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EC number: 265-449-9 | CAS number: 65113-55-5
- 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
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2023
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
Data source
Reference
- Reference Type:
- study report
- Title:
- Unnamed
- Year:
- 2 023
- Report date:
- 2023
Materials and methods
Test guideline
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 112 (Dissociation Constants in Water)
- GLP compliance:
- not specified
Test material
- Reference substance name:
- [4-[p,p'-bis(dimethylamino)benzhydrylidene]cyclohexa-2,5-dien-1-ylidene]dimethylammonium m-[[p-anilinophenyl]azo]benzenesulphonate
- EC Number:
- 265-449-9
- EC Name:
- [4-[p,p'-bis(dimethylamino)benzhydrylidene]cyclohexa-2,5-dien-1-ylidene]dimethylammonium m-[[p-anilinophenyl]azo]benzenesulphonate
- Cas Number:
- 65113-55-5
- Molecular formula:
- C25H30N3.C18H14N3O3S
- IUPAC Name:
- [4-[p,p'-bis(dimethylamino)benzhydrylidene]cyclohexa-2,5-dien-1-ylidene]dimethylammonium m-[[p-anilinophenyl]azo]benzenesulphonate
- Test material form:
- solid: particulate/powder
Constituent 1
- Reference substance name:
- [4-[p,p'-bis(dimethylamino)benzhydrylidene]cyclohexa-2,5-dien-1-ylidene]dimethylammonium m-[[p-anilinophenyl]azo]benzenesulphonate
- EC Number:
- 265-449-9
- EC Name:
- [4-[p,p'-bis(dimethylamino)benzhydrylidene]cyclohexa-2,5-dien-1-ylidene]dimethylammonium m-[[p-anilinophenyl]azo]benzenesulphonate
- Cas Number:
- 65113-55-5
- Molecular formula:
- C25H30N3.C18H14N3O3S
- IUPAC Name:
- [4-[p,p'-bis(dimethylamino)benzhydrylidene]cyclohexa-2,5-dien-1-ylidene]dimethylammonium m-[[p-anilinophenyl]azo]benzenesulphonate
- Test material form:
- solid: particulate/powder
- Dissociating properties:
- not determined
- Remarks:
- No results could be calculated, as the molar extinction coefficients do not follow a clear trend in dependence of the pH. This might be originated by the existence of the two ionic compounds present in the test item with respective dissociation constants
- Remarks on result:
- not determinable
- Remarks:
- No results could be calculated, as the molar extinction coefficients do not follow a clear trend in dependence of the pH. This might be originated by the existence of the two ionic compounds present in the test item with respective dissociation constants influencing each other.
- Conclusions:
- No results could be calculated, as the molar extinction coefficients do not follow a clear trend in dependence of the pH. This might be originated by the existence of the two ionic compounds present in the test item with respective dissociation constants influencing each other.
Therefore, the photometer method was deemed to be not feasible for the determination of the dissociation constant of the test item. - Executive summary:
The determination of the dissociation constant of the test item (batch: 924249) in compliance to the OECD-Guideline 112 was determined to be not feasible.
Possibly due to the low water solubility (20 – 660 µg/L), it is neither possible to clearly determine a single dissociation constant using the titration method, nor to calculate results using the photometer method.
For the titration method, the test solution should have a concentration of at least 0.01 M, corresponding to approx. 7 g/L, or at half the saturation concentration. Both of these are possibilities for the determination according to OECD 112, as the water solubility is expected to be very low, the performance of the study is not feasible.
For the photometer method, no results could be calculated, as the molar extinction coefficients do not follow a clear trend in dependence of the pH.
The third possibility given in the guideline, the conductrometric method, was not tested, as the necessary test item concentration should be in the range of 0.1 M, i.e. approx. 72 g/L, which exceeds the expected water solubility at several magnitudes.
Reference
Constituent 1
Results and discussion
Dissociation constant
Any other information on results incl. tables
Titration method: Due to the very low solubility of the test item and the limitations regarding the volumes of the titrants used, the titration method was dismissed beforehand. The water solubility was determined to be in the range of 20 – 660 µg/L according to the OECD 105. The validity criteria of this guideline could not be met, but the used method was the best approach available and possible.
The photometer method was used for the determination of the dissociation constant, i.e. the dissociation of the test item must have an impact on the UV‑Vis absorption. Therefore, a significant difference of the absorption for at least a single wavelength must be present.
If this is the case, the dissociation constant can be calculated with known concentrations and for various pH values. These values should be within acceptable ranges to be valid.
Test solutions of nominal 10 mg/L were prepared by dilution of a test item stock solution of nominal 100 g/L in dichloromethane with various puffer solutions in the range of 1 – 14.
The absorption spectra of each test solution was measured (against separate blank solutions with buffer and dichloromethane but without test item). After the addition of the spiking solution to the respective buffer, a part of the test item did precipitate. The buffers were filtered via syringe filter (pore-size of 0.2 µm) before the photometric measurement. Additionally, the color of the test solutions did change depending on the pH value.
pH Value | Color |
1 | Deep pink |
2 | Bluish violet |
3 ‑ 7 | Violet |
9 | Weak violet |
12 ‑ 14 | Yellow |
For the definitive determination, 570 nm was chosen as the test wavelength, where the spectra show a significant difference in the absorption. 1 L of puffer solution at pH 12 was spiked with 0.1 mL test item stock solution (100 g/L in dichloromethane), resulting in a solution of 10 mg/L. The exact pH value was measured and an aliquot was taken and the absorption at 570 nm was determined.
Afterwards, hydrochloric acid was added to the whole sample until a nominal pH value of 11 was achieved with documentation of the exact pH value and the volume of used hydrochloric acid to determine the exact concentrations. Another aliquot was taken to determine the absorption at 570 nm.
This step was repeated for several pH values until a pH value of 1.
pH | c | E | ε | cHA/cA- | pKs | |
Nominal | Measured | |||||
12 | 12.053 | 0.00001409 | 0.221 | 15689 | Assumed to be fully undissociated | |
11 | 10.783 | 0.00001400 | 0.479 | 34205 | -0.7962 | n.a. |
10 | n.d. | 0.00001400 | n.a. | n.a. | -1.2405 | n.a. |
9 | 9.021 | 0.00001400 | 0.625 | 44646 | -0.8697 | n.a. |
8 | 7.737 | 0.00001400 | 0.654 | 46725 | -0.8784 | n.a. |
7 | 6.990 | 0.00001399 | 0.661 | 47237 | -0.8804 | n.a. |
6 | 6.081 | 0.00001398 | 0.663 | 47410 | -0.8811 | n.a. |
5 | 4.977 | 0.00001398 | 0.667 | 47719 | -0.8822 | n.a. |
4 | 4.081 | 0.00001395 | 0.643 | 46092 | -0.8759 | n.a. |
3 | 3.036 | 0.00001392 | 0.558 | 40077 | -0.8453 | n.a. |
2 | 2.078 | 0.00001372 | 0.402 | 29299 | -0.7228 | n.a. |
1 | 1.408 | 0.00001269 | 0.247 | 19462 | Assumed to be fully dissociated |
n.d. Erroneously skipped during preparation; value not determined
n.a. Not applicable
No results could be calculated, as the molar extinction coefficients do not follow a clear trend in dependence of the pH. This might be originated by the existence of the two ionic compounds present in the test item with respective dissociation constants influencing each other.
Therefore, the photometer method was deemed to be not feasible for the determination of the dissociation constant of the test item.
Applicant's summary and conclusion
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