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EC number: 806-543-7 | CAS number: 215917-77-4
- 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
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Dissociation constant
Administrative data
Link to relevant study record(s)
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2022-02-08
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 112 (Dissociation Constants in Water)
- Version / remarks:
- 1981
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 7.6
- Temp.:
- 20 °C
- Conclusions:
- The dissociation constant of the test item in water was determined to be 7.64 at 20 °C.
- Executive summary:
A study was conducted according to OECD Guideline 112 to determine the dissociation constant of the test item using the spectrophotometric method. A volume of 2.5 mL of the stock solution (0.5 mg/mL; dissolved in acetonitrile) was added to 25 mL of the various buffer solutions. UV absorption spectra of all the test solutions were recorded in 190 – 400 nm wavelength range. Control solutions containing acetonitrile were used as the reference. Spectra of the pH 2.9 (unionised form) and pH 10.1 (ionised form) test solutions was examined in 282-292 nm range. Greatest difference between the absorbance curves was found at 286.5 nm, therefore this wavelength was chosen for the evaluation. The dissociation constant of the test item in water was determined to be 7.64 at 20 °C.
Reference
Spectra of the pH 2.9 (unionised form) and pH 10.1 (ionised form) test solutions was examined in 282-292 nm range. Greatest difference between the absorbance curves was found at 286.5 nm, therefore this wavelength was chosen for the evaluation.
The pH and absorbance values corresponding to 286.5 nm were tabulated and plotted.
pKa was calculated with the following formula:
pKa= pH – log (AHA-A)/(A-AA-)
where pKa negative base-10 logarithm of the acid dissociation constant
pH pH measured for the test solution
A absorbance measured for the test solution
AHA absorbance measured for the unionised form
AA- absorbance measured for the ionised form
Absorbance of the test solutions and the calculated pKa values are summarised in the following table.
pH | Absorbance | pKa |
6.84 | 0.433 | 7.54 |
7.05 | 0.432 | 7.76 |
7.24 | 0.534 | 7.65 |
7.44 | 0.625 | 7.64 |
7.57 | 0.694 | 7.63 |
7.76 | 0.759 | 7.69 |
7.90 | 0.868 | 7.60 |
8.32 | 1.011 | 7.63 |
Mean | 7.64 | |
Standard deviation | 0.06 |
Description of key information
The dissociation constant of the test item in water was determined to be 7.64 at 20 °C.
Key value for chemical safety assessment
- pKa at 20°C:
- 7.64
Additional information
A study was conducted according to OECD Guideline 112 to determine the dissociation constant of the test item using the spectrophotometric method. A volume of 2.5 mL of the stock solution (0.5 mg/mL; dissolved in acetonitrile) was added to 25 mL of the various buffer solutions. UV absorption spectra of all the test solutions were recorded in 190 – 400 nm wavelength range. Control solutions containing acetonitrile were used as the reference. Spectra of the pH 2.9 (unionised form) and pH 10.1 (ionised form) test solutions was examined in 282-292 nm range. Greatest difference between the absorbance curves was found at 286.5 nm, therefore this wavelength was chosen for the evaluation. The dissociation constant of the test item in water was determined to be 7.64 at 20 °C.
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