Green Synthesis, Characterization, and the Prediction of Its Thermochemical Properties of the Isomers 3,4- and 3,5-Bis(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)benzoic Acid

Abstract

The solid-state synthesis of the 3,4- and 3,5-bis(1,3-dihydro-1,3-dioxo-2H-isoindole-2-yl) benzoic acid isomers (hereafter referred to as DIAs) is reported using a solvent-free strategy aligned with the principles of green chemistry. A previously reported methodology was employed, and the relationship between molecular structure and thermal behavior was evaluated. Structural characterization was performed by infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), and mass spectrometry, confirming the formation of the proposed bisphthalimide derivatives. Thermal properties were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), allowing the determination of thermal stability, melting points, and associated thermal events. Additionally, theoretical quantum calculations were employed to predict the thermochemical properties of the DIAs, as well as those of 3,4- and 3,5-diaminobenzoic acid, which are useful for calculating the reaction equilibrium properties. The combined experimental and computational approach provides more in-depth insight into the physicochemical behavior of these systems and demonstrates the feasibility of the proposed solvent-free synthetic strategy.