REACTION OF THE SI-CL BOND WITH TRIALKYL ORTHOFORMATES - PREPARATION OF ALKOXY-SUBSTITUTED SILANES

Trialkyl orthoformates in the presence of aluminium chloride represent quite useful reagents to generate silicon alkoxides from chloro silan es. 3-Cyanopropyltrichlorosilane and 2-[(2-trichlorosilyl)ethyl]-pyrid ine give the triethoxy compounds 3-cyanopropyltriethoxysilane and 2-[( 2-triethoxysilyl)ethyl]-pyridine respectively. Via this route, in meth ylchlorooligosilanes a partial or complete exchange of the chlorine su bstituents for alkoxy groups occurs depending on the starting molar ra tio of silane:HC(OR)(3) (R = Me, Et). SiCl2Me groups react to SiClMe(O R) first before SiMe(OR)(2) groups are formed. (Si)(2)SiClMe units are not affected by HC(OR)(3). (C) 1997 Elsevier Science S.A.