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Physical & Chemical properties

Dissociation constant

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Description of key information

experimental determination not feasible (mixture); individual components expected to be ionised in the environmental pH range (4 – 9) based on the presence of acidic (pKa ~ 4) and basic (pKa ~ 10) functional groups in the respective structures (QSAR, Marvin Sketch)

Key value for chemical safety assessment

Additional information

It is not technically feasible to experimentally determine the dissociation constants of DOPA-Glycinate due to the material being a mixture of a number of soluble components.It should also be noted that OECD guideline number 112 only applies to active substances if the water solubility cannot be measured.

The components making up the substance are assumed to be ionised in the environmental pH range (4 – 9) based on the presence of acidic (pKa ~ 4) and basic (pKa ~ 10) functional groups in the respective structures.

This is confirmed by the provision of pKa values for the indivdual components of DOPA-Glycinate using QSAR (generated by MarvinSketch). 

Overall, based on the properties, dissociation is not relevant under practical conditions, since at neutral, environmental and physiological pH conditions, >90% of the constituents should be in the ionic form.