Thermodynamics of phase transitions and heat capacities of monosubstituted n-alkanaminium bromides above room temperature

Abstract

POLANDDifferential scanning calorimetry was applied to examine the thermodynamics of solidstate phase transitions and fusion processes of compounds of the general formula (nCpHzp+INH3)Br (where p = 0-3). The heat capacities of the compounds in the range from ambient temperature to the onset of their volatilization were also studied. All the thermochemical characteristics reveal a dependence on the structure of the alkanaminium cations.In several earlier papers, we have reported the results of studies on the thermal features of various salts of nitrogen organic bases [1][2][3][4][5]. On the basis of these investigations, we were able to derive basic thermochemical quantities for the pure compounds, i.e. their standard enthalpies of formation and crystal lattice energies, as well as those characterizing their decomposition. Unfortunately, the applied method appeared to be insufficient for quantitative examination of the thermal behaviour of the compounds below the onset of their dissociation and volatilization. This note reports the results of differential scanning calorimetry determinations of heat capacities and enthalpies of solid-state phase transitions and melting for selected nalkanaminium bromides. Despite the investigations undertaken in the past, the knowledge of the latter problems is still incomplete [6][7][8][9][10][11][12][13].