Recyclable Fe3O4 Nanoparticles Catalysts for Aza-Michael Addition of Acryl Amides by Magnetic Field

Liu, Zhenxing; Luo, Dan; Li, Mingming; Xing, Xiaofei; Ma, Zhihua; Xu, Hao

doi:10.3390/catal7070219

Cited by 30 publications

(21 citation statements)

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“…[46][47][48] However, the report on the use of metal oxide nanocatalyst for such reaction is very limited. 12,[49][50][51] The benet of using metal oxide NPs as catalyst such as high efficiency, enhanced surface to volume ratio, expected high atom economy, easy recovery and recyclability has prompted us to use the synthesized CuO NPs as catalyst for aza-Michael reaction.…”

Section: Introductionmentioning

confidence: 99%

Green synthesis of CuO nanoparticles using Lantana camara flower extract and their potential catalytic activity towards the aza-Michael reaction

2020

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Aza-Michael addition is one of the most exploited reactions in organic chemistry. It is regarded as one of the most popular and efficient methods for the creation of the carbon-nitrogen bond, which is a key feature of many bioactive molecules. Herein, we report the synthesis of CuO nanoparticles by an alkaline hydrolysis process in the presence of the flower extract of Lantana camara, an invasive weed, followed by calcination in air at 400 C. Microscopic results indicated that the plant extract played an important role in the modulation of the size and shape of the product. In the presence of extract, porous CuO nanostructures are formed. While mostly aggregated rod-shaped CuO nanostructures are formed in the absence of extract. The products are pure and highly crystalline possessing the monoclinic phase. The CuO nanoparticles have been used as a catalyst in the aza-Michael addition reaction in aqueous medium under ultrasound vibration. The product yield is excellent and the catalyst is reusable up to the fifth cycle. The catalyst system can be extended to various substituted substrates with excellent to moderate yields.

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Section: Introductionmentioning

confidence: 99%

Green synthesis of CuO nanoparticles using Lantana camara flower extract and their potential catalytic activity towards the aza-Michael reaction

2020

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“…Even though the photocatalytic efficiency of the AgCl@AgAu NPs was decreased in natural media, the versatile and practical capability of AgCl@AgAu NPs for the removal of environmental pollutants was clearly demonstrated. The stability of heterogeneous catalysts is an important issue for reaction efficiency [54,55]. Under harsh oxidative or reductive conditions, NP catalysts could easily become non-catalytic due to their irreversible aggregation in the reaction mixture, where different phases of reactants and catalysts coexist.…”

Section: Resultsmentioning

confidence: 99%

Structurally and Compositionally Tunable Absorption Properties of AgCl@AgAu Nanocatalysts for Plasmonic Photocatalytic Degradation of Environmental Pollutants

et al. 2020

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Composite nanomaterials having Ag nanoparticles (NPs) that decorate nanostructured AgCl (Ag/AgCl) are promising as plasmonic photocatalysts because of the visible-light absorption of Ag NPs. However, the narrow absorption bands of Ag NPs near 400 nm cause inefficient absorption in the visible range and, consequently, unsatisfactory photocatalytic activity of Ag/AgCl nanomaterials. In this study, we introduce a new class of AgCl-based photocatalysts that are decorated with bimetallic Ag and Au NPs (AgCl@AgAu NPs) for visible-light-driven photocatalytic degradation of organic pollutants. Polyvinylpyrrolidone induces selective reduction of noble metal precursors on AgCl while leaving AgCl intact. The extended composition of the decorating NPs red-shifts the absorption band to 550–650 nm, which allows the catalysts to take advantage of more energy in the visible range for improved efficiency. Furthermore, we control the structures of the AgCl@AgAu NPs, and investigate their correlation with photocatalytic properties. The versatility, chemical stability, and practical application of the AgCl@AgAu NPs are demonstrated using various organic pollutants, recycling experiments, and natural aqueous media, respectively. Our fundamental investigation on the synthesis and applications of AgCl-based nano-photocatalysts is highly valuable for designing plasmonic photocatalysts and expanding their utilization.

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“…Also, in this case, most of the studies are based on similar systems (azobenzene derivatives), but a larger variability could be obtained by employing different photo-sensible units (for example, spiropyran, stilbene, diarylethene). Further study of alternative stimuli such as variations of chemical composition of the surrounding medium (at the moment current studies are limited to variations of pH or ionic strength), electric and magnetic field (whose employment, in most of the cases, is limited to obtain an easy separation of catalysts after the end of their work [64,65] or to the induction of heating [66] for endothermic reactions) or mechanical stress (also thanks to the exploitation of piezoelectric effect for the generation of catalytically active species [67]) would be desirable, paving the way to the preparation of dynamic systems based on new and unconventional strategies. The preparation of macroscopic catalytic devices has already opened the way in this direction, finding alternative strategies in comparison to the traditional dispersion of heterogeneous catalysts in solution, which also enabled the synergistic combination of precise temporal and spatial control of chemical reactions.…”

Section: Discussionmentioning

confidence: 99%

Switchable Stimuli-Responsive Heterogeneous Catalysis

Vassalini

Alessandri

2018

Catalysts

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Heterogeneous catalytic systems based on the use of stimuli-responsive materials can be switched from an "on" active state to an "off" inactive state, which contributes to endowing the catalysts with unique functional properties, such as adaptability, recyclability and precise spatial and temporal control on different types of chemical reactions. All these properties constitute a step toward the development of nature-inspired catalytic systems. Even if this is a niche area in the field of catalysis, it is possible to find in literature intriguing examples of dynamic catalysts, whose systematic analysis and review are still lacking. The aim of this work is to examine the recent developments of stimuli-responsive heterogeneous catalytic systems from the viewpoint of different approaches that have been proposed to obtain a dynamic control of catalytic efficiency. Because of the variety of reactions and conditions, it is difficult to make a quantitative comparison between the efficiencies of the considered systems, but the analysis of the different strategies can inspire the preparation of new smart catalytic systems.Catalysts 2018, 8, 569 2 of 25 fields [6] and mechanical stress [7], have also been exploited. A large variability can also be observed in the type of system response: variations of chemical properties, solubility, shape, volume, color, aggregation state, electrical properties, magnetic properties, mechanical properties, etc. are all possible. Thanks to this high versatility, artificial smart materials have found application in various sectors [8], ranging from medicine to national security and structural engineering [9]. They are commonly employed for drug delivery [10], self-healing [11], sensing [12], actuations [13], information storage [14], etc. Their use for catalytic purposes has been remarkably less investigated, even if heterogeneous catalysis can fully take advantage of the dynamic behavior of smart materials. For example, it is possible to make a catalyst to pass from a state of activity (an "on" state) to a state of inertness (an "off" state) in a controlled way, with a precise temporal control, obtaining switchable catalysis. In other circumstances, the possibility of modulating the reaction rate in a continuous way, regulating the amount of accessible active sites and accelerating or lowering the reaction rate in a non-discrete way, is more interesting, and in this case we can also exploit stimuli-responsive materials. It is also possible to create microenvironments in which the reaction occurs preferentially, accomplishing a spatial control on the reaction development. In addition, the responsiveness of the employed systems can be exploited to improve the recyclability of the catalytic system, making the catalyst separation from the reaction medium and its reuse easier.In this review, we analyze some of the latest works on dynamic systems in the field of heterogeneous catalysis. Many more examples can be found for homogeneous catalysis, but most of them have been already analyzed in previ...

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Recyclable Fe3O4 Nanoparticles Catalysts for Aza-Michael Addition of Acryl Amides by Magnetic Field

Cited by 30 publications

References 50 publications

Green synthesis of CuO nanoparticles using Lantana camara flower extract and their potential catalytic activity towards the aza-Michael reaction

Green synthesis of CuO nanoparticles using Lantana camara flower extract and their potential catalytic activity towards the aza-Michael reaction

Structurally and Compositionally Tunable Absorption Properties of AgCl@AgAu Nanocatalysts for Plasmonic Photocatalytic Degradation of Environmental Pollutants

Switchable Stimuli-Responsive Heterogeneous Catalysis

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