Thermochemical study to assess the energetical and structural effects of nitro substituents in methyl benzoate isomers

Combined experimental and computational studies were performed aiming the analysis of energetic properties vs structural characteristics of three methyl nitrobenzoate isomers (methyl 2-nitrobenzoate, M2NB, methyl 3-nitro benzoate, M3NB, methyl 4-nitrobenzoate, M4NB). The experimental studies include the determination of the enthalpy of formation in the condensed state (crystal and liquid) of the compounds by static combustion, and the determination of enthalpies of phase transition, using Differential Scanning Calorimetry, high temperature Calvet microcalorimetry and the Knudsen effusion method. These data were combined to derive the enthalpy of formation of the methyl nitrobenzoate isomers in the gaseous phase, at T = 298.15 K. At the computational level, the gas-phase enthalpy of formation of the methyl nitrobenzoate isomers were estimated using theoretical approaches, resorting to the G3(MP2)//B3LYP composite method and to appropriate hypothetical gas-phase reactions. The enthalpies of formation obtained experimental and computationally will be discussed and the energetic structural synergies for the three methyl nitrobenzoate, along with other analogous isomers, will be also analyzed.

Automated summary

This study investigates the energetic properties and structural characteristics of three methyl nitrobenzoate isomers using a combination of experimental and computational approaches. Experimental studies determine the enthalpy of formation in different states and phase transition enthalpies, while computational methods estimate the gas-phase enthalpy of formation. The study analyzes the obtained data and discusses the energetic-structural synergies for the isomers.