Standard enthalpies of formation of N,N′-(1,3-phenylene)bis(phthalimide) and N,N′-(1,3-phenylene)bis(phthalimide-5-carboxilic acid)

Abstract

N,N′-(1,3-phenylene)bis(phthalimide) and N,N′-(1,3-phenylene)bis(phthalimide-5-carboxilic acid), were synthetized in solid phase without solvents, using mechanochemistry; the first compound could be purified with a high mole fraction. However, it was not possible to obtain the second with high purity. The thermochemical properties of compound N,N′-(1,3-phenylene)bis(phthalimide) were determined from experimental data,. The enthalpy of fusion, temperatures of fusion and decomposition as well as heat capacities as a function of temperature, were acquired by means of Differential Scanning Calorimetry (DSC). The standard enthalpy of formation in solid phase was determined from the energy of combustion, which was obtained using combustion calorimetry. Its enthalpy of formation in gas phase was calculated using the standard enthalpy of formation in solid phase as well as the enthalpy of sublimation, which was determined by thermogravimetric data. Experimental values for N,N′-(1,3-phenylene)bis(phthalimide) and three methods of contribution of groups, were used to estimate the enthalpy of formation in gas phase for N,N′-(1,3-phenylene)bis(phthalimide-5-carboxilic acid). In order to make the estimation, it was necessary to calculate some group additivity values (GAVs), corresponding to cyclic imides.