Comprehensive thermodynamic study of methylprednisolone

Abstract

© 2016 Elsevier LtdIn the present work the temperature dependence of heat capacity for methylprednisolone has been measured for the first time over the temperature range from 6 to 350 K using by precision adiabatic vacuum calorimetry. Based on the experimental data, the thermodynamic functions of the methylprednisolone, namely, the heat capacity, enthalpy H°(T) − H°(0), entropy S°(T) − S°(0) and Gibbs function G°(T) − H°(0) have been evaluated from the experimental values for the range from T → 0 to 350 K. Standard molar enthalpy of combustion (−11898.9 ± 6.7) kJ·mol−1 of the methylprednisolone was measured for the first time using high-precision combustion calorimeter. The standard molar enthalpy of formation in the crystalline state (−1045.8 ± 7.3) kJ·mol−1 of compound at 298.15 K was derived from the combustion experiments. The standard molar enthalpy of sublimation at 298.15 K (194.5 ± 2.2) kJ·mol−1 was measured by using the quartz-crystal microbalance (QCM). Using combination of the adiabatic and combustion calorimetry with the result from QCM, the thermodynamic functions of the methylprednisolone at T = 298.15 K and p = 0.1 MPa have been calculated.