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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2017
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
Guideline:
other: REACH Guidance on QSARs R.6, OECD 107, "Partition Coeficient (n-octanol/water): Shake Flask Method" (2) and No. 123 "Partition Coeficient (n-octanol/water): Slow Stirring Method”
Principles of method if other than guideline:
The determination was performed using a fragment based approach in which the molecule is divided into large and small fragments and each fragment is related to a specific log KOW contribution which may be positive or negative. The final log KOW is determined by simple addition of the fragments. The predicted log KOW values have been validated against high quality experimental studies generally using the shake-flask method but slow-stir values have been used when available. The results are considered to be as accurate as those from a good quality OECD 107 or 123 study.
Specific details on test material used for the study:
The substance is a mixture, the Log Kow therefore is based on seperately determined QSAR endpoints for each constiuent. Please refer to the study reports;

QSAR PREDICTION REPORTING FORMAT (QPRF) FOR THE LOG KOW PREDICTION OF 1-METHOXY-1-METHYL-4-(2-PROPANYLIDENE)CYCLOHEXANE

QSAR PREDICTION REPORTING FORMAT (QPRF) FOR THE LOG KOW PREDICTION OF 1-METHOXY-1-METHYL-4-(1-PROPEN-2-YL)CYCLOHEXANE

QSAR PREDICTION REPORTING FORMAT (QPRF) FOR THE LOG KOW PREDICTION OF 1-METHOXY-4-(2-METHOXY-2-PROPANYL)-1-METHYLCYCLOHEXANE

QSAR PREDICTION REPORTING FORMAT (QPRF) FOR THE LOG KOW PREDICTION OF (4R)-4-(2-METHOXYPROPAN-2-YL)-1-METHYLCYCLOHEXENE
Key result
Type:
log Pow
Partition coefficient:
>= 1.9 - <= 3.2
Temp.:
25 °C
Remarks on result:
other: QSAR prediction
Details on results:
The result in Table 1 describe the log KOW values anticipated further to a n-octanol/water partitioning study.

Table 1: Predicted Log Kow values

Constituents Log Kow at 25 ∘C

(4R)-4-(2-methoxy-2-propanyl)-1-methylcyclohexene

3.2

cis-1-methoxy-4-(2-methoxypropan-2-yl)-1-methylcyclohexane

1.9

cis-1-methoxy-1-methyl-4-(2-propanylidene)cyclohexane

3.2

2-[(1S)-4-methyl-3-cyclohexen-1-yl]-2-propanol

2.5

trans-1-methoxy-1-methyl-4-(1-propen-2-yl)cyclohexane

3.2

1-methoxy-1-methyl-4-(2-propanylidene)cyclohexane

3.1

trans-1-methoxy-4-(2-methoxypropan-2-yl)-1-methylcyclohexane

1.9

Conclusions:
This QSPR model has been validated as a QSAR model to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) in as much as this is possible for this model and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following OECD Guideline for Testing of Chemicals No. 107, or 123.

This model is based on a ‘Regression based-Fragment Approach’ (RFA) where linear regression equations for a series of common structures (for example alkanes) have been generated using high quality log KOW data and are included in the iSafeRat® database.

All the required fragment contribution values were available from the iSafeRat® log KOW module. Since no missing fragments were identified, the constituents of Reaction mass of (4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene and cis-1-methoxy-4-(2-methoxypropan-2-yl)-1-methylcyclohexane are within the structural fragment domain of the model.

The log Kow of constituents was reliably predicted to be in the range of 1.9 - 3.2 at 25 C.
Executive summary:

The Log Kow for constituents of Reaction mass of (4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene and cis-1-methoxy-4-(2-methoxypropan-2-yl)-1-methylcyclohexane were reliably predicted using the iSafeRat® Log Kow module with the molecular structure (SMILE code) as the inputs.

The log Kow of constituents was reliably predicted to be in the range of 1.9 - 3.2 at 25 C.

Description of key information

The Log Kow of the constituents of the reaction mass (4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene and cis-1-methoxy-4-(2-methoxypropan-2-yl)-1-methylcyclohexane had an estimated range of 1.9 - 3.2 at 25 °C (REACH guidance on QSAR's R.6, OECD 107 "Partition Coeficient (n-octanol/water): Shake Flask Method", OECD 123 "Partition Coefficient (n-octanol/water): Slow Stirring Method”, Thomas, P. (2017)).

Key value for chemical safety assessment

Additional information

No single value is applicable for this substance as it is a multi-constituent. Individual values derived for the relevant composition of this substance are presented in the following table.

Predicted Log Kow values

Constituent Log Kow at 25 ∘C

(4R)-4-(2-methoxy-2-propanyl)-1-methylcyclohexene

3.2

cis-1-methoxy-4-(2-methoxypropan-2-yl)-1-methylcyclohexane

1.9

cis-1-methoxy-1-methyl-4-(2-propanylidene)cyclohexane

3.2

2-[(1S)-4-methyl-3-cyclohexen-1-yl]-2-propanol

2.5

trans-1-methoxy-1-methyl-4-(1-propen-2-yl)cyclohexane

3.2
1-methoxy-1-methyl-4-(2-propanylidene)cyclohexane 3.1
trans-1-methoxy-4-(2-methoxypropan-2-yl)-1-methylcyclohexane 1.9