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Environmental fate & pathways

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Di (2-hydroxypropyl)tallow amine has a calculated pKa value of 5.75 (SPARC) for protonation of the nitrogen and this pKa is most likely almost independent of the alkyl chain length as observed for primary alkyl amines (EU-RAR). This means that the largest fraction of the molecule is unprotonated under environmental conditions (pH 6 -8). There is no measured vapour pressure for di (2-hydroxypropyl) tallow amine. A vapour pressure of 0.00073 Pa was measured for the C12 -18 ethoxylated amine at 20 °C and this vapour pressure will be used as a worst-case for the primary fatty amine propoxylates. The solubility of this di (2 -hydroxypropyl)tallow amine will be influenced by the pH. In a slow stir experiment a water solubility of 0.2 mg/L was observed at 20°C and pH 9.3. When the pH is lowered an increase of the water solubility is anticipated.

Evaporation from water is based on the low vapour pressure and the observed water solubility is very unlikely. The actual dissolved concentration in water will be extremely low as propoxylated amines will sorb strongly to sorbents both based on hydrophobicity and ionic interaction. For silt soil a Kd of 4526 L/kg was observed for di (2 -hydroxyethyl) oleylamine which has an identical calculated pKa as di (2 -hydroxypropyl)tallow amine. This Kd corresponds to a Koc of 90520 L/kg indicating that once sorbed the substance has a low leaching potential. This result is read-across to bis (2 -hydroxypropyl)tallow amine for risk assessment purposes. Justification for read-across is presented in IUCLID Chapter 13.