5339-85-5Relevant articles and documents
Gold(I)-Thiolate Oligomers for Catalytic Hydrogenation of Nitroaromatics in Aqueous and Organic Medium
You, Jyun-Guo,Jin, Dun-Yuan,Tseng, Wei-Bin,Tseng, Wei-Lung,Lin, Po-Chiao
, p. 4558 - 4567 (2020/08/19)
Thiolated gold nanoclusters (AuNCs) have been introduced to efficiently and selectively catalyze the hydrogenation of nitroaromatics due to the strong interaction of their S?Au-S staple motifs with the nitro groups of nitroaromatics. However, without a gold core, gold(I)-thiolate oligomers (AuSOs) with S?Au-S staple motifs are rarely explored as catalysts for nitroaromatics. Here, we report a straightforward strategy for the synthesis of AuSOs through hydroxyl radical-induced leaching of glutathione-capped gold nanoparticles (GSH-AuNPs). Raman spectroscopy and matrix-assisted laser desorption/ionization-time of flight mass spectrometry demonstrated that hydroxyl radical-triggered etching of the GSH-AuNPs resulted in the production of AuSOs, including Au4(GSH)7 and Au7(GSH)9. The AuSOs were found to catalyze NaBH4-mediated hydrogenation of 4-nitrophenol to 4-aminophenol with a chemoselectivity of ～100 percent and a normalized rate constant (Knor) of 4.8×105 s? g?1. In addition to the high affinity of the S?Au?S staple motifs for 4-nitrophenol, the unusual catalytic activity of the AuSOs was attributable to the fact that they efficiently catalyzed the production of H2 from NaBH4 and the reaction of dissolved oxygen and NaBH4. The chemoselectivity and applicability of the AuSOs were further verified by performing the catalytic reaction of methyl 2-(2-nitrophenyl) acetate or methyl 4-nitrobenzoate with NaBH4.
Hydrogenation Properties of Nanostructured Tungsten Carbide Catalysts in a Continuous-Flow Reactor
Braun, Max,Esposito, Davide
, p. 393 - 397 (2017/02/15)
Tungsten monocarbide (WC) obtained through a urea glass route showed a high activity and chemoselectivity for the continuous-flow reduction of a variety of nitro compounds under milder conditions than those reported previously. The favorable effect of the nanostructure was shown by comparison with other commercially available WC materials. Moreover, WC functioned as an efficient support for Ni nanoparticles. This expanded its range of applicability and led to a bimetallic Ni@WC composite characterized by a high activity for the hydrogenation of cardanol, a phenolic lipid obtained from cashew nut shells.
Alloying Gold with Copper Makes for a Highly Selective Visible-Light Photocatalyst for the Reduction of Nitroaromatics to Anilines
Xiao, Qi,Sarina, Sarina,Waclawik, Eric R.,Jia, Jianfeng,Chang, Jin,Riches, James D.,Wu, Haishun,Zheng, Zhanfeng,Zhu, Huaiyong
, p. 1744 - 1753 (2016/03/15)
Finely control of product selectivity is an essential issue in organic chemical production. In the synthesis of functionalized anilines via reduction of the corresponding nitroarenes, the challenge is to selectively reduce only the nitro group in the presence of other reducible functional groups in nitroarene molecules at a high reaction rate. Normally, the nitroarene is reduced stepwise through a series of intermediates that remain as byproducts, increasing the aniline synthesis cost. Here we report that alloying small amounts of copper into gold nanoparticles can alter the reaction pathway of the catalytic reduction under visible-light irradiation at ambient temperature, allowing nitroaromatics to be transformed directly to anilines in a highly selective manner. The reasons for the high efficiency of the photocatalytic reduction under these comparatively benign conditions as well as the light-excited reaction mechanisms are discussed. This photocatalytic process avoids byproducts, exhibits a high reaction rate and excellent substituent tolerance, and can be used for the synthesis of many useful functionalized anilines under environmentally benign conditions. Switching of the reaction pathway simply by tailoring the bimetallic alloy NPs of the photocatalysts is effective for engineering of product chemoselectivity.
