Adiabatic calorimetry of organic salts. Tetra-n-hexylammonium perchlorate

Abstract

We have measured the heat capacity of a zone refined sample of tetra-n-hexylammonium perchlorate (99.94% pure, by analysis of the fusion curve). Values of the transition temperatures, enthalpies and entropies are: fusion 379.18 K, 16 350 J mol^–1, 43.10 J K^–1 mol^–1; transition (1) 367.51, 2658, 7.24; transition (2) 355.91, 5839, 16.42; transition (3) 333.57, 22 990, 68.93. We interpret fusion and transition (3) as being due, respectively, to ionic melting (break down of the lattice) and “melting” of the hexyl groups. Transitions (1) and (2) are explained by re-orientation of the perchlorate anions.