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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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: 1.39

Key value for chemical safety assessment

pKa at 20°C:

Additional information

The dissociation Constant of Fatty acids, C12 -14, alpha-sulfo, disodium salts was determined on freeze-dried material according Guideline 112 (BASF study report 21 -14230 -3, 2022).

Dissociation constant in water was determined at 20.1 °C by using the conductometric method.

Result: The dissociation constant of the test item was determined to 1.39

The substance is a salt which is a reaction product of acid and base that retain their ionic character.

In addition, the dissociation constant on the single compound has been calculated, respectively.

The representative fatty acid part (in form of Dodecanoic acid, 2-sulfo and Tetradecanoic acid, 2-sulfo) were calculated with SPARC.

1) Dodecanoic acid, 2-sulfo:


calculated pKa= 4.21 at 25°C

2) Tetradecanoic acid, 2-sulfo:


calculated pKa= 5.49 at 25°C