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Diss Factsheets

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:
11 Mar 1992
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:
METHOD
By inspection of the chemical formula it can be expected that the test compound, will have no pK in an accessible range.
Nevertheless the following test was conducted:
4.463 mg of the test compound was dissolved in 25 mL methanol.
1 mL of this solution was diluted 1:10 with each of the following solutions:
0.1 N HCl (pH 1.0)
0.067 M Phosphate buffer (pH 7.0)
0.072 M Borax buffer (pH 10.0)
At each pH, absorption spectra in the range 210 to 320 nm were taken using a spectrophotometer Lambda 16 (1 cm cells, room temperature).
GLP compliance:
yes
Dissociating properties:
no
Remarks on result:
not determinable
Remarks:
the test substance has no dissociation within the range pH 1 to pH 10 at room temperature.

RESULTS

The obtained spectra, with the test substance at pH 1, pH 7 and pH10, were identical indicating that there is indeed no pKa in the range pK 0 to at least pK 10.

Conclusions:
The test substance does not dissociation within the range pH 1 to pH 10.
Executive summary:

A study was performed to evaluate the dissociation constant of the test substance in water in compliance with GLP. The spectra recorded using a neutral, acidic and basic solution lead to the conclusion that no dissociation was to be expected within the range pH 1 to pH 10.

Description of key information

No dissociation at the range of pH 1 - 10, test substance was prepared in methanol, spectrophotometer, Jäkel 1992.

Key value for chemical safety assessment

Additional information