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Physical & Chemical properties

Partition coefficient

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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
A partition coefficient value of 2.7 was obtained for the substance using an accepted calculation method. The result is considered to be reliable.

Description of key information

log Kow [4,4,7,7 -tetraethoxy-3,8-dioxa-4,7-disiladecane]: 2.7 at 20°C (QSAR) 

log Kow [1,1,1,4,4,4 -hexahydroxy-1,4-silabutane]:-4.0 at 20°C (QSAR)

log Kow [ethanol]: -0.3

Key value for chemical safety assessment

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

Additional information

A predicted partition coefficient value of 2.7 was determined for the submission substance using a validated QSAR estimation method. The result is considered to be reliable.

In contact with water, 4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disiladecane hydrolyses moderately to form 1,1,1,4,4,4-hexahydroxy-1,4 -silabutane and ethanol. A predicted log Kow for the silanol hydrolysis product is estimated to be -4.0 at 20°C using a validated QSAR estimation method. This result is considered to be reliable.

Ethanol has a reported log Kow of -0.3 (Hansch C 1995).


Hansch. C., A. Leo and D. Hoekman (1995). Exploring QSAR. Hydrophobic, Electronic, and Steric Constants. ACS Professional Reference Book.,: American Chemical Society