Dibutyl hydrogen phosphate

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2013

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:

QSAR prediction

Guideline:

other: REACH guidance QSARs R6, May/July 2008

Principles of method if other than guideline:

Estimation Program Interface EPI-Suite version 4.11: KOWWIN for estimating the logarithmic octanol-water partition coefficient (log Kow).
The Estimation Programs Interface was developed by the US Environmental Agency's Office of Pollution Prevention and Toxics and Syracuse Research Corporation (SRC).© 2000 - 2012 U.S. Environmental Protection Agency for EPI SuiteTM. Published online in November 2012.

GLP compliance:

no

Type of method:

other: QSAR

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

In order to estimate the octanol-water partition coefficient (log Kow) for the dissociated form, the corresponding sodium salt of dibutyl hydrogen phosphate (CAS No. 16298-74-1) was chosen as surrogate for calculation.
Values relate to pure substance.
SMILES: CCCCOP(O([Na]))(=O)OCCCC; (dissociated form)

Key result

Type:

log Pow

Partition coefficient:

-0.9

Remarks on result:

other: dissociated form

In order to estimate the octanol-water partition coefficient (log Kow) for the dissociated form, the corresponding sodium salt of dibutyl hydrogen phosphate (sodium dibutyl phosphate, CAS No. 16298-74-1) was chosen as surrogate for calculation, as generally estimation by the program apply to compounds that are predominantly in a non-ionized/non-dissociated form.

Validity of model:

1. Defined Endpoint: Octanol-water partition coefficient

2. Unambiguous algorithm: KOWWIN considers sodium dibutyl phosphate as "ion pair" compound and gives a corresponding estimate; effectively, the estimate for the sodium salt of dibutyl hydrogen phosphate is an estimate for ionized/dissociated corresponding acid. Therefore sodium dibutyl phosphate can be considered as surrogate for the dissociated form of dibutyl hydrogen phosphate. The molecule is separated into distinct atom/fragments using an Atom/Fragment Contribution method. Based on structure of the molecule, the following fragments were applied for the substance: -CH3 aliphatic carbon, -CH2 aliphatic carbon, -O-P aliphatic attach, O=P, misc-O-{Na, K, Li}.

The number of times of the fragments that occurs in the structure of the substance applied by the program is verified.

3. Applicability domain: With a molecular weight of 232.19 g/mole the substance is within the range of the training set (18.02 - 719.92) as well as in the range of the validation set (27.03 - 991.15).

4. Statistical characteristics: Correlation coefficient of the total training set r² = 0.982; Correlation coefficient of the total validation set r² = 0.943.

5. Mechanistic interpretation: The structural fragments used as descriptors reflect the lipophilic or hydrophobic properties of the substances, and so the octanol-water partition coefficient.

6. Adequacy of prediction: The result for the dissociated form of dibutyl hydrogen phosphate falls within the applicability domain described above and the estimation rules applied for the substance appears appropriate. Therefore the predicted value can be considered reliable yielding a useful result for further assessment.

Conclusions:

The QSAR determination of the logarithmic octanol-water partition coefficient using the model KOWWIN included in the Estimation Program Interface (EPI) Suite v4.11 revealed a value of -0.90 for the dissociated form of dibutyl hydrogen phosphate. The predicted value can be considered reliable yielding a useful result for further assessment.

Executive summary:

The logarithmic octanol-water partition coefficient (log Kow) for dibutyl hydrogen phosphate was predicted using the QSAR calculation of the Estimation Program Interface (EPI) Suite v4.11. The log Kow was estimated to be -0.90 for the dissociated form of dibutyl hydrogen phosphate. The predicted value can be considered reliable yielding a useful result for further assessment.

Reference 2

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2013

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:

QSAR prediction

Guideline:

other: REACH guidance QSARs R6, May/July 2008

Principles of method if other than guideline:

Estimation Program Interface EPI-Suite version 4.11: KOWWIN for estimating the logarithmic octanol-water partition coefficient (log Kow).
The Estimation Programs Interface was developed by the US Environmental Agency's Office of Pollution Prevention and Toxics and Syracuse Research Corporation (SRC).© 2000 - 2012 U.S. Environmental Protection Agency for EPI SuiteTM. Published online in November 2012.

GLP compliance:

no

Type of method:

other: QSAR

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

Values relate to pure substance.
SMILES: O=P(OCCCC)(OCCCC)O; (non-dissociated form)

Key result

Type:

log Pow

Partition coefficient:

2.89

Remarks on result:

other: non-dissociated form

Validity of model:

1. Defined Endpoint: Octanol-water partition coefficient

2. Unambiguous algorithm: The molecule is separated into distinct atom/fragments using an Atom/Fragment Contribution method. Based on structure of the molecule, the following fragments were applied for the non-dissociated form: -CH3 aliphatic carbon, -CH2 aliphatic carbon, -O-P aliphatic attach, O=P, -OH phosphorus attach. The number of times of the fragments that occurs in the structure of the substance applied by the program is verified.

3. Applicability domain: With a molecular weight of 210.21 g/mole (non-dissociated form) dibutyl hydrogen phosphate is within the range of the training set (18.02 - 719.92) as well as in the range of the validation set (27.03 - 991.15).

4. Statistical characteristics: Correlation coefficient of the total training set r² = 0.982; Correlation coefficient of the total validation set r² = 0.943.

5. Mechanistic interpretation: The structural fragments used as descriptors reflect the lipophilic or hydrophobic properties of the substances, and so the octanol-water partition coefficient.

6. Adequacy of prediction: The result for dibutyl hydrogen phosphate falls within the applicability domain described above and the applied estimation rules appear appropriate. Therefore the predicted value can be considered reliable yielding a useful result for further assessment.

Conclusions:

The QSAR determination of the logarithmic octanol-water partition coefficient for dibutyl hydrogen phosphate using the model KOWWIN included in the Estimation Program Interface (EPI) Suite v4.11 revealed a value of 2.89 for the non-dissociated form. The predicted value can be considered reliable yielding a useful result for further assessment.

Executive summary:

The logarithmic octanol-water partition coefficient (log Kow) for dibutyl hydrogen phosphate was predicted using the QSAR calculation of the Estimation Program Interface (EPI) Suite v4.11. The log Kow was estimated to be 2.89 for the non-dissociated form of dibutyl hydrogen phosphate. The predicted value can be considered reliable yielding a useful result for further assessment.

Description of key information

The QSAR determination of the logarithmic octanol-water partition coefficient for the substance using the model KOWWIN included in the Estimation Program Interface (EPI) Suite v4.11 revealed a value of -0.90 for the dissociated form of the substance, and 2.29 for the non-dissociated form.

Key value for chemical safety assessment

Log Kow (Log Pow):

-0.9

at the temperature of:

25 °C

Additional information

The logarithmic octanol-water partition coefficient (log Kow) for dibutyl hydrogen phosphate was predicted using the QSAR calculation of the Estimation Program Interface (EPI) Suite v4.11. The log Kow was estimated to be -0.90 for the dissociated form, and 2.29 for the non-dissociated form of dibutyl hydrogen phosphate. The predicted values can be considered reliable yielding a useful result for further assessment.

pH-value and temperature were not reported.

In addition an experimentally determined log Kow of 0.57 is available, which indicates a good correlation to the estimated value for the dissociated form of dibutyl hydrogen phosphate. Since a pKa value of 1.0 indicates that dibutyl hydrogen phosphate is mainly present in the dissociated form at environmental relevant pH, the value of -0.90 is considered for assessment.