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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:
From January 31 to February 1, 2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
GLP compliance:
not specified
Dissociating properties:
yes
No.:
#1
pKa:
>= 2.9 - <= 6.9
Temp.:
22 °C

The pKa value for the alkaline range was not determined because the test substance decomposes in alkaline solutions.

The pkA value was calculated using the following formula:

pKa=pH+log(dm-d)/(d-di)

Conclusions:
The dissociation constant was determined under the test conditions to be between 2.9 and 6.9 at 22°C in the acidic pH range.
No clear dissociation was observed in the alkaline range due to decomposition of the test item.
Executive summary:

A study was performed to determine the dissociation constant of Reactive Navy FC63805 according to OECD guideline 112.

Dissociation was determined using spectrophotometric determination. The pKa determination was performed by adding test substance to hydrochloric acid or sodium hydroxide solution and measuring subsequently the pH and the UV-Vis spectra (200 to 800 nm) of each resulting solution.

The dissociation constant was determined to be between 2.9 and 6.9 at 22 °C in the acidic pH range. No clear dissociation was observed in the alkaline range due to decomposition of the test item.

Description of key information

The dissociation constant was determined to be between 2.9 and 6.9 at 22°C in the acidic pH range.
No clear dissociation was observed in the alkaline range.

Key value for chemical safety assessment

Additional information

A study was performed to determine the dissociation constant of the test substance according to OECD guideline 112 and in compliance with GLP.

Dissociation was determined using spectrophotometric determination. The pKa determination was performed by adding test substance to hydrochloric acid or sodium hydroxide solution and measuring subsequently the pH and the UV-Vis spectra (200 to 800 nm) of each resulting solution.

The dissociation constant was determined to be between 2.9 and 6.9 at 22°C in the acidic pH range.

No clear dissociation was observed in the alkaline range.