Semi-Empirical Computation on Mechanism of Imidazolines and Benzimidazoles Synthesis and Their QSAR Studies

Abstract

A green, mild and anaerobic synthesis of imidazolines and benzimidazoles from aldehydes and diamines using I₂/KI/K₂CO₃/H₂O system has been investigated by semi-empirical methods. The observed efficient direction of the above synthesis has been modeled from a comparison of the energies of four possible transition states arising from mono and di additions of iodines in the configured molecules. In the reaction I₁ B is the most favorable transition state [TS] which is shown to be 20 Kcal/mol by PM₃ analyses. The resulting trends of relative transition states energies are in excellent agreement with the experimental observations. Also, the bond order, bond length, heat of formation is in good agreement to the formation of product B. In order to establish the suitable mechanism of the reaction a quantitative structure activity relationship analysis has been made using hydrophobicity as the molecular descriptor. In this analysis the values of refractivity, polarizability, hydration energy, electron affinity, ionization potential and dipole moment of the compounds have been correlated with their hydrophobicity which has been taken as the molecular property.