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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:
february 2018
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:
OECD Guidelines for the Testing of Chemicals. Test No. 112: Dissociation Constants in Water (Titration Method-Spectroscopic Method-Conductometric Method)
Deviations:
no
GLP compliance:
no
Dissociating properties:
yes
No.:
#1
pKa:
ca. 7.97
Temp.:
22 °C
Remarks on result:
other: in ethanol:water
No.:
#2
pKa:
ca. 7.99
Temp.:
22 °C
Remarks on result:
other: in ethanol:water

Titration was performed in a total of 4 different solvents, THF, acetone, isopropanol and ethanol (each with water).

Only results with Ethanol:water are tabulated above, as these were the only ones with a very well-defined titration curve.

All other solvents resulted in less well-defined curves and less accurate pKa values within 8.02 -8.10, which are consistent with ethanol:water results tabulated above.

Conclusions:
The pKa of the tets item at 22°C was 8.0.
Executive summary:

The pKa of the tets item at 22°C was 8.0.

Description of key information

The test item has a pKa of 8.0 at 22°C.

Key value for chemical safety assessment

pKa at 20°C:
8

Additional information