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.
研究人员通过在气相或 THF(或 THF/
乙醚)中控制相应异
氰酸硅烷的
水解,合成了标题低
硅氧烷。RSi(NCO)3(R = Me,Vinyl)与
水-
1,4-二氧六环蒸汽的气相
水解得到了二
硅氧烷[R(OCN)2Si]2O,产率分别为 85%(R = Me)和 90%(R = Vinyl)。进一步对二
硅氧烷进行气相
水解,可得到线性四
硅氧烷 NCO[SiR(NCO)O]3SiR(NCO)2 ,产率分别为 71%(R = Me)和 69%(R = Vinyl)。通过在 THF 中
水解二
硅氧烷或线型四
硅氧烷,合成了环四
硅氧烷 [R(OCN)SiO]4,产率分别为 12%(R = Me)和 33%(R =
乙烯基),或 24%(R = Me)和 58%(R =
乙烯基)。另一方面,由 RSi(OPri)(NCO)2制备的[R(OCN)(PriO)Si]2O在 THF/
乙醚中的温和条件下
水解得到线性四
硅氧烷 OCN[SiR(OPri)O]3SiR(OPri)(NCO),产率分别为 50%(R = Me)和 56%(R = Vinyl)、而环状四
硅氧烷[R(PriO)SiO]4 则是在 THF 中以更苛刻的条件
水解二
硅氧烷得到的,产率为 61-62%。