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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Dodecamethylcyclohexasiloxane (D6) is a liquid at standard temperature and pressure, with a melting point of -3°C at 1013 hPa, and a boiling point of 245°C at 1013 hPa. It has a density slightly less than that of water (0.98 g/cm3 at 20°C) and a kinematic viscosity value of 5.6 mm2/s at 20°C. It has a predicted vapour pressure of 4.7 Pa at 25°C.

The substance is not classified for flammability on the basis of a measured flash point of 91°C at 1013 hPa and boiling point of 245°C at 1013 hPa in accordance with Regulation (EC) No. 1272/2008. D6 has a measured autoignition temperature of 368-371°C at 1013 hPa and it is not explosive and not oxidising on the basis of structural examination.

In contact with water, D6 will hydrolyse very slowly with a hydrolysis half-life of 42 h at pH 4, approximately 9600 h (401 days) at pH 7 and 125 h at pH 9 and 25°C. The product of hydrolysis is dimethylsilanediol. .

[-Si(CH3)2O-]6+ 6H2O → 6(CH3)2Si(OH)2

D6 has low water solubility of approximately 5 µg/l at 23°C, and a high log Kow of 8.87. Based on an examination of the chemical structure, the substance is not expected to dissocite under relevant environmental conditions. Further testing for water-based physicochemical properties is waived due to the low solubility.