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Physical & Chemical properties

Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
27 October 2016
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 QSAR reports in Section 4.7 of this dossier for the Log Kow values for each of the constituents.
Key result
Type:
log Pow
Partition coefficient:
>= 1.9 - <= 4.7
Temp.:
25 °C
Remarks on result:
other: QSAR predicted value
Details on results:
The result in Table 1 describe the log Kow values anticipated further to a n-octanol/water partitioning study.

Table 1       Log Kow values at 25 ºC

Constituent Name

Log Kow

(4R)-4-isopropenyl-1-methylcyclohexene (limonene)

4.6

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

3.2

1-methyl-4-(2-propanylidene)cyclohexene (terpinolene)

4.5

cis-1-methoxy-1-methyl-4-(1-propen-2-yl)cyclohexane (cis-1-methoxy-8-pmenthene)

3.2

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

2.5

trans-1-methoxy-1-methyl-4-(1-propen-2yl)cyclohexane (trans-1-methoxy-8-p-menthene)

3.2

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

3.1

cis-1-methoxy-4-(2-methoxypropan-2-yl)-1-methylcyclohexane (cis-1,8-dimethoxy-p-menthane)

1.9

trans-1-methoxy-4-(2-methoxypropan-2-yl)-1-methylcyclohexane (trans-1,8-dimethoxyp-menthane)

1.9

7-methyl-3-methylene-1,6-octadiene (myrcene)

4.7

1-methyl-4-(2-propanyl)-1,3-cyclohexadiene (α-terpinene)

4.6

1-methyl-4-(2-propanyl)-1,4-cyclohexadiene (γ-terpinene)

4.5

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 table above.

Conclusions:
The Log Kow of the constituents of Reaction mass of (4R)-isopropenyl-1-methylcyclohexene and (4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene, estimated using the iSafeRat v.2.2 QSAR, were in the range of 1.9 - 4.7 at 25°C.

The QSAR model meets the criteria set out in section 1.3 of Annex XI to REACH and can be considered a reliable endpoint.
Executive summary:

The Log Kow for constituents of Reaction mass of (4R)-4 -isopropenyl-1-methylcyclohexene and (4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene 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 - 4.7 at 25 ºC.

Description of key information

Constituent 1 ( (4R)-4-isopropenyl-1-methylcyclohexene): Log Kow = 4.6 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

Log Kow (Log Pow):
4.16
at the temperature of:
25 °C

Additional information

Log Kowvalues at 25 ºC

Constituent Name

Log Kow

(4R)-4-isopropenyl-1-methylcyclohexene (limonene)

4.6

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

3.2

1-methyl-4-(2-propanylidene)cyclohexene (terpinolene)

4.5

cis-1-methoxy-1-methyl-4-(1-propen-2-yl)cyclohexane (cis-1-methoxy-8-pmenthene)

3.2

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

2.5

trans-1-methoxy-1-methyl-4-(1-propen-2yl)cyclohexane (trans-1-methoxy-8-p-menthene)

3.2

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

3.1

cis-1-methoxy-4-(2-methoxypropan-2-yl)-1-methylcyclohexane (cis-1,8-dimethoxy-p-menthane)

1.9

trans-1-methoxy-4-(2-methoxypropan-2-yl)-1-methylcyclohexane (trans-1,8-dimethoxyp-menthane)

1.9

7-methyl-3-methylene-1,6-octadiene (myrcene)

4.7

1-methyl-4-(2-propanyl)-1,3-cyclohexadiene (α-terpinene)

4.6

1-methyl-4-(2-propanyl)-1,4-cyclohexadiene (γ-terpinene)

4.5

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 table above.

For constituent 1 ( (4R)-4-isopropenyl-1-methylcyclohexene) the log Kow = 4.6 is used for chemical safety assessment.