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All total 116 Articles be foundA rapid and green synthetic approach for hierarchically assembled porous ZnO nanoflakes with enhanced catalytic activity
Sinhamahapatra, Apurba,Giri, Arnab Kanti,Pal, Provas,Pahari, Sandip Kumar,Bajaj, Hari C.,Panda, Asit Baran
, p. 17227 - 17235 (2012)
Three dimensionally (3D) assembled hierarchical porous ZnO structures are of key importance for their applications in sensors, lithium-ion batteries, solar cells and in catalysis. Here, the controlled synthesis of 3D hierarchically porous ZnO architectures constructed of two dimensional (2D) nano-sheets through the calcination of a hydrozincite [Zn5(CO 3)2(OH)6] intermediate is presented. The intermediate 3D hierarchical hydrozincite has been synthesized by a novel organic surfactant and solvent free aqueous protocol at room temperature using an aqueous solution of ammonium carbonate and laboratory grade bulk ZnO in a short time (20-30 min). The amount of carbonate and the reaction temperature play a crucial role in the formation of the 3D hierarchical morphology and on the basis of the experimental results a probable reaction mechanism is proposed. On calcination, the synthesized 3D hierarchical hydrozincite resulted in ZnO with an almost identical morphology to the parental hydrozincite. On decomposition a porous structure having a surface area of 44 m2 g-1 is obtained. The synthesized hierarchical ZnO morphology exhibits an improved catalytic activity for the synthesis of 5-substituted-1H-tetrazoles with different nitriles and sodium azide than that of nanocrystalline ZnO and bulk ZnO, as well as other developed solid catalysts. The catalyst is easily recyclable without a significant loss in catalytic activity. The Royal Society of Chemistry 2012.
1-Disulfo-[2,2-bipyridine]-1,1-diium chloride ionic liquid as an efficient catalyst for the green synthesis of 5-substituted 1H-tetrazoles
Aali, Elaheh,Gholizadeh, Mostafa,Noroozi-Shad, Nazanin
, (2021/08/30)
A simple, green and efficient method has been developed for the synthesis of 5-substituted 1H-tetrazole derivatives through [2+3] cycloaddition reaction in good to excellent yields between various benzonitriles and sodium azide. For this purpose, 1-disulfo-[2,2-bipyridine]-1,1-diium chloride ([BiPy](HSO3)2Cl2) system as an ionic liquid catalyst have been extended for the construction of these valuable products. This procedure has significant advantages, including using ethylene glycol as a green solvent. The other advantages of this method are inexpensive and ease the preparation of the catalyst, mild reaction conditions, green reaction medium, easy workup, short reaction time, and simple experimental process.
Magnetic nitrogen-doped carbon derived from silk cocoon biomass: a promising and sustainable support for copper
Akbarzadeh, Parisa,Koukabi, Nadiya,Tahmasbi, Marzieh
, (2021/12/01)
In this study, a magnetic nitrogen-doped carbon-based copper (MNC-Cu) catalyst was fabricated so that natural silk cocoons undergo thermal processes and then activate by combining with Fe3O4 MNPs as a suitable substrate for placement copper metal. The efficiency of the generated catalyst in the synthesis of 5-substituted 1H-tetrazole derivatives was evaluated by the [3 + 2] cycloaddition reaction of aromatic aldehydes, azide ions, and hydroxylamines. FT-IR, FE-SEM, EDS, TEM, XRD, TGA, and VSM techniques have been adopted to identify and validate this heterogeneous catalyst. The observation from EDS, elemental mapping, XRD, and FT-IR analysis confirms the immobilization of Cu metals on the MNC surface and uniform distribution of species and then no aggregation occurs during functionalization. VSM results show the magnetic feature of fabricated catalyst, and based on the leaching test, the amount of catalyst leaching was negligible. Moreover, this reaction is a one-pot multicomponent reaction (MCRs) or more precisely a one-pot, three-component reaction, which is one of the advantages of this work. The fabricated catalyst shows high efficiency, good stability, and considerable reactivity in synthesizing 5-substituted 1H-tetrazole derivatives. So it can be seen that the fabricated magnetic catalyst is a useful and practical catalyst for synthesizing [3 + 2] cycloaddition reactions. Reusability and recyclability for five sequential runs without notable increase and reduction in activity are other advantages. In addition, the magnetic properties of this heterogeneous catalyst led to easy and quickly recovered and striking copper leaching. Graphical abstract: [Figure not available: see fulltext.]
