Experimental and computational thermochemistry of 3- and 4-nitrophthalic acids

摘要: Abstract In this work, we present experimental and theoretical thermochemistry of the 3- 4-nitrophtalic acids. We report their standard molar enthalpies formation in crystalline phase, at T = 298.15 K, which were obtained from energies combustion. The latter determined through an isoperibolic bomb calorimeter. measured change-phase enthalpies, as well fusion sublimation by differential scanning calorimetry (DSC) thermogravimetry (TG). Also via DSC, found heat capacity equations (in phase) for both isomers functions temperature. crystal- gas-phase previous measurements. addition, computed using composite Gaussian-G4 method atomization reactions. final a weighted Boltzmann averaging procedure, weights estimated Gibbs free energy T = 298.15 K. absolute differences between are below 3.3  kJ · mo l −1 . Finally, apply our results obtaining isomerization enthalpy to 4-nitrophthalic acid, difference nitrophthalic acids anhydrides.