Incompletely Condensed Silsesquioxanes: Formation and Reactivity

Abstract

ABSTRACT:Hydrolysis reaction products from aryltrialkoxysilanes were studied in various solvents with alkali and alkaline earth metal hydroxides. Definite products could be isolated when sodium hydroxide was used. Reaction of trimethoxy-or triethoxyphenylsilane with equimolar amounts of sodium hydroxide to the silicon compound in refluxing water-i-propanol gave cyclic sym-cis tetraphenylsilsesquioxanetetraol tetrasodium salt as the principal product. When a little excess of sodium hydroxide than half molar amounts to the silicon compound was used, only small amounts of the cyclic tetramer was noticed among the initial products together with cubic octaphenylsilsesquioxane, evidenced by mass spectroscopy. Heptaphenylsilsesquioxanetriol trisodium salt was formed after refluxing for 4 h and following stirring for 15 h at room temperature. With longer reaction time, a double-decker octaphenyl silsesquioxanetetraol tetrasodium salt was obtained in high yield with the consumption of heptaphenylsilsesquioxanetriol. While the silanols of double-decker octaphenyl silsesquioxanetetraol were thermally stable against condensation up to 230 C, the sodium salt smoothly reacted with dimethyldichlorosilane to give completely condensed cage, 7,7,17,17-tetramethyl-1,3,5,9,11,13,15,19-octaphenylhexacyclo[9.

Synthesis of a “Butterfly Cage” Based on a Double‐Decker Silsesquioxane

“…Compound 2 was recrystallized in a mixed solvent of chloroform and 2‐propanol (2:1) affording colorless crystals. A report describing the facile synthesis of 1 b , coupled with the dichlorodimethylsilane afforded T 8 D 2 ( 2 ) and set the groundwork for this procedure . However, the crystal structure of 2 was not determined with the proposed DDSQ structure at that time.…”

“…The doubly‐extended butterfly cage T 8 D 4 3 , T 8 D 6 4 , and T 8 D 8 5 , both ends of which are linked to oligosiloxane chains, were synthesized in 91 %, 86 %, 64 %, respectively by the reaction of DDSQ‐tetraol 1 a with methyl substituted oligosiloxane in the presence of triethylamine (Scheme ). Tetraol 1 a can be prepared in high yield from DDSQ‐(ONa) 4 1 b that was easily synthesized from trimethoxyphenylsilane in 2‐propanol via hydrolytic condensation using sodium hydroxide and refluxing for 4 h followed by stirring for 15 h at 20 °C according to a previously reported method . The condensation reactions between tetraol 1 a and dichlorooligosiloxanes are somewhat slow, requiring a reaction time of 14 h at room temperature and several hours at reflux.…”

“…The 1 H NMR, 13 C NMR, and 29 Si NMR spectra (Figure ) clearly showed the T main SQ frame with d ‐structure siloxanes were formed . All other spectral data were used to assign the product structures.…”

Silsesquioxane-Based Polymers: Synthesis of Phenylsilsesquioxanes with Double-Decker Structure and Their Polymers

“…The structure of DD-OH was confi rmed by 29 Si-NMR and other spectroscopic analyses (Scheme 2) [10,11]. In quite recent time, Lee reported that the double-decker shaped silsesquioxane seems to be produced with the consumption of the partial cage and the cyclic siloxanes in the same condition [12].…”

Preparation and characterization of polybenzoxazine/trisilanol polyhedral oligomeric silsesquioxanes composites

“…Trisilanolphenyl POSS was synthesized from phenyltrialkoxysilane, NaOH and deioned water, and then acidified by acetic acid according to the literature method [21,22]. The solution was distilled by reduced pressure, and white crystal solid was dried under vacuum.…”