The synthesis and properties of a novel room-temperature ionic liquid hexaalkylguanidium salts 4 and 5 were reported. The reaction of 1,3-dimethyl-2-imidazolidinon with POCl 3 and n-BuNH 2 afforded to pentaalkyl-guanidine(2), which reacted with CH 3I, generated hexaalkylguanidium(3). The hexaalkylguanidium salts 4 and 5 were synthesized by the reaction of hexaalkylguanidium(3) with KPF 6, AgBF 4 respectively. The results showed that both compounds 4 and 5 were room-temperature ionic liquids. The structures of these compounds were determined by 1H NMR, 13C NMR, IR and MS spectra data. Compounds 4 and 5 were found to have better solublities in organic solvents and better thermal stabilities.
