[S-2:1].[Na+].[Na+].[S].Cl[CH2:6][CH2:7][CH2:8][Si:9]([O:16][CH2:17][CH3:18])([O:13][CH2:14][CH3:15])[O:10][CH2:11][CH3:12]>C(O)C>[CH2:11]([O:10][Si:9]([CH2:8][CH2:7][CH2:6][S:1][S:1][CH2:6][CH2:7][CH2:8][Si:9]([O:16][CH2:17][CH3:18])([O:10][CH2:11][CH3:12])[O:13][CH2:14][CH3:15])([O:16][CH2:17][CH3:18])[O:13][CH2:14][CH3:15])[CH3:12]17.8 kg of virtually anhydrous sodium sulfide are mixed with 190 l of ethanol and added to an enameled 500 l capacity reactor. This is followed by the addition through a fine nozzle of 13.85 kg of sulfur in molten form. The mixture is heated to 50° C. and 190 l of 3-chloropropyltriethoxysilane are metered in within 10 minutes. On account of the exothermic reaction the temperature of the reactor contents rises to 74° C. A further 4.45 kg of virtually anhydrous sodium sulfide are added at this temperature. Three further portions of sodium sulfide are added at 5 minute intervals (i.e. each 5 minutes), the temperature of the reactor contents rising to 82° C. After completion of the sodium sulfide addition the reaction mixture is kept for 1.5 hours at 82-83° C. and the sodium chloride that has precipitated is separated after cooling the mixture. A yellow product is obtained after evaporating the reaction mixture in vacuo and renewed fine filtration. HPLC analysis confirms the presence of a product with a mean polysulfane chain length of 2.
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