PRODUCTION OF METHYLCHLOROSILANE

Methylchlorosilanes are prepared from silicon and methyl chloride in the presence of a copper catalyst and optionally promoter substances, the production rates of the individual methylchlorosilanes, based on the surface area of the silicon employed, being controlled by the structural parameter QF of the silicon. The structural parameter QF is determined by (a) cutting up silicon test specimens to form a cut surface. (b) totaling on the cut surface the areas of the precipitates of intermetallic phases having a longitudinal shape to give an area number A, (c) totaling on the cut surface the areas of precipitates of intermetallic phases having a circular shape to give an area number B, and (d) obtaining the quotient of the area number A and the area number B, called the structural parameter QF.