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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
other: calculation method
Partition coefficient type:
octanol-water
Key result
Type:
log Pow
Partition coefficient:
> 12 - < 16
Temp.:
20 °C
Remarks on result:
other: pH not applicable (estimation method)

The partition coefficient was estimated by a calculation method based on the theoretical fragmentation of the molecule into substructures for which relaible log Pow increments are known. The logPow is obtained by summing the fragment values and the correction term for intramolecular interactions. The log Pow was calculated individually for the different molecules of the test item.

For the molecule with the shortest chain length a logPow of 12.12 was estimated, while for the other two components a log Pow of 14.08 and 16.05 was derived.

As an example, the details of the fragmentation of the molecule with the mid chain length is given in the table below:

Type

Number

Fragment description

coefficient

value

Fragment

4

-CH3 (aliphatic carbon)

0.5473

2.1892

Fragment

24

-CH2 (aliphatic carbon)

0.4911

11.7864

Fragment

2

-NH (aliphatic attached)

-1.4962

-2.9924

Fragment

18

Aromatic carbon

0.2940

5.2920

Fragment

4

-N (aliphatic N, one aromatic attached)

-0.9170

-3.6680

Fragment

2

-NC(=O)N- (urea)

1.0453

2.0906

Fragment

2

OC(=O)N (carbamate)

0.1283

0.2566

Factor

2

ring rx

-0.5500

-1.1000

constant

Equation constant

0.2290

log Pow estimated

14.0834

Conclusions:
The log Pow of the test item is most probably in the range between 12 and 16 estimated using the model calculation.
Executive summary:

The main test according to OECD Guideline 107 could not be applied. Also the HPLC method as described in OECD Guideline 117 was not applicable.

Therefore, the partition coefficient was calculated on theoretical fragmentation of the molecule.

Based on this claculation, the log Pow of the test item is most probably in the range between 12 and 16.

Description of key information

Partition coefficient: Log Pow  > 10 (calculated)

Key value for chemical safety assessment

Additional information

In a preliminary test, a moderate solubility in n-octanol and a very poor solubility in water was found indicating a partition coefficient above 4. Hence, a main test according to OECD Guideline 107 could not be performed. Also the HPLC method as described in OECD Guideline 117 was not possible, because the HPLC method uses a solvent mixture of acetonitrile and tertahydrofurane as eluent.

Therefore, the partition coefficient was calculated based on the theoretical fragmentation of the molecule.

For the component with the shortest chain length a logPow of 12.12 was estimated, while for the other two components a log Pow of 14.08 and 16.05 was derived.