Magnetic carbon nanotube-enhanced imidazolium ionic liquid (CNTs-ZnFe2O4-IL); A novel catalyst for selective oxidation of benzyl alcohol to benzaldehyde

This work reports a multifunctional nanocatalyst, CNTs-ZnFe₂O₄-IL, designed for efficient, selective, and magnetically recoverable oxidation of alcohols to aldehydes. The catalyst integrates zinc ferrite (ZnFe₂O₄) nanoparticles onto carboxyl-functionalized carbon nanotubes (CNTs) and immobilizes them with an imidazolium-based ionic liquid. Characterization by XRD, FTIR, TEM, TGA, VSM, SEM-EDX, and BET confirms successful synthesis and the advantageous architecture: magnetic ZnFe₂O₄ facilitates easy magnetic separation, CNTs provide high surface area and improved nanoparticle dispersion, and the ionic liquid layer offers unique solvating and activating properties that enhance catalysis. Catalytic performance was demonstrated in the selective oxidation of benzyl alcohol to benzaldehyde using tert-butyl hydroperoxide (TBHP) as a green oxidant. At 50°C, the catalyst delivered exceptionally high yields (90–97%) across a broad substrate scope of 21 substituted benzyl alcohols, displaying strong functional group tolerance and high selectivity toward aldehyde without over-oxidation to benzoic acid. The magnetic nature enables straightforward recovery, and the catalyst-maintained activity and selectivity over six consecutive reuse cycles with negligible performance loss. CNTs-ZnFe₂O₄-IL offers a sustainable, cost-effective protocol for aerobic oxidations, aligning with green chemistry principles by eliminating solvents, minimizing waste, and enabling easy catalyst recycling.