Registration Dossier

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Tetradecamethylhexasiloxane (L6) is a liquid at ambient temperature and pressure, with a measured melting point of <-130°C and a measured boiling point of 246.1°C at 1013 hPa. It has a measured relative density of 0.893 at 20°C, a measured kinematic viscosity of 2.9 mm2/s at 20°C and measured vapour pressure values of 0.27 Pa at 20°C, 0.74 Pa at 30°C and 5.7 Pa at 50°C.

The substance is not classified for flammability in accordance with Regulation (EC) No. 1272/2008 on the basis of a measured flash point of 111°C and measured boiling point of 246.5°C at 95.6 kPa. It has a measured auto-ignition temperature of 341°C at 955 -974 hPa, and is not explosive and not oxidising on the basis of structural examination.

In contact with water, L6 reacts slowly with a half-lives of 12.1 hours (0.5 days) at pH 4, 5.8 hours (0.24 days) at pH 5, 6300 hours (262.5 days) at pH 7 and 36.5 hours (1.5 days) at pH 9 and 20-25°C.

The stated half-life is for removal of parent. Complete reaction to the ultimate end products will take longer. The equation for the reaction is stated below:

(CH3)3SiO[Si(CH3)2)O]4Si(CH3)3+ 5H2O → 2(CH3)3SiOH + 4(CH3)2Si(OH)2

L6 has a log Kow of >9.41 at 25°C (read-across from a structural analogue) and a predicted water solubility of 2.3E-06 mg/l at 20°C. The substance is not surface active based on structural examination.

Additional information