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Diss Factsheets

Physical & Chemical properties

Partition coefficient

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Administrative data

Link to relevant study record(s)

Reference
Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
supporting 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 the publicly available KOWWIN v1.68 program (USEPA 2011). KOWWIN is part of EPI Suite v4.1 and may be downloaded from http://www.epa.gov/oppt/exposure/pubs/episuite.htm. 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. The authors of this QMRF have carried out additional validation and found the method to be applicable organosilicon compounds, excluding di- and tri-alkoxysilanes.

USEPA 2011. KOWWIN v. 1.68, US EPA. 2011. Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.10. United States Environmental Protection Agency, Washington, DC, USA. Available at http://www.epa.gov/oppt/exposure/pubs/episuite.htm.
Type of method:
calculation method (fragments)
Partition coefficient type:
octanol-water
Type:
log Pow
Partition coefficient:
-2.9
Temp.:
20 °C
Remarks on result:
other: value for unionised form
Type:
log Pow
Partition coefficient:
-4
Temp.:
20 °C
pH:
7
Remarks on result:
other: corrected for ionisation
Type:
log Pow
Partition coefficient:
-4
Temp.:
20 °C
pH:
2
Remarks on result:
other: corrected for ionisation
Type:
log Pow
Partition coefficient:
-4
Temp.:
20 °C
pH:
4
Remarks on result:
other: corrected for ionisation
Type:
log Pow
Partition coefficient:
-3.5
Temp.:
20 °C
pH:
9
Remarks on result:
other: corrected for ionisation
Details on results:
The amine group in the substance will protonate in solution; therefore, the estimated log Kow for the unionised form was corrected for ionisation using the equation CORR = 1/1 +10A(pH-pKa) [where A = 1 for acids, -1 for bases; pH = pH-value of the environment; pKa = acid/base dissociation constant].
Conclusions:
log Kow values of -4, -4, -4 and -3.5 at pH 2, pH 4, pH 7 and pH 9, respectively, were obtained for the hydrolysis product of the registered substance, using an accepted calculation method. The result is considered to be reliable.

Description of key information

Key value for chemical safety assessment

Log Kow (Log Pow):
-4
at the temperature of:
20 °C

Additional information

log Kow of the silanol hydrolysis product