Poly(tetrafluoroethylene)-Stabilized Metal Nanoparticles: Preparation and Evaluation of Catalytic Activity for Suzuki, Heck, and Arene Hydrogenation in Water

Abstract

Poly(tetrafluoroethylene)-stabilized Pd nanoparticles (PTFE-PdNPs) were prepared in water with 4-methylphenylboronic acid as a reductant and characterized using powder X-ray diffraction, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Small PdNPs with a fairly uniform size were obtained in the presence of PTFE, whereas aggregation of palladium was observed in the absence of PTFE. PTFE-PdNPs showed high catalytic activity for the Suzuki coupling reaction in water and were reused without any loss of activity. No palladium species were observed by ICP-AES analysis in the reaction solution after the reaction, nor was any change in particle size observed after the recycle experiment. PTFE-PdNPs also exhibited excellent catalytic activity and reusability for the Heck reaction in water. Although palladium species were not detected in the reaction solution after the reaction, aggregates and smaller sizes of PdNPs were observed in the TEM image of the recovered catalyst. PTFE was also useful as the stabilizer of rhodium nanoparticles (RhNPs) prepared by reduction with NaBH 4 . PTFE-RhNPs showed high catalytic activity and reusability toward arene hydrogenation under mild conditions.

Recent Progress of Metal Nanoparticle Catalysts for C–C Bond Forming Reactions

“…These heterogeneous gel-phase catalysts were successfully applied for several C-C coupling reactions (Scheme 29) [306][307][308]. Simple hydrophobic polymers without a coordination site such as polystyrene and poly(tetrafluoroethylene) have been confirmed to stabilize metal NPs and polymer-supported metal NPs were applicable to the recyclable catalyst for several reactions in water [309][310][311][312][313].…”

A palladium(0)–threonine complex immobilized on the surface of magnetic mesocellular foam: an efficient, stable, and magnetically separable nanocatalyst for Suzuki, Stille, and Heck cross-coupling reactions

“…To solve these issues, the heterogenization of homogeneous catalysts, especially heavy metal complexes, and expensive palladium nanoparticles on the surface of the organic and inorganic solid hosts, has been developed. 21–23 Different supports such as metal oxides 24 zeolites 25 carbon materials 26 and mesoporous silica 27 are used for the immobilization of palladium nanoparticles. Among various supporters, magnetic nanoparticles have attracted great attention due to their inherent magnetic properties, low toxicity, easy synthesis, environmental-friendly, easy separation, and reusability in consecutive reactions.…”

Room-temperature coalescence of Pd nanoparticles with sacrificial templates and sintering agents, and their catalytic activities in the Suzuki coupling reaction

“…Here, various sintering agents such as KOH, CTAC and HCl were examined. As porous Pd structures are expected to be heterogeneous catalysts, the Suzuki coupling reaction, which is a wellknown Pd-catalyzed reaction, [37][38][39][40] was performed for the evaluation of the catalytic abilities.…”