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Physical & Chemical properties

Dissociation constant

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Description of key information

waiver, considered to be scientifically unjustified

Key value for chemical safety assessment

Additional information

In accordance with Column 2 adaptation statement of REACH Annex IX, information requirement section 7.16, this study does not need to be conducted since the dissociation constant is not considered critical owing the poor water solubility of this UVCB substance (0.57 mg/L at 20 °C ). Indeed, in view of the difficulties associated with the evaluation of aquatic toxicity of poorly water soluble complex UVCB substances in order to assess the ecotoxicological parameters to Daphnia and to Algae of this substance Water Accommodated Fractions (WAF) were necessary in order to ensure that the organisms were sufficiently exposed. In addition, for the assessment of ready biodegradability, a modification of the standard method was required owing to poor water solubility of the substance and an attempt was made to evaluate the hydrolysis of the substance as a consequence of pH but this was not feasible owing to the poor water solubility.

Consequently, as regards the dissociation constant it is considered that this study is scientifically unjustified; no dissociation is to be expected under naturally relevant pH conditions.