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Physical & Chemical properties

Vapour pressure

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Description of key information

Vapour pressure [dichloro(dimethyl)silane]: 14600 Pa at 20°C, 22800 Pa at 30°C and 34400 Pa at 40°C (EU Method A.4) Vapour pressure (dimethylsilanediol): 7 Pa at 25°C (QSAR)

Key value for chemical safety assessment

Vapour pressure:
14 600 Pa
at the temperature of:
20 °C

Additional information

Several reliable measured vapour pressure values are available for the substance. Measured vapour pressure values of 14600 Pa at 20°C, 22800 Pa at 30°C and 34400 Pa at 40°C were determined for the substance using a relevant test method. For the purpose of environmental exposure assessment, an interpolated vapour pressure of 18300 Pa at 25°C was obtained from the regression reported in the study report. The result is considered to be reliable and is selected as key study. This value is supported by other available reliable vapour pressure values of 18130 Pa at 20°C, 17970 Pa and 19120 Pa at 25°C. In other available secondary sources to which reliability could not be assigned, vapour pressure values of 5700 Pa at 0°C, 14700 Pa - <20000 Pa at 20°C, 29300 Pa at 30°C, 50000 Pa - <55000 Pa at 50°C and 60000 Pa at 55°C were reported for the substance.

Variations in the vapour pressure values may be caused by variations in purity of the test substance and in the test method used. All values are of the same order of magnitude and consistent with the substance being highly volatile. The key study has been selected from several reliable results because it is the only test known to have been conducted according to EU or international guidelines.

In contact with water, dichloro(dimethyl)silane reacts very rapidly to produce dimethylsilanediol and hydrochloric acid as products of hydrolysis. The vapour pressure of the silanol hydrolysis product was predicted to be 7 Pa at 25°C using a validated QSAR estimation method.