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Partition coefficient

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Reference
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
Justification for type of information:
QSAR prediction from an well known and acknowledged tool. See below under 'Overall remarks, attachments' for applicability domain.
Qualifier:
according to
Guideline:
other: REACH guidance on QSARs: Chapter R.6. QSARs and grouping of chemicals
Principles of method if other than guideline:
Since the test substance is a UVCB with similar constituents varying mainly in carbon chain lengths, the partition coefficient values were estimated for the individual components followed by the determination of an overall weighted-average value using the mole fractions of all the individual components.
Key result
Type:
log Pow
Partition coefficient:
ca. 7.28
Temp.:
25 °C
Remarks on result:
other: Weighted average partition coefficient estimation using KOWWIN v1.68

Full test results:

Chemical names SMILES Mole fraction Xi = (mi/Mi)/∑ (mi/Mi) Log Kow LogKow*xi Domain evaluation
C16 phosphate monoester potassium salt CCCCCCCCCCCCCCCCOP(=O)([O-])[O-].[K+].[K+] 0.027764218 1.62 0.044978034 ID - Molecular weight and molecular fragments
C16 phosphate diester potassium salt CCCCCCCCCCCCCCCCOP(=O)([O-])OCCCCCCCCCCCCCCCC.[K+] 0.025229503 10.88 0.274496992 ID - Molecular weight and molecular fragments
Octadecanol CCCCCCCCCCCCCCCCCCO 0.591062355 7.7164 4.560873558 ID - Molecular weight and molecular fragments
Hexadecanol CCCCCCCCCCCCCCCCO 0.355943923 6.7342 2.396997569 ID - Molecular weight and molecular fragments
    1   7.277346154  

ID - In Domain, OD- Out Domain

KOW
       
                 Log Kow(version 1.68 estimate): 1.62      
       
SMILES : CCCCCCCCCCCCCCCCOP(=O)(O(K))O(K)      
CHEM  :  Domain evaluation    
MOL FOR: C16 H33 O4 P1 K2    MW (Training set) MW (Validation)
MOL WT : 398.61 ID 719.92 991.15
-------+-----+--------------------------------------------+---------+--------      
 TYPE | NUM |       LOGKOW FRAGMENT DESCRIPTION        | COEFF | VALUE       
-------+-----+--------------------------------------------+---------+--------   Training set Validation set
 Frag | 1 | -CH3   [aliphatic carbon]               | 0.5473 | 0.5473 ID 13 20
 Frag | 15 | -CH2-  [aliphatic carbon]               | 0.4911 | 7.3665 ID 18 28
 Frag | 3 | -O-P   [aliphatic attach]               |-0.0162 | -0.0486 ID 4 6
 Frag | 1 | O=P                                      |-2.4239 | -2.4239 ID 1 4
 Factor| 2 | misc-O-{Na,K,Li}  [coef*(1+0.5*(NUM-1))] |-2.7000**| -4.0500      
 Const |    | Equation Constant                        |        | 0.2290      
-------+-----+--------------------------------------------+---------+--------      
 NOTE |    | An estimated coefficient (**) used                 |      
-------+-----+--------------------------------------------+---------+--------      
                                                        Log Kow  =  1.6203      
       
                 Log Kow(version 1.68 estimate): 10.88      
       
SMILES : CCCCCCCCCCCCCCCCOP(=O)(O(K))OCCCCCCCCCCCCCCCC      
CHEM  :       
MOL FOR: C32 H66 O4 P1 K1    MW (Training set) MW (Validation)
MOL WT : 584.95 ID 719.92 991.15
-------+-----+--------------------------------------------+---------+--------      
 TYPE | NUM |       LOGKOW FRAGMENT DESCRIPTION        | COEFF | VALUE       
-------+-----+--------------------------------------------+---------+--------   Training set Validation set
 Frag | 2 | -CH3   [aliphatic carbon]               | 0.5473 | 1.0946 ID 13 20
 Frag | 30 | -CH2-  [aliphatic carbon]               | 0.4911 | 14.7330 ID 18 28
 Frag | 3 | -O-P   [aliphatic attach]               |-0.0162 | -0.0486 ID 4 6
 Frag | 1 | O=P                                      |-2.4239 | -2.4239 ID 1 4
 Factor| 1 | misc-O-{Na,K,Li}  [coef*(1+0.5*(NUM-1))] |-2.7000**| -2.7000      
 Const |    | Equation Constant                        |        | 0.2290      
-------+-----+--------------------------------------------+---------+--------      
 NOTE |    | An estimated coefficient (**) used                 |      
-------+-----+--------------------------------------------+---------+--------      
                                                        Log Kow  = 10.8841      
       
       
                 Log Kow(version 1.68 estimate): 7.72      
       
SMILES : CCCCCCCCCCCCCCCCCCO      
CHEM  :       
MOL FOR: C18 H38 O1    MW (Training set) MW (Validation)
MOL WT : 270.50 ID 719.92 991.15
-------+-----+--------------------------------------------+---------+--------      
 TYPE | NUM |       LOGKOW FRAGMENT DESCRIPTION        | COEFF | VALUE       
-------+-----+--------------------------------------------+---------+--------   Training set Validation set
 Frag | 1 | -CH3   [aliphatic carbon]               | 0.5473 | 0.5473 ID 13 20
 Frag | 17 | -CH2-  [aliphatic carbon]               | 0.4911 | 8.3487 ID 18 28
 Frag | 1 | -OH    [hydroxy, aliphatic attach]      |-1.4086 | -1.4086 ID 6 9
 Const |    | Equation Constant                        |        | 0.2290      
-------+-----+--------------------------------------------+---------+--------      
                                                        Log Kow  =  7.7164      
                 Log Kow(version 1.68 estimate): 6.73      
       
SMILES : CCCCCCCCCCCCCCCCO      
CHEM  :       
MOL FOR: C16 H34 O1    MW (Training set) MW (Validation)
MOL WT : 242.45 ID 719.92 991.15
-------+-----+--------------------------------------------+---------+--------      
 TYPE | NUM |       LOGKOW FRAGMENT DESCRIPTION        | COEFF | VALUE       
-------+-----+--------------------------------------------+---------+--------   Training set Validation set
 Frag | 1 | -CH3   [aliphatic carbon]               | 0.5473 | 0.5473 ID 13 20
 Frag | 15 | -CH2-  [aliphatic carbon]               | 0.4911 | 7.3665 ID 18 28
 Frag | 1 | -OH    [hydroxy, aliphatic attach]      |-1.4086 | -1.4086 ID 6 9
 Const |    | Equation Constant                        |        | 0.2290      
-------+-----+--------------------------------------------+---------+--------      
                                                        Log Kow  =  6.7342      
Conclusions:
Using the KOWWIN v1.68 program (EPI Suite v4.11), the weigthted average partition coefficient of the test substance was calculated to be 7.28.

Executive summary:

The partition coefficient value for the test substance were estimated using the KOWWIN v1.68 program (EPI Suite v4.11). Since the test substance is a UVCB with similar constituents varying mainly in carbon chain lengths, the partition coefficient values were estimated for the individual components followed by the determination of an overall weighted-average value using the mole fractions of all the individual components. SMILES codes were used as the input parameter for the partition coefficient estimation for the individual constituents. The estimated partition coefficient of the constituents were found to range from 1.62 to 10.88 leading to a weighted average value of 7.28 (US EPA, 2018), indicating that the test substance is not very soluble in water (US EPA, 2012). The estimates for the major constituents are considered to be reliable, as they fall within of the applicability domain.

Description of key information

The partition coefficient of the test substance was estimated using the KOWWIN v1.68 program (EPISuite v4.11) (US EPA, 2018).

Key value for chemical safety assessment

Log Kow (Log Pow):
7.28
at the temperature of:
25 °C

Additional information

Partition coefficient range: 1.62 to 10.88