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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

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 constant of HEBMP-xNa has been read across from the parent acid. In aqueous solution HEBMP-xNa will dissociate. Four 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. As HEBMP-xNa is a salt of HEBMP-H, the dissociation constant of HEBMP-H fulfils the requirement of REACH.

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 are reported in section 4.20.