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Vapour pressure

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Description of key information

Calculation:  2.99E-015, at 25 °C.

Key value for chemical safety assessment

Additional information

Column 2 of the REACH Regulation Annex VII provides the following specific rules for adaptation of the standard information requirement for vapour pressure:

‘The study does not need to be conducted if the melting point is above 300 °C. If the melting point is between 200 °C and 300 °C, a limit value based on measurement or a recognised calculation method is sufficient.’

Based on the OECD Guideline 104, the calculated values of the vapour pressure can be used:

- for deciding which of the experimental methods is appropriate,

- for providing an estimate or limit value in cases where the experimental method cannot be applied due to technical reasons (including where the vapour pressure is very low, e.g., less than 10-3 Pa).

 The estimation method proposed by the OECD 104 is the modified Watson correlation, for which the only experimental data required is the normal boiling point.

The substance during the DSC analysis showed a melting point at 249.77 °C (onset at 244.47 °C, enthalpy = 24.61 J/g). From 375 °C onwards, there is massive decomposition of the test substance before any boiling occurs.

Therefore, the modified Watson correlation cannot be used. Nevertheless a prediction made by Epiwin 4.1 of the US EPA by a Modified Grain method has been conducted and the vapour resulted: 2.99E-015, at 25 °C.

The smile notation used for estimation is: NC1=CC=C(O)C2=C1C(=O)C1=C(O)C=C(C(N)=C1C2=O)C1=CC=C(O)C=C1