Mono- and Disubstituted Polyfluoroalkylimidazolium Quaternary Salts and Ionic Liquids

Abstract

Synthesis and characterization of mono and polyfluoroalkyl-substituted imidazolium quaternary salts and ionic liquids are reported. Reactions of 1-methylimidazole or 1-butylimidazole with an excess of polyfluoroalkyl halides at 80 ºC under neat conditions produced the quaternary salts. Similarly, sodium imidazolate with an excess of polyfluoroalkyl halides also gave quaternary salts. Metathesis reactions of quaternary salts with KPF₆, LiN(SO₂CF₃)₂ and KSO₃CF₃ in water gave ionic liquid products in good yields. All new compounds were characterized from ¹H, ¹⁹F, and ¹³C NMR, IR, and MS spectra, and elemental analyses. DSC was used to determine melting points. Densities of the room temperature liquids fall between 1.44-1.85 g/cm³. The X-ray structure of 3f was obtained.

Key words

quaternary salts - ionic liquids - alkylations - fluorine - heterocycles - imidazolium

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