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Physical & Chemical properties

Dissociation constant

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Reference
Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
August 2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: non-GLP
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
GLP compliance:
no
Dissociating properties:
yes
No.:
#1
pKa:
8.45
Temp.:
21 °C
Remarks on result:
other: ideal pKa
Conclusions:
The ideal pKa was determined as pKa 1 = 8.45 (@21°C).
Executive summary:

Results are presented below for the ideal pKa for ideal endpoint. Three pKa values were plotted against three different sample weights and extrapolated back to zero weight to give the ideal pKa value. The individual pKa results did not meet the test guideline for suggested repeatability quality criteria of + 0.1 pKa units of the mean. Observation of the test substance’s limited water solubility may have contributed to the degree of measurement uncertainty and also the sample weight vs pKa relationship. In lieu of these results, the pKa was also calculated using ACD/Labs prediction software,.

Summary of Titration test results:

pKa 1 = 8.45 at 21°C

This dissociation constant was confirmed by QSPR using ACD/Labs software.

Description of key information

The ideal pKa has been determined as pKa 1 = 8.45 @ 21°C

Key value for chemical safety assessment

pKa at 20°C:
8.45

Additional information

The pKa was titrated at 21°C and Dissociation constants were determined as ideal pKa. Theoretical calculation of dissociation constans using ACD labs software confirmed these results.