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Physical & Chemical properties

Partition coefficient

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partition coefficient
Data waiving:
study technically not feasible
Justification for data waiving:
the study does not need to be conducted because the substance decomposes
partition coefficient
Type of information:
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
See attached QMRF/QPRF
Principles of method if other than guideline:
The result was obtained using an appropriate QSAR method (see attached QMRF and QPRF for details).

The model is an adaptation of the existing SRC model KOWWIN v1.67, which is a component of the EPIWIN Suite. The model is based on fragment values. That is, the chemical structure is broken down into its constituent functional groups, and the contribution of each group toward the overall partition coefficient is calculated. The constants used within KOWWIN have been derived by SRC from a wide range of organic chemicals. Whilst this method is good in principle, the model was developed using a wide range of organic chemicals and only a few organosilicon compounds. Therefore, a validation procedure was undertaken to assess the applicability of the model to alkoxysilane compounds. It was noted that the model under-predicted log Kow for alkoxysilanes; therefore, a correction factor is applied when this structural feature is present. The adapted model applies to di- and tri-alkoxysilanes.
Partition coefficient type:
Key result
log Pow
Partition coefficient:
20 °C
ca. 7
A partition coefficient value of 0.3 at 20°C was obtained for the substance using a validated QSAR method. The result is considered to be reliable.

Description of key information

Log Kow [tris(2-methoxyethoxy)vinylsilane]: 0.3 at 20°C (QSAR)

Log Kow [vinylsilanetriol]: -2.0 at 20°C (QSAR)

Log Kow [2-methoxyethanol]: -0.77

Key value for chemical safety assessment

Log Kow (Log Pow):
at the temperature of:
20 °C

Additional information

The requirement to conduct an n-octanol/water partition coefficient study for the submission substance is waived because in contact with water, the submission substance hydrolyses rapidly to form vinylsilanetriol and 2-methoxyethanol.

However, the submission substance has been predicted to have a log Kow value of 0.3 at 20°C using a validated QSAR estimation method.

Similarly, the partition coefficient of the silanol hydrolysis product, vinylsilanetriol, has been calculated as -2.0 at 20°C using a validated QSAR estimation method.

The partition coefficient of the non-silanol hydrolysis product, 2-methoxyethanol was reported in a secondary source as -0.77 (Hansch 1995).


Hansch, C., Leo, A., D. Hoekman. Exploring QSAR - Hydrophobic, Electronic, and Steric Constants. Washington, DC: American Chemical Society., 1995., p. 7