A Novel Water-Dispersible/Magnetically Recyclable Pd Catalyst for C–C Cross-Coupling Reactions in Pure Water

Abstract

A novel water-dispersible magnetically recyclable Pd heterogeneous catalyst, denoted as Pd-γ-Fe2O3-2-ATP-TEG-MME, was initially synthesized and then characterized by diverse methods such as FT-IR, TEM, TGA, XPS, VSM, ICP, and elemental analysis. The new catalyst was utilized as a water-dispersible/magnetically separable Pd heterogeneous catalyst for C–C cross-coupling reactions including cyanation of aryl halides, fluoride-free Hiyama and Suzuki reactions in neat water. By using this approach numerous arylcyanides and biaryls were synthesized in good to high yields via the reaction of aryl iodides, bromides, and chlorides (far more extensively available and cheaper than aryl iodides and bromides) with K4[Fe­(CN)6]·3H2O, triethoxyphenylsilane, or phenyl boronic acid, respectively. The presence of triethylene glycol tags with hydrophilic character on the Pd-complex supported on magnetic nanoparticles provides dispersion of the catalyst particles in water, which leads to both higher catalytic performance and also facile catalyst recovery and reuse by successive extraction and final magnetic separation. Using water as a green solvent, high turnover number (TON), facile catalyst recovery and reuse, simple workup, and not requiring any additive make this method an ecofriendly protocol for the C–C cross-coupling reactions.

A New Nanomagnetic Pd-Co Bimetallic Alloy as Catalyst in the Mizoroki-Heck and Buchwald–Hartwig Amination Reactions in Aqueous Media

“…As the melamine is rich with nitrogen and contains triazine rings with high stability, melamine-based dendrimers (MBD) with abundant metal-binding nitrogen groups have aroused a lot of interest recently for the incorporation of metal nanoparticles for using in catalytic reactions. [17][18][19] In our continuous interest in developing a greener catalyzed reaction, 4,[20][21][22][23][24][25][26][27][28] herein, a melamine-based dendrimer was built to the 1.5-generation onto the -Fe2O3 surface employing a divergent method to synthesize -Fe2O3@melamine-based dendrimer (-Fe2O3@MBD). Bimetallic Pd-Co alloy nanoparticles were then attached to -Fe2O3@melamine-based dendrimer via a co-complexation method followed by reduction with sodium borohydide.…”

g-C3N4/γ-Fe2O3/TiO2/Pd: a new magnetically separable photocatalyst for visible-light-driven fluoride-free Hiyama and Suzuki–Miyaura cross-coupling reactions at room temperature

“…This limitation has been overcome by the replacement of fluoride ions with inorganic bases. [20][21][22] Among the various transition metals developed to catalyze the Hiyama and Suzuki-Miyaura cross-coupling reactions, palladium has been the first choice and is still considered as the most common metal for C-C coupling reactions. 23 Traditionally, these cross-coupling reactions are performed under homogeneous palladium catalytic systems with relatively high activity and selectivity.…”

“…25 In this line, extensive efforts have been done to conduct the Hiyama and Suzuki-Miyaura crosscoupling reactions through the heterogeneous Pd-based catalytic systems by Pd immobilization/stabilization on different supports such as mesoporous materials, polymer, graphene oxide, carbon compounds, metal oxides, and magnetic nanoparticles (MNPs). 15,22,[26][27][28][29] Among these supporting materials, using MNPs has the merit of simple and convenient catalyst isolation from the reaction mixture by using an external magnetic field. The majority of the abovementioned heterogeneous Pd catalytic systems require elevated temperatures and prolonged reaction times, which may lead to undesired side reactions.…”

High Performance Magnetically Separable G‐C3N4/γ‐Fe2O3/TiO2 Nanocomposite with Boosted Photocatalytic Capability towards the Cefixime Trihydrate Degradation under Visible‐Light

“…Considering the importance of using green and safe light sources and convenient catalyst recovery and recycling in wastewater treatment processes, and in continuation of our persistent research interest in introducing new magnetically recyclable heterogeneous nanocatalysts [40][41][42][43][44][45][46] herein, we have reported the fabrication of a high-performance g-C 3 N 4 /γ-Fe 2 O 3 / TiO 2 nanocomposite. After its characterization by various techniques, it was utilized as a magnetically separable visiblelight-driven photocatalyst towards the CEF degradation under the blue LED illumination.…”