Thermodynamics of polynuclear aromatic molecules I. Heat capacities and enthalpies of fusion of pyrene, fluoranthene, and triphenylene

Abstract

The heat capacities of three crystalline condensed-ring aromatic substances were studied from 5 to 350 K by adiabatic cryogenic calorimetry and into the liquid phase with the intermediate-range adiabatic calorimeter. The heat capacities, entropies, and enthalpies at 298 K, together with the triple points and enthalpies of melting are: A gradual transition in pyrene occurs near 120.8 K with an associated enthalpy increment of 68.8 cal mol-1. The nature of the melting process is considered.