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Physical & Chemical properties

Dissociation constant

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Description of key information

pKa= 10.2 at 25°C


Key value for chemical safety assessment

Additional information

According to OECD method 112, the method directs that test solution concentrations should not exceed the lesser of 0.01 M or half the saturation concentration. If the substance is only sparingly soluble, it may be dissolved in a small amount of a water-miscible solvent prior to adding to the concentrations indicated above.

The water solubility of test substance was determined to be < 0.001 mg/L. This level was the limit of quantitation for the method. To determine the dissociation constant, solutions would have to be prepared at concentrations of half this level or lower. In consequence of the extremely poorly water solubility and the fact that an analytical method could not be developed to meet this low quantitation limit, the dissociation constant test could not be performed and must be estimated by the calculation.

The calculation was using the software program SPARC v.4.6

Since the test substance is extremely poorly water soluble and the calculated pKa value of the phenolic OH-group falls outside the environmentally relevant pH range (5-9) thus this can be suggested that it would therefore be undissociated under normal conditions.