LAUSR

New insight of the formation mechanism of chalcones is presented in the current study. Ab initio calculations were applied in studying the mechanistic pathways for the base-catalyzed Claisen–Schmidt condensation for obtaining chalcones (1,3-diphenyl-2-propen-1-ons). The energies of the stationary points along the reaction coordinate were obtained at two levels of theory—MP2/6-31 + G(d,p) and SCS-MP2/6-31 + G(d,p). The role of water in the reaction mechanisms is examined. The theoretical results show that the process is catalyzed by an ancillary water molecule. The reaction mechanism, proposed in this study, consists of two reactions—an activation of the acetophenone by a removal of proton is followed by the attack of the formed acetophenone anion to the aromatic aldehyde, which through few steps leads to the formation of the final product—chalcone. The first reaction proceeds very fast in one step while the second reaction goes through four steps and three intermediate complexes before the formation of the final product.