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EC number: 619-020-1 | CAS number: 94361-06-5
- 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
Link to relevant study record(s)
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 24 Jan 1989 to 30 Jan 1989
- 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:
- May 1981
- GLP compliance:
- yes
- Dissociating properties:
- no
- Remarks on result:
- other: the test substance has no dissociation within the range pH 3 to pH 10
- Conclusions:
- The test substance has no dissociation within the range pH 3 to pH 10.
- Executive summary:
The study was performed to evaluate the dissociation constant of the test substance in water according to OECD TG 112 in compliance with GLP. Potentiometric titrations of the test substance were conducted in water at 20 °C at constant ionic strength (I= 0.1 M; KCl) under nitrogen. The results show that the test substance does not have acid/base properties in the pH range between 3 and 10.In other words: the identity of the compound remains unchanged when it is dissolved in water under field conditions.
Reference
RESULTS AND DISCUSSION
The graphical representation of the 6 titrations shows that the 6 titrations yield practically the same results and that there are no significant differences between titrations with or without test substance present. The pH-mL points follow exactly the pattern to be expected for the titration of a strong acid with a strong base: At the beginning
of the titration the pH increases approximately linearly with the volume of base. Near the equivalence point (where 2.0 mL 0.01 M NaOH have been added to 2.0 mL 0.01 M HCl) a sharp rise of the pH occurs. At the end of the titration the pH increases only smoothly as determined by the activity of OH- and the pK of water. The only significant differences between the 6 titrations occur near the equivalence point. This of course is due to the fact that in this zone small differences in the total amount of added base have a large influence on the pH.
From this qualitative inspection of the titration data it is evident that between pH 3.5 and 10 test substance in water has neither acid nor base character, i.e., under ambient conditions (de)protonation of test substance does not occur.
A quantitative evaluation of the titration data was done by means of the program "TITFIT", which performs a non-linear least-squares fit according to the Newton-Gauss-Marquardt technique. The selection of the proper chemical model was straightforward since each of the six data sets is as expected for the titration of a strong acid. In our case all the concentrations are known and therefore, there are only two parameters for each set of titration data to be adjusted: 1. the proton activity coefficient (in TITFIT its; inverse value, 1/α, is used) which determines the low-pH part· o the titration and 2. the pK of water (in TITFIT its negative decadic logarithm, pKw, is used) which determines the high-pH region.
Fitting each set of titration data separately showed that the assumed model indeed gave a good fit of the data. The standard deviation between experimental and calculated points was 0.05 mL throughout, the values for 1/α were 2.6 - 2.7, and for pKw 13.6 - 13.7 was calculated. The fact that the calculated parameters for the six titrations closely agreed clearly shows the absence of an influence of test substance on the titration curve.
Table 1 Titration data
Titration | Control | Control | Control | Substance | Substance | Substance |
Exp. pH for buffer pH 4.00 | 4.07 | 4.06 | 4.08 | 4.04 | 4.08 | 4.08 |
Exp. pH for buffer pH 7.00 | 6.99 | 6.99 | 6.99 | 6.96 | 7.00 | 7.00 |
Volume of NaOH (mL) | pH (corrected values) | |||||
0.00 | 3.52 | 3.53 | 3.52 | 3.54 | 3.53 | 3.53 |
0.20 | 3.57 | 3.58 | 3.57 | 3.59 | 3.58 | 3.58 |
0.40 | 3.63 | 3.63 | 3.62 | 3.65 | 3.64 | 3.63 |
0.60 | 3.69 | 3.70 | 3.69 | 3.71 | 3.70 | 3.69 |
0.80 | 3.76 | 3.78 | 3.76 | 3.78 | 3.77 | 3.77 |
1.00 | 3.86 | 3.87 | 3.84 | 3.87 | 3.86 | 3.86 |
1.20 | 3.97 | 3.97 | 3.97 | 3.99 | 3.98 | 3.97 |
1.40 | 4.11 | 4.12 | 4.12 | 4.14 | 4.13 | 4.12 |
1.60 | 4.35 | 4.35 | 4.35 | 4.38 | 4.36 | 4.36 |
1.80 | 4.85 | 4.83 | 4.85 | 4.90 | 4.82 | 4.85 |
2.00 | 8.88 | 8.94 | 8.78 | 8.93 | 7.76 | 8.19 |
2.20 | 9.63 | 9.59 | 9.59 | 9.61 | 9.46 | 9.44 |
2.40 | 9.89 | 9.86 | 9.86 | 9.87 | 9.79 | 9.78 |
Description of key information
Key value for chemical safety assessment
Additional information
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