Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

The extrapolated dissociation constant of the test item in water was 9.7 ± 0.3 at 20 °C. 

Key value for chemical safety assessment

pKa at 20°C:

Additional information

Key study

BATELLE (2003)

A study was conducted according to OECD Guideline 112 to determine the dissociation constant of the test item. A saturated solution of the test item (approximately 1E7 mol/L) gave a too low absorbance to allow any accurate measurement. Water/methanol mixture was used to obtain higher absorbance due to increased solubility. The obtained experimental value was corrected since the alcohol content in the final solution exceeded 1 %. A set of ten values of pka was obtained from absorbance and pH measurements of these solutions. The dissociation constant of the test item in water/methanol (33/67) was experimentally found to be 9.2 ± 0.3 at 20 °C. The extrapolated dissociation constant of the test item in water was 9.7 ± 0.3 at 20 °C. 

Supporting information

RCC (1988)

Because the water solubility of test item is very low (< 5E5 g/L; data submitted by the sponsor) no significant absorbance can be obtained at a saturated concentration of the test substance in water. Hence, the dissociation constants of the test item in water cannot be determined using the methods as outlined in the test guidelines.