Continuous synthesis of peralkylated imidazoles and their transformation into ionic liquids with improved (electro)chemical stabilities.
A versatile and efficient method to synthesize tetrasubstituted imidazoles via a one-pot modified Debus-Radziszewski reaction and their subsequent transformation into the corresponding imidazolium ionic liquids is reported. The tetrasubstituted imidazoles were also synthesized by means of a continuous flow process. This straightforward synthetic procedure allows for a fast and selective synthesis of tetrasubstituted imidazoles on a large scale. The completely substituted imidazolium dicyanamide and bis(trifluoromethylsulfonyl)imide salts were obtained via a metathesis reaction of the imidazolium iodide salts. The melting points and viscosities are of the same order of magnitude as for their non-substituted analogues. In addition to the superior chemical stability of these novel ionic liquids, which allows them to be applied in strong alkaline media, the improved thermal and electrochemical stabilities of these compounds compared with conventional imidazolium ionic liquids is also demonstrated by thermogravimetrical analysis (TGA) and cyclic voltammetry (CV). Although increased substitution of the ionic liquids does not further increase thermal stability, a definite increase in cathodic stability is observable.
Department of Sustainable Chemistry and Technology, SynBioC Research Group, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
Cedric
C
Maton
Nils
N
De Vos
Bart I
BI
Roman
Evert
E
Vanecht
Neil R
NR
Brooks
Koen
K
Binnemans
Stijn
S
Schaltin
Jan
J
Fransaer
Christian V
CV
Stevens
D003484:Cyanamide / Q000138:chemical synthesis / Q000737:chemistry; D055664:Electrochemical Techniques; D007093:Imidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D007094:Imides / Q000138:chemical synthesis / Q000737:chemistry; D052578:Ionic Liquids / Q000138:chemical synthesis* / Q000737:chemistry
D007093:Imidazoles; D007094:Imides; D052578:Ionic Liquids; D003484:Cyanamide