| 摘要 |
The invention comprises silarylene silanes of the formula HR2SiR1SiR2H where R is a monovalent hydrocarbon radical free from aliphatic unsaturation and R1 is a p-phenylene, 4,41-diphenylene, 4,41-diphenylene ether, 4,41-dimethylene benzene or 4,410dimethylene-diphenyl ether radical, and cyclotrisiloxanes of the formula (R2SiR1SiR2O-)3, and also comprises the use of these compounds for obtaining the corresponding silane diols and higher polysiloxanes. The silanes are prepared by reacting a dihalide XR1X, X being Cl or Br, with magnesium and a silane R2HSiX. A conventional Grignard solvent is preferably used, and the system may be activated by a trace of iodine or a reactive halide. The cyclic trisiloxanes are prepared by hydrolysing the silanes, preferably with aqueous ethanol and an alkali metal hydroxide catalyst, producing a siloxane of intermediate molecular weight which is thermally cracked in the presence of lithium hydroxide, and distilling off the cyclic compound. The in its turn can be polymerized using the usual alkaline catalysts to obtain high molecular weight linear polymers. The silanes can also be converted to the corresponding alkoxy silanes by reaction with alcohol using metallic sodium as catalyst. These alkoxy silanes can be hydrolysed with water, preferably in the presence of a hydroxide or pyridine, to produce the silane diols. These diols can also be prepared directly from the hydrogenosilanes by hydrolysing with strong alkali metal hydroxide solutions in aqueous alcohol followed by neutralization with an acid or acid salt. The silanols can be polymerized to high molecular weight, linear, orientable polymers by heating with alkali metal hydroxides or the amine salts of carboxylic acids as described in Specification 895,091. Copolymers with the usual siloxanes may also be prepared leading to rubbers. Uses: fibres, films, moulded articles. |
