Synthesis and structural insights of substituted 2-iodoacetanilides and 2-iodoanilines

Abstract

This study reports a simple and efficient method for the direct iodination of substituted anilines with molecular iodine and copper acetate in acetic acid producing 2-iodoacetanilies and 2-iodoanilines. Employing density functional theory (B3LYP) and MidiX basis set, computational study is performed to calculate equilibrium geometries, IR vibrational frequencies, and thermodynamic properties including change of energy, enthalpy and Gibbs free energies. The optimized geometries indicated longer C–I bond distance (2.133Å) which makes iodine slightly positive. The partial atomic charge profile and electrostatic potential further confirmed that most of the iodinated products are capable of forming a distinct “halogen bonding”. The thermodynamic properties disclosed that all iodination reactions are endothermic. Understanding the substituents’ effect, molecular frontier orbital (MO) calculations are conducted finding the HOMO, LUMO and HOMO–LUMO gaps for all compounds. The MO calculations revealed that two electron-withdrawing iodine groups have significant influence on lowering the HOMO–LUMO gap compared to one iodine group in the products.