On the in situ formation of carbenes in ionic liquids

Abstract

Ionic liquids are considered as tunable designer liquids that may provide the perfect environment or active species for chemical reactions. N-Heterocyclic carbenes are known to be important organocatalysts enabling novel and specific routes for general synthetic strategies. There has been a lot of speculation about the role, stability, and the existence of in situ formed carbenes in ionic liquids. Here, we show that cation stabilised carbenes can exist in room temperature ionic liquids as reactive intermediates detectable with liquid microbeam IR laser desorption mass spectrometry. The experimental results were supported by density functional theory. Intriguingly, we also found that carbenes appear to correlate with and may be the origin of strong chemisorption of carbon dioxide in ionic liquids.