Registration Dossier
Registration Dossier
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EC number: 701-184-1 | CAS number: -
Dissociation constant
Administrative data
Link to relevant study record(s)
- Endpoint:
- dissociation constant
- Type of information:
- calculation (if not (Q)SAR)
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- accepted calculation method
- Remarks:
- This is an accepted calculation method supported by a limited amount of additional validation.
- Justification for type of information:
- See attached document
- Principles of method if other than guideline:
- Predictive method
- GLP compliance:
- no
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 1.3
- Temp.:
- 20 °C
- No.:
- #2
- pKa:
- 2
- Temp.:
- 20 °C
- No.:
- #3
- pKa:
- 3.4
- Temp.:
- 20 °C
- No.:
- #4
- pKa:
- 4.1
- Temp.:
- 20 °C
- No.:
- #5
- pKa:
- 5.9
- Temp.:
- 20 °C
- No.:
- #6
- pKa:
- 6.6
- Temp.:
- 20 °C
- No.:
- #7
- pKa:
- 8
- Temp.:
- 20 °C
- No.:
- #8
- pKa:
- > 10
- Temp.:
- 20 °C
- Conclusions:
- HMDTMP acid was determined to have eight dissociation constants using a relevant estimation method.
Reference
HMDTMP was determined to have
eight pKa values, of:
1.3
2
3.4
4.1
5.9
6.6
8
>10
Description of key information
Dissociation constant: HMDTMP acid has eight ionisable phosphonate groups.
Key value for chemical safety assessment
Additional information
In aqueous solution, HMDTMP (4 -7K) will ionise to form HMDTMP acid and potassium ions. Dissociation constants are obtained for the salt by valid read-across from the parent acid. Eight dissociation constants as listed below were obtained for the parent acid using an appropriate estimation method. The result is considered reliable and selected as key study.
pKa1 = 1.3
pKa 2 = 2
pKa 3 = 3.4
pKa 4 = 4.1
pKa 5 = 5.9
pKa 6 = 6.6
pKa 7 = 8
pKa 8 = >10
Similarly, in available secondary source to which reliability could not be assigned, six dissociation constant values as listed below are reported for the substance.
pKa 3 = 3.25
pKa 4 = 5.12
pKa 5 = 5.68
pKa 6 = 6.23
pKa 7 = 7.71
pKa 8 = 11.82
An approximate experimental determination, using stoichiometric titration and pH determination of aqueous solutions, has been conducted. This is considered to provide suitable and practical information, which is fit for purpose in the context of REACH chemical safety assessment. This data is reported in section 4.20.
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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