Fluorine-containing ionic liquids from N-alkylpyrrolidine and N-methylpiperidine and fluorinated acetylacetones:: Low melting points and low viscosities

A family of new fluorine-containing ionic liquids (3-14) was synthesized in high yield by the reaction of N-alkylpyrrolidine, N-methylpiperidine and fluorinated 1,3-diketones: 1,1,1,5,5,5-hexafluoroacetylacetone, 1,1,1-trifluoro-2,4-pentanedione and 4,4,4-trifluoro-1-phenyl-1,3-butanedione. Their properties, such as the phase-transition temperature, density, and viscosity, were determined. Most of them show relatively low melting points and low viscosities. The influence of fluorinated 1,3-diketonate anions and the structural variation in cyclic amine cations on the above physicochemical properties was examined. X-ray single-crystal diffraction analysis of compound 7 confirms the proton transfer from 4,4,4-trifluoro-1-phenyl-1,3-butanedione to N-butylpyrrolidine. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).