Octa, deca, and dodeca(4-nitrophenyl) cage silsesquioxanes via 4-trimethylsilylphenyl derivatives

Abstract

Pure octa, deca, and dodeca(4-nitrophenyl) cage silsesquioxanes were obtained by regio-selective 4-nitration of octa, deca, and dodeca(4-trimethylsilylphenyl) cage silsesquioxanes via ipso-substitution of trimethylsilyl-phenyl bonds by fuming nitric acid. 3-Nitration of octa(4-methylphenyl)octasilesquioxane was also described. The starting octa(4-methyl-, 4-isopropyl- and 4-trimethylsilylphenyl)octasilsesquioxanes were selectively formed in 9-21% isolated yield in the presence of hydrochloric acid. Mixtures of octa, deca and dodecasilsesquioxanes, with decasilsesquioxane as the main component, were formed in the presence of tetrabutylammmonium fluoride as a catalyst. All the cage compounds could be separated mainly by crystallization.

Cage octaphenylsilsesquioxane from cyclic tetrasiloxanetetraol and its sodium salt

“…As already discussed, Olsson and Laine have reported the preparation of a mixture of functionalized T 8 compounds through electrophilic substitution reactions like nitration or bromination of phenyl rings [15,16]. However, the selectivity was not well-controlled.…”

“…Acetic acid (0.37 g, 6.24 mmol) was added dropwise to THF (30 mL) dispersion of sodium 4-bromo-substituted phenylcyclotetrasiloxanolate (1.0 g, 1.04 mmol), reported by Pizzotti et al [16]. After stirring for 2 h, water (200 mL) and ether (100 mL) were added to the reaction mixture.…”

Novel organic–inorganic hybrids based on T8 and T10 silsesquioxanes: synthesis, cage-rearrangement and properties

“…Especially, when both T 10 and T 12 compounds have similar chemical and physical properties, it is difficult to find a simple method of their separation. 12 Moreover, separation of cage-like compounds 15 possessing different numbers of side-chains is also cumbersome. For instance, Laine et al pointed out that styrenyl-functionalized cage silsesquioxanes exhibited the same retention times during chromatographic purification, although they had different numbers of phenyl substituents.…”

“…For 30 example, Kawakami et al reported the formation of T 8 , T 10 and T 12 cages (octa-, deca-, and dodeca-4-nitrophenyl cage silsesquioxanes) during hydrolysis of 4-substitutedphenyltriethoxysilane in the presence of tetrabutylammonium fluoride (TBAF). 15 To obtain pure fractions, various 35 crystallizations using acetonitrile/THF (v/v, 1:1), hexane, and ethanol/hexane (v/v, 1:4) systems were carried out, and each fraction was purified by further recrystallization. Also, Laine et al, inspired by the Kawakami procedure, utilized it for T 10/12 stilbenevinyl-silsesquioxane separation.…”

“…Thin layer chromatography (TLC) was performed on Merck silica gel 60 F254 plates. Chromatograms were visualized using UV light (254 15 nm). For detection of amine, the chromatograms were first dipped in a 5% (w/v) solution of ninhydrin in 95% aqueous ethanol, and finally charred on a hot plate.…”