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Physical & Chemical properties

Vapour pressure

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Description of key information

Vapour pressure (whole substance): 22.7 Pa at 25°C (QSAR)
Vapour pressure (individual constituents of the substance): 4.1E-11 to 5.4E+02 Pa at 25°C (QSAR)

Key value for chemical safety assessment

Vapour pressure:
22.7 Pa
at the temperature of:
25 °C

Additional information

The vapour pressure of the whole substance was determined by calculation. The mole fraction of each constituents of Crude Tall Oil (CTO) was multiplied by its predicted vapour pressure. The result obtained was summed together to obtained the predicted total vapour pressure of the substance.

Predicted vapour pressure for the whole substance is preferred for the purpose of human health exposure assessment while the vapour pressure of individual constituents is useful for environmental risk characterisation. The vapour pressure of the individual constituents was determined using a validated QSAR estimation method. Vapour pressure in the range 4.1E-11 to 5.4E+02 Pa was determined for the constituents of the substance. CTO is a UVCB substance with about 80 constituents including fatty acids, resin acids, neutrals such as alcohols and high molecular weight polymeric compounds. For environmental risk assessment, the properties of the substance are assessed using the 'block approach'. The vapour pressure of each 'block' has been determined based on the weighted average of each constituent in the block. Predicted vapour pressure of 4.9E-08 to 5.4E+02 Pa was determined for all 'blocks' in CTO. The vapour pressure of CTO as a whole substance is calculated to be 23 Pa at 25°C.

In another supporting study, calculated vapour pressure values of 0.1 mmHg, 0.01 mmHg and 0.0001 mmHg at 150°C, 100°C and 50°C respectively was obtained for CTO.

Individual samples could have higher vapour pressure if any unexpected impurities are present.