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EC number: 240-539-0 | CAS number: 16484-77-8
- 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:
- 02 February 1999 to 22 June 1999
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 112 (Dissociation Constants in Water)
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- EPA OPPTS 830.7370 (Dissociation constants in water)
- Deviations:
- no
- GLP compliance:
- yes
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 3.7
- Temp.:
- 25 °C
- Conclusions:
- Under the conditions of the study the dissociation constant of the test material was found to be 2.0 x 10^-4 (equivalent pKa = 3.7).
- Executive summary:
The dissociation constant of the test material was assessed according to OECD Test Guideline 112 and in compliance with GLP.
The titration method was employed in order to determine the dissociation constant of the test material.
A solution of the test material is prepared in purified water such that the concentration does not exceed the lower of 0.01M or half the saturation concentration. The test solution is titrated with standard acid or base solution as appropriate, and the pH measured after each addition of titrant. The pKa is calculated from the points on the titration curve.
Triplicate samples (approximately 43 to 45 mg) of the test material were dissolved in purified water (100 mL) to form the test solutions. The purified water used to prepare the test solutions was freshly drawn from a water purification unit, boiled and cooled, and then stored under nitrogen prior to use. The quality of the water was such that no carbon dioxide should be present - this was confirmed by the fact the blank titration of pure water was consistent with the absence of carbon dioxide.
Portions (25 mL) of the approximately half-saturated solutions were then titrated with 0.01M aqueous potassium hydroxide. An equivalent blank titration was performed. In order to perform the titrations, a Corning 250 pH meter fitted with a Mettler Toledo Inlab 420 electrode was employed. The test temperature during the measurements was 25 °C.
The dissociation constant of the test material was determined directly from the graphical representations of the data. For each titration, the end point volume was determined as the volume at which the rate of change of the pH of the test solution was greatest. The pKa value for the compound is then calculated as the pH at half of the end point volume.
Under the conditions of the study the dissociation constant of the test material was found to be 2.0 x 10^-4 (equivalent pKa = 3.7).
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 19 January 1996 to 09 February 1996
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 112 (Dissociation Constants in Water)
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 2.8
- Temp.:
- 20 °C
- Conclusions:
- Under the conditions of the study, the dissociation constant of pure test material has been determined using the potentiometric method. The pKa was estimated to be 2.8 ± 0.1 at 20 °C.
- Executive summary:
The dissociation constant of the test material was assessed according to OECD Test Guideline 112 and in compliance with GLP using the potentiometric method.
Three test solutions were prepared by dissolving about 35 mg of test material in 100 mL of boiled water by using mild magnetic stirring. These solutions were titrated with the 0.025 M NaOH solution at about 20 °C and the pH was recorded after each addition of titrant. The pH and cumulative volumes of titrant were recorded. For each titration, the dissociation constant was calculated for ten points. The pH and cumulative volumes of titrant added were recorded by automatic titrator for each titration experiment. Then, for each titration, the dissociation constant was calculated for ten points and the mean value was obtained by averaging the ten pKa values. The calculation was done using the stoichiometric concentrations of HA and A- (schematizing the acid and basic forms of the compound) after each step of neutralisation and correcting these concentrations for the hydrogen ion concentrations.
The titrant concentration was determined by titrating three potassium hydrogen phthalate solutions at about 0.35 g/L in water and was found to be 0.0243 mol/L.
The pKa of the test material was determined in triplicate at about 20 °C.
Under the conditions of the study, the dissociation constant of pure test material has been determined using the potentiometric method. The pKa was estimated to be 2.8 ± 0.1 at 20 °C.
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 11 April 1990 to 20 August 1990
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 112 (Dissociation Constants in Water)
- Deviations:
- no
- GLP compliance:
- yes
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 2.5
- Temp.:
- 22 °C
- Conclusions:
- Under the conditions of the study the dissociation constant (pKa) for the test material was determined to be 2.50 at ambient temperature (approx 22 °C).
- Executive summary:
The dissociation constant for the test material was assessed according to OECD method 112 and in compliance with GLP by titration.
The dissociation constant for the test material was determined by titration of a 0.001 M aqueous solution (100 mL) of the test material with sodium hydroxide at ambient temperature.
Under the conditions of the study the dissociation constant (pKa) for the test material was determined to be 2.50 at ambient temperature (approx 22 °C).
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- August 1991
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 112 (Dissociation Constants in Water)
- Deviations:
- no
- GLP compliance:
- yes
- Dissociating properties:
- yes
- pKa:
- >= 3.66 - <= 3.7
- Temp.:
- 20 °C
- Conclusions:
- Under the conditions of the study the test material has a pKa of 3.68 (s ≤ 0.05) in the concentration range of 0.5 - 0.6 mmol/L at a temperature of 20 °C in an aqueous system. The corresponding Ka = 2.09 x 10^4.
- Executive summary:
The dissociation constant was assessed according to OECD Guideline 112 and in compliance with GLP.
A titration method was used with the test material dissolved in DMSO and NaOH.
Under the conditions of the study the test material has a pKa of 3.68 (s ≤ 0.05) in the concentration range of 0.5 - 0.6 mmol/L at a temperature of 20 °C in an aqueous system. The corresponding Ka = 2.09 x 10^4.
Referenceopen allclose all
Determination of the Titrant Concentration
The titrant concentration was determined by titrating three potassium hydrogen phthalate solutions at about 0.35 g/L in water and was found to be 0.0243 mol/L.
Determination of pKa for Benzoic Acid
The pKa of benzoic acid was determined in triplicate at about 20 °C using the method of calculation described above and the formulas a - c. The 3 values obtained were respectively 4.07, 4.15 and 4.01. The average value was 4.08 and was consistent with the pKa given in the OECD Guideline 112: pKa of benzoic acid at 20 °C is 4.12.
Determination of pKa for the Test Material
The pKa of the test material was determined in triplicate at about 20 °C.
Test |
pKa |
Standard Deviation |
Mean pKa |
Deviation |
1 |
2.98 |
0.02 |
2.79 |
0.14 |
2 |
2.74 |
0.03 |
-0.05 |
|
3 |
2.69 |
0.04 |
-0.10 |
Determination
|
Ve |
pKa |
1 |
10.10 |
2.50 |
2 |
10.10 |
2.49 |
|
Mean pKa value = 2.50 |
The pKa-values of the three titrations were in the range of 3.66 - 3.70. The standard deviation of each titration s ≤ 0.05. The mean value was 3.68 (Ka = 2.09 x 10^4).
Titration |
1 |
2 |
3 |
||||||
Weight A.I. (mg/L) |
121.92 |
120.44 |
121.28 |
||||||
Weight A.I. (mmol/L) |
0.568 |
0.561 |
0.565 |
||||||
Vt (mL) |
5.83 |
5.65 |
5.76 |
||||||
|
V (mL) |
pH |
pKa |
V (mL) |
pH |
pKa |
V (mL) |
pH |
pKa |
2.4 |
3.60 |
3.76 |
2.3 |
3.60 |
3.76 |
2.4 |
3.60 |
3.75 |
|
2.5 |
3.60 |
3.72 |
2.4 |
3.63 |
3.76 |
2.5 |
3.60 |
3.72 |
|
2.6 |
3.64 |
3.73 |
2.5 |
3.63 |
3.73 |
2.6 |
3.61 |
3.69 |
|
2.7 |
3.64 |
3.70 |
2.6 |
3.65 |
3.72 |
2.7 |
3.63 |
3.68 |
|
2.8 |
3.65 |
3.68 |
2.7 |
3.65 |
3.70 |
2.8 |
3.65 |
3.67 |
|
2.9 |
3.65 |
3.65 |
2.8 |
3.68 |
3.69 |
2.9 |
3.65 |
3.64 |
|
3.0 |
3.68 |
3.65 |
2.9 |
3.70 |
3.68 |
3.0 |
3.68 |
3.64 |
|
3.1 |
3.70 |
3.64 |
3.0 |
3.71 |
3.66 |
3.1 |
3.70 |
3.63 |
|
3.2 |
3.78 |
3.68 |
3.1 |
3.74 |
3.66 |
3.2 |
3.70 |
3.60 |
|
3.3 |
3.78 |
3.66 |
3.2 |
3.75 |
3.63 |
3.3 |
3.73 |
3.60 |
|
Mean value |
3.69 |
Mean value |
3.70 |
Mean value |
3.66 |
||||
s |
0.04 |
s |
0.04 |
s |
0.05 |
Description of key information
Comb (2000b)
Under the conditions of the study the dissociation constant of the test material was found to be 2.0 x 10^-4 (equivalent pKa = 3.7).
Cousin (1996)
Under the conditions of the study, the dissociation constant of pure test material has been determined using the potentiometric method. The pKa was estimated to be 2.8 ± 0.1 at 20 °C.
O'Connor (1990)
Under the conditions of the study the dissociation constant (pKa) for the test material was determined to be 2.50 at ambient temperature (approx 22 °C).
Redeker (1991)
Under the conditions of the study the test material has a pKa of 3.68 (s ≤ 0.05) in the concentration range of 0.5 - 0.6 mmol/L at a temperature of 20 °C in an aqueous system. The corresponding Ka = 2.09 x 10^4.
Key value for chemical safety assessment
Additional information
Comb (2000b)
The dissociation constant of the test material was assessed according to OECD Test Guideline 112 and in compliance with GLP. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).
The titration method was employed in order to determine the dissociation constant of the test material.
A solution of the test material is prepared in purified water such that the concentration does not exceed the lower of 0.01M or half the saturation concentration. The test solution is titrated with standard acid or base solution as appropriate, and the pH measured after each addition of titrant. The pKa is calculated from the points on the titration curve.
Triplicate samples (approximately 43 to 45 mg) of the test material were dissolved in purified water (100 mL) to form the test solutions. The purified water used to prepare the test solutions was freshly drawn from a water purification unit, boiled and cooled, and then stored under nitrogen prior to use. The quality of the water was such that no carbon dioxide should be present - this was confirmed by the fact the blank titration of pure water was consistent with the absence of carbon dioxide.
Portions (25 mL) of the approximately half-saturated solutions were then titrated with 0.01M aqueous potassium hydroxide. An equivalent blank titration was performed. In order to perform the titrations, a Corning 250 pH meter fitted with a Mettler Toledo Inlab 420 electrode was employed. The test temperature during the measurements was 25 °C.
The dissociation constant of the test material was determined directly from the graphical representations of the data. For each titration, the end point volume was determined as the volume at which the rate of change of the pH of the test solution was greatest. The pKa value for the compound is then calculated as the pH at half of the end point volume.
Under the conditions of the study the dissociation constant of the test material was found to be 2.0 x 10^-4 (equivalent pKa = 3.7).
Cousin (1996)
The dissociation constant of the test material was assessed according to OECD Test Guideline 112 and in compliance with GLP using the potentiometric method. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).
Three test solutions were prepared by dissolving about 35 mg of test material in 100 mL of boiled water by using mild magnetic stirring. These solutions were titrated with the 0.025 M NaOH solution at about 20 °C and the pH was recorded after each addition of titrant. The pH and cumulative volumes of titrant were recorded. For each titration, the dissociation constant was calculated for ten points. The pH and cumulative volumes of titrant added were recorded by automatic titrator for each titration experiment. Then, for each titration, the dissociation constant was calculated for ten points and the mean value was obtained by averaging the ten pKa values. The calculation was done using the stoichiometric concentrations of HA and A- (schematizing the acid and basic forms of the compound) after each step of neutralisation and correcting these concentrations for the hydrogen ion concentrations.
The titrant concentration was determined by titrating three potassium hydrogen phthalate solutions at about 0.35 g/L in water and was found to be 0.0243 mol/L.
The pKa of the test material was determined in triplicate at about 20 °C.
Under the conditions of the study, the dissociation constant of pure test material has been determined using the potentiometric method. The pKa was estimated to be 2.8 ± 0.1 at 20 °C.
O'Connor (1990)
The dissociation constant for the test material was assessed according to OECD method 112 and in compliance with GLP by titration.The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).
The dissociation constant for the test material was determined by titration of a 0.001 M aqueous solution (100 mL) of the test material with sodium hydroxide at ambient temperature.
Under the conditions of the study the dissociation constant (pKa) for the test material was determined to be 2.50 at ambient temperature (approx 22 °C).
Redeker (1991)
The dissociation constant was assessed according to OECD Guideline 112 and in compliance with GLP.The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).
A titration method was used with the test material dissolved in DMSO and NaOH.
Under the conditions of the study the test material has a pKa of 3.68 (s ≤ 0.05) in the concentration range of 0.5 - 0.6 mmol/L at a temperature of 20 °C in an aqueous system. The corresponding Ka = 2.09 x 10^4.
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