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EC number: 215-662-8 | CAS number: 1338-24-5
Partition coefficient
Administrative data
Link to relevant study record(s)
- Endpoint:
- partition coefficient
- Type of information:
- (Q)SAR
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- guideline study with acceptable restrictions
- Justification for type of information:
- QSAR prediction
- Qualifier:
- according to guideline
- Guideline:
- other: REACH guidance on QSARs R.6, 2008
- Qualifier:
- according to guideline
- Guideline:
- other: REACH Chapter R.7A - Endpoint specific guidance, 2008. Table R.7.1-24
- Principles of method if other than guideline:
- Partition coefifcients were estimated using the validated EPISuite modelling tool (US EPA). The method used is KOWWIN v 1.68 which is an atom fragment contribution method.
- GLP compliance:
- no
- Remarks:
- not applicable
- Type of method:
- other: (Q)SAR Tool:KOWWIN v 1.68
- Partition coefficient type:
- octanol-water
- Specific details on test material used for the study:
- For Smiles notation and C-number please see under Any other information on materials and methods incl. tables
- Type:
- log Pow
- Partition coefficient:
- > 2.05 - < 13.25
- Remarks on result:
- other: No pH and temperature value was reported
- Details on results:
- Validity of model
1. Defined endpoint: log Kow
2. Unamibous algorithm: Linear regression QSAR log P = Σ(fini ) + Σ(cjnj ) + 0.229 in which fi = coefficient for fragment/atom, cj =
coefficient for correction factor, ni,nj = numbers of fragment/atoms/correction factors
3. Applicability domain: There is no real applicability domain defined, but the applicability is expected to be better if the molecular weight of
the substance falls within the ranges of molecular weights of the training set (18.02 - 719.92) and the validation set (27.03-991.15). The
number of fragments does not exceed the maximum number of fragments in the training set or the validation set.
4. Statistical characteristics: training set: N = 2447, coefficient of determination R2=0.982, validation set: N = 10946, coefficient of
determination R2=0.943
5. Mechanistic Interpretation: the structure is divided into fragments (atom or larger functional groups) and coefficient values of each
fragment or group are summed together to yield the log P estimate.
Adequacy of the prediction: the naphtehnic acids fall within the applicability domain described above (molecular weight = 116.16 -432.74 and the
number of fragments does not exceed the number in the training and test set) and, therefore, the predicted value can be considered reliable
taking into account that the standard deviation error of prediction is 0.478 for logKow - Conclusions:
- The partition coefficient for different structures of naphthenic acids ranges from 2.05 to 13.25, for smaller and larger molecules respectively.
- Executive summary:
The log Pow was estimated with KOWWIN version 1.68. This QSAR model is included in the EpiSuite programs developed by Syracuse Research Corporation for US-EPA. The calculated log Pow for different structures of naphthenic acids ranges from 2.05 to 13.25, for smaller and larger molecules respectively.
The most prominent group of naphthenic acids has 10 to 19 carbon numbers, for this group the logPow has a range from 3.76 to 7.92.
- Endpoint:
- partition coefficient
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 4 (not assignable)
- Rationale for reliability incl. deficiencies:
- secondary literature
- Principles of method if other than guideline:
- Data were taken from a secondary source. Original source data were not available for review
- GLP compliance:
- not specified
- Partition coefficient type:
- octanol-water
- Type:
- log Pow
- Partition coefficient:
- >= 5
- Conclusions:
- The log Kow of Naphthenic Acid was reported to be >= 5 under the described conditions.
Referenceopen allclose all
Due to the complex composition of naphthenic acid, unequivocal determination of the log Kow of naphthenic acid mixtures cannot be made. To gain an understanding of the partitioning potential, partition coefficients are calculated for a selection of different possible structures. The selection is made based on the substance identification and is therefore a good representation of the composition of naphthenic acids.
Tabulated values for various naphthenic acid molecules are:
|
| C-number | Ring | Branch | SMILES | Mw | Log Kow |
| C6 | - | - | C(=O)(O)CCCCC | 116,16 | 2,0512 |
| C7 | - | - | C(=O)(O)CCCCCC | 130,19 | 2,5423 |
| C8 | - | - | C(=O)(O)CCCCCCC | 144,22 | 3,0334 |
| C8 | 1 pentane | - | C(=O)(O)CCC1CCCC1 | 142,2 | 2,8475 |
| C9 | - | methyl | C(=O)(O)CCCC(C)CCC | 158,24 | 3,451 |
| C10 | - | ethyl | C(=O)(O)CCCC(CCC)CC | 172,27 | 3,9421 |
| C10 | 1 pentane | - | C(=O)(O)CCC1C(CC)CCC1 | 170,25 | 3,7562 |
| C11 | 1 pentane | - | C(=O)(O)CCC1C(CCC)CCC1 | 184,28 | 4,2473 |
| C12 | 1 hexane | - | C(=O)(O)CCC1C(CCC)CCCC1 | 198,31 | 4,7384 |
| C12 | 1 pentane | - | C(=O)(O)CCC1C(CCCC)CCC1 | 198,31 | 4,7384 |
| C12 | 2 pentanes fused | - | C(=O)(O)CCC1C2C(C)CCC2CC1 | 196,29 | 3,7948 |
| C13 | 2 pentanes | - | C(=O)(O)CCC1C(C2CCCC2)CCC1 | 210,32 | 5,0436 |
| C13 | pentane hexane fused | O=C(O)CCC2CCCC1CCC(C)C12 | 210,32 | 4,2859 | |
| C14 | 1 hexane | - | O=C(O)C1C(CCCCCCCC)CCC1 | 226,36 | 5,7206 |
| C14 | 2 pentanes | - | C(=O)(O)CCC1CC(C2C(C)CCC2)CC1 | 224,35 | 5,4612 |
| C14 | 2 pentanes fused | - | C(=O)(O)CCCC1C2C(CC)CCC2CC1 | 224,35 | 4,777 |
| C15 | - | propyl | C(=O)(O)CCCCC(CCCCCC)CCC | 242,41 | 6,3976 |
| C15 | 1 pentane | ethyl | C(=O)(O)CCC1C(CC(CCC)CC)CCC1 | 240,39 | 6,1382 |
| C15 | 2 pentanes | - | C(=O)(O)CCC1C(CC2CC(C)CC2)CCC1 | 238,37 | 5,9523 |
| C15 | 2 hexanes fused | O=C(O)CCC1CCC2CCCC(CC)C2C1 | 238,37 | 5,2681 | |
| C15 | 3 pentanes fused | - | C(=O)(O)CCCC1C2C3C(CC2CC1)CCC3C | 250,38 | 4,8156 |
| C16 | 1 pentane | - | C(=O)(O)CCC1C(CCCCCCCC)CCC1 | 254,42 | 6,7028 |
| C16 | 2 pentanes | - | C(=O)(O)CCC1CC(C2C(CCC)CCC2)CC1 | 252,4 | 6,4434 |
| C16 | 2 hexane | - | C(=O)(O)C1C(CCC2C(C)CCCC2)CCCC1 | 252,4 | 6,4434 |
| C16 | 3 pentanes of which 2 fused | - | C(=O)(O)CC1C2C(CC3CCCC3)CCC2CC1 | 250,38 | 5,5733 |
| C17 | 1 pentane | - | C(=O)(O)CCC1C(CCCCCCCCC)CCC1 | 268,44 | 7,1939 |
| C17 | 4 pentanes fused | - | C12(C3C(CC(=O)O)CCC3CC1)C1C(CCC1)CC2 | 262,4 | 5,1567 |
| C18 | 1 hexane | propyl | C(=O)(O)CCC1C(CC(CCCC)CCC)CCCC1 | 282,47 | 7,6115 |
| C18 | 3 pentanes of which 2 fused | - | C(=O)(O)CCCCC1C2C(C3CCCC3)CCC2CC1 | 278,44 | 6,5555 |
| C19 | 2 pentanes fused | ethyl | C(=O)(O)CCCCC1C2C(C(CCC)CC)CCC2CC1 | 294,48 | 7,159 |
| C19 | 2 pentane | propyl | C(=O)(O)CC1CC(CC(CCC2CCCC2)CCC)CC1 | 294,48 | 7,9167 |
| C25 | 2 hexane | propyl | C(=O)(O)CCCC(CCC1C(CCC2C(C)CCCC2)CCCC1)CCC | 378,64 | 10,7898 |
| C30 | 2 hexane | propyl | C(=O)(O)CCC(CCCC1C(CCC2C(CCCCCC)CCCC2)CCCC1)CCC | 448,78 | 13,2453 |
| C30 | 3 hexane | - | C(=O)(O)CCCCCCC1C(CCC2C(CCCC3CCCCC3)CCCC2)CCCC1 | 446,76 | 13,1329 |
| C30 | 3 hexanes fused | ethyl-ethyl | O=C(O)CCCCC(CC)CCC1CC2CCCC3CC(CCC(CC)CC)CC(C1)C23 | 446,76 | 12,2282 |
| C30 | 2 hexanes fused 1 not | propyl | O=C(O)CCCC(CCC)CCCC1CCC2CC(CCC2C1)CC3CCCC(C)C3 | 432,74 | 11,8106 |
No further details given.
Description of key information
A range of 2.05 to 13.25 for the log Kow was obtained using the EPISuite modelling tool considered reliable with restrictions (K2) and assigned as key study. A not assignable (K4) literature reference reported a value of >5 (NIOSH, 2007) and was used as supporting study.
Key value for chemical safety assessment
- Log Kow (Log Pow):
- 7.65
Additional information
Because naphthenic acids is a UVCB, physicochemical properties vary according to the proportions of the individual compounds in their composition. Therefore it is not possible to set a specific value for partition coefficient. To gain an understanding of partition coefficient characteristics of naphthenic acids, various hydrocarbon acidic structures which are shown to predominate in naphthenic acids were estimated for partition coefficient using the EPISuite computer model (US EPA, 2009). A range of values between 2.05 and 13.25 are reported. These results are supported by data found in secondary literature (log Pow>5).
Value used for CSA: >5
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