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Adsorption / desorption

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Description of key information

Experimental data not required, log Koc estimated with QSPR methods

Key value for chemical safety assessment

Koc at 20 °C:
345.62

Additional information

Studies on the adsorption coefficient of the substance are not required as allyl hexanoate is readily biodegradable. In addition, the physicochemical properties indicate the low potential of the substance for adsorption. As the Koc is required for the computation of environmental exposures, the Koc value has been estimated by using accepted QSPR methods and modelling programs. The experimental value of the log Kow = 3.191 was used in the calculations.

The KOCWIN v2.00 model predicts the Koc with two different models based on First Order Molecular Connectivity Index and the octanol-water partition coefficient:

MCI-method: Koc = 117.5 L/kg, log Koc = 2.07

Kow-method: Koc = 420.7 L/kg, log Koc = 2.624

The Koc value is also estimated with a number of QSAR methods that are based on the octanol-water partition coefficient of the substance, i.e. on real physicochemical properties of the substance.

Gerstl (1990. Estimation of organic chemical sorption by soils. Journal of Contaminant Hydrology 6, 357-375):

equation is log Koc = 0.679 * log Kow + 0.094; Koc = 182.26 L/kg, log Koc = 2.26

Sabljic & Güsten (1995. QSARs for soil sorption. In: Overview of Structure-Activity Relationships for Environmental Endpoints, Part 2: Description of selected models. Hermens JLM (editor)):

equation for non-hydrophobic is log Koc = 0.52 * log Kow + 1.02; Koc = 477.9 L/kg, log Koc = 2.679

equation for esters is log Koc = 0.49 * log Kow + 1.05; Koc = 410.76, log Koc = 2.614

All methods based on the octanol-water partition coefficient give a consistent set of data points for the Koc value. The geometric mean of the log values of Koc obtained with the methods based on the log Kow of the substance gives a log Koc = 2.5386 and this value will be used further in the chemical safety assessment. The estimated Koc of the substance indicates medium mobility of allyl hexanoate in soil and sediment according to the classification scheme of McCall et al. (1981).

[LogKoc: 2.5386]