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Registration Dossier
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EC number: 204-427-5 | CAS number: 120-80-9
Dissociation constant
Administrative data
Link to relevant study record(s)
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: The IUPAC Data Series are among "reference books containing peer-reviewed physico-chemical data" cited in the ECHA guidance document on information requirements and chemical safety assessment (R.7a).
- Qualifier:
- no guideline available
- Principles of method if other than guideline:
- no data
- GLP compliance:
- not specified
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 9.23
- Temp.:
- 25 °C
- Remarks on result:
- other: Acid-base constant: 5.88 * 10E-10
- No.:
- #2
- pKa:
- 13.05
- Temp.:
- 25 °C
- Remarks on result:
- other: Acid-base constant: 9.55 * 10E-14
- Conclusions:
- pKa1 = 9.23 and pKa2 = 13.05
- Executive summary:
The peer-reviewed IUPAC Data Series report the following dissociation constants for catechol: pKa1 = 9.23 and pKa2 = 13.05. In the aquatic environment, pH mainly varies from 6 to 8. As a result, at these environmentally relevant pH, catechol should appear under its non-dissociate form.
Reference
Description of key information
pKa1 = 9.23 and pKa2 = 13.05
Key value for chemical safety assessment
Additional information
A peer-reviewed document is available and flagged as a key study. Based on the pKa values reported, and knowing the pH of natural aqueous media, catechol should appear under its non-dissociated form at environmentally relevant pH.
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