Estimation of the Differential Molar Heat Capacities of Organic Compounds at Their Melting Point

Methods for the estimation of the differential molar heat capacity, the difference between the heat capacity of the solid and the liquid form of organic compounds at their melting point (delta)cp(Tm), are presented. Three schemes are considered: the first involves use of group contribution methods for the prediction of solid heat capacity (cpS) and liquid heat capacity (cpL); the other two, empirical correlations through the entropy of fusion at the melting point (delta)Sf(Tm). Recommendations for the different categories of organic compounds are made that provide substantial improvement over the commonly used assumption of (delta)cp = 0, in the prediction of ideal solid solubility and solid vapor pressure.