Facile preparation of nanostructured Pd-Sch-δ-FeOOH particles: A highly effective and easily retrievable catalyst for aryl halide cyanation and p-nitrophenol reduction

Iron based compounds are good candidates as supports to immobilize different transition metals due to their eco-friendly nature, capability of facilitating chemical modifications, inexpensiveness, high stability and easy recoverability. In this study, palladium nanoparticles (Pd NPs) were successfully stabilized on designed Schiff base modified delta-FeOOH particles as a highly effective and readily recoverable heterogeneous catalyst (Pd-Sch-delta-FeOOH nanocatalyst). The catalyst was fabricated via a facile multi-step approach without utilizing any additional reducing agents. The Pd-Sch-delta-FeOOH was characterized by Fourier transforms infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET). Characterization studies confirmed that the prepared small sized Pd NPs were spherically shaped and well dispersed on the surface of Schiff base modified delta-FeOOH. The catalytic efficiency of Pd-Sch-delta-FeOOH nanocatalyst was then tested in the preparation of benzonitriles through cyanation of aryl halides using K-4[Fe(CN)(6)] has been utilized as a cyanation agent and also reduction of p-nitrophenol (p-NP) using NaBH4 as the reducing agent. Benzonitriles were characterized using GC-MS. Catalytic studies showed that benzonitriles were obtained in good reaction yields in the presence of heterogeneous Pd-Sch-delta-FeOOH nanocatalyst (87-98%). It was found that Pd-Sch-delta-FeOOH was also a useful nanocatalyst for p-NP reduction at ambient temperature in eco-friendly media within 2 min. The reduction rate for p-NP with Pd-Sch-delta-FeOOH was measured via UV-Vis spectroscopy from 250 nm to 550 nm. Furthermore, Pd-Sch-delta-FeOOH nanocatalyst was able to remain active for six successive runs due to its recyclable/reusable nature.