Energétique des liaisons inter- et intramoléculaires dans les trois isomères du benzènediamine

Abstract

The present work is concerned with a thermodynamic study of the three benzenediamine (BDA) isomers (general formula: C 6 H 8 N 2 ). It was achieved using four techniques: combustion calorimetry of small amounts of substance (a few milligrams), sublimation calorimetry, differential thermal analysis, and heat capacity measurements. From this study it was possible: to determine the enthalpies of combustion; sublimation, and fusion of these compounds as well as their triple point temperatures; to discuss the relative stability of the three molecules; to determine the experimental resonance energies and to compare them with the theoretical values; to determine the atomization enthalpies and to compare them with the values calculated from the energetical contributions previously obtained in our laboratory; to determine the intermolecular enthalpy bonds; to consider the existence of an intramolecular hydrogen bond in the ortho isomer. Keywords: benzenediamine isomers; enthalpy of combustion, of sublimation, of fusion, of inter- and intramolecular bonds.