Recent Developments in Nanostructured Palladium and Other Metal Catalysts for Organic Transformation

Abstract

Nanocatalysis is an emerging field of research and is applicable to nearly all kinds of catalytic organic conversions. Nanotechnology is playing an important role in both industrial applications and academic research. The catalytic activities become pronounced as the size of the catalyst reduces and the surface area-to-volume ratio increases which ultimately enhance the activity and selectivity of nanocatalysts. Similarly, the morphology of the particles also has a great impact on the activity and selectivity of nanocatalysts. Moreover, the electronic properties and geometric structure of nanocatalysts can be affected by polar and nonpolar solvents. Various forms of nanocatalysts have been reported including supported nanocatalysts, Schiff-based nanocatalysts, graphene-based nanocatalysts, thin-film nanocatalysts, mixed metal oxide nanocatalysts, magnetic nanocatalysts, and core-shell nanocatalysts. Among a variety of different rare earth and transition metals, palladium-based nanocatalysts have been extensively studied both in academia and in the industry because of their applications such as in carbon-carbon cross-coupling reactions, carbon-carbon homocoupling reactions, carbon-heteroatom cross-coupling reactions, and C-H activation, hydrogenation, esterification, oxidation, and reduction. The current review highlights the recent developments in the synthesis of palladium and some other metal nanocatalysts and their potential applications in various organic reactions.

Green Procedure for Aerobic Oxidation of Benzylic Alcohols with Palladium Supported on Iota-Carrageenan in Ethanol

“…Additionally, a biphasic aerobic oxidation of alcohols was performed by using palladium nanoparticles in a polyethylene glycol matrix as the catalyst and supercritical carbon dioxide as the substrate and product phase [ 29 ]. In contrast to our findings, however, it is well known that the aggregation of palladium nanoparticles, which results in a reduction in the surface area-to volume ratio, usually renders palladium nanoparticles less active and selective [ 33 ]. It was therefore suggested that other factors are responsible for the reaction enhancement effect, such as changes in the palladium oxidation state, palladium distribution on the surface, palladium nanoparticle morphologies, rate of nanoparticle formation, changes in the support structure, mass transfer limitations, etc.…”

“…Nanoparticles of palladium have been intensively studied in a wide range of catalytic applications, including C-C coupling reactions (e.g., Suzuki, Heck, Sonogashira, Negishi, Stille, Kumada and Hiyama), hydrogenation and electrochemical reactions in fuel cells [ 33 , 35 ]. There are also several reports showing the successful employment of palladium nanoparticles in oxidation reactions.…”

“…It was therefore suggested that other factors are responsible for the reaction enhancement effect, such as changes in the palladium oxidation state, palladium distribution on the surface, palladium nanoparticle morphologies, rate of nanoparticle formation, changes in the support structure, mass transfer limitations, etc. Nanoparticles of palladium have been intensively studied in a wide range of catalytic applications, including C-C coupling reactions (e.g., Suzuki, Heck, Sonogashira, Negishi, Stille, Kumada and Hiyama), hydrogenation and electrochemical reactions in fuel cells [33,35]. There are also several reports showing the successful employment of palladium nanoparticles in oxidation reactions.…”

“…Palladium catalysts, which have found widespread application in organic synthesis, were also extensively used to this end, and they employed different supports, such as silica [ 25 ], graphene [ 26 ], aluminum hydroxide [ 27 ], MnCeOx [ 28 ], and poly(ethyleneglycole) [ 29 ]. Additionally, the most active species in many systems were palladium nanoparticles [ 29 , 30 , 31 , 32 , 33 ].…”

Suporte Lignocelulósico De Bambu Impregnado Com Paládio E Sua Aplicação Para Reação De Suzuki

“…As propriedades já conhecidas do paládio associada à escala nano que possui características próprias e muito vantajosas criam materiais muito interessantes e com um grande potencial de aplicação em diversas áreas. 43,44 . Geralmente, recebem o nome de nanopartículas materiais que possuem dimensões entre 1-100 nm.…”