H 6 P 2 W 18 O 62 /Nanoclinoptilolite as an efficient nanohybrid catalyst in the cyclotrimerization of aryl methyl ketones under solvent-free conditions

A new type of nanohybrid material H 6 P 2 W 18 O 62 /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 H 6 P 2 W 18 O 62 (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.