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EC number: 692-731-2 | CAS number: 76950-43-1
- 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:
- 27 Mar 2013
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 112 (Dissociation Constants in Water)
- GLP compliance:
- no
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 8.37
- Temp.:
- 20 °C
Reference
SPARC predictions
8.38 and 8.78 (two respective tertiary amine reaction sites)
15.24 (hydroxyl group as reaction site)
Experimental results
Neutralization by hydrochloric acid:
Test substance solution was titrated by 0.1 N hydrochloric acid three times. 10 points before equivalence points were selected and pKa was calculated.
pKa = pH + log[BH+]/[B]
[BH+]: (Normal acid titration solution) * (factor of titration solution) * (added volume of titration solution (mL))/(volume of test solution (mL))
[B]: Concentration of test solution (M) – [BH+]
1st titration:
No. |
Volume [mL] |
pH |
[BH+] |
[B] |
log ([BH+]/[B]) |
pKa |
1 |
2.00 |
8.58 |
0.003846 |
0.006154 |
- 0.20 |
8.38 |
2 |
2.05 |
8.57 |
0.003939 |
0.006061 |
- 0.19 |
8.38 |
3 |
2.10 |
8.55 |
0.004031 |
0.005969 |
- 0.17 |
8.38 |
4 |
2.15 |
8.53 |
0.004123 |
0.005877 |
- 0.15 |
8.38 |
5 |
2.20 |
8.51 |
0.004215 |
0.005785 |
- 0.14 |
8.37 |
6 |
2.25 |
8.49 |
0.004306 |
0.005694 |
- 0.12 |
8.37 |
7 |
2.30 |
8.47 |
0.004398 |
0.005602 |
- 0.11 |
8.36 |
8 |
2.35 |
8.46 |
0.004489 |
0.005511 |
- 0.09 |
8.37 |
9 |
2.40 |
8.45 |
0.004580 |
0.005420 |
- 0.07 |
8.38 |
10 |
2.45 |
8.46 |
0.004671 |
0.005329 |
- 0.06 |
8.36 |
Mean pKa: 8.37, standard deviation: 0.01
2nd titration:
No. |
Volume [mL] |
pH |
[BH+] |
[B] |
log ([BH+]/[B]) |
pKa |
1 |
2.00 |
8.60 |
0.003846 |
0.006154 |
- 0.20 |
8.40 |
2 |
2.05 |
8.58 |
0.003939 |
0.006061 |
- 0.19 |
8.39 |
3 |
2.10 |
8.56 |
0.004031 |
0.005969 |
- 0.17 |
8.39 |
4 |
2.15 |
8.52 |
0.004123 |
0.005877 |
- 0.15 |
8.37 |
5 |
2.20 |
8.52 |
0.004215 |
0.005785 |
- 0.14 |
8.38 |
6 |
2.25 |
8.49 |
0.004306 |
0.005694 |
- 0.12 |
8.37 |
7 |
2.30 |
8.48 |
0.004398 |
0.005602 |
- 0.11 |
8.37 |
8 |
2.35 |
8.46 |
0.004489 |
0.005511 |
- 0.09 |
8.37 |
9 |
2.40 |
8.44 |
0.004580 |
0.005420 |
- 0.07 |
8.37 |
10 |
2.45 |
8.42 |
0.004671 |
0.005329 |
- 0.06 |
8.36 |
Mean pKa: 8.38; standard deviation: 0.01
3rd titration:
No. |
Volume [mL] |
pH |
[BH+] |
[B] |
log ([BH+]/[B]) |
pKa |
1 |
2.00 |
8.59 |
0.003846 |
0.006154 |
- 0.20 |
8.39 |
2 |
2.05 |
8.56 |
0.003939 |
0.006061 |
- 0.19 |
8.37 |
3 |
2.10 |
8.55 |
0.004031 |
0.005969 |
- 0.17 |
8.38 |
4 |
2.15 |
8.54 |
0.004123 |
0.005877 |
- 0.15 |
8.39 |
5 |
2.20 |
8.51 |
0.004215 |
0.005785 |
- 0.14 |
8.37 |
6 |
2.25 |
8.49 |
0.004306 |
0.005694 |
- 0.12 |
8.37 |
7 |
2.30 |
8.47 |
0.004398 |
0.005602 |
- 0.11 |
8.36 |
8 |
2.35 |
8.46 |
0.004489 |
0.005511 |
- 0.09 |
8.37 |
9 |
2.40 |
8.44 |
0.004580 |
0.005420 |
- 0.07 |
8.37 |
10 |
2.45 |
8.42 |
0.004671 |
0.005329 |
- 0.06 |
8.36 |
Mean pKa: 8.37; standard deviation: 0.01.
Neutralization by sodium hydroxide:
Test substance solution was titrated by 0.1 N sodium hydroxide once. No significant change in pH was observed around equivalence points (approx. 5 mL of added volume).
Interpretation
pKa was 8.37 as a result of the dissociation constant measurement of the test substance (tertiary amine) using neutralization titration with hydrochloric acid. This value was similar to the predicted pKa at tertiary amine sites: 8.38 and 8.75. Because the literature pKa value of a similar substance DABCO (1,4-diazacyclo[2.2.2]octane) is 2.97 and 8.82, pKa = 8.37 is considered as the first step of dissociation.
Since the measurement of pKa by sodium hydroxide resulted in no pH change around the equivalence points, pKa was not able to be measured. The predicted values of hydroxyl group of the test substance, and methanol used as analogue, are 15.24 and 15.50, respectively. This is the reason why the titration method is not an appropriate method in this case.
Description of key information
8.37 at 20 °C (OECD 112, titration method)
Key value for chemical safety assessment
- pKa at 20°C:
- 8.37
Additional information
Obtained pKa value results from the measurement of the test substance (tertiary amine) using neutralization titration with hydrochloric acid. This value is similar to the with SPARC predicted pKa at tertiary amine sites: 8.38 and 8.75. Because the literature pKa value of a similar substance DABCO (1,4-diazacyclo[2.2.2]octane) is 2.97 and 8.82, pKa = 8.37 is considered as the first step of dissociation.
Since the measurement of pKa by sodium hydroxide resulted in no pH change around the equivalence points, pKa was not able to be measured. The predicted values of hydroxyl group of the test substance, and methanol used as analogue, are 15.24 and 15.50, respectively. This is a reason why the titration method is not an appropriate method in this case.
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