Protic ionic liquids-promoted efficient synthesis of quinazolines from 2-aminobenzonitriles and CO2 at ambient conditions

•The catalyst can be prepared through a facile proton transfer from easily accessible materials.•[HTMG][Im] renders a smooth-performing reaction at room temperature and atmospheric pressure.•The catalyst can be recovered and reused efficiently.•Bifunctional role of [HTMG][Im] is verified by NMR, in-situ FT-IR spectroscopy and DFT study.