- Tandem selective reduction of nitroarenes catalyzed by palladium nanoclusters
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We report a catalytic tandem reduction of nitroarenes by sodium borohydride (NaBH4) in aqueous solution under ambient conditions, which can selectively produce five categories of nitrogen-containing compounds: anilines, N-aryl hydroxylamines, azoxy-, azo- and hydrazo-compounds. The catalyst is in situ-generated ultrasmall palladium nanoclusters (Pd NCs, diameter of 1.3 ± 0.3 nm) from the reduction of Pd(OAc)2 by NaBH4. These highly active Pd NCs are stabilized by surface-coordinated nitroarenes, which inhibit the further growth and aggregation of Pd NCs. By controlling the concentration of Pd(OAc)2 (0.1-0.5 mol% of nitroarene) and NaBH4, the water/ethanol solvent ratio and the tandem reaction sequence, each of the five categories of N-containing compounds can be obtained with excellent yields (up to 98%) in less than 30 min at room temperature. This tunable catalytic tandem reaction works efficiently with a broad range of nitroarene substrates and offers a green and sustainable method for the rapid and large-scale production of valuable N-containing chemicals.
- Yan, Ziqiang,Xie, Xiaoyu,Song, Qun,Ma, Fulei,Sui, Xinyu,Huo, Ziyu,Ma, Mingming
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supporting information
p. 1301 - 1307
(2020/03/11)
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- Palladium Nanoparticles on Silica Nanospheres for Switchable Reductive Coupling of Nitroarenes
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Abstract: In this study, we synthesized a robust and sustainable Pd/SiO2 nanospheres catalyst. Further, its catalytic activity was demonstrated for the direct reductive coupling of nitroarenes under mild conditions. While the reaction with Pd nanoparticles on other supporting materials such as modified carbon materials and TiO2, under similar conditions, resulted formation of amines exclusively. Therefore, it was confirmed that the SiO2 was found to be the best supporting material towards the selective reductive coupling of nitroarenes. Also, the catalyst could be recycled up to five cycles with a marginal loss of product yield ( 2% yield). Graphic Abstract: [Figure not available: see fulltext.].
- Lakshminarayana, Bhairi,Manna, Arun Kumar,Satyanarayana,Subrahmanyam, Ch.
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p. 2309 - 2321
(2020/02/18)
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- Green and highly efficient approach for the reductive coupling of nitroarenes to azoxyarenes using the new mesoporous Fe3O4@SiO2@Co–Zr–Sb catalyst
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Efficient, green, simple and environmentally friendly approach for the straightforward reductive coupling of nitroarenes to the corresponding azoxyarenes has been developed in the presence of Fe3O4@SiO2@Co–Zr–Sb as a novel recyclable nanocatalyst. The Co–Zr–Sb trimetallic nanoparticles immobilized on silica-layered magnetite have been prepared by the co-precipitation method. The mesoporous catalyst has been characterized by FT-IR, SEM, EDX, VSM, TEM and XRD analyses. The chemoselective hydrogenation of nitrobenzenes was carried out successfully in refluxing water to afford the corresponding azoxybenzenes within 2–10?min in good to high yields. The reusability of the heterogeneous nanocatalyst has also been studied using the FT-IR and SEM analyses. The catalyst was utilized four times in sequential runs without significant loss of activity. The current research includes remarkable advantages of short reaction times, absence of hazardous organic solvents, mild reaction conditions, high yields, using water as a green solvent and the ability to utilize the recyclable nanomagnetic catalyst.
- Zeynizadeh, Behzad,Gilanizadeh, Masumeh
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p. 2969 - 2984
(2020/04/10)
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- Unexpected observations during the total synthesis of calothrixin B-sodium methoxide as a source of hydride
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During the total synthesis of calothrixin B, various novel and unexpected results were noticed such as cleavage of C-N bond in imine using sodium cyanoborohydride, sodium methoxide as a hydride source for reduction, deformylation in the presence of bromine, and deacylation using ceric ammonium nitrate (CAN). A detailed mechanism has been proposed for the unexpected results and a few of them are generalized. Temperature dependent NMR studies have been carried out for confirmation of the structure of one of the intermediates in the synthetic sequence.
- Bhosale, Shrikar M.,Momin, Aadil A.,Kunjir, Shrikant,Rajamohanan,Kusurkar, Radhika S.
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supporting information
p. 155 - 162
(2014/01/06)
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- Mechanism of the Reaction of Sodium Hydroxide and Nitrobenzylsulphones
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Aqueous sodium hydroxide reacts with sulphonyl>acetic acid (1) to give 4,4'-diformylazoxybenzene and 4,4'-dicarboxyazoxybenzene as the main products, while in 50percent water-dioxane medium the products are 4,4'-dihydroxymethylazoxybenzene, 4,4'-dicarboxyazoxybenzene besides 4-carboxy, 4'-hydroxymethylazoxybenzene and its isomer. 4-Nitrosobenzaldehyde is an intermediate in this reaction which via a Cannizzaro reaction gives the reaction products.Other 2-, 3- and 4-nitrobenzyl sulphones are studied.
- Riad, Y.,Asaad, A. Naguib,Nahas, Hind Moustafa El,Madkour, A. Emad El Din
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p. 157 - 172
(2007/10/03)
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