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Physical & Chemical properties

Dissociation constant

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Description of key information

Experimental data could not be determined according to OECD guideline 112.
Calculated results:
pKa1 = 15.10 ± 0.10, pKa1 is associated with the hydroxyl group.
pKa2 = 1.39 ± 0.50, pKa2 is associated with the sulfonic acid function.

Key value for chemical safety assessment

Additional information

A guideline study (OECD 112) did not deliver results for the dissociation constants of sodium 2 -hydroxyethanesulphonate. Therefore, a calculation was performed for the corresponding 2-hydroxyethanesulphonic acid with a commercially available software tool. Two values for the two functional groups were predicted. Each value is provided with its 95% confidence limits:

pKa1 = 15.10 ± 0.10, pKa1 is associated with the hydroxyl group.

pKa2 = 1.39 ± 0.50, pKa2 is associated with the sulfonic acid function.

The calculated data are consistent with what would be expected for the functional groups present in the molecule.

From this data it can be concluded that under environmental relevant conditions 2 -hydroxyethanesulphonic acid exists only in its single ionized form, represented by the hydroxysulfonate anion.