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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:
20 Nov 1995 to 13 Dec 1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Version / remarks:
May 1981
GLP compliance:
yes
Dissociating properties:
no
Remarks on result:
not determinable
Remarks:
The test substance has no dissociation within the range pH 2 to pH 12

The spectra were recorded in a solution consisting mainly of methanol in order to improve the solubility of test item and to facilitate the experimental procedure. The actual concentrations of the acidic and basic test solutions were 0.1 N HCI and 0.1 N NaOH respectively. If the solutions were prepared in aqueous media then the pH of these solutions would have been 1 and 13, respectively. Even if in the methanolic solutions the pK values were to alter by one unit, the conditions used are still sufficient to draw the conclusion that there is no dissociation in the range pH 2 to pH 12.

Conclusions:
The test substance has no dissociation within the range pH 2 to pH 12.
Executive summary:

The study was performed to evaluate the dissociation constant of the test item in water according to OECD TG 112 and in compliance with GLP. The ultraviolet / visible spectra recorded in neutral, acidic and basic solution lead to the conclusion that no dissociation was to be expected within the range pH 2 to pH 12.

Description of key information

no dissociation at pH 2 - 12, OECD 112, test substance was prepared in methanol, spectrophotometer, Stulz 1995

Key value for chemical safety assessment

Additional information