Palladium immobilized on amidoxime‐functionalized magnetic Fe₃O₄ nanoparticles: a highly stable and efficient magnetically recoverable nanocatalyst for sonogashira coupling reaction

Abstract

We describe the synthesis of a novel Fe 3 O 4 /amidoxime (AO)/Pd nanocatalyst by grafting of AO groups on Fe 3 O 4 nanoparticles and subsequent deposition of Pd nanoparticles. Prior to grafting of AO, the 2-cyanoethyl-functionalized Fe 3 O 4 nanoparticles prepared through combining 2-cyanoethyltriethoxysilane and Fe 3 O 4 were treated with hydroxylamine. The AO-grafted Fe 3 O 4 nanoparticles were then used as a platform for the deposition of Pd nanoparticles. The catalyst was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, scanning and transmission electron microscopies, vibrating sample magnetometry, wavelength-and energy-dispersive X-ray spectroscopies and inductively coupled plasma analysis. Fe 3 O 4 /AO/Pd is novel phosphine-free recyclable heterogeneous catalyst for Sonogashira reactions. Interestingly, the novel catalyst could be recovered in a facile manner from the reaction mixture by applying an external magnet device and recycled seven times without any significant loss in activity.Fe 3 O 4 /AO/Pd as an effective nano catalyst in the sonogashira reaction

Biosynthesis of palladium nanoparticles using Rosa canina fruit extract and their use as a heterogeneous and recyclable catalyst for Suzuki–Miyaura coupling reactions in water

“…In the diffractogram, there are four distinct reflections at 40° (111), 46° (200), 68° (220) and 82° (311), which according to crystallographic planes, the face‐centred cubic crystalline structure is indexed for metallic palladium (Pd(0)). The XRD results identify the presence of Pd NPs which is in accord with previous reports …”

“…Thus, catalysis under ligand‐free conditions is an area of high importance. Encouraged by our previous works on C–C coupling reactions, in the present study, we tested the catalytic activity of the Pd NPs for the Suzuki–Miyaura coupling reaction in water under ligand‐free conditions (Scheme ).…”

“…The product was purified by column chromatography (hexane–ethyl acetate, 1:5) to obtain the desired purity. All of the products are known and were identified by comparison of their physical and spectral data with those of authentic samples …”

Solid-Supported Palladium Catalysts in Sonogashira Reactions: Recent Developments

“…Thus, different trioxysilane derivatives have been introduced recently as linkers ( Figure 17). The catalyst 51 has been used in the Sonogashira process between haloarenes and phenylacetylene, giving the expected disubstituted alkynes with moderate to excellent results [97]. The reaction allowed using not only iodides and bromides but also chlorides, with only a small decrease in the yield and increase in the reaction time.…”

Recyclable palladium catalyst cloths for carbon-carbon coupling reactions

“…Furthermore, there is a strong drive towards making more use of environmentally friendly solvents during pharmaceutical production (such as ethanol-water mixtures). 8,9,10 Heterogeneous (supported) catalysts can potentially address many of the aforementioned drawbacks associated with homogeneous palladium catalyst carbon-carbon coupling reactions. Existing commercially available materials include Pd/C, Pd/Al 2 O 3 , and loose polymer fibre anchored palladium(II) centres, 11,12 however these all require post-reaction filtration steps.…”