2,4-xylenol

Partition coefficient

Link to relevant study record(s)

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 a well-known and acknowledged tool. See below under ''attached justification' for QPRF containing methodology and domain evaluation details.

Qualifier:

according to guideline

Guideline:

other: REACH guidance on QSARs: Chapter R.6. QSARs and grouping of chemicals

Principles of method if other than guideline:

The partition coefficient (log Kow) value for the test substance were estimated using the KOWWIN v.1.68. program in EPI SuiteTM v4.11. The log Kow values were predicted for the main constituent and the impurity (present at >0.1%) using SMILES codes as the input parameter.

Type of method:

other: Fragment constant method

Partition coefficient type:

other: QSAR prediction

Key result

Type:

log Pow

Partition coefficient:

2.61

Remarks on result:

other: predicted value of the main constituent

Remarks:

KOWWIN v.1.69. EPI SuiteTM v4.11

Type:

log Pow

Partition coefficient:

3.15

Remarks on result:

other: predicted value for the impurity

Remarks:

using KOWWIN v.169 of EPI Suite TM v.4.11

Table 1: Log Kow predictions: Fragment constant method

Constituents	Mean/adjusted conc	Log KOW	Domain evaluation
2,4-xylenol	99.50 %	2.61	MW (ID), Structural fragments (ID)
2,4,6-trimethylphenol	0.50 %	3.15	MW (ID), Structural fragments (ID)

Details on results:

 2,4-xylenol

Log Kow(version 1.69 estimate): 2.61
Experimental Database Structure Match:
Name    : 2,4-DIMETHYLPHENOL
CAS Num : 000105-67-9
Exp Log P: 2.30
Exp Ref : HANSCH,C ET AL. (1995)
SMILES : Cc1ccc(O)c(C)c1
CHEM  :
MOL FOR: C8 H10 O1
MOL WT : 122.17							ID	720
-------+-----+--------------------------------------------+---------+--------
TYPE | NUM |       LOGKOW FRAGMENT DESCRIPTION        | COEFF | VALUE
-------+-----+--------------------------------------------+---------+--------
Frag | 2 | -CH3   [aliphatic carbon]               | 0.5473 | 1.0946							ID	13
Frag | 6 | Aromatic Carbon                          | 0.2940 | 1.7640							ID	24
Frag | 1 | -OH    [hydroxy, aromatic attach]       |-0.4802 | -0.4802							ID	3
Const |    | Equation Constant                        |        | 0.2290
-------+-----+--------------------------------------------+---------+--------
Log Kow  =  2.6074

 2,4,6-trimethylphenol

Log Kow(version 1.69 estimate): 3.15
Experimental Database Structure Match:
Name    : 2,4,6-TRIMETHYLPHENOL
CAS Num : 000527-60-6
Exp Log P: 2.73
Exp Ref : SANGSTER (1993)
SMILES : Cc1cc(C)c(O)c(C)c1
CHEM  :
MOL FOR: C9 H12 O1							ID	720
MOL WT : 136.20
-------+-----+--------------------------------------------+---------+--------
TYPE | NUM |       LOGKOW FRAGMENT DESCRIPTION        | COEFF | VALUE
-------+-----+--------------------------------------------+---------+--------
Frag | 3 | -CH3   [aliphatic carbon]               | 0.5473 | 1.6419							ID	13
Frag | 6 | Aromatic Carbon                          | 0.2940 | 1.7640							ID	24
Frag | 1 | -OH    [hydroxy, aromatic attach]       |-0.4802 | -0.4802							ID	3
Const |    | Equation Constant                        |        | 0.2290
-------+-----+--------------------------------------------+---------+--------
Log Kow  =  3.1547

Conclusions:

Using the fragment constant method, of KOWWIN V.1.68 program of EPI SuiteTM, the partition coefficient (log Kow) value fof the main constituent and the impurity were predicted to bee of 2.61 and 3.15 respectively.

Executive summary:

The partition coefficient (log Kow) value for the test substance was predicted using the fragment constant method, of KOWWIN v.1.68 program. The log Kow values of the main constituent as well as the impurity (present above 0.1%) were predicted using SMILES codes as the input parameter. Using the fragment constant method, the log Kow values for the main constituent and the impurity were predicted to be 2.61 and 3.15 respectively (US EPA, 2021), suggesting moderate lipophilicity. The predictions were assessed to be within the molecular and structural domains. Further, considering the similarity between predicted and the experimental values for the three nearest structural analogues the overall predictions for the constituents can be considered to be accurate with low uncertainty.

Description of key information

The partition coefficient of the test substance was predicted using the KOWWIN v.1.68 module of EPI SuiteTM V.4.11 (US EPA, 2021)

Key value for chemical safety assessment

Log Kow (Log Pow):

2.61

Additional information

The Partition coefficient (log Kow) value for main constituent and the impurity were predicted to be 2.61 and 3.15 respectively, suggesting a moderate lipophilicty potential for the test substance. Further, considering that the predictions for the main constituent and the impurity are in the same range, the value corresponding to the main constituent has been considered further for hazard/risk assessment.