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Dissociation constant

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Key value for chemical safety assessment

pKa at 20°C:

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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.