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Physical & Chemical properties

Vapour pressure

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Description of key information

Vapour pressure (1,1,3,3-tetramethyldisiloxane): 18000 Pa at 25°C (OECD 104)
Vapour pressure (dimethylsilanol): 770 Pa at 25°C (QSAR)
Vapour pressure (dimethylsilanediol): 7 Pa at 25°C (QSAR)

Key value for chemical safety assessment

Vapour pressure:
18 000 Pa
at the temperature of:
25 °C

Additional information

Measured vapour pressures of 15000 Pa and 18000 Pa at 20°C and 25°C respectively were determined for the substance using the static method under OECD 104 test guideline and in compliance with GLP. The result is considered to be reliable and was selected as key study. In another study conducted using a relevant test method, vapour pressures of 14000 Pa and ~23300 Pa at 20°C and 31.4°C respectively were determined for the substance. Similarly, a vapour pressure of 15000 Pa at 20°C was reported for the substance in a secondary source to which no reliability can be assigned. The study with the highest reliability was selected as key study.

In contact with water, the substance hydrolyses rapidly to form dimethylsilanol as the intermediate hydrolysis product and dimethylsilanediol as the ultimate hydrolysis product. Vapour pressure values of 770 Pa and 7 Pa at 25°C were determined for dimethylsilanol and dimethylsilanediol respectively using a validated QSAR estimation method.