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Physical & Chemical properties

Dissociation constant

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Description of key information

The pKa values for tartaric acid are: pKa1=2.98 and pKa2=4.34.
With regard tartaric acid salts, the dissociation constant study does not need to be performed in accordance with section 1 of REACH Annex XI, since salts are reaction products of acids and bases that retain their ionic character.

Key value for chemical safety assessment

Additional information

A collection of the pKa was performed for tartaric acid and its salts (i.e. monosodium, monopotassium, sodium potassium, sodium, potassium and calcium tartrate). As result, the following values were found:

EC name

pKa1

pKa2

(+)-tartaric acid

2.93 - 2.98

4.23 - 4.34

(-)-tartaric acid 

2.93 - 3.00

4.23

(±)-tartaric acid

2.96 - 3.03

4.24 - 4.37

 mesotartaric acid

3.11 - 3.17

4.80 - 4.91

With regard tartaric acid salts, the dissociation constant study does not need to be performed in accordance with section 1 of REACH Annex XI, since salts are reaction products of acids and bases that retain their ionic character.