Thermodynamic analysis of DSC data for acetaminophen polymorphs

This article provides a thermodynamic analysis of DSC data for acetaminophe n polymorphic forms I and II by measurement of heat capacity. Form I is fou nd to have lower heat capacity and free energy and hence better stability t han Form II down to at least -30 degreesC. The transition temperature below which Form II becomes more stable was determined to be less than -120 degr eesC. Form I is more stable than Form II as a consequence of its higher ent ropy, since its crystallographic packing arrangement is of larger energy.