Registration Dossier

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

The substance as registered is stable only as an alkaline aqueous solution at pH >14. Tripotassium propylsilanetriolate is the potassium salt of propylsilanetriol. In solution tripotassium propylsilanetriolate will be completely dissociated to propylsilanetriolate and three free potassium ions. Under comparable conditions of concentration and pH, propylsilanetriolate is equivalent to the parent acid propylsilanetriol; the first pKa of propylsilanetriol is approximately 10.

The substance has a measured melting point of ≤-65°C and a measured boiling point of 113°C. The density of the substance was measured to be 1.318 g/cm3 at 20°C. The measured boiling point and density are consistent with a 15 – 20% w/w solution of potassium hydroxide in water. The substance has a measured dynamic viscosity of 9.3 mPa.s at 20°C. 

The substance is not classified as flammable according to Regulation (EC) No. 1272/2008 on the basis of a measured flash point of >95°C.

The substanceis only stable in aqueous solution (60-65% w/w water) and is thus miscible with water. At pH 7 and low concentration (conditions relevant for the environment), the monomer (propylsilanetriol) will predominate, while under certain conditions (for example, concentrations in the grams per litre range, at neutral pH), the dimer, trimer and higher oligomers or polymers may be formed in solution. The log n-octanol water partition coefficients of propylsilanetriol and its dimer and trimer are predicted as -1.4, -0.2 and 0.3 respectively. Similarly, propylsilanetriol, its dimer and trimer have a predicted vapour pressure of 4.6E-03 Pa, 1.5E-06 Pa and 1.3E-09 Pa at 25°C respectively.

The substance is not expected to be surface active, it is not explosive and does not possess oxidising properties on the basis of structural examination. The auto ignition temperature of the substance is waived because the substance is only stable in aqueous solution. The autoignition temperature of the substance is expected to be similar to the autoignition temperature of the solvent in which it is stable, in this case, potassium hydroxide solution. 

Additional information