Supported Palladium on Magnetic Nanoparticles–Starch Substrate (Pd-MNPSS): Highly Efficient Magnetic Reusable Catalyst for C–C Coupling Reactions in Water

Abstract

A novel heterogeneous Pd−catalyst system (Pd-MNPSS) was developed using immobilization of Pd species (Pd II and Pd 0 ) on starch-functionalized magnetic nanoparticles. For the synthesis of Pd-MNPSS catalyst, first, magnetic nanoparticles (MNPs) were prepared and coated with a silica layer (Fe 3 O 4 @SiO 2 ) to increase their stability and functionalization capability. The Fe 3 O 4 @SiO 2 particles were reacted with thionyl chloride (SOCl 2 ) to generate chlorosilyl groups on the surface of MNPs. Reaction of starch with chloro-functionalized MNPs leads to a magnetic reusable polyhydroxy-functionalized substrate (MNPSS), which is highly suitable for immobilization of Pd metal on its surface. This catalyst system was designed to be applied in Pd-catalyzed organic coupling reactions in water. Finally, the Pd-MNPSS catalyst was prepared via reaction of MNPSS and Pd(OAc) 2 . After characterization of the Pd-MNPSS catalyst it was applied in the Heck and Sonogashira coupling reactions in water solvent, and excellent results were obtained. The catalyst system was separated from the reaction mixture employing an outside magnetic field. In these processes the catalyst was reusable for 5 times without remarkable decrease in its activity. The Pd-MNPSS catalyst has many advantages especially in the workup process related to our previously reported catalyst systems, Pd supported on silica−starch substrate (PNP-SSS) and Pd supported on silica− cyclodextrin substrate (PNP-SCD).

Solid-Supported Palladium Catalysts in Sonogashira Reactions: Recent Developments

“…The final adsorption of palladium salt and in situ reduction by the support lead the catalyst 65, which was used to catalyze the Sonogashira coupling. The reaction worked well for both electron-rich and electron-poor haloarenes and phenylacetylene, obtaining the expected 1,2-diarylethyne products in high yields [111]. As in previous cases, the best results in terms of reaction time and yields were obtained when iodoarenes were used, and the worst when the relate chloroarenes were employed.…”

The β‐cyclodextrin decorated with palladium nanoparticles without pretreatment: An efficient heterogeneous catalyst for biaryls synthesis

“…Various metal nanoparticles‐based heterogeneous catalysts have been used in ionic liquids, polymers, and organic–inorganic fluorinated hybrid materials as well as inorganic supports such as silica, carbon materials and alumina for biaryls synthesis . Recently, magnetic nanoparticles are reported as an outstanding support for the heterogeneous catalysts . In addition to the inorganic supports for preparation of heterogeneous catalysts, some natural products such as cyclodextrins have been used as the stabilizer and dispersing reagents in compliance with green chemistry principles …”

Magnetite tethered mesoionic carbene‐palladium (II): An efficient and reusable nanomagnetic catalyst for Suzuki‐Miyaura and Mizoroki‐Heck cross‐coupling reactions in aqueous medium

“…Also, MNPs‐MIC‐Pd nanomagnetic catalyst is superior in terms of non‐toxicity, price, stability and ease of separation than the previously reported ones. Furthermore, the recyclability MNPs‐MIC‐Pd nanomagnetic catalyst is easier and rapid than those of other reported catalysts …”