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Physical & Chemical properties

Vapour pressure

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Description of key information

The AHTN vapour pressure of 0.07 Pa has been determined by the gas saturation method.

Key value for chemical safety assessment

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

Additional information

The melting point and boiling point of AHTN are 54°C and 326°C respectively. The REACH technical guidance document on information requirements and chemical safety assessment (May 2008) states that ideally two vapour pressures at different temperatures in the range of 0 to 50°C should be reported. Hence, a measured value at 25°C and a calculated value at 50°C have been selected.

No phase transition (solid-liquid) occurs and AHTN remains stable in the 25-50°C temperature range. The vapour pressure at 25°C has been experimentally determined by the gas saturation method and the vapour pressure at 50°C has been derived using EPI suite. EPI suite uses the formula described by MacKay, that was also put forward in the REACH technical guidance document. The vapour pressure is very low at room temperature and although the vapour pressure rises sharply with temperature within the temperature range of 25 to 50°C, the vapour pressure at 50°C is in absolute terms still very low.

The reliability of the model has been verified by comparing the calculated and measured vapour pressures at 25°C and both values are very close.

In the risk assessment, the experimental value has been put forward.