Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Additional information

Octamethyltrisiloxane (L3) is a liquid at ambient temperature and pressure, with a measured melting point of -87.8°C and a measured boiling point of 152.4°C. It has a measured relative density of 0.82 at 20°C, a measured kinematic viscosity of 0.842 mm2/s at 20°C and a measured vapour pressure of approximately 400 Pa and 530 Pa at 20°C and 25°C respectively.

The substance has a measured flash point ranging from 31.5 to 37°C and a measured boiling point of 152.4°C. Variations in the flash point values may be as a result of the variation in the purity of the test substance and the test method used. It has a measured self-ignition temperature of 340°C, and is not explosive and not oxidising on the basis of structural examination.

In contact with water, L3 reacts slowly with a half-life of 329 h (13.7 days) at pH 7, 5.09 h at pH 5 and 9.76 h at pH 9 and 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]2Si(CH3)2+ 2H2O → 2(CH3)3SiOH + (CH3)2Si(OH)2

L3 has a measured log Kow of 6.6 at 25°C and a measured water solubility of 0.034 mg/l at 23°C. The substance is not surface active based on structural examination.