Molar Heat Capacity and Thermodynamic Properties of 4-Methyl-4-cyclohexene-1,2-dicarboxylic Anhydride [C9H10O3]

The molar heat capacity Cp,m of 4-methyl-4-cyclohexene-1,2-dicarboxylic anhydride was measured over the temperature range from T = 80 K to T = 361 K with a small-sample automated adiabatic calorimeter. The melting point Tm and the molar enthalpy ΔfusHm and entropy ΔfusSm of fusion for the compound were determined to be (335.54±0.41) K, (17.67±0.04) kJ·mol-1, and (52.65±0.04) J·K-1·mol-1, respectively. Thermodynamic functions [HT − H298.15] and [ST − S298.15] were derived in the temperature range from T = 80 K to T = 361 K with a temperature interval of 5 K. The purity of the sample in mole fraction used in the adiabatic calorimetry study was determined to be 0.9940 by using the fractional melting technique. The thermal stability of the compound was investigated by differential scanning calorimetry (DSC) and a thermogravimetric (TG) technique, and the process of the mass loss of the sample was due to evaporation instead of thermal decomposition.