Vaporization and Sublimation Enthalpies of Acetanilide and Several Derivatives by Correlation Gas Chromatography

Abstract

The vaporization and fusion enthalpies of acetanilide and several of its derivatives have been measured and combined to provide their corresponding sublimation enthalpies. Since all of the materials examined are solid at T = 298.15 K, the vaporization enthalpies measured by correlation gas chromatography at this temperature are for the subcooled liquid state. Fusion enthalpies have also been adjusted to T = 298.15 K. The compounds examined and their vaporization enthalpies measured at T = 298.15 K include the following values (in kJ·mol–1): acetanilide (82.1 ± 3.0), 4-methylacetanilide (86.2 ± 3.2), 4-methoxyacetanilide (92.0 ± 3.4), 3-ethoxyacetanilide (94.1 ± 3.5), and 4-ethoxyacetanilide (94.8 ± 3.5). The following fusion enthalpies (kJ·mol–1) and fusion temperatures (onset temperatures, K) were measured by differential scanning calorimetry (DSC): acetanilide (22.1 ± 0.1), (386.9 ± 0.1), 4-methylacetanilide (29.4 ± 0.2), (421.3 ± 0.3), 4-methoxyacetanilide (25.4 ± 0.3), (398.2 ± 1.2), 3-ethoxyacetanilide (28.9 ± 0.4), (368.0 ± 0.4), 4-ethoxyacetanilide (32.0 ± 0.1), (407 ± 0.1), and benzanilide (31.2 ± 0.7), (435 ± 0.3). Sublimation enthalpies calculated from vaporization and fusion enthalpies at T = 298.15 K compared favorably with available literature values.