Synthesis of pyridinium-based salts: Catalytic application at the synthesis of six membered O-heterocycles

Abstract

In this paper, a range of pyridinium-based ionic liquid (IL) and molten salts (MSs) with various counter ions were designed, synthesized and fully characterized. These novel ionic liquid and molten salts were prepared via the reaction of [PySO3H]Cl with AlCl3, FeCl3, NaBF4 and KPF6 to produce the desired catalysts [PySO3H]X (X = AlCl4, FeCl4, BF4 and PF6). The structure of these catalysts were investigated by FT-IR, NMR (1H, 13C, 27Al, 19F) and mass spectra as well as the use of the XRD, SEM, TG, DTG and DTA techniques. Magnetic measurements (VSM) of [PySO3H]FeCl4 as a magnetic molten salts was also investigated. Three categories of six membered O-heterocyclic compounds such as 2-amino-4H-chromene, 2-amino-4,8-dihydropyrano and 2-amino-4H-pyrans were prepared in the presence of a catalytic amount of the above said molten salts. These synthesized O-heterocyclic compounds are highly regarded due to their biological activities.