2,4,6-tri-tert-butylphenol

Vapour pressure

Description of key information

The vapour pressure of the test material was determined to be 3.5 x 10^-2 Pa (2.6 x 10^-4 mm Hg) at 20 °C, and 7.3 x 10^-2 Pa (5.5 x 10^-4 mm Hg) at 25 °C.

Key value for chemical safety assessment

Vapour pressure:

0.073 Pa

at the temperature of:

25 °C

Additional information

There are three studies available to address this endpoint, one key and two supporting.

 

The key study, the vapour pressure of the test material has been investigated in a study which was performed under GLP conditions and in accordance with the standardised guidelines OECD 104, EU Method A.4 and US EPA OPPTS 830.7950. The study has been awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

A suspension of the test material in n-hexane was applied to the surface of a roughened glass plate as a homogeneous layer. The plate was dried at 30 °C under nitrogen in the thermogravimetric analyser (TGA). The amount of dried test material was 14.8 or 15.2 mg.

The weight loss of the test material was measured continuously as a function of time at defined isothermal temperatures. The evaporation rate of the test material (VT) was calculated from the weight loss of the compound. The PT values at the defined isothermal temperatures were determined using the vapour pressure equation with constants specific for the experimental arrangement. Linear regression analysis of the log PT values and 1/T was performed using a least squares method. The PT values of the test material at 20 and 25 °C were determined using the vapour pressure regression curve.

The experiments were performed under a flow of nitrogen and at atmospheric pressure.

Under the conditions of the study, the vapour pressure of the test material was determined to be 3.5 x 10^-2 Pa (2.6 x 10^-4 mm Hg) at 20 °C, and 7.3 x 10^-2 Pa (5.5 x 10^-4 mm Hg) at 25 °C.

In the first suppoting study, the vapour pressure of the test material was estimated using the MPBPWIN model v1.43 (EPI Suite v4.11). The study was awarded a reliability score of 2 in accordance with the criteria set forth by Klimisch et al. (1997).

The MPBPWIN model estimates the vapour pressure of a substance using three models: the Antoine Method (applicable to gases and liquids); the Modified Grain Method (applicable to solids, liquids and gases); and the Mackay Method (applicable to aliphatic and aromatic hydrocarbons and also halogenated aliphatic and aromatic compounds).

The suggested vapour pressure of solids is given as the Modified Grain Method. Due to the limited applicability of the Mackay Method, this is not suggested as the selected vapour pressure by the MPBPWIN model. The molecular weight of the test material is within the training set range.

The vapour pressure was calculated to be 0.0266 Pa at 25 °C and 0.0002 mm Hg at 25 °C (Modified Grain Method).

 

The second supporting study was awarded a reliability score of 4 in accordance with the criteria set forth by Klimisch et al. (1997). In this study there is a value quoted for the vapour pressure of the test material in the US HPV submission relating to the alkyl phenols. The HPV document makes reference to the fact that the value was obtained from Perry’s Chemical Engineers Handbook, 6th Ed. However, at the time of submission it had not been possible to obtain the original reference. Therefore no further data is available in relation to the value obtained.

The vapour pressure of the test material was quoted as 0.088 Pa at 25 °C (0.000661 mm Hg at 25 °C).