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An Intermediate for the Clean Synthesis of Ionic Liquids: Isolation and Crystal Structure of 1,3‐Dimethylimidazolium Hydrogen Carbonate Monohydrate
Author(s) -
Bridges Nicholas J.,
Hines C. Corey,
Smiglak Marcin,
Rogers Robin D.
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200700055
Subject(s) - ionic liquid , chemistry , decarboxylation , carbonate , salt (chemistry) , inorganic chemistry , halide , hydrogen , carboxylate , catalysis , carbonic acid , solvent , crystal structure , dimethyl carbonate , organic chemistry
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.