Experimental and computational thermochemical study of the dichloronitrobenzene isomers

The standard (p° = 0.1 MPa) molar enthalpies of formation of 2,4-, 2,5-, 3,4- and 3,5-dichloronitrobenzene isomers, in the crystalline state, at T = 298.15 K, were derived from the standard (p° = 0.1 MPa) massic energies of combustion, in oxygen, at T = 298.15 K, measured by rotating bomb combustion calorimetry. The standard molar enthalpies of sublimation of the four isomers, at T = 298.15 K, were obtained by high-temperature Calvet microcalorimetry.-ΔcUm∘(cr)/(kJ·mol-1)-ΔfHm∘(cr)/(kJ·mol-1)ΔcrgHm∘/(kJ·mol-1)2,4-Dichloronitrobenzene2792.8 ± 0.947.4 ± 1.287.8 ± 1.72,5-Dichloronitrobenzene2793.0 ± 1.847.2 ± 2.087.4 ± 2.53,4-Dichloronitrobenzene2774.1 ± 1.266.1 ± 1.485.8 ± 2.53,5-Dichloronitrobenzene2769.6 ± 0.970.6 ± 1.283.2 ± 1.5Full-size tableTable optionsView in workspaceDownload as CSVFrom the determined experimental results, the values of the gaseous standard (p° = 0.1 MPa) molar enthalpies of formation were derived. The gas-phase enthalpies of formation of all the six chloronitrobenzene isomers were also estimated by the Cox scheme and by computational thermochemistry methods and compared with the available experimental values.