Thermodynamic properties of perchlorates

Abstract

The standard heats of formation of alkyl ammonium perchlorates,and 3) have been determined by solution reaction calorimetry. Using these and corresponding data for the alkyl ammonium halides and nitrates, a set of self-consistent 'thermochemical' radii for the alkyl ammonium ions were obtained. The Kapustinskii equation was used to estimate lattice energies of the alkyl ammonium perchlorates and these data were included in a thermochemical cycle to derive the proton affinities of the parent alkyl amines.The polymorphic phase transitions of these alkyl ammonium perchlorates have been investigated via Differential Scanning Calorimetry over the temperature range -90° to 250°C. The transition temperatures and enthalpies have been recorded. The enthalpy of the II - I phase transition of ammonium perchlorate has been reported for the first time by a direct method. These data allow the effect of increasing the sise of the alkyl group and the transition temperatures to be correlated.The perchlorates, Me have been synthesised and their standard heats of formation determined by solution reaction calorimetry. An improved synthesis of tri(p-nitrophenyl)methyl chloride has also been reported.