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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Dodecamethylpentasiloxane (L5) is a liquid at ambient temperature and pressure, with a measured melting point of -80°C and a boiling point of 210 - 232°C. It has a density of 0.88 - 0.94 g/cm3 at 20°C, a kinematic viscosity of 1.7 mm2/s at 20°C and a predicted vapour pressure of 7.8 Pa at 25°C.

The substance is not classified for flammability on the basis of a measured flash point of 79°C and boiling point of 210 - 232°C. It has a measured auto-ignition temperature of 350°C, and is not explosive and not oxidising on the basis of structural examination.

In contact with water, L5 reacts slowly, half-lives of 14 hours at pH 5, 30.3 days (728 hours) at pH 7 and 21.1 hours at pH 9 and 25°C. The stated half-life is for removal of parent substance. Complete reaction to the ultimate end products will take longer. The reaction equation is shown below:

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

The substance has a measured water solubility of 0.00007 mg/l at 23°C and a measured log Kow of 9.4 at 25°C. The substance is not surface active based on examination of the chemical structure.