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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:
experimental study
Adequacy of study:
key study
Study period:
08 April 1997
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
Dissociation constant was calculated by the Hammett and Taft Correlations.
GLP compliance:
no
Specific details on test material used for the study:
Name: FAT 40557/A
Colour: Red-brown
Aggregate State at
Room Temperature: Solid
Solubility in Water: > 100 g/l (20 °C)
Dissociating properties:
yes
No.:
#1
pKa:
-7.16
Remarks on result:
other: Arenesulfonic acid 1 (Hammett)
No.:
#2
pKa:
-7.18
Remarks on result:
other: Arenesulfonic acid 2 (Hammett)
No.:
#3
pKa:
-6.9
Remarks on result:
other: Arenesulfonic acid 3 (2x) (Hammett)
No.:
#4
pKa:
-6.99
Remarks on result:
other: Arenesulfonic acid 4 (Hammett)
No.:
#5
pKa:
-7.09
Remarks on result:
other: Arenesulfonic acid 5 (Hammett)
No.:
#6
pKa:
< 0
Remarks on result:
other: Azobenzene (2x) (General estimation)
No.:
#7
pKa:
8.07
Remarks on result:
other: Hydroxy arene (2x) (Hammett)
No.:
#8
pKa:
1
Remarks on result:
other: Nitrogen in ring 1 (2x) (Hammett)
No.:
#9
pKa:
0.52
Remarks on result:
other: Nitrogen in ring 2 (2x) (Hammett)
No.:
#10
pKa:
-1.13
Remarks on result:
other: Nitrogen in ring 3 (2x) (Hammett)

The pKa calculated using the Taft equation of Secondary amine 1 (2x) and secondary amine 2 (2x) is 0.42 and 0.58, respectively.

Conclusions:
The acid dissociation constants of the test substance was evaluated to be in the range from pKa -7.18 to 8.07.
Executive summary:

The dissociation constant in water of the test substance was calculated and twelve pKa's were estimated. The dissociation constant of the test substance was estimated to be in the range from pKa -7.18 to 8.07. The behaviour of the test substance in aqueous solution is dominated by the strongly acidic -SO3H-groups. The whole molecule is 6 -fold negatively charged and is present in anionic form over the whole environmentally relevant pH range.

Description of key information

The acid dissociation constants of the test substance was evaluated to be in the range from pKa -7.18 to 8.07.

Key value for chemical safety assessment

Additional information

The dissociation constant in water of the test substance was calculated and twelve pKa's were estimated (RCC 1997). The dissociation constant of the test substance was estimated to be in the range from pKa -7.18 to 8.07. The behaviour of the test substance in aqueous solution is dominated by the strongly acidic -SO3H-groups. The whole molecule is 6 -fold negatively charged and is present in anionic form over the whole environmentally relevant pH range.