Computational profiling of the fast, base-free synthesis of quinolin-2(1H)-ones

Quinolinones are heterocyclic aromatic compounds with various pharmacological activities. Their importance has brought about the need for green synthetic methods. Exploring greener pathways using an experimental trial and error approach is costly and hazardous hence computational investigations of the existing mechanistic pathways are an alternative. This study focuses on the computational study of a fast, base-free aqueous synthesis of quinolin-2(1H)-one. Molecular simulations were done using DFT, MP2, and CCSD(T) to obtain reaction energy profiles of quinoline-2(1H)-one in gas phase, water, and dichloromethane. The profiles for the two-step reaction helped to elucidate the energy barriers for the chemical reaction. The barrier for the reaction in water and dichloromethane in the first step was 22.44 and 20.58 kcal/mol, respectively, while for the second step 27.24 and 28.35 kcal/mol were obtained. HOMO-LUMO analysis and quantum theory of atoms in molecules calculations were done to give further insight into the reaction. The energy gap for the final product was 0.24942 eV indicating a stable molecule possible to participate in other reactions. The stability was supported by average rho and Laplacian of 0.253169 and −0.55821, respectively.