Registration Dossier
Registration Dossier
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EC number: 221-576-1 | CAS number: 3148-73-0
Dissociation constant
Administrative data
Link to relevant study record(s)
Description of key information
pKa1=10.9, pKa2=12.1, optical absorption, Chekanova 2002
pKa=10.86±0.05, 25±0.2°C, titration, Weber 1961
Key value for chemical safety assessment
- pKa at 20°C:
- 10.9
Additional information
The first dissociation constant reported by both Chekanova (2002) and Weber (1961), pKa=10.9 and 10.86 respectively, are in very good agreement - especially considering the use of different experimental techniques. Weber reported the temperature dependance of the pKa, with ΔpKa=0.11 for a 15°C change. As a result the uncertainty derived from the unreported experimental temperature in Chekanova's value (presumably "room temperature") is negligible. Other reported literature values reference back to these two original sources.
The first dissociation constant at 20°C is taken to be pKa=10.9, and this endpoint is deemed to be met according to Annex XI, Section 1.2, on the basis of the weight-of-evidence of two independent measurements using different experimental techniques reported in the scientific literature. The available data is considered relevant and adequate for risk assessment purposes, and conclusive.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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