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Physical & Chemical properties

Water solubility

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Description of key information

Water solubility [triethylsilane]: 2 mg/l at 20°C (QSAR)

Water solubility [triethylsilanol]: 1E+06 mg/l at 20°C (QSAR); however, above approximately 30 mg/l condensation reactions can occur over time, limiting the concentration dissolved in water.

Key value for chemical safety assessment

Water solubility:
2 mg/L
at the temperature of:
20 °C

Additional information

A predicted water solubility value of 2 mg/l at 20°C was obtained for triethylsilane using a validated QSAR estimation method. The result is considered to be reliable.

In contact with water, triethylsilane hydrolyses slowly to form triethylsilanol and hydrogen.

The silanol hydrolysis product, triethylsilanol may undergo condensation reactions in solution to give the siloxane dimer (hexaethyldisiloxane; CAS No: 994-49-0) and a dynamic equilibrium is established. The overall rate of condensation is dependent on nominal loading, temperature, and pH of the system, as well as what else is present in solution. It may also change over time.

The condensation reactions of monosilanols may be modelled as an equilibrium between monomer and dimer. The reaction is reversible unless the dimer concentration exceeds its solubility; in this case, the dimer forms a separate phase, driving the equilibrium towards the dimer. For triethylsilanol, at loadings above about 30 mg/l the concentration of the dimer is predicted to exceed its solubility, resulting in formation of a separate phase. In addition, the dimer is expected to have a high volatility from water and this may cause losses from water under some conditions. Further information is given in a supporting report (PFA 2016am) attached in Section 13.

The water solubility of the silanol hydrolysis product, triethylsilanol has been calculated using a validated QSAR method to be 1E+06 mg/l. However, the saturation concentration may in reality be limited by the formation of less soluble dimer rather than the solubility of the monomer itself.

Reference:

PFA (2016am). Silanols and aquatic systems. Report number: 404.105.003; Report date: 2016-02-16