18023-33-1Relevant articles and documents
Syntheses and properties of sila-functional oligosiloxanes - Linear and cyclic tetrasiloxanes with methyl and vinyl groups
Gunji, Takahiro,Watanabe, Miho,Abe, Koji,Abe, Yoshimoto
, p. 341 - 346 (2003)
The syntheses of the titled oligosiloxanes by controlled hydrolysis of the corresponding isocyanatosilanes under vapor phase or in THF (or THF/ether) were investigated. The vapor phase hydrolysis of RSi(NCO)3 (R = Me, Vinyl) with a water-1,4-dioxane vapor gave the disiloxanes [R(OCN)2Si]2O in yields of 85% (R = Me) and 90% (R = Vinyl). Further vapor phase hydrolysis of the disiloxanes provided the linear tetrasiloxanes NCO[SiR(NCO)O]3SiR(NCO)2 in yields of 71% (R = Me) and 69% (R = Vinyl). The cyclotetrasiloxanes [R(OCN)SiO]4 were synthesized in yields of 12% (R = Me) and 33% (R = Vinyl) or 24% (R = Me) and 58% (R = Vinyl) by hydrolysis of the disiloxanes or of the linear tetrasiloxanes in THF, respectively. On the other hand, the linear tetrasiloxanes OCN[SiR(OPri)O]3SiR-(OPri)(NCO) were obtained in yields of 50% (R = Me) and 56% (R = Vinyl) by hydrolysis of [R(OCN)(PriO)Si]2O prepared from RSi(OPri)(NCO)2 under mild conditions in THF/ether, while the cyclic tetrasiloxanes [R(PriO)SiO]4 were afforded in the yield of 61-62% by hydrolysis of the disiloxanes under more severe conditions in THF.
PREPARATION OF ALKOXYSILANES BY ETHERIFICATION OF CHLOROSILANES WITH REMOVAL OF HYDROGEN CHLORIDE BY VAPOR OF THE BOILING SOLVENT.
Belyakova,Pomerantseva,Efimova,Chernyshev
, p. 426 - 427 (2007/10/02)
Etherification of chlorosilanes with alcohols is the usual method of obtaining alkoxysilanes. Hydrogen chloride formed as a byproduct must be removed so as to avoid side reactions and increase the yield. The vapor of boiling solvent was used as an agent to remove hydrogen chloride from the reaction zone. Various solvents were tried and their effect on yield was studied. Removal of hydrogen chloride with the vapor of the boiling solvent during etherification of chlorosilanes makes it possible to obtain alkoxysilanes in 80-90% yield as the result of strong suppression of side reactions.
