Registration Dossier

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 is a liquid at standard temperature and pressure, with a melting point of <-20°C, and a measured boiling point of 269°C. It has a measured relative density of 1.0328 at 20°C, a predicted kinematic viscosity of 8.9 mm2/s at 20°C and a measured vapour pressure of 9 Pa and 12 Pa at 20°C and 25°C respectively.

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 and a measured boiling point of 269°C. 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 hydrolyses at a moderate rate (half-lives of 0.8 - 1.2 h at pH 4, 40 - 90 h at pH 7 and 0.5 - 0.9 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 1000 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 at 20°C, predicted). It is not surface active and is much less volatile than the parent substance (vapour pressure = 2.9E-05 Pa at 25°C, predicted).

Additional information