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Dissociation constant

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Reference
Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Study initiation date: 29 June 2009 Study completion date: 19 October 2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Version / remarks:
adopted on 12 May 1981
Deviations:
no
GLP compliance:
yes
Dissociating properties:
yes
No.:
#1
pKa:
10.8
Temp.:
23.5 °C
Remarks on result:
other: based on two replicate determinations

Details on replicate determinations:

First run

Second run

pKa

10.78

10.77

pH value of aqueous solution

11.4

11.4

Mean value of pKa

10.8

For the plot of a titration curve, see attached figure below.

Conclusions:
Dissociation constant (OECD 112): pKa = 10.8 (alkaline functionality; at 23.5 °C)
Executive summary:

The dissociation constant of the test item was determined in a valid GLP compliant study performed according to OECD guideline no. 112 [adopted on 12 May 1981] with the titration method.

Result:

Dissociation constant (at 23.5 °C): pKa = 10.8 (alkaline functionality).

Description of key information

Dissociation constant (OECD 112):  pKa = 10.8 (alkaline functionality; at 23.5 °C)

Key value for chemical safety assessment

pKa at 20°C:
10.8

Additional information

The dissociation constant of the test item was determined in a valid GLP compliant study performed according to OECD guideline no. 112 [adopted on 12 May 1981] with the titration method.

Result:

Dissociation constant (at 23.5 °C): pKa = 10.8 (alkaline functionality).