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Physical & Chemical properties

Partition coefficient

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Reference
Endpoint:
partition coefficient
Data waiving:
study technically not feasible
Justification for data waiving:
other:

Description of key information

The partition coefficient could not be determined using a procedure designed to be compatible with EC Method A8 and OECD Guideline No. 117 as the substance hydrolyses rapidly. A calculated estimate of the water solubility using WSKOW v 1.42 (US EPA) gave 2.8E-07 mg/L. The test item was shown to dissolve in n-octanol at approximately 5.0E05 mg/L (equivalent to 50% w/w). Using these values to estimate a partition coefficient value gave a log Pow of 12.3.

Key value for chemical safety assessment

Log Kow (Log Pow):
12.3
at the temperature of:
20 °C

Additional information

The partition coefficient could not be determined using a procedure designed to be compatible with EC Method A8 and OECD Guideline No. 117. The test substance is highly unstable in contact with water. This meant that the shake-flask method was not applicable as the test item comes into direct contact with water and would have hydrolysed in the time required to complete the study. The Guidelines for the HPLC method state that the method is not applicable if the test item reacts with the mobile phase. The test item was known to react with water and also expected to be reactive with methanol as it is a protiotic solvent. To assess this some injections were run. The test item was prepared at 1000 and 10000 mg/L in tetrahydrofuran, which had bee dried by addition of anhydrous sodium sulphate to remove entrained water. This proved unsuccessful as no definitive peak(s) that represented the test item could be detected. The method was therefore proved not to be applicable. The next approach was the calculation of partition coefficient based on the test item's solubility in n-octanol and water. Again from the water solubility test it was known that a single definitive value for the water solubility of the test item was not possible because of hydrolysis. A calculated estimate of the water solubility using WSKOW v 1.42 (US EPA) gave 2.8E-07 mg/L. The test item was shown to dissolve in n-octanol at approximately 5.0E05 mg/L (equivalent to 50% w/w). Using these values to estimate a partition coefficient value gave a log Pow of 12.3. In comparison the estimated log Pow using KOWWIN v 1.68 was 11.1. Although an estimate of the partition coefficient was calculated, due to the ready hydrolysis of the test item, it would be expected that it exists in the environment as its hydrolysis products: boric acid and 2-propyl heptan-1-ol. These components are already registered with partition coefficient values available; so it was considered that further testing with respect to these components was not required.