Synthesis of 2-arylbenzimidazoles under mild conditions catalyzed by a heteropolyacid-containing task-specific ionic liquid and catalyst investigation by electrospray (tandem) mass spectrometry

A task-specific ionic liquid constituted by a Bronsted acid (1-(3-sulfopropyl)-3-methyl-imidazolium hydrogen sulfate) as the cation, namely MSI, and by [PW12O40](3-) as the triply charged counter-anion, namely PW (a heteropolyacid derivative), was used as an efficient catalyst for the condensation reaction between aldehydes and o-phenylenediamines.