Synthesis,Characterization, and Physicochemical Properties of Hydrophobic Pyridinium‐based Ionic Liquids with N‐Propyl and N‐Isopropyl

Synthesis and physicochemical properties of four pyridinium‐based ionic liquids (ILs), N‐propylpyridinium bromide N‐propylPyr]⁺Br]^–, N‐isopropylpyridinium bromide N‐isopropylPyr]⁺Br]^–, N‐propylpyridinium hexafluorophosphate N‐propylPyr]⁺PF₆]^–, and N‐isopropylpyridinium hexafluorophosphate N‐isopropylPyr]⁺PF₆]^– are reported. The molecular structures of these compounds were characterized by FT‐IR, ¹H, ¹⁹F, and ³¹P NMR, spectroscopy. The thermal properties, conductivity, and solubility of these ionic liquids were also investigated. The effects of propyl and isopropyl alkyl lateral chain at the N‐position of pyridinium cation on the thermal stability, conductivity, and solubility of ionic liquids are discussed. The results obtained confirmed that the ionic liquids based on pyridinium cations exhibit higher decomposition temperature, low melting points, immiscible with water, and their conductivities are mainly influenced by mobility of ions.