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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

The determination of this property was done according to a weight of evidence approach based on available literature references.

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.