Calorimetric study of bromoacetophenone isomers

Abstract

The standard (po=0.1MPa) molar enthalpies of formation of 2-, 2′-, 3′- and 4′-bromoacetophenones were derived from the standard molar energies of combustion in oxygen, to yield CO2 (g) and HBr·600H2O (l) at T=298.15K, measured by rotating bomb combustion calorimetry. The standard molar enthalpies associated with phase transitions of the isomers studied at T=298.15K, were obtained by high temperature Calvet microcalorimetry. The standard (po=0.1MPa) molar enthalpies of formation of all the bromoacetophenone isomers in the gaseous phase at T=298.15K were derived from the experimental results. The gas-phase enthalpies of formation were also estimated by the empirical scheme developed by Cox and the values obtained were compared with the experimental ones. The results are interpreted in terms of the energetic increments for the introduction of the substituents in the benzene ring.