Synthesis of 5, 6-diaroylisoindoline-1, 3-dione and computational approaches for investigation on structural and mechanistic insights by DFT

Abstract

ABSTRACT This study represents a theoretical investigation of the coupling reaction between isoindoline-1, 3-dione (phthalimide) and aroyl chloride. Firstly, density functional theory (DFT) was employed to explore the structural insights of the coupled product 5, 6-diaroyl isoiondoline-1, 3-dione. The dispersion corrected functional ωB97X-D was applied to determine the transition states of the coupling reaction in the gas phase and in the solution phase by the SMD solvation model. In two-step mechanism, the calculated results indicate that the energy barrier of the C–C bond formation between benzoyl cation and phthalimide is the rate determining step of the reaction, and the activation energy was found 53.3 kcal/mol in1,4-dioxane. Moreover, thermodynamic calculation shows that the aroylation reactions are either spontaneous or nonspontaneous depending on the aroyl halide used although all these reactions are exothermic. However, B3LYP/6-311+G (d, p) functional was applied to compute equilibrium geometry, HOMO–LUMO energy gap (3.9–4.1 eV), dipole moments, polarizability and first order hyper polarizability to understand the structural features of the products. Moreover, experimental and computed FT-IR analysis of the phthalimide derivatives showed well correlation. Finally, for the synthesis of 5, 6-diaroyl isoiondoline-1, 3-dione from phthalimide and aroyl halide is herein described.