultrasound provided the formation of high quality Na dispersion in toluene and its active surface which was important for the synthesis of polysilanes in Wurtz-type coupling reaction was freshly and continuously regenerated during the process. The polysilanes products were mixtures of high molecular weight polymers with Mw of ∼10^6 and low molecular weight polymers with Mw of ∼10^3. It was found that the formation of high molecular weight polymer was greatly influenced by the substituents R3, directly attached to Si. On the contrary, changes on substituents (R1, R2) gave no fiffluences at all. Overall yields for polysilanes were 75-99% in general but high molecular weight polysflanes were obtained as a major product when substituent R3 is nhexyl group and low molecular weight polysilanes were obtained as a major product when substituent R3 is cyclohexyl and 2-phenylethyl groups. Effects of reaction conditions to polysilane yields were investigated.
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