An Intermediate for the Clean Synthesis of Ionic Liquids: Isolation and Crystal Structure of 1,3‐Dimethylimidazolium Hydrogen Carbonate Monohydrate

Abstract 1,3‐Dimethylimidazolium‐2‐carboxylate and carbonic acid have been used to prepare a 1,3‐dimethylimidazolium hydrogen carbonate salt by means of a Krapcho reaction. The ability to form hydrogen carbonate azolium salts allows for them to be used as precursors for fast, efficient, environmenta...

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Bibliographic Details
Published in:Chemistry – A European Journal
Main Authors: Bridges, Nicholas J., Hines, C. Corey, Smiglak, Marcin, Rogers, Robin D.
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 2007
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Online Access:http://dx.doi.org/10.1002/chem.200700055
https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fchem.200700055
https://onlinelibrary.wiley.com/doi/full/10.1002/chem.200700055
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Summary:Abstract 1,3‐Dimethylimidazolium‐2‐carboxylate and carbonic acid have been used to prepare a 1,3‐dimethylimidazolium hydrogen carbonate salt by means of a Krapcho reaction. The ability to form hydrogen carbonate azolium salts allows for them to be used as precursors for fast, efficient, environmentally benign, and halide‐free syntheses of many ionic liquids by a simple, acid–base reaction of virtually any acid (inorganic, organic, and organic noncarboxylic) with a p K a less than that of HCO 3 − . Additionally, the kinetics of this reaction can be accelerated by employing catalytic amounts of DMSO (a traditional Krapcho solvent used in decarboxylation reactions) to catalyze the decarboxylation. The crystal structure of 1,3‐dimethylimidazolium hydrogen carbonate monohydrate is the first example of an imidazolium‐based hydrogen carbonate salt. There is a strong 2D hydrogen‐bonded network with facially π‐stacked imidazolium cations located in the cavities created by this framework.