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High-yield multicomponent synthesis of triazolo[1,2-a]indazole-triones using silica-coated ZnO nanoparticles as heterogeneous catalyst in the presence of ultrasound

Abstract

We report here a comprehensively detailed systematic investigations on a new method of an ultrasound-assisted synthesis of 4(a-m) triazolo[1,2-a]indazole-triones (TAITs) using the multicomponent condensation reaction among dimedone, 4-phenylurazole and various individual aryl aldehydes in the presence/ absence of SiO2, ZnO and SiO2-coated ZnO (ZnO@SiO2) nanoparticles (NPs) or nanorods as heterogeneous catalysts in deionized water (DIW) at considerably low temperature (~60 oC). For this, the nanorods are synthesized in an efficient, facile and scalable wet chemical route in DIW at 27 oC. Oxygen-excess ZnO nanorods of ~21 nm diameter with up to nearly 259 nm length become rather complicated internal structure with smooth-looking surface of oxygen-deficient ZnO@SiO2 nanorods of about 48 nm in diameter. Remarkably, attributed to oxygen deficiency, ZnO@SiO2 NPs exhibit excellent catalytic activities with good to high yield of TAIT products, brilliant recyclability up to six runs, over -30 mV zeta potential (ζ) value, smallest hydrodynamic diameter (HD) of 752 nm, best dispersion stability and largest specific surface area of 97.5 m2/g. Therefore, the greenest reaction medium for both the synthesis of these catalysts as well as TAITs was realized, making it environmental-friendly doubly-green reactions with wide application potential due to their high efficiency, ease of handling and cost effectiveness.

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Publication details

The article was received on 31 Oct 2017, accepted on 09 Nov 2017 and first published on 09 Nov 2017


Article type: Paper
DOI: 10.1039/C7GC03279J
Citation: Green Chem., 2017, Accepted Manuscript
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    High-yield multicomponent synthesis of triazolo[1,2-a]indazole-triones using silica-coated ZnO nanoparticles as heterogeneous catalyst in the presence of ultrasound

    D. Verma, V. Sharma, G. S. Okram and S. Jain, Green Chem., 2017, Accepted Manuscript , DOI: 10.1039/C7GC03279J

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