Vapour Pressures and Heats of Sublimation of Some Vat Dyes

The vapour pressures, latent heats of sublimation and associated entropy changes of some vat dyes have been determined by the transpiration method. The heats of sublimation are discussed in terms of the dyes’ molecular structure. This article presents evidence for the existence of a specific linear relationship between the enthalpy change and the entropy change in sublimation