Experimental thermochemical study of 2,5- and 2,6-dichloro-4-nitroanilines

The standard (p° = 0.1 MPa) molar enthalpies of formation of 2,5- and 2,6-dichloro-4-nitroanilines, in the gaseous phase, at T = 298.15 K, were derived from the combination of the values of the standard molar enthalpies of formation in the crystalline phase, at T = 298.15 K, and the standard molar enthalpies of sublimation, of each compound, at the same temperature. The standard molar enthalpies of formation, in the crystalline phase, at T = 298.15 K, were derived from the standard massic energies of combustion of the two isomers, in oxygen, at T = 298.15 K, measured by rotating-bomb combustion calorimetry. The standard molar enthalpies of sublimation were calculated, by application of the Clausius–Clapeyron equation, to the vapour pressures at several temperatures measured by Knudsen effusion technique.CompoundΔfHm∘(cr)/(kJ·mol-1)ΔcrgHm∘/(kJ·mol-1)2,5-Dichloro-4-nitroaniline−85.6±1.9114.3±0.92,6-Dichloro-4-nitroaniline−107.3±1.4109.2±0.9Full-size tableTable optionsView in workspaceDownload as CSVThe values of the standard (p = 0.1 MPa) molar enthalpies of formation of 2,5- and 2,6-dichloro-4-nitroanilines, in the gaseous phase, at T = 298.15 K, were compared with those estimated by the Cox scheme.