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EC number: 222-746-8 | CAS number: 3598-16-1
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Partition coefficient
Administrative data
Link to relevant study record(s)
- Endpoint:
- partition coefficient
- Type of information:
- (Q)SAR
- Adequacy of study:
- weight of evidence
- Study period:
- 2009
- 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
- Remarks:
- Documented QSAR from a well established program.
- Justification for type of information:
- The result obtained by the calculation method is further endorsed by the closeness of the results for the free acid phenoxy acetic acid by using either the experimental method or the same calculation method as used here. See the records "Hansch 1995.Partition coefficient PhAA" and "QSAR.Partition coefficient PhAA".
1. SOFTWARE
The logKow is estimated using the QSAR model KOWWIN v1.67. The programme is part of the Estimation Programs Interface (EPI) SuiteTM that was developed by the US Environmental Protection Agency's Office of Pollution Prevention and Toxics and Syracuse Research Corporation (SRC).
2. MODEL (incl. version number)
KOWWIN v1.67.
3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
Structures are entered by SMILES notations. For the SMILES see under Test Material Information.
4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Important information on the performance, development and application of EPI SuiteTM, and the individual programs within it, can be found under the Help tab of the programme. Copyright United States Environmental Protection Agency for EPI SuiteTM. See also https://www.epa.gov/tsca-screening-tools/epi-suitetm-estimation-program-interface
- Defined endpoint: Yes, partition coefficient n-octanol/water..
- Unambiguous algorithm: A description and equations are provided in the User Guide included in the Help to the programme.
- Defined domain of applicability: The minimum and maximum values for molecular weight are ca. 27 and 990. For details see under the Help tab of the programme.
- Appropriate measures of goodness-of-fit and robustness and predictivity:
KOWWIN has been tested on an external validation dataset of 10 946 compounds (compounds not included in the training set). The validation set includes a diverse selection of chemical structures that rigorously test the predictive accuracy of any model. It contains many chemicals that are similar in structure to chemicals in the training set, but also many chemicals that are different from and structurally more complex than chemicals in the training set.
The validation set estimation error is within 0.2 for 39.6 % and 1.5 for 99.1 % of the substances.
- Mechanistic interpretation: The article by Meylan, W.M. and P.H. Howard of 1995 Atom/fragment contribution method for estimating octanol-water partition coefficients. J. Pharm. Sci. 84: 83-92, describes the program methodology, i.e. the "fragment constant" methodology of KOWWIN.
5. APPLICABILITY DOMAIN
- Descriptor domain: The intended application domain is organic chemicals. Inorganic and organometallic chemicals generally are outside the domain.
- Structural and mechanistic domains: See the description included in the Help of the programme.
- Similarity with analogues in the training set: KOWWIN has been tested on an external validation dataset of 10 946 compounds (compounds not included in the training set). The validation set includes a diverse selection of chemical structures that rigorously test the predictive accuracy of any model. It contains many chemicals that are similar in structure to chemicals in the training set, but also many chemicals that are different from and structurally more complex than chemicals in the training set.
- Other considerations (as appropriate): /
6. ADEQUACY OF THE RESULT
The estimated logPow is adequate if not too close to the threshold criteria set in adaptations of endpoints in column 2 or in CLP.
The result obtained by the calculation method is further endorsed by the closeness of the results for the free acid phenoxy acetic acid by using either the experimental method or the same calculation method as used here. See the records "Hansch 1995.Partition coefficient PhAA" and "QSAR.Partition coefficient PhAA". - Reason / purpose for cross-reference:
- other: QSAR model supporting information
- Reason / purpose for cross-reference:
- other: QSAR model supporting information
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- The logKow was estimated using the QSAR model KOWWIN v1.67 within EpiSuite v4.0.
- GLP compliance:
- no
- Type of method:
- calculation method (fragments)
- Partition coefficient type:
- octanol-water
- Key result
- Type:
- log Pow
- Partition coefficient:
- -2.48
- Remarks on result:
- other: Temperature and pH are not available for QSAR-methods.
- Executive summary:
The logKow was estimated using the model KOWWIN v1.67 within EpiSuite v4.0.
The log Kow of Na phenoxyacetate is calculated to -2.48.
Reference
KOWWIN Program (v1.67) Results: =============================== Log Kow(version 1.67 estimate): -2.48 SMILES : c1(OCC(=O)O([Na]))ccccc1 CHEM : Na Phenoxy acetic acid MOL FOR: C8 H7 O3 Na1 MOL WT : 174.13 |
TYPE | NUM | LOGKOW FRAGMENT DESCRIPTION | COEFF | VALUE | |
Frag | 1 | -CH2- [aliphatic carbon] | 0.4911 | 0.4911 | |
Frag | 6 | Aromatic Carbon | 0.2940 | 1.7640 | |
Frag | 1 | -O- [oxygen, one aromatic attach] | -0.4664 | -0.4664 | |
Frag | 1 | -C(=O)O [ester, aliphatic attach] | -0.9505 | -0.9505 | |
Factor | 1 | C(=O)-O-{Na,K,Li} [coef*(1+0.5*(NUM-1))] | -3.5500 | -3.5500 | |
Const | Equation Constant | 0.2290 | |||
Log Kow = | -2.4828 |
Description of key information
Using the QSAR KOWWIN model for the salt and the free acid and comparing
the obtained data of the free acid with experimental data, it was concluded that the calculated value of the log Pow of sodium phenoxyacetate of -2.48 is reliable.
Key value for chemical safety assessment
- Log Kow (Log Pow):
- -2.48
Additional information
The results for the free acid phenoxy acetic acid (PhAA) were not used here to obtain a result for the target substance sodium phenoxyacetate (NaPhAA) by read-across. But it was the purpose of this exercise to check the reliability of the QSAR-method that was applied to estimate the partition coefficient of NaPhAA. The reliability was checked by comparing the experimentally determined partition coefficient for PhAA with the calculated result for PhAA, using the same estimation method as for NaPhAA.
Data from phenoxyacetic acid PhAA were obtained in addition to data on sodium phenoxyacetate NaPhAA. Both substances are well soluble in water. It can be assumed that the salt NaPhAA is dissociated to Na+ and the anion phenoxyacetate in dilute aqueous solution. PhAA is ionized in the neutral pH range, see section 4.21, according to the reported dissociation constant of 3.17. PhAA can therefore be expected also to be present as the anion phenoxyacetate in dilute and neutral aqueous solutions.
The logPow for PhAA was calculated to 1.33 respectively was experimentally determined to 1.34 for the non-ionized molecule at low pH. The closeness of both data, 1.33 and 1.34, is a good indicator that the used QSAR model is reliable for this substance.
The calculated log Pow of the salt NaPhAA is lower than that of the free acid, which is not unexpected as the salt is dissociated at the about neutral pH in dilute aqueous solution, impeding the dissolution in the unpolar octanol.
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