Stable Silanetriols That Contain tert‐Alkoxy Groups: Versatile Precursors of Siloxane‐Based Nanomaterials

Abstract

Novel tert-alkoxysilanetriols (ROSi(OH)(3), R=adamantyl and 3-ethyl-3-pentyl) have been prepared from the corresponding tert-alkoxytrichlorosilanes and successfully used as molecular building blocks to produce ordered siloxane-based nanomaterials. Controlled hydrolysis of the alkoxytrichlorosilanes led to the formation of crystalline powders of alkoxysilanetriols that were stable under ambient conditions. Solid-state polycondensation of the alkoxysilanetriols occurred upon heating, which led to the formation of ordered silica-organic nanocomposites with laminated morphologies. On the other hand, silylation of the tert-alkoxysilanetriols with chlorotrimethoxysilane enabled us to synthesize well-defined oligomeric alkoxysilanes (ROSi[OSi(OMe)(3)](3)). Hydrolysis and polycondensation of these oligomers followed by acid treatment gave microporous silica with narrow pore size distributions. Thus, tert-alkoxy groups serve not only as protecting groups of siloxane species to regulate hydrolysis and polycondensation, but also as templates to generate micropores thereby providing unique synthetic pathways for the design of ordered silica-based materials.

Selective Formation of Alkoxychlorosilanes and Organotrialkoxysilane with Four Different Substituents by Intermolecular Exchange Reaction

“…Organoalkoxysilanes having two or three different alkoxy groups are potentially useful for producing new siloxane‐based materials because of the different reactivities among alkoxy groups. For example, long‐chain alkoxy groups and sterically hindered tertiary alkoxy groups are more stable against hydrolysis than short‐chain and lower alkoxy groups, which allows the formation of nanostructured materials by self‐assembly of oligosiloxanes having both Si−OR and Si−OH groups . The reactivity of alkoxysilanes for siloxane bond formation with a Lewis acid catalyst also depends on the type of alkoxy groups.…”

An Innovative Approach for Highly Selective Direct Conversion of CO2 into Propanol using C2H4 and H2

“…If the Si(OH) 3 moiety is however sterically protected by bulky substituents, stable and chemically robust compounds can be easily obtained with applications ranging from bioactivity to supramolecular chemistry and surface modifications 20–22. Even stable silanetriols themselves may act as valuable starting materials for a controlled oligomerization as was shown recently 17,23–26…”

At the Edge of Stability – Preparation of Methyl‐substituted Arylsilanetriols and Investigation of their Condensation Behavior

“…[20][21][22] Even stable silanetriols themselves may act as valuable starting materials for a controlled oligomerization as was shown recently. [17,[23][24][25][26] Since the first report of a silanetriol, i.e. PhSi(OH) 3 , [1] a number of aryl-substituted silanetriols of the type X-C 6 H 4 -Si(OH) 3 (X = p-NMe 2 ; p-OMe; p-Me; m-Me; m-Cl; m-CF 3 ), as well as TipSi(OH) 3 (Tip = 2,4,6-triisopropyl-phenyl), TerSi(OH) 3 [Ter = "terphenyl" = bis(2,4,6-trimethyl-phenyl-)-phenyl-] and aryl linked bis-silanetriols have been reported.…”