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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Link to relevant study record(s)

Reference
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.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#2
pKa:
1.3
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#3
pKa:
2.7
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#4
pKa:
3.4
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#5
pKa:
3.4
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#6
pKa:
5.9
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#7
pKa:
5.9
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#8
pKa:
7
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#9
pKa:
> 9
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.
No.:
#10
pKa:
> 9
Temp.:
25 °C
Remarks on result:
other:
Remarks:
The result is based on QSAR prediction at ambient temperature.

BHMT-H was determined to have ten pKa values, of: 
pKa 1 = 1.3

pKa 2 = 1.3
pKa 3 = 2.7
pKa 4 = 3.4

pKa 5 = 3.4
pKa 6 = 5.9
pKa 7 = 5.9

pKa 8 = 7.0

pKa 9 = >9

pKa 10 = >9

Conclusions:
BHMT acid was determined to have ten dissociation constant using a relevant estimation method. The result is considered reliable.

Description of key information

Dissociation constant (BHMT-H): BHMT acid has ten ionisable phosphonate groups

Key value for chemical safety assessment

Additional information

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

 

BHMT-H was determined to have ten pKa values, of: 

pKa 1 = 1.3

pka 2 = 1.3

pKa 3 = 2.7

pKa 4 = 3.4

pKa 5 = 3.4

pka 6 = 5.9

pKa 7 = 5.9

pKa 8 = 7.0

pKa 9 = >9

pKa 10 = >9

 

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 (Liebsch 2012).