Optimised microwave-assisted synthesis of methylcarbonate salts: a convenient methodology to prepare intermediates for ionic liquid libraries

The reaction of 1-butylpyrrolidine with dimethyl carbonate to yield the ionic liquid precursor,
1-butyl-1-methylpyrrolidinium methylcarbonate, has been investigated under microwave heating
conditions and the reaction parameters optimised to achieve 100% yield of the pyrrolidinium salt
with no by-products in under 1 h. The reactions of tributylamine, trioctylphosphine, and
1-butylimidazole with dimethyl carbonate under comparable conditions have also been evaluated,
yielding the corresponding methylcarbonate salts which can be used as intermediates for the
preparation of halide-free ionic liquids without generating any undesirable salt wastes.