Perfluorinated 1,2,3‐ and 1,2,4‐Triazolium Ionic Liquids

Abstract

Dialkyl triazolium triflimides with perfluorinated side chains were prepared as hydrophobic ionic liquids (ILs) for surface impregnation. The key feature of the new materials are relatively short perfluorohexyl residues (nC6F13 = RF) as the fluorinated part of the cations, making the target compounds beneficial alternatives to established products because of their enhanced degradability and therefore lower bioaccumulativity. As heterocyclic scaffold, either 1,2,3‐triazole or 1,2,4‐triazole were chosen. As the two alkyl moieties, either two RFCH2CH2 groups or one RFCH2CH2 and one Et residue were applied. The diethyl congeners were also prepared. Fluorinated starting materials were RFCH2CH2OTf as alkylating reagent or RFCH2CH2N3 as 1,3‐dipole for a copper catalyzed cycloaddition (CuAAC) with trimethylsilyl acetylene. After sequential CuAAC and alkylation reactions, the triflimide salts were finally obtained from the intermediate iodides or triflates with the aid of an ion exchange resin. Out of 14 triazolium salts prepared, four compounds have finally been identified as hydrophobic ILs (contact angles between 85° and 100° with mp. < 100 °C), being promising materials for surface impregnation: the 1,2,3‐triazolium triflate and triflimide with two fluorinated alkyl residues, and the 1,2,4‐triazolium triflimides (two regioisomers) with one fluorinated alkyl residues and one ethyl group.