Solvent-free synthesis of compounds containing chromene core catalyzed by novel Bronsted acidic ionic liquids-ClO4

A series of novel sulfonic acid-functionalized Bronsted 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, H-1 and C-13 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.

Automated summary

A series of novel sulfonic acid-functionalized Bronsted acidic ionic liquids (BAILs) with perchlorate counter anion are introduced in this study. These ionic liquid catalysts are prepared in high yields through simple and eco-friendly procedures, and have been proven to be efficient for the synthesis of chromenes under solvent-free conditions. The method offers high yields, decreased reaction times, cleaner reactions, and ease of operation with applicability to diverse substrates.