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Physical & Chemical properties

Dissociation constant

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Description of key information

The pKa value for 4-Hydroxy-TEMPO was calculated as 5.07.

Key value for chemical safety assessment

pKa at 20°C:
5.07

Additional information

The dissociation constant of 4-Hydroxy-TEMPO is determined by QSAR estimation with the programme SPARC v.4.6 that is recommended in the REACH Guidance on information requirements and chemical safety assessment, Chapter R.7.1.17.3, Table R.7.1-36, thus the calculated value is reliable with restrictions. Therfore SPARC software v4.6 ( developed at the University of Georgia through grants from USEPA) was used. The supporting study reports a dissociation constant of 5.9. A pka value of 5.07 was predicted by the QSAR model. The differences between the theoretical and the practial value can be explained by the structure and the temperature.