| Methods for making SiCl4 under mild conditions from tetramethoxysilane and other readily available materials in high yields by routes which present few major engineering challenges have been investigated. Much of the emphasis of the work is on the synthesis of SiCl4 from tetramethoxysilane and SOCl2 with dimethylformamide as a catalyst. This synthesis gives SiCl4 in good yields at atmospheric pressure and moderate temperatures. Some emphasis is on the use of catalysts other than dimethylformamide including dimethylacetamide, triethylamine, and (chloromethylene)dimethyliminiumchloride all of which are effective catalysts, and on the use of higher tetraalkoxysilanes. The higher tetraalkoxysilanes investigated serve as good reactants. The byproduct of the tetraalkoxysilane-SOCl2 reactions is the alkyl chloride, methyl chloride when tetramethoxysilane is used.;Emphasis is given also to the uncatalyzed synthesis of SiCl4 from tetramethoxysilane and HCl gas. This work shows that one methoxy group of tetramethoxysilane can be displaced by a chloro group under mild conditions. Additional work shows that the displacement of one methoxy group can be achieved with liquid HCl at low temperatures. These results suggest that the replacement of all four methoxy groups by chloro groups can be achieved with the use of a dehydrating agent, appropriate temperatures and pressures, and suitable adjustment of reactant and product flows in the reaction vessel.;In separate work, methods for the preparation of silicate scroll polymers with trimethylsiloxy groups grafted on one side of the scroll, a diameter of several hundred Angstroms, and a core of about 50 Angstroms which is filled with PbS have been investigated. In this work, the unfilled scroll polymer was made, partially unfurled, filled with Pb(OAc)4, and treated with thioacetamide and H2S gas. This gave the PbS-filled scroll polymer. In related work, the cores of the same scroll polymer were filled with platinum by treating the partially unfurled polymer with a platinum catalyst, Karstedt's catalyst, and then heating the treated polymer. This work opens the way to make silicone-insulated nanorods of semiconductors such as CdS and CdSe, and silicone-insulated nanowires of highly conducting metals such as silver. |
