Micellar effects upon synthesis of 1,2-dihydro-1-arylnaphtho[1,2-e][1,3]oxazine-3-ones in water at room temperature

Abstract

In this study, the efficient synthesis of naphthoxazinones via a three-component reaction of β-naphthol, benzaldehyde, and urea in the presence of the micellar catalyst sodium dodecyl sulfate (SDS) in an aqueous medium was comprehensively investigated. The reactions were performed under both room temperature and ultrasonic conditions, yielding satisfactory results in both cases. However, the use of ultrasound resulted in an increased yield and a remarkable reduction in reaction time. The micellar structure of SDS creates a hydrophobic microenvironment that concentrates the nonpolar β-naphthol and benzaldehyde molecules in the micelle core. At the same time, the highly polar urea remains in the surrounding aqueous phase, with the reaction occurring at the interface between these two phases. This molecular arrangement increases the local concentration of reactants and lowers the activation energy, thereby facilitating the condensation process. In addition to its high yield, this method offers significant environmental advantages because it uses water as the solvent.