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Diss Factsheets
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EC number: 701-182-0 | CAS number: -
- 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
Dissociation constant
Administrative data
Link to relevant study record(s)
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Principles of method if other than guideline:
- Sodium palmitate was titrated with 0.1 M sodium hydroxide at 25°C to determine the neutralisation endpoint. The dissociation constant was determined from the mean of five titrations of each solution. The pKa was calculated as the solution's pH at half the neutralisation volume.
- GLP compliance:
- no
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 8.6 - 8.8
- Temp.:
- 25 °C
- Remarks on result:
- other: Mean of five determinations
- Conclusions:
- The dissociation constant, pKa, of sodium palmitate is 8.6 - 8.8 at 25°C.
- Executive summary:
Kanicky et al. (2000) titrated sodium palmitate with sodium hydroxide and calculated the mean pKa from the pH at half the neutralisation volume for each of the five replicates. The study is a non-GLP, non-guideline experiment, available in a peer-reviewed published journal article. The experiment follows sound scientific principles, with limitations in design and/or reporting, and is considered adequate for assessment.
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Principles of method if other than guideline:
- Potassium stearate was titrated with 0.1 M hydrocloric acid at 20°C to determine the neutralisation endpoint. The dissociation constant was determined from the mean of five titrations of each solution. The pKa was calculated as the solution's pH at half the neutralisation volume.
- GLP compliance:
- no
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 10.15
- Temp.:
- 20 °C
- Remarks on result:
- other: Mean of five replicates
- Conclusions:
- The dissociation constant, pKa, of potassium stearate is 10.15 at 20°C.
- Executive summary:
Kanicky and Shah (2002) titrated potassium stearate with hydrochloric acid and calculated the mean pKa from the pH at half the neutralisation volume for each of the five replicates. The study is a non-GLP, non-guideline experiment, available in a peer-reviewed published journal article. The experiment follows sound scientific principles, with limitations in design and/or reporting, and is considered adequate for assessment.
- Endpoint:
- dissociation constant
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Remarks:
- Read across data
- Justification for type of information:
- REPORTING FORMAT FOR THE ANALOGUE APPROACH
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
At neutral pH, and within the limits of solubility, the substance is expected to dissociate into aluminium species, mainly aluminium hydroxide and fatty acid anions. The fatty acid anions would then be expected to achieve equilibrium with respect to the H+ ions in the water (depending on the pKa of the fatty acids) and at neutral pH there would be ionised acids, unionised acids, and aluminium hydroxide species. As the dissociation constant of the substance is expected to be determined by the equilibrium of the fatty acids with the hydrogen ions in the water, read across between the same fatty acids is considered to be justified.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The target substance comprises of a mixture of stearate (C18, saturated) and palmitate (C16, saturated) fatty acids. Therefore, stearate and palmitate salts are considered as read across substances.
3. ANALOGUE APPROACH JUSTIFICATION
The measured dissociation constant for sodium palmitate of 8.8 (Kanicky et al. 2000) and for potassium stearate of 10.15 (Kanicky and Shah 2002) are both relatively high and thus any dissociated fatty acid would be expected to be unionised (protonated) at environmental pH.
4. DATA MATRIX
Kanicky et al. (2000) titrated sodium palmitate with sodium hydroxide and calculated the mean pKa from the pH at half the neutralisation volume for each of the five replicates. Kanicky and Shah (2002) titrated potassium stearate with hydrochloric acid and calculated the mean pKa from the pH at half the neutralisation volume for each of the five replicates. The studies are non-GLP, non-guideline experiments, available in peer-reviewed published journal articles. The experiments follow sound scientific principles and are considered adequate for assessment. - Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 8.6 - 8.8
- Temp.:
- 25 °C
- Remarks on result:
- other: Mean of five determinations
- Conclusions:
- The dissociation constant, pKa, of sodium palmitate is 8.6 - 8.8 at 25°C.
- Executive summary:
Kanicky et al. (2000) titrated sodium palmitate with sodium hydroxide and calculated the mean pKa from the pH at half the neutralisation volume for each of the five replicates. The study is a non-GLP, non-guideline experiment, available in a peer-reviewed published journal article. The experiment follows sound scientific principles, with limitations in design and/or reporting, and is considered adequate for assessment.
- Endpoint:
- dissociation constant
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Remarks:
- Read across data
- Justification for type of information:
- REPORTING FORMAT FOR THE ANALOGUE APPROACH
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
At neutral pH, and within the limits of solubility, the substance is expected to dissociate into aluminium species, mainly aluminium hydroxide and fatty acid anions. The fatty acid anions would then be expected to achieve equilibrium with respect to the H+ ions in the water (depending on the pKa of the fatty acids) and at neutral pH there would be ionised acids, unionised acids, and aluminium hydroxide species. As the dissociation constant of the substance is expected to be determined by the equilibrium of the fatty acids with the hydrogen ions in the water, read across between the same fatty acids is considered to be justified.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The target substance comprises of a mixture of stearate (C18, saturated) and palmitate (C16, saturated) fatty acids. Therefore, stearate and palmitate salts are considered as read across substances.
3. ANALOGUE APPROACH JUSTIFICATION
The measured dissociation constant for sodium palmitate of 8.8 (Kanicky et al. 2000) and for potassium stearate of 10.15 (Kanicky and Shah 2002) are both relatively high and thus any dissociated fatty acid would be expected to be unionised (protonated) at environmental pH.
4. DATA MATRIX
Kanicky et al. (2000) titrated sodium palmitate with sodium hydroxide and calculated the mean pKa from the pH at half the neutralisation volume for each of the five replicates. Kanicky and Shah (2002) titrated potassium stearate with hydrochloric acid and calculated the mean pKa from the pH at half the neutralisation volume for each of the five replicates. The studies are non-GLP, non-guideline experiments, available in peer-reviewed published journal articles. The experiments follow sound scientific principles and are considered adequate for assessment. - Reason / purpose for cross-reference:
- read-across source
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 10.15
- Temp.:
- 20 °C
- Remarks on result:
- other: Mean of five replicates
- Conclusions:
- The dissociation constant, pKa, of potassium stearate is 10.15 at 20°C.
- Executive summary:
Kanicky and Shah (2002) titrated potassium stearate with hydrochloric acid and calculated the mean pKa from the pH at half the neutralisation volume for each of the five replicates. The study is a non-GLP, non-guideline experiment, available in a peer-reviewed published journal article. The experiment follows sound scientific principles, with limitations in design and/or reporting, and is considered adequate for assessment.
Referenceopen allclose all
Description of key information
The dissociation constant, pKa, of the substance has been read across from sodium palmitate, with a pKa of 8.6 - 8.8 at 25°C and potassium stearate, with a pKa of 10.15 at 20°C.
Key value for chemical safety assessment
Additional information
The dissociation constants have been taken from published articles, read across from sodium palmitate (Kanicky et al 2000), potassium stearate (Kanicky and Shah 2002).
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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