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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Link to relevant study record(s)

Description of key information

pKa = 8.87 (HPLC)
pKa = 8.16 (25°C, potentiometry)
pKa = 8.35 (review article)

Key value for chemical safety assessment

pKa at 20°C:

Additional information

Several reliable sources reporting consistently similar values for the pKa of Propylparaben in the range of 8.16 to 8.87 determined by different methods. Considering all available values in a weight-of-evidence approach results in an average value of pKa = 8.46 for the dissociation constant of the hydroxylic function of Propylparaben. This value was used as key value for chemical safety assessment.