Study on incompletely condensed "Double-Decker" type silsesquioxane: Their thermal and chemical reactivities

POLY 621

Dong Woo Lee, dw-lee@jaist.ac.jp, Graduate School of Materials Science, Japan Advanced Institute of Science and Technology, Asahidai 1-1, Tatsunokuchi, Ishikawa, 923-1292, Japan and Yusuke Kawakami, kawakamilab@jaist.ac.jp, School of Materials Science, Japan Advanced Institute of Science and Technology, Asahidai 1-1, Nomi, 923-1292, Japan.
Reaction products from (p-substituted phenyl)trialkoxysilane were studied in various solvents with lithium hydroxide, sodium hydroxide, and calcium hydroxide as catalyst. The crude products were treated with trimethylchlorosilane. The major product was concluded as a “double-decker” type octaphenylsilsesquioxane, 5,11,14,17-tetra(trimethylsiloxy) tetracyclo[7.3.3.33,7]octasiloxane by MALDI-TOF MS, 1H and 29Si-NMR and single crystal X-ray diffraction analyses. The highest yield of the octaphenylsilsesquioxane tetrasilanolate was obtained in the sodium hydroxide-catalyzed hydrolysis in refluxing water-2-propanol mixture. Unambiguous X-ray structures were obtained for the tetrasilanol, obtained by neutralization of the sodium salt with acetic acid, and the tetra(trimethylsilyl) ether. While the silanol groups of the tetrasilanol were stable up to 500ºC, the sodium salt smoothly reacted with dimethyldichlorosilane or methyldichlorosilane to give 7,7,17,17-tetramethyl-1,3,5,9,11,13,15,19-octaphenylhexacyclo[9.13.11,9.13,15.15,13.111,19]decasiloxane, and 7,17-dihydro-7,17-dimethyl-1,3,5,9,11,13,15,19-octaphenylhexacyclo [9.13.11,9.1.3,15.15,13.111,19]decasiloxane, as intramolecularly bridged product, respectively, at room temperature.