A magnetically retrievable air and moisture stable gold and palladium nanocatalyst for efficient C−C coupling reactions

Abstract

In this study, we report the synthesis of a highly stable, magnetically retrievable gold and palladium nanocatalyst (AuPd@AMNPs), highly active in Suzuki cross-coupling and related homocoupling reactions. The active catalytic component in this system is palladium, which can only be stabilized in the presence of gold nanoparticles. There is no significant loss of activity even after prolonged storage exposed air and moisture. The versatile nature AuPd@AMNPs is demonstrated through the selective catalysis of the homocoupling of phenylboronic acid under low concentrations of O 2 and the oxidation of phenylboronic acid to phenol under high O 2 concentrations. AuPd@AMNPs also demonstrated Ullmann-type homocoupling of 4-iodotolene with excellent yields. The magnetically retrieved catalyst could be re-used up to six times in Suzuki–Miyaura cross-coupling with consistently high activity and with a minimal loss of the noble metal species. Through these reactions we show that the gold-stabilized AuPd@AMNPs can be used as stable and recyclable palladium reservoir for multiple palladium-catalysed reactions.

Recent Advances in Supported Bimetallic Pd–Au Catalysts: Development and Applications in Organic Synthesis with Focused Catalytic Action Study

“…Recently, the amine group functionalized iron oxide NPs supported Pd 50 -Au 50 catalyst has been reported for the SMC reaction with a good extent of recyclability, and magnetic separation from the reaction mixture was the key feature of this work. 115 The Bania et al work also includes the SMC reaction between p-chloro benzaldehyde and phenylboronic acids applying ZSM-Y supported Pd−Au NPs as catalyst (Scheme 8a). In this work, 4-halobenzyl alcohols were also applied as the aryl halide coupling partner for the SMC reaction.…”

“…Li, Cao, and their co-workers introduced a Pd-decorated Au supported on tetragonal-phase zirconia (ZrO 2 -t) catalyzed two-step protocol, that is, p -xylene synthesis from 5-HMF and ethylene (Scheme ). Moreover, mesoporous Fe 2 O 3 supported Pd–Au BMCs have also gained considerable attention because of their magnetic separation from a reaction mixture after successful catalytic transformations such as C–C coupling, 4-nitrophenol reduction (Table , entry 5–6), , photocatalytic degradation of acetone, and one step synthesis of N -alkyl amines from amines and alcohols (Scheme b) . In view of volatile organic compounds (VOC) decomposition, molybdenum trioxide (MoO 3 ) nanowires supported bimetallic Pd–Au successfully degraded TCE as well as hybrid Na 2 Mo 4 O 13 /MoO 3 supported Pd–Au were also employed for oxidation of organic dyes in wet air conditions .…”

“… ,,, Moreover, various conventional SMC reactions catalyzed by supported Pd–Au BMCs also have been reported, and their superiority in comparison to monometallic Pd catalysts has always been witnessed in terms of activity, selectivity, and stability. Recently, the amine group functionalized iron oxide NPs supported Pd 50 -Au 50 catalyst has been reported for the SMC reaction with a good extent of recyclability, and magnetic separation from the reaction mixture was the key feature of this work …”

Recent developments of supported and magnetic nanocatalysts for organic transformations: an up-to-date review

“…Less reactive aryl halides were performed at higher temperatures to meet the conversion. The yield of the product depends on the presence of electron-withdrawing and releasing groups in the aromatic derivatives (Goonesinghe et al 2020). Ayad et al (2019) engineered green and water-soluble Pd NPs supported on phosphonic acids for the Suzuki Miyaura, Sonogashira, and Heck cross-coupling reactions.…”