Efficient and Selective Oxidation of Aromatic Benzyl Alcohols to Their Corresponding Aldehydes Catalyzed by a Chitosan-Anchored VO(acac)2en-Schiff Base Nanohybrid

Abstract

This study presents the rational design and synthesis of a novel heterogeneous nanocatalyst, CSBs@V (Chitosan@ VO[(acac)2en]), constructed through a three-step, energy-efficient protocol: (i) solvent-free condensation of acetylacetone with ethylenediamine to generate an aliphatic Schiff base ligand, (ii) immobilization onto chitosan via methanol-mediated reflux, and (iii) coordination of oxovanadium(IV) to afford a chitosan-anchored VO(acac)2-Schiff base nanohybrid. Comprehensive characterization by FT-IR, FE-SEM/EDX, TEM, BET, TGA, and elemental mapping confirms uniform dispersion of vanadium active sites within the chitosan scaffold, mesoporous textural features, and high thermal stability. Under optimized conditions (70 °C, TBHP, acetonitrile), CSBs@V achieves selective oxidation of benzyl alcohol to benzaldehyde with 88–98% isolated yield at 0.14 mol% V loading, with > 95% selectivity and rapid conversion. The catalyst retains > 87% of its initial activity over five consecutive cycles, with only minor vanadium leaching (~ 7%) and preserved morphology upon reuse. Key advantages include a biodegradable chitosan support, mild reaction conditions, facile catalyst recovery, and minimal metal leaching. The synergy between vanadium redox chemistry and the sustainable polysaccharide framework offers a scalable, eco-friendly platform for green oxidation catalysis, providing a robust foundation for mechanistic studies, substrate expansion, and industrial implementation.