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EC number: 260-829-0 | CAS number: 57583-35-4
Partition coefficient
Administrative data
Link to relevant study record(s)
- Endpoint:
- partition coefficient
- Type of information:
- calculation (if not (Q)SAR)
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- accepted calculation method
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Calculation method using experimentally derived water solubility and n-octanol solubility values.
- GLP compliance:
- yes
- Type of method:
- other: Calculation method using experimentally derived water solubility and n-octanol solubility values.
- Partition coefficient type:
- octanol-water
- Analytical method:
- other: Not required
- Key result
- Type:
- Pow
- Partition coefficient:
- > 55 400
- Temp.:
- 20 °C
- pH:
- 6.3
- Key result
- Type:
- log Pow
- Partition coefficient:
- > 4.74
- Temp.:
- 20 °C
- pH:
- 6.3
- Details on results:
- The partition coefficient was calculated to be greater than 5.54 x 10^4, log10 Pow >4.74.
- Conclusions:
- Under the conditions of the study the n-octanol/water Partition Coefficient was calculated to be greater than 5.54 x 10^4, log10 Pow >4.74.
- Executive summary:
The partition coefficient of the test material was calculated using the water solubility and the solubility in n-octanol.
Under the conditions of the study the n-octanol/water Partition Coefficient was calculated to be greater than 5.54 x 10^4, log10 Pow >4.74.
Reference
Description of key information
Butler (2020)
Under the conditions of the study the n-octanol/water Partition Coefficient was calculated to be greater than 5.54 x 10^4, log10 Pow >4.74.
Key value for chemical safety assessment
- Log Kow (Log Pow):
- 4.74
- at the temperature of:
- 20 °C
Additional information
Butler (2020)
The partition coefficient of the test material was calculated using the water solubility and the solubility in n-octanol. The study was awarded a reliability score of 2 in accordance with the criteria set forth by Klimisch et al. (1997).
Under the conditions of the study the n-octanol/water Partition Coefficient was calculated to be greater than 5.54 x 10^4, log10 Pow >4.74.
Tognucci (1999)
OECD Guidelines 107 and 117 define the octanol-water partition coefficient (Pow) as the ratio of equilibrium concentrations of a dissolved substance in the two-phase system, usually expressed as a base ten logarithm (i.e., log Pow = log [C octanol/C water]). In order to obtain relevant results from these tests, tin levels in the test system must be less than the saturation concentration of the test substance in the water phase (this avoids "forcing" the partition equilibrium). Due to the low expected solubilities of most organotin compounds (particularly the stabilizers), concentrations of the test substance would be too low for current analytical techniques to detect.
Also, as the organotin stabilizers are practically insoluble in the water phase, a high log Pow value is expected. However, the presence of even a small amount of a more water-soluble impurity (i.e., <<1%) significantly increases the amount of tin in the water phase, which in turn reduces the log Pow value. In fact, for compounds expected to have high log Pow values (i.e., >6), the test substance would need to be purified to >99.9999999% in order to prevent impurities from contributing to the result. Additionally, current analytical techniques are unable to completely characterize the named test substance in solution (i.e., the complete alkyl tin compound, including the organic ligand). Also, the named substance may not even exist in aqueous solution, but rather rapidly hydrolyses to another more water-soluble form (e.g., hydroxide, oxide, etc.). Therefore, current literature values reported for the log Pow of organotin compounds might be more representative of the water-soluble impurities or hydrolysis reaction products present in the test system, rather than the named substance.
As significant technical difficulties exist and the presence of the actual named test substance in aqueous solution is doubtful, the current OECD Guidelines 107 or 117 are not suitable for determining the octanol-water partition coefficient of this compound. Therefore, testing was not conducted and data generated by property-estimation software (e.g., KOWWIN version 1.67) was reported instead. The estimated log Pow is 8.5.
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