Preparation of Chloropolysilane from the Copper-catalyzed Reaction of Silicon Metal and Hydrogen Chloride

Abstract

The copper catalyzed reaction of silicon metal powder with hydrogen chloride by flow method was studied in order to find a convenient preparative method of chloropolysilane, and also to elucidate the mechanism of this reaction.This reaction was found to start at about 170∼230°C, and once the reaction occurred, the contact mass is activated and the reaction takes place even at 170°C. When the most adequate conditions were adopted, chloropolysilanes were obtained in the condensate as efficiently as 30 wt.% yield based on hydrogen chloride.As to the mechanism of the reaction, it seems to be plausible that the first step of the reaction is an attack of hydrogen chloride on aluminum which is usually present in the commercial silicon metal. The second step is the reaction between silicon hydride, which is derived from the first step reaction upon the silicon contact mass and metallic copper forming the silicon-copper bonding. The third step is the cleavage reaction of copper-activated silicon by hydrogen chloride to produce chlorosilanes under the presence of aluminum chloride. The aluminum chloride is also derived from the first step reaction, and copper is regenerated in metal form which can circulate among the latter two reaction steps as long as the effective silicon component is present.