Calorimetric study and thermal analysis of crystalline 2,4-dinitrobenzaldehyde (C7H4N2O5)

Calorimetric study and thermal analysis for 2,4-dinitrobenzaldehyde were performed. The low-temperature heat capacity of this compound was measured with a precise automated adiabatic calorimeter over the temperature range from (78 to 368) K. The melting point, molar enthalpy, and molar entropy of fusion of this substance were determined to be (344.91 ± 0.15) K, (21,177 ± 14) J · mol−1, and (61.40 ± 0.07) J · K−1 · mol−1, respectively. The melting temperatures for the sample and the absolutely pure compound have been obtained from fractional melting experiments to be (344.910 and 345.146) K, respectively, and the chemical purity of the sample was calculated to be 0.9950 mol fraction according to the Van't Hoff equation. The thermal stability of the compound was further investigated by differential scanning calorimetry and thermogravimetric analysis.