Process for the preparation of organosilicon compounds

Preparation of organosilicon compound (I) comprises reacting halogenalkoxysilane (II) with a dry polysulfide (III) dry sulfide (IV) and optionally a sulfur in an organic solvent; removing the mixture containing (I) and the solid material with water containing at least a buffer from the organic solvent and separating the binding phase. Preparation of organosilicon compound (I) of formula ((R 1>R 2>R 3>SiR 4>) 2S x) comprises reacting halogenalkoxysilane compound (II) of formula (R 1>R 2>R 3>SiR 4>X) with a dry polysulfide compound (III) of formula (M 2S z) dry sulfide (IV) of formula (M 2S) and optionally a sulfur in an organic solvent; removing the mixture containing (I) and the solid material (MX) with water containing at least a buffer from the organic solvent and separating the binding phase. R 1>-R 3>alkyl, alkoxy (preferred) or aryl; R 4>1-30C-aliphatic/aromatic hydrocarbon; x : greater than 1; X : halogen atom; M : alkali cation, an ammonium or semi alkaline earth or zinc cation; and z : 2-8.