Plasmonic Silver‐Nanoparticle‐Catalysed Hydrogen Abstraction from the C(sp³)−H Bond of the Benzylic C_αatom for Cleavage of Alkyl Aryl Ether Bonds

Abstract

Selective activation of the C(sp 3 )À H bond is an important process in organic synthesis, where efficiently activating a specific C(sp 3 )À H bond without causing side reactions remains one of chemistry's great challenges. Here we report that illuminated plasmonic silver metal nanoparticles (NPs) can abstract hydrogen from the C(sp 3 )À H bond of the C α atom of an alkyl aryl ether β-O-4 linkage. The intense electromagnetic nearfield generated at the illuminated plasmonic NPs promotes chemisorption of the β-O-4 compound and the transfer of photo-generated hot electrons from the NPs to the adsorbed molecules leads to hydrogen abstraction and direct cleavage of the unreactive ether C β À O bond under moderate reaction conditions ( � 90 °C). The plasmon-driven process has certain exceptional features: enabling hydrogen abstraction from a specific C(sp 3 )À H bond, along with precise scission of the targeted CÀ O bond to form aromatic compounds containing unsaturated, substituted groups in excellent yields.

Deconstructive annulation mediated one-pot synthesis of xanthene derivatives

“…Zhu and co-workers reported silver nanoparticle mediated C(sp 3 )-O cleavage reaction. 25 Jana and co-workers reported a silver mediated aryl migration reaction via Smiles rearrange-ment. 26 Generally, silver salts in the presence of strong oxidants such as peroxydisulfates are known to carry out diverse organic transformations.…”

Probing local charge transfer processes of Pt–Au heterodimers in plasmon-enhanced electrochemistry by CO stripping techniques

“…For plasmon-enhanced catalytic reactions, three typical effects are commonly considered for the enhancement, namely the hot charge carriers, local photothermal heating 13,42 and strong electromagnetic fields. 4,43 In the case of plasmonenhanced electrochemistry based on heterostructure catalysts, hot charge carriers (e-h pairs) are the major contributors. 44,45 For Au nanocubes, the current increases slightly upon plasmonic excitation because the generated hot carriers tend to have a short lifetime and decay in a short time.…”

“…Local surface plasmon resonance (LSPR), a unique optical property of plasmonic nanomaterials (e.g., gold, silver, and copper), is a collective free electron oscillation confined in nanomaterials when they are excited by light of the corresponding resonance wavelength. [1][2][3][4][5] Electrocatalysis enhanced by the LSPR effect has received extensive attention owing to its potential applications in efficient solar energy utilization. [6][7][8][9] However, the time-scale mismatch between the ultrafast dynamics of resonance energy relaxation (femtoseconds to nanoseconds) and electrocatalytic processes (milliseconds to minutes) hampers the effective utilisation of the resonance energy in catalytic reactions.…”

Plasmonics: A Versatile Toolbox for Heterogeneous Photocatalysis

“…[ 143 ] Very recently, Han and coworkers have reported that Ag NPs supported on alumina functionalized by amino groups can efficiently activate selectively the C–H bond of the carbon atom bonded to the oxygen in a model alkyl aryl ether, 1‐phenoxy‐2‐phenylethane. [ 144 ] The conversion was negligible when the same reaction is performed in dark conditions, demonstrating that hot electrons generated by light absorption are involved in the process. This result paves the way toward the depolymerization of lignin, since the β–O–4 linkage in 1‐phenoxy‐2‐phenylethane represents up to 60% of the linkages found in this important natural polymer.…”