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Dissociation constant

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Endpoint:
dissociation constant
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification
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.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#2
pKa:
2.7
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#3
pKa:
5.9
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#4
pKa:
> 8
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.

HEBMP-H was determined to have four pKa values, of: 
pKa1 = 1.3
pKa2 = 2.7
pKa3 = 5.9
pKa4 = >8


Conclusions:
HEBMP acid was determined to have four dissociation constant using a relevant estimation method. The result is considered reliable.
Endpoint:
dissociation constant
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification
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.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#2
pKa:
2.7
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#3
pKa:
7.3
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.

HEBMP-H cyclic condensation product was determined to have three pKa values, of: 
pKa1 = 1.3
pKa2 = 2.7
pKa3 = 7.3


Conclusions:
HEBMP acid cyclic condensation product was determined to have three dissociation constant using a relevant estimation method. The result is considered reliable.

Description of key information

Dissociation constant (HEBMP-H): HEBMP acid has four ionisable protons.

Dissociation constant (HEBMP-H cyclic): HEBMP-H cyclic has three ionisable protons.

Key value for chemical safety assessment

Additional information

The dissociation constants listed below were obtained for the substance using an appropriate estimation method. The result is considered to be reliable and is selected as key study.

The non-cyclic constituent has four dissociation constants as listed below:

pKa1 = 1.3
pKa2 = 2.7
pKa3 = 5.9
pKa4 = >8

Similarly, the cyclic constituent has three dissociation constants as listed below:

pKa1 = 1.3

pKa2 = 2.7

pKa3 = 7.3

 

An approximate experimental determination, using stocichiometric 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.