Iridium Nanoparticles on SPIONs as a Catalyst for N‐Heteroarene and Styrene Hydrogenation Reactions and their DFT Studies

Abstract

In this study, iridium nanoparticles (IrNPs) on superparamagnetic iron oxide nanoparticles (SPIONs) are used to catalyze N‐heteroarene and styrene hydrogenation processes. The IrNP@SPIONs catalyst was fabricated by reducing the Ir‐salt precursors in deionized water on SPIONs (Fe₃O₄), and its catalytic reactivity for the hydrogenation of N‐heteroarenes and styrene under mild reaction conditions as hydrogen under pressure was evaluated. The catalyst was characterized by FTIR, Raman, XRD, SEM, XPS, ICP‐OES, and TEM. The results showed that IrNPs@SPIONs exhibited >99 % conversion with 1,2,3,4‐tetrahydroquinoline (py‐THQ) selectivity under 30 bar H₂ at 100 °C temperature in 24 h using DCM as a solvent. The functional group tolerance of 6‐chloroquinoline demonstrated 99 % chemoselectivity towards the 6‐chloro‐tetrahydroquinoline (6‐Cl‐py‐THQ) formation. The reactivity trend in 2‐, 4‐, and 8‐methylquinoline was evaluated and corroborated with the DFT studies. The catalytic application was extended to the hydrogenation of styrene, which resulted in a 70 % conversion with >99 % ethylbenzene selectivity. The hydrogenation of 2‐bromostyrene produced a 75 % conversion with >99 % chemoselectivity of 2‐bromoethylbenzene.