Solvent‐free synthesis of compounds containing chromene core catalyzed by novel Brønsted acidic ionic liquids‐ClO4

A series of novel sulfonic acid‐functionalized Brønsted acidic ionic liquids (BAILs) with perchlorate counter anion are introduced. These ionic liquid catalysts were prepared through simple and eco‐friendly procedures in high yields. Various analytical techniques such as Fourier transform infrared, 1H and 13C NMR, electro‐spray ionization mass spectrometry, elemental analysis (CHNS), and thermogravimetric techniques were used for well characterization of these catalysts. Next, the prepared BAILs were applied as efficient catalysts with high yields under solvent‐free conditions for the synthesis of chromenes. The proposed method offers several superiorities, such as high yields, decreased reaction times, cleaner reactions, and the lack of laborious workup or purification procedures. The simplicity in operation, applicability, and feasibility of this protocol for diverse substrates makes it an efficient alternative to conventional methods. Three novel Brønsted acidic ionic liquids (BAILs) with perchlorate anion were prepared and their catalytic role for the synthesis of 2‐amino‐4H‐chromenes under solvent‐free condition at 110°C. The superiorities of these BAILs are: clean and green conditions, simple separation with extraction by dissolving in water. The reusability study showed that these catalysts are stable up to six consecutive runs.