Pentaalkylmethylguanidinium methylcarbonates - versatile precursors for the preparation of halide-free and metal-free guanidinium-based ILs

Pentaalkylmethylguanidinium methylcarbonates 6 can easily be prepared from pentaalkylguanidines 5 and dimethyl carbonate (DMC) in a sustainable solvent-free synthesis. Most of the title compounds are room temperature ionic liquids (RTILs) which provide convenient access to halide-free guanidinium-based ILs (GILs) 7 via acid-base reactions and subsequent decarboxylation, similar to industrially important imidazolium methylcarbonates 1.