Syntheses and properties of isocyanatodisiloxanes and their alkoxy- substituted derivatives

Article abstract of DOI:10.1246/bcsj.71.2967

Isocyanatooligosiloxanes and their alkoxy derivatives were synthesized. The hydrolysis of triisocyanato(methyl)silane followed by distillation provided 1,1,3,3-tetraisocyanato-1,3-dimethyldisiloxane in good yield. The reaction of 1,1, 3,3-tetraisocyanato-1,3-dimethyldisiloxane with ethanol, isopropyl alcohol, and t-butyl alcohol proceeded selectively to afford partially alkoxy substituted isocyanatodimethyldisiloxanes, (RO)n(NCO)(4- n)Me₂Si₂O (R = Et, n = 1 - 4; R = Pr(i), n = 1 - 4; and R = Bu(t), n = 1 - 2). On the other hand, the hydrolysis of tetraisocyanatosilane provided a mixture of isocyanatooligosiloxanes. Hexaisocyanatodisiloxane was isolated by distillation from the reaction mixture with some impurities produced by the disproportionation of hexaisocyanatodisiloxane on heating. The reaction of hexaisocyanatodisiloxane with alcohols provided partially alkoxy-substituted isocyanatodisiloxanes, [(RO)(n)(NCO)(3-n)Si]₂O (R = Et, n = 2-3; R = Pr(i), n = 1 - 3; and R = Bu(t), n = 1 - 2), selectively and in high yield.