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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

4,4,13,13-Tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane (CAS 56706-10-6, EC No. 260-350-7, S2) is a light-yellow liquid with a sulfur-like odour at standard temperature and pressure, with a melting point of < -20°C at 1013 hPa. It has a measured relative density of 1.0328 at 20°C, a predicted kinematic viscosity of 2.3 mm2/s at 20°C and a measured vapour pressure of 9 Pa at 20°C and 12 Pa at 25°C. The substance has a predicted log Kow of 5.2 and predicted water solubility of 0.014 mg/l at 20°C.


The substance is not classified for flammability according to Regulation (EC) No. 1272/2008 on the basis of a measured flash point of 136°C at 1013 hPa and a measured boiling point of 269°C at 1004 hPa. It has a measured auto-ignition temperature of 220°C at 1008 hPa, and is not explosive and not oxidising on the basis of chemical structure.


In contact with water, the substance undergo hydrolysis at a moderate rate (predicted half-lives of 0.8 - 1.2 h at pH 4, 40 - 80 h at pH 7 and 0.5 - 1 h at pH 9 and 20-25°C) resulting in the formation (3-{[3-(trihydroxysilyl)propyl]disulfanyl}propyl)silanetriol and ethanol, according to the following equation:


C18H42O6S2Si2 + 6H2O → C6H18O6S2Si+ 6CH3CH2OH


Ethanol is miscible with water, has low log Kow (-0.3) and high vapour pressure (7910 Pa at 25°C).


The saturation concentration in water of the silanol hydrolysis product, (3-{[3-(trihydroxysilyl)propyl]disulfanyl}propyl)silanetriol, is limited by condensation reactions to approximately 100 mg/l. However, it is very hydrophilic (calculated solubility is 1.0E+06 mg/l using a QSAR method) and has a low log Kow (-3.0 at 20°C, predicted). It is not surface active and is much less volatile than the parent substance with a predicted vapour pressure of 6.3E-12 Pa at 25°C.

Additional information