Imidazolium-based ionic liquids bearing a polyfluorinated alkyl group on the cation were efficiently synthesized in excellent yields and selectivities from the one-pot reaction of a fluoroolefin with [1-alkyl-3H-imidazolium]X, where X = Cl, NO 3 , CF 3 CO 2 , BF 4 or (CF 3 SO 2 ) 2 N, formed in situ from the interaction of an alkylimidazole with an acid, HX.Ionic liquids (ILs) have received great interest in various fields of chemistry, due to their unique properties such as negligible vapor pressures, wide liquid temperature ranges, and highly polar yet non-coordinating character. 1 More importantly, the physical and chemical properties of ILs can be tailored to specific purposes by introducing a functional group or groups on the cation and/or anion. ILs bearing ether, ester, sulfonate, amino or hydroxy groups have been employed as electrolytes for lithium batteries, 2 capture agents for CO 2 and SO 2 separation, 3 and media for nanoparticle preparation. 4ILs bearing fluorinated functional groups have attracted particular attention because the properties of conventional ILs can be significantly altered. For instance, the inertness to organic solvents, resistance to corrosive acids and bases, and resistance to extremes of temperature and pressure can be greatly improved by the presence of highly electron-withdrawing fluorine atoms. 5 Accordingly, a number of methods have been reported for the preparation of fluorinated ILs, but most of the reports have been focused on the synthesis of ILs with a fluorinated anion such as BF 4 -, PF 6 -, TFSI -, TFES -, BETI -and CF 3 CO 2 -. 6 In contrast, very little is known for the synthesis of ILs bearing a fluorinated functional group on the cation. A representative example is the two-step reaction of alkyl imidazole with fluoroalkyl iodide followed by anion metathesis with an alkali metal salt (MY), as shown in Scheme 1. 7 However, this methodology has serious drawbacks such as the use of costly fluoroalkyl iodide, low selectivity toward the formation of fluoroalkylated product 5 (imidazolium iodide), and the involvement of tedious and problematic anion exchange.Herein, we report a straightforward and highly selective one-pot synthesis of 1-alkyl-3-polyfluoroalkyl imidazolium-based ionic liquids (Scheme 2). Scheme 2 New synthetic route to fluorinated ILsImidazolium-based ILs bearing a fluorinated alkyl group on the cation were obtained in high yields from a one-pot reaction of alkylimidazole with the corresponding acids, in the presence of a fluoroolefin. To our knowledge, this is the first example of the synthesis of fluorinated ILs directly from the reaction between a quaternary imidazolium salt and a fluoroolefin. A typical synthesis of a 1-alkyl-3-polyfluoroalkyl imidazolium salt is as follows: In a 100 mL high-pressure glass reactor, 1-butylimidazole (7.6 mmol) was reacted with trifluoroacetic acid (TFA; 7.6 mmol) in tetrahydrofuran (35 mL) at 0°C for one hour. To this solution was added hexafluoropropylene (HFP; 15.2 mmol) and reacted for five hours at ambient tempera...
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