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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Dissociation constant

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Administrative data

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Description of key information

Dissociation constant (OECD 112): 5.8 at 22 °C (mean of 7 determinations) 

Key value for chemical safety assessment

pKa at 20°C:

Additional information

The key value was determined according to OECD Guideline 112 (Rocchio, 1990). The UV/Vis absorption spectrum at 300 nm is obtained from solutions of constant concentration under a pH condition where the substance is essentially unionized and fully ionized and at several intermediate pHs. From the pH and absorbance values at the chosen wavelength, seven values for the pKa are calculated using data from at least 5 pHs where the compound is at least 10 % and less than 90 % ionized.