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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Key value for chemical safety assessment

pKa at 20°C:

Additional information

The reaction mass of glycerol and thioglycolic acid is a complex mixture. Therefore, pKa values for individual components of the mixture were estimated by QSAR using SPARC (v. 4.5) chemical reactivity models for estimation ionization pKa in water. There are three types of ionisable groups present in the components of the reaction mass: thiol, hydroxyl and carboxyl groups. pKa values of individual components of the reaction mass are: 1,2-propanediol-3-sulfanylacetate: pKa,SH=8.40 at 20°C;

2-hydroxy-1,3-propanediyl bis(mercaptoacetate): pKa1,SH=8.07, pKa2,SH=8.68, pKa3,OH=13.78 at 20°C;

glycerol: does not dissociate in pH range -0.2 to 14 at 20°C;

1,3-propanediol-2-sulfanylacetate: pKa,SH=8.38 at 20°C;

mercaptoacetic acid: pKa1,COOH=3.76, pKa2,SH=10.04 at 20°C and

1,2,3-propanetriyl tris(mercaptoacetate): pKa1,SH=7.79, pKa2,SH=8.29, pKa3,SH=8.78 at 20°C.