Patent ID: 8129556

Claim:
Process for preparing organosilanes of the general formula I where R is the same or different and is a C 1 -C 8 -alkyl, C 1 -C 8 -alkenyl, C 1 -C 8 -aryl or C 1 -C 8 -aralkyl group or an OR′ group, R′ is the same or different and is a C 1 -C 24 branched or unbranched monovalent alkyl or alkenyl group, an aryl group, an aralkyl group, hydrogen, an alkyl ether group —(CR III 2 ) y′ —O-Alk, where y′=1-20, or an alkyl polyether group —(CR III 2 O) y -Alk or —(CR III 2 —CR III 2 —O) y -Alk, where y=2-20, R III is independently H or an alkyl group and Alk is a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic monovalent C 1 -C 30 hydrocarbon group, R″ is a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic divalent C 1 -C 30 hydrocarbon group which is optionally substituted by F, Cl, Br, I, HS, NH 2 or NHR′, m is a mean sulphur chain length of 1.5 to 4.5, by reacting (haloorganyl)alkoxysilane of the formula II where R, R′ and R″ are each as defined above and Hal is chlorine, bromine, fluorine or iodine, with hydrous alkali metal hydrogensulphide, sulphur and alkali metal carbonate in alcohol, wherein the molar (haloorganyl)alkoxysilane of the formula II to alkali metal hydrogensulphide ratio is between 1:0.45 and 1:0.75, and the molar alkali metal hydrogensulphide to alkali metal carbonate ratio is between 1:0.5 and 1:1.5.