Registration Dossier
Registration Dossier
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EC number: 609-256-3 | CAS number: 365400-11-9
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:
- 26 Sept 2003 - 8 Sept 2005
- 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:
- spectrophotometric method
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Remarks:
- GLP certifying authority: Hess. Ministerium für Umwelt, Landwirtschaft und Forsten, Wiesbaden, Germany
- Dissociating properties:
- yes
- pKa:
- 4.2
- Temp.:
- 23 °C
- Remarks on result:
- other: SD= 0.15
Reference
Final Results - Dissociation Constant by OECD 112 (spectrophotometric method)
The dissociation constant of the test substance was determined according to OECD-Guideline 112, spectrophotometric method. Three individual experiments were carried out measuring the pH dependency of the UV-VIS spectra of the test item at room temperature. The result of each experiment is summarized in the following table.
Experiment |
pKa value |
SD |
A | 3.97 | 0.20 |
B |
4.25 |
0.47 |
C |
4.22 |
0.19 |
Mean |
4.15 |
0.15 |
The dissociation constant of the test substance is: pKa = 4.2 (SD= 0.15)
Result - pKa of Reference Substance (benzoic acid)
|
Temperature(°C) | pKa value of Benzoic acid (mean) |
This study |
22 to 23 |
4.18 |
OECD guideline 112 |
20 |
4.12 |
ADRIEN ALBERT and E.P.SERJEANT1
|
25 |
4.199 |
1The Determination of Ionization Constants, ADRIEN ALBERT and E. P.SERJEANT; Second edition 1971
The finding for the dissociation constant of benzoic acid is in an acceptable range compared with the reference values.
Description of key information
4.2 at 23 °C (OECD 112, spectrophotometric method)
Key value for chemical safety assessment
- pKa at 20°C:
- 4.2
Additional information
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