Vapour pressure and vapourisation enthalpy of pyridine N ‐oxide

The vapour pressure of pyridine N ‐oxide was measured using a boiling point method at different temperatures from 389.02 to 546.33 K and the constants of the Antoine equation for the substance were determined. The vapourisation enthalpy of pyridine N ‐oxide at the normal boiling point is calculated to be 58.8 ± 1.8 kJ mol −1 . Based on Othmer's method, the standard enthalpy of vapourisation ${\rm \Delta }_{{\rm vap}} H(298.15\;{\rm K})$ is estimated to be 66.6 ± 0.1 kJ mol −1 by using pyridine as the reference substance. Furthermore, Watson equation is employed to verify the reliability of ${\rm \Delta }_{{\rm vap}} H(298.15\,{\rm K})$ and the results demonstrate that the value of ${\rm \Delta }_{{\rm vap}} H(298.15\;{\rm K})$ is acceptable. © 2011 Canadian Society for Chemical Engineering