Abstract: In a Rochow process, organohalosilanes are prepared by reacting metallic silicon particles with an organohalide in the presence of a copper catalyst and a co-catalyst. The invention uses as the co-catalyst a powder of co-catalyst active element-copper alloy containing substantial strain energy because this co-catalyst can reduce the activation time taken until a steady state is reached, which has been an outstanding problem in Rochow reaction, maintain the steady state over time and increase the selectivity of desired diorganodihalosilane for eventually increasing the yield based on the starting silicon.

Abstract: In the synthesis of organohalosilanes by the direct process of reacting an organic halogen with metallic silicon powder, a metallic copper catalyst in the form of a thermally active metallic copper powder having large strain energy is used.

Abstract: In a Rochow process, organohalosilanes are prepared by reacting metallic silicon particles with an organohalide in the presence of a copper catalyst and a co-catalyst. The invention uses as the co-catalyst a powder of co-catalyst active element-copper alloy containing substantial strain energy because this co-catalyst can reduce the activation time taken until a steady state is reached, which has been an outstanding problem in Rochow reaction, maintain the steady state over time and increase the selectivity of desired diorganodihalosilane for eventually increasing the yield based on the starting silicon.

Abstract: Organohalosilanes are prepared by reacting an organic halide with metallic silicon particles in the presence of a metallic copper catalyst which is a metallic copper powder in flake form having a bulk specific gravity of 1-3 g/cm3 and a mean particle size of 10 &mgr;m to 1 mm as measured by laser diffraction particle size distribution analysis.