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Physical & Chemical properties

Dissociation constant

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Description of key information

One reliable key study was performed on the registered reaction mass. The experimental value of dissociation constant at 20°C of monoester component was measured at 7.1. In addition, the strong acidic functional group of the monester and the diester was estimated by calculation to be 1.60 ± 0.50 for both components.

Key value for chemical safety assessment

pKa at 20°C:
7.1

Additional information

One reliable key study was performed on the reaction mass using a titration technique according to Method 112 of the OECD Guidelines for Testing of Chemicals, 12 May 1981 and under GLP. No deviation from the guidelines was observed during the test.

Due to the test item being a mixture and the need to neutralize the initial strongly acidic functional phosphate group present, it was not possible to apply standard titration technique calculation procedures. Therefore, the environmentally relevant dissociation constant for the monoester component was estimated from the point of inflexion from the neutralization curve. Four determinations gave a value of dissociation constant of monoester component of 7.1 at 20.0±0.5°C.

In addition, both the monoester component and the diester component were identified as having a strong acidic functional group which would result in a permanent anionic charge over the complete environmentally relevant pH range of 5 to 9. The dissociation constant of this group was estimated to be 1.60±0.50 for both components (ACD/Labs, pKa, Algorithm version: v12.1.0.50374).