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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:
2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Dissociating properties:
no
Remarks on result:
other: The test item shows virtually no dissociation.

Three different approaches were made. A determination of the dissociation constant wasn't possible as the test item shows virtually no dissociation.

When using the volumetric method, a test item concentration above 100 mg/L should be used , as weaker solutions show only small changes in pH. The test item isn't sufficiently soluble in water. Solubility was determined in study 07120704G910 with 49 mg/L. Larger concentrations didn't dissolve, even when adding HCL or NaOH. Therefore, this method could not be used.

For testing the applicability of the conductometric method, a saturated solution of the test item was prepared and its conductivity was measured. The saturated solution showed a conductivity of 1.7 µS/cm, lower concentrations gave no dose-response-relation, and the

absolute values were very small. Therefore, the conductometric method could not be used, either.

Then, the photometric method was applied. No significant differences in the spectra of six test item solutions with different pHs could be found. Therefore, the photometric method didn't yield results, either.

As the test item N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1 H-azepine-1-carboxamide) shows virtually no measurable dissociation in aqueous solutions, determination of the dissociation constant is not possible.

Conclusions:
No measurable dissociation in aqueous solutions, therefore the determination of the dissociation constant is not possible.
Executive summary:

No measurable dissociation in aqueous solution.

Description of key information

The test item shows virtually no dissociation.

Key value for chemical safety assessment

Additional information

As the test item N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1 H-azepine-1-carboxamide)

shows virtually no measurable dissociation in aqueous solutions, determination of the dissociation

constant is not possible.