51777-38-9Relevant articles and documents
Protecting and Leaving Functions of Trimethylsilyl Groups in Trimethylsilylated Silicates for the Synthesis of Alkoxysiloxane Oligomers
Yoshikawa, Masashi,Tamura, Yasuhiro,Wakabayashi, Ryutaro,Tamai, Misa,Shimojima, Atsushi,Kuroda, Kazuyuki
supporting information, p. 13990 - 13994 (2017/10/31)
The concept of protecting groups and leaving groups in organic synthesis was applied to the synthesis of siloxane-based molecules. Alkoxy-functionalized siloxane oligomers composed of SiO4, RSiO3, or R2SiO2 units were chosen as targets (R: functional groups, such as Me and Ph). Herein we describe a novel synthesis of alkoxysiloxane oligomers based on the substitution reaction of trimethylsilyl (TMS) groups with alkoxysilyl groups. Oligosiloxanes possessing TMS groups were reacted with alkoxychlorosilane in the presence of BiCl3 as a catalyst. TMS groups were substituted with alkoxysilyl groups, leading to the synthesis of alkoxysiloxane oligomers. Siloxane oligomers composed of RSiO3 and R2SiO2 units were synthesized more efficiently than those composed of SiO4 units, suggesting that the steric hindrance around the TMS groups of the oligosiloxanes makes a difference in the degree of substitution. This reaction uses TMS groups as both protecting and leaving groups for SiOH/SiO? groups.
Dendritic, nanosized building block for Siloxane-based materials: A spherosilicate dendrimer
Kawahara, Kazufumi,Hagiwara, Yoshiaki,Kuroda, Kazuyuki
supporting information; scheme or table, p. 13188 - 13196 (2012/02/06)
A spherosilicate dendrimer (DMS-1) with closely spaced reaction sites (Si-H groups) on the dendrimer surface has been synthesized by stepwise silylation of double-four-ring silicate with chlorotriethoxysilane (ClSi(OEt)3) and subsequently with chlorodimethylsilane (ClSiHMe2). DMS-1 consists of a maximum of 40 Si atoms in the interior frameworks and 24 reactive Si-H groups on the surface. Because DMS-1 is spherical and about 1.5 nm in diameter, it can be regarded as the smallest well-defined silica-based nanoparticle. DMS-1 also forms molecular crystals and is soluble in typical organic solvents. A molecularly ordered silica-based hybrid can be prepared by heating a cast film of DMS-1 at 180 °C for 5 days. The surface of DMS-1 can be modified by hydrosilylation with 1-hexadecene, triethoxyvinylsilane, and allylic-terminated tetraethylene glycol monomethyl ether. More than 20 Si-H groups out of 24 react with these reagents. The solubilities of the products depend on the modification. DMS-1 is not only a building block for nanohybrids, but also the smallest and most precisely designed siloxane-based nanoparticle.
