Introduction of a new ionic liquid solid acid based on clay as an efficient, recyclable and thermally stable catalyst for organic transformations

Abstract

Ammonium hydrogen sulfate based ionic liquid immobilized on Na+–montmorillonite (AHS@MMT) was prepared via anchoring ammonium hydrogen sulfate propyltriethoxysilane onto sodium montmorillonite by covalent bonds.

Double Brønsted Acidic Media Immobilized on Carbonized Sugarcane Bagasse (CSCB) as a New and Efficient Solid Acid Catalyst for the Synthesis of Coumarins, Dicoumarols and Xanthenes

“…The observed broad band in AHS@CSCB, at 2600–3600 cm −1 can be associated to the acidic O−H starching, which overlapped with the N−H starching. Also, the existence of a small shoulder at 1210 cm −1 corresponded to the S−O bond of SO 3 H groups …”

“…Also, the existence of a small shoulder at 1210 cm À 1 corresponded to the SÀ O bond of SO 3 H groups. [85]…”

“…Versatile heterogeneous catalysts based on ionic liquids have been used to promote the preparation of coumarins and xanthenes, but many of them suffer from disadvantages such as expensive reagents and difficult synthesis route, long reaction times and use of hazardous materials. So, introduction of a new methodology using an inexpensive and green support for the synthesis of a novel solid acid catalyst is still in demand.…”

“…[75] These materials are of crucial importance due to their pharmaceutical and biological properties including, analgesic potential and antiinflammatory, [76] antibacterial, [77,78] antiviral, [79] anti-proliferative activity, [80] and photodynamic therapy. [81] Versatile heterogeneous catalysts based on ionic liquids have been used to promote the preparation of coumarins and xanthenes, [82][83][84][85][86][87] but many of them suffer from disadvantages such as expensive reagents and difficult synthesis route, long reaction times and use of hazardous materials. So, introduction of a new methodology using an inexpensive and green support for the synthesis of a novel solid acid catalyst is still in demand.…”

Efficient one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones catalyzed by a new heterogeneous catalyst based on Co-functionalized Na+-montmorillonite

“…14 Also, Sarvi et al have presented syntheses of different xanthenes and coumarins in the presence of AHS@MMT. 15 Dihydropyrimidinones (DHPMs) are an outstanding class of heterocyclic compounds. Many properties, such as antibacterial, antioxidant, anti-HIV and anticancer activities have been reported for these compounds.…”