Silver Nanoparticles in Organic Transformations

Applications of Plasmon-Enhanced Nanocatalysis to Organic Transformations

“…When selecting a plasmonic metal for a reaction of interest, catalytic properties (under thermal conditions) are also worth looking into. For example, the selectivity of Ag for carbonyl reduction against alkene is well-known, 398 while Au NPs have been used extensively for many different types of oxidation and reduction reactions. 188 In general, two effects are observed in the plasmonenhanced catalysis literature.…”

“…Reduction of aldehydes and ketones was performed at 1 atm of H 2 and 80 °C and showed excellent selectivity toward CO over CC bonds. Ag-based catalysis had been previously reported for reduction of carbonyls, but harsh conditions are usually required to induced heterolytic hydrogen gas dissociation 492 whereas homoleptic cleavage of H 2 at the surface of Ag NCs was promoted by plasmon-activation at atmospheric pressure. H 2 dissociation via hot electron transfer from the Ag surface to σ* orbitals was followed by transfer of thus formed photoactivated hydrogens to the substrates adsorbed at the surface of the PNPs and finally gave the corresponding alcohols with good to excellent yields (Figure 20).…”

Silver Cyanide Powder‐Catalyzed Selective Epoxidation of Cyclohexene and Styrene with its Surface Activation by H2O2(aq) and Assisted by CH3CN as a Non‐Innocent Solvent

“…The additional amide signals on the AgCN surface were detected from the two spectroscopic methods (XPS and 13 C-SS NMR). The results imply that this sacrificial species 2 from the solvent can behave like surface and subsurface chlorines assisting silver NP for ethylene epoxidation, [9,30] chelating to the low coordination sites and weakening the AgÀ O interactions. The process makes the regeneration of electrophilic oxygen or surface OH ad species much facile for epoxidation and improves the selectivity by accelerating the product desorption.…”

“…[1b,c,8] Ag materials/nanoparticles (NPs) have been extensively studied for the epoxidation of simple olefins such as ethylene/propylene in the gas phase. [9] X-ray photoelectron spectroscopy (XPS) technique allows us to identify that the nucleophilic and electrophilic oxygen species (O 1s binding energies of 528.5 and 530.0 eV, respectively) are crucial surface intermediates for the olefin activation/oxidation/combustion. Adding electrophilic oxygen to the olefins π-bond can be the rate-determining step for the epoxidation reaction.…”

“…Furthermore, several studies have reported that the silver particles in water can also conduct efficient nitriles hydration to amide derivatives under aerobic conditions beyond the ambient temperature. [9,12] The pre-adsorbed oxygen atom (O ad ) on the Ag surface served as Brønsted base that interacts with surface water yields nucleophilic adsorbed hydroxide (OH ad ) species for nitrile hydration (Route 3, Scheme 1). [9,12a] Control experiments suggested that Ag(CN) n 1À n type complex intermediates likely participate in the catalytic hydration of nitriles without any cyanide poisoning effects towards the catalytic metal surface.…”