H6P2W18O62/Nanoclinoptilolite as an efficient nanohybrid catalyst in the cyclotrimerization of aryl methyl ketones under solvent-free conditions

A new type of nanohybrid material H6P2W18O62/nanoclinoptilolite was fabricated and performed as an efficient and reusable catalyst in the mild and one-pot condensation of different acetophenones. The operational simplicity, easy work-up, cost-effective, and solvent-free nature of the present methodology were accompanied with good to excellent yields of the desired 1,3,5-triarylbenzenes from a wide range of alkyl, aryl, and cyclic ketones. The nanocatalyst was prepared via immobilization of Wells-Dawson heteropolyacid H6P2W18O62 (HPA) on the surface of nanoclinoptilolite (NCP). The nanohybrid material was easily recovered and reused successfully at least seven times without significant loss of catalytic activity. XRD, SEM, UV-Vis, MS-ICP, DTA, and FT-IR studies confirmed that the heteropolyacid is well dispersed on the surface of NCP. This protocol developed is a safe and convenient alternate method for the synthesis of 1,3,5-triarylbenzenes utilizing an eco-friendly and a highly reusable natural nanocatalyst. Furthermore, water was the only by-product, which made the present methodology environmentally benign.