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Physical & Chemical properties

Dissociation constant

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Description of key information

The substance is predicted to possess a dissociation constant in the region of 12.13, which represents dissociation of the neutral molecules to form ions.  The substance is therefore expected to exist virtually exclusively in neutral, unionised form throughout the environmentally relevant range of pH 5 to pH 9.

Key value for chemical safety assessment

Additional information

In accordance with section 1 of REACH Annex XI, the dissociation constant study (required in section 7.16) does not need to be conducted as inspection of the chemical structure shows no functional groups which are associated with dissociation behaviour at relevant environmental conditions. The Chemical Abstract Service (CAS) Registry file contains an estimated pKa value for the substance of 12.13 ± 0.70 at 25ºC, which was calculated using the Advanced Chemistry Development (ACD) model. This pKa is interpreted to represent the dissociation of one of the hydroxyl groups to form an alkoxide anion and a proton, and supports the expectation that the substance will exist virtually exclusively in neutral, unionised form throughout the environmentally relevant range of pH 5 to pH 9.