Thermal anomalies in the adducts of urea with n-paraffins. A theoretical treatment

Abstract

Calculations have been made of the potential energy as a function of the orientation of the n-paraffin molecules in the urea channel. An Ising treatment was then used with an approximation similar to that of Weiss being applied to the interactions between paraffin molecules in neighbouring channels. Using reasonable values for the parameters of the intermolecular potentials, gradual transitions involving extra heat absorption were found in the temperature region in which they are found experimentally. The relatively higher transition temperatures of the adducts of “odd” n-paraffins were also successfully predicted.