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EC number: 225-806-1 | CAS number: 5089-72-5
Partition coefficient
Administrative data
Link to relevant study record(s)
- 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
- 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 (EPIWIN 2009 and Meylan 1995). It 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. Certain correction factors may also apply. Whilst this method is good in principle, it suffers from not having reliable fragment values for substances containing Si-O bonds; hence, some re-parameterisation has been explored. The constants used within WATER-NT have been derived by SRC from a wide range of organic chemicals. - GLP compliance:
- no
- Type of method:
- other: QSAR
- Key result
- Type:
- log Pow
- Partition coefficient:
- 1.2
- Temp.:
- 20 °C
- pH:
- 7
- Conclusions:
- An octanol-water partition coefficient value of 1.2 was obtained using an accepted calculation method. The result is considered to be reliable.
- 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
- 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 existing SRC model KOWWIN v 1.68, which is a component of the EPI Suite v4.10 (EPIWIN 2011 and Meylan 1995). It 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 constant used within KOWWIN have been derived by SRC from a wide range of organic chemicals. - GLP compliance:
- no
- Type of method:
- other: QSAR
- Partition coefficient type:
- octanol-water
- Type:
- log Pow
- Partition coefficient:
- -3.4
- Temp.:
- 20 °C
- pH:
- 7
- Conclusions:
- An octanol-water partition coefficient value of -3.4 was obtained using an appropriate calculation method. The result is considered to be reliable.
Referenceopen allclose all
Description of key information
N-[3-(triethoxysilyl)propyl]ethylenediamine: Log Kow 1.2 (QSAR)
N-[3-(trihydroxysilyl)propyl]ethylenediamine: Log Kow -3.4 (QSAR)
Ethanol: Log Kow -0.3 (measured)
Key value for chemical safety assessment
- Log Kow (Log Pow):
- 1.2
- at the temperature of:
- 20 °C
Additional information
The requirement to test the substance for n-octanol/water partition coefficient is waived because in contact with water the substance rapidly hydrolyses to form N-[3-(trihydroxysilyl) propyl]ethylenediamine and ethanol. The hydrolysis half-lives at 25°C, pH 4, 7 and 9 are 15 min, approximately 165 min and 14 min respectively.
A predicted log Kow value of -3.4 was determined for N-[3-(trihydroxysilyl) propyl]ethylenediamine using a QSAR estimation method. This prediction refers to the un-ionised form of the hydrolysis product. The hydrolysis product may be ionised in an environmentally relevant pH range, therefore values for the Pow must be derived for both the un-ionised and the ionised form (log D). The estimated log Kow was corrected using the equation provided in the ECHA Guidance R.7a (2008). Since the molecule has two basic groups, two pKa values were calculated using the ACE and JChem acidity and basicity calculator, where the pKa is defined as the acid dissociation constant of the conjugated acid. From the two pKa values, Log D ranges of -8.2 to -8.8 at pH 4; -5.2 to - 5.8 at pH 7 and -3.6 to -3.9 at pH 9 were determined for the hydrolysis product.
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