Process for reducing the sulfane chain length of bis(silylorganyl) polysulfanes

A process for reducing the sulfane chain length of bis(silylorganyl)polysulfanes, wherein an organosilicon compound of the general formula

• Z-Alk-S.sub.x -Alk-Z (I)
• in which Z denotes groupings ##STR3## in which R.sup.1 represents a linear or branched alkyl group having 1 to 5 C atoms, a cycloalkyl residue having 5 to 8 C atoms, the benzyl residue or the phenyl residue optionally substituted by methyl, ethyl or chlorine, R.sup.2 denotes an alkoxy group having a linear or branched carbon chain having 1 to 5 C atoms or a cycloalkoxy group having 5 to 8 C atoms, the phenoxy group or the benzyl group, wherein R.sup.1 and R.sup.2 may each have identical or different meanings, Alk denotes a divalent saturated or monounsaturated linear or branched hydrocarbon residue having 1-10 C atoms or the group ##STR4## x denotes an integer from 3 to 8, in particular from 4 to 6 and n denotes an integer from 1 to 4 is reacted with an anhydrous sulfide of the general formula
• Me.sub.2 S (II)
• in which Me represents an alkali metal, in particular sodium or an equivalent of an alkaline earth metal atom or of zinc or ammonium, and an organosilicon compound of the general formula
• Z-Alk-Y (III)
• in which Z and Alk have the above-stated meanings and Y means Cl, Br, wherein the molar ratio of the polysulfane and of the Me.sub.2 S is selected in accordance with the desired sulfur content of the polysulfane to be partially desulfurised and of the desired product, and the desulfurised polysulfane is obtained pure or in the form of a mixture with other polysulfanes.