Standard molar enthalpies of formation of 1- and 2-cyanonaphthalene

The standard (p° = 0.1 MPa) molar enthalpies of formation, in the crystalline state, of the 1- and 2-cyanonaphthalene were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static-bomb combustion calorimetry. Vapor pressure measurements at different temperatures, using the Knudsen mass loss effusion technique, enabled the determination of the enthalpy, entropy, and Gibbs energy of sublimation, at T = 298.15 K, for both isomers. The standard molar enthalpies of sublimation, at T = 298.15 K, for 1- and 2-cyanonaphthalene, were also measured by high-temperature Calvet microcalorimetry.-ΔcUm∘(cr)/(kJ·mol-1)ΔfHm∘(cr)/(kJ·mol-1)ΔcrgHm∘(cr)/(kJ·mol-1)1-Cyanonaphthalene5514.4 ± 1.6188.5 ± 2.288.6 ± 0.52-Cyanonaphthalene5510.5 ± 1.7184.6 ± 2.292.1 ± 0.1Full-size tableTable optionsView in workspaceDownload as CSVCombining these two experimental values, the gas-phase standard molar enthalpies, at T = 298.15 K, were derived and compared with those estimated by employing two different methodologies: one based on the Cox scheme and the other one based on G3MP2B3 calculations. The calculated values show a good agreement with the experimental values obtained in this work.

► Enthalpies of formation of 1- and 2-cyanonaphthalene were measured by combustion calorimetry. ► Vapor pressures of crystalline 1- and 2-cyanonaphthalene obtained by Knudsen effusion mass loss technique. ► Enthalpies, entropies and Gibbs functions of sublimation at T = 298.15 K were calculated.