Registration Dossier
Registration Dossier
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EC number: 250-807-9 | CAS number: 31795-24-1
Vapour pressure
Administrative data
Link to relevant study record(s)
Description of key information
Vapour pressure [potassium methylsilanetriolate in aqueous solution]: not necessary
Vapour pressure: 0.05 Pa, 5.9E-05 Pa and 3.0E-07 Pa at 25°C for methylsilanetriol, and dimer and trimer of methylsilanetriol respectively. (QSAR)
Key value for chemical safety assessment
Additional information
The requirement to conduct a vapour pressure study for potassium methylsilanetriolate is waived because the substance is only stable in aqueous solution; therefore, the test is scientifically unjustified. A secondary source reported a vapour pressure of 2.3 kPa at 20°C for the vapour pressure of the aqueous solution; this reflects the vapour pressure of water.
At pH 9 or below and low concentration (conditions relevant for the environment), the monomer (methylsilanetriol) will predominate. Therefore, a vapour pressure of 0.05 Pa at 25°C was predicted for methylsilanetriol using a validated QSAR estimation method.
Similarly, under certain conditions such as high concentration, the dimer and trimer of methylsilanetriol may be formed in solution. Vapour pressure values of 5.9E-05 Pa and 3.0E-07 Pa at 25°C were predicted for the dimer and trimer of methylsilanetriol respectively using a validated QSAR estimation.
The vapour pressure of the silanolate salt is expected to be negligible.
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