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Physical & Chemical properties

Dissociation constant

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Description of key information

The study is not scientifically justified.

Key value for chemical safety assessment

Additional information

The substance is a UVCB which contains partially neutralized forms of various different aminomethyl phosphonic acid species. Most of the individual acidic constituent species are also polyprotic ie contain multiple ionisable acidic functions (-PO3H and/or CO2H). It is not technically possible to determine a precise acid dissociation constant since there are so many different acidic constituents/functionalities present.  Any experimental determination would generate meaningless data due to the presence of multiple overlapping equilibria. Furthermore, due to the nature and complexity of the substance composition, it is also not possible to generate a simple prediction of the acid dissociation constant for the technical substance. The possibility of undertaking a study on the isolated main constituent species in the form of the acid was also considered however all attempts to isolate this substance have been unsuccessful, so this is not a technically feasible alternative. However, since the phosphonate group is a strong acid, significant ionization of the acidic constituent species would be anticipated under physiological and environmental conditions.