Hexaalkylguanidinium Trifluoromethanesulfonates – A General Synthesis from Tetraalkylureas and Triflic Anhydride, and Properties as Ionic Liquids

More than thirty hexaalkylguanidinium trifluoromethanesulfonates 12 were prepared from N,N‐diethyl‐N′,N′‐dimethylurea, N,N‐dibutyl‐N′,N′‐diethylurea, or tetrabutylurea, triflic anhydride, and a dialkylamine or cyclic sec‐amine in two steps. The combination of the urea and triflic anhydride first yields a bis(tetraalkylamidinio)ether bis(triflate) 10, which is then converted into a salt 12 by reaction with the amine component. The reaction sequence can also be carried out as a one‐pot procedure. Eighteen of the prepared guanidinium triflates 12 constitute room‐temperature ionic liquids, which were characterized for their melting point, glass transition temperature, viscosity, and refractive index. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)