Extremely functional and easily tuneable green ionic liquids

Functional ionic liquids are materials that are not merely alternative reaction media, but that can also be taught other tricks. We discovered a class of Extremely Functional Ionic Liquids made by an efficient green synthesis starting from trialkylamines or trialkylphosphines and dimethylcarbonate. The synthesis of these liquids will be described. The resulting methyltrialkylonium ionic liquids can be easily and irreversibly anion exchanged thereby allowing to tune properties such as melting point, solubility, acid–base properties, stability, and viscosity, yielding a plethora of different ionic liquids with only CO2 and methanol as by-products. (a) The irreversible reaction of these ionic liquids with acids makes these ionic liquids extremely efficient as acid scavengers. (b) The members of this class of ionic liquids which bear a CH3OCO2- or HOCO2- anion are unexpectedly basic and can be used as organocatalysts for base-promoted C-C bond forming reactions, such as Micheal, Henry, Baylis-Hillman, and others. Comparison with traditional basic organocatalysts such as phosphazenes, DABCO, DBU, DMAP indicate that these new materials are more active, although the reasons are not yet fully understood. (c) Nitrate anion exchanged ionic liquids can be used, for example, as catalysts for electrophilic aromatic oxychlorination. (d) Due to the fact that CO2 is liberated in the presence of an acid, they can in principle be used as new foaming agents.