Stable and Surface‐active Co Nanoparticles Formed from Cation (x) Promoted Au/x‐Co₃O₄ (x=Cs) as Selective Catalyst for [2+2+1] Cyclization Reactions

Abstract

Surface‐active and highly stable cobalt nanoparticles generated from alkali ion‐promoted gold catalyst for catalyzed carbonylative [2+2+1] cyclization reaction, is described. The gold nanoparticle‘s (AuNPs) role was assumed to dissociate the CO and H2 into atomic species on the catalyst surface by spillover, which in‐situ reduces the robust mesoporous cobalt oxide to metallic cobalt (Co3+→Co2+→Co), as the active catalytic species that catalyzed the reaction; thereby providing up to 93 % yield of cyclopentenone adducts. Prior to this, catalyst pre‐treatment with H2 gas (130 °C, 3 h, 20 atm) was performed to reduce the catalyst. It appeared that the low reducibility temperature and increased surface basicity ascribed to the presence of alkali ion‐promoters in the catalyst revealed a strong correlation with the catalyst activity, for the intra‐ and intermolecular reactions under milder reaction conditions. Thus, a sustainable, highly reusable, and environmentally friendly green catalyst for the carbonylation reaction, such as Pauson‐Khand, was developed.

Bifunctional Cs−Au/Co3O4 (Basic and Redox)‐Catalyzed Oxidative Synthesis of Aromatic Azo Compounds from Anilines

“…However, these cations significantly enhanced the catalytic performance for the oxidative coupling of a diverse array of anilines to symmetric and unsymmetric aromatic azo compounds. As previously demonstrated by our group, alkali metal ions on the surface of reducible metal oxides and catalysts can improve the nanomaterials′ basic strength concentration and catalytic activity [4,5,24] . According to Helwani and coworkers, the presence of these highly electropositive cations in catalysts, which create basic sites, can cause defects in the materials [26] .…”

“…Recently, gold catalysts for sustainable and green organic synthesis have attracted considerable scientific attention due to their broad range of applications and efficiency. [1][2][3][4][5] Initially thought inert, gold became apparent as a selective and active catalyst to others, such as platinum, for a range of reactions after a significant breakthrough in its usage at the nanoscale level. [6] Recent advancements in the gold catalyst's practical utility and applications, especially in gold metal and support interactions, have paved the way for new methods for their practical utility and applications.…”

“…Metal‐support interactions have resulted in significant advancements in the development of commercially viable organic compounds. On the other hand, modifying (doping) support materials and catalysts with alkali metals has previously been shown to induce a phenomenon, increase their binding properties, and significantly improve the overall catalytic performance of the catalyst [4,7] …”

Alkali-modified heterogeneous Pd-catalyzed synthesis of acids, amides and esters from aryl halides using formic acid as the CO precursor

“…The spinel mesoporous Co 3 O 4 is versatile and constitutes an interesting class of nanomaterials for noble metal support in vast catalytic reactions due to the intrinsic catalytic activity they exhibit. [41][42][43][44] Notably, incorporating dopants such as alkali metals into catalysts has developed into an interesting and active eld in catalysis. We recently reported that alkali metals might induce a phenomenon and improve the overall catalyst activity.…”

“…We recently reported that alkali metals might induce a phenomenon and improve the overall catalyst activity. 2,41,45 Various studies have documented the increased catalytic activity of these alkali-promoted catalysts due to their electronic and structural effects on these nanomaterials. [46][47][48] It was discovered in this study that doping with alkali metals stabilized and induced the active dispersed palladium species on reducible Co 3 O 4 , thus minimizing active site leaching, acting as a potential "in-built" cationic Lewis acid co-catalyst, and improving the catalyst's binding properties.…”