4,4,13,13-tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

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.

Type of method:

calculation method (fragments)

Partition coefficient type:

octanol-water

Key result

Type:

log Pow

Partition coefficient:

5.2

Temp.:

20 °C

pH:

ca. 7

Conclusions:

A partition coefficient value of 5.2 at 20°C was obtained for the substance using an accepted calculation method. The result is considered to be reliable.

Description of key information

log K_ow [4,4,13,13-tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane]: 5.2 (QSAR)

 

log K_ow [(3-{[3-(trihydroxysilyl)propyl]disulfanyl}propyl)silanetriol]: -3.0 (QSAR)

 

log K_ow [ethanol]: -0.3

Key value for chemical safety assessment

Log Kow (Log Pow):

5.2

at the temperature of:

20 °C

Additional information

A predicted log K_ow value of 5.2 at 20°C was determined for the substance using a validated QSAR estimation method. The result is considered to be reliable.

 

In contact with water, the substance will undergo hydrolysis at a moderate rate to form (3-{[3-(trihydroxysilyl)propyl]disulfanyl}propyl)silanetriol and ethanol.

 

The silanol hydrolysis product, (3-{[3-(trihydroxysilyl)propyl]disulfanyl}propyl)silanetriol has a predicted log K_ow value of -3 at 20°C using a QSAR estimation method. The results are slightly outside the applicability domain of the prediction model, but the prediction is indicative of a very low log K_ow for the silanol hydrolysis products.

 

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

 

Reference:

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