HPA decorated Halloysite Nanoclay: An efficient catalyst for the green synthesis of Spirooxindole derivatives

et al. 2018

Applied Organom Chemis

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A novel heterogeneous catalyst is prepared through functionalization of halloysite nanotube with 1H-1,2,3-triazole-5-methanol and subsequent immobilization of silver nanoparticles through bio-assisted approach using Arctiumplatylepis extract. The resulting catalyst, Ag@HNTs-T, was characterized by using SEM/EDX, BET, XRD, FTIR, ICP-AES, TGA, DTGA and elemental mapping analysis. Moreover, we computationally assessed metal-ligand interactions in Ag@HNTs-T complex model to interpret the immobilization behavior of silver nanoparticles on HNTs surface via quantum chemistry computations. The catalytic activity of the catalyst was studied for the synthesis of propargylamines via A 3 and KA 2 coupling reactions under ultrasonic irradiation. The results demonstrated that Ag@HNTs-T could efficiently promote these reactions to furnish the corresponding products in high yields and short reaction times. The study of the recyclability of the catalyst and Ag(0) leaching confirmed that the catalyst was recyclability up to four reaction runs with slight Ag(0) leaching.

Section: Introductionmentioning

confidence: 86%

Ultrasonic and bio‐assisted synthesis of Ag@HNTs‐T as a novel heterogeneous catalyst for the green synthesis of propargylamines: A combination of experimental and computational study

Malmir

Heravi

et al. 2018

Applied Organom Chemis

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“…In the continuation of our research on disclosing the catalytic utility of Hal 23,24 , recently we have reported facile recovery and high reusability of magnetic Hal 25,26 . On the other hand, our research on the catalytic activity of IL-Hal hybrid 27,28 showed that the presence of ILs on the Hal can efficiently improve anchoring of nanoparticles and suppressing their leaching. In this work we design and synthesize a novel catalyst through multi-step procedure, Fig.…”

mentioning

confidence: 94%

Bio-assisted synthesized Pd nanoparticles supported on ionic liquid decorated magnetic halloysite: an efficient catalyst for degradation of dyes

Mohammadi

Heravi

2020

Sci Rep

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Using natural materials, i.e. halloysite nanoclay that is a biocompatible naturally occurring clay and Heracleum persicum extract that can serve as a green reducing agent, a novel magnetic catalyst, fe 3 o 4 / Hal-Mel-TEA(IL)-Pd, has been designed and fabricated. To prepare the catalyst, halloysite was first magnetized (magnetic particles with mean diameter of 13.06 ± 3.1 nm) and then surface functionalized with melamine, 1,4 dibromobutane and triethanolamine to provide ionic liquid on the halloysite surface (5 wt%). The latter was then used as a support to immobilize Pd nanoparticles that were reduced by Heracleum persicum extract. The characterization of the catalyst established that the loading of Pd in fe 3 o 4 /Hal-Mel-TEA(IL)-Pd was very low (0.93 wt%) and its specific surface area was 63 m 2 g −1 . Moreover, the catalyst showed magnetic property (Ms = 19.75 emu g −1 ) and could be magnetically separated from the reaction. The catalytic performance of the magnetic catalyst for reductive degradation of methyl orange and rhodamine B in the presence of NaBH 4 in aqueous media was investigated. The activation energy, enthalpy, and entropy for the reduction of methyl orange were estimated as 42.02 kJ mol −1 , 39.40 kJ mol −1 , and −139.06 J mol −1 K −1 , respectively. These values for rhodamine B were calculated as 39.97 kJ mol −1 , 34.33 kJ mol −1 , and −155.18 Jmol −1 K −1 , respectively. notably, fe 3 o 4 /Hal-Mel-TEA(IL)-Pd could be reused for eight reaction runs with negligible loss of the catalytic activity (~3%) and Pd leaching (0.01 wt% of the initial loading).Application of low-cost, biocompatible and available natural compounds for the catalytic purposes has attracted tremendous attention. In this regard, use of halloysite (Hal) that is a dioctahedral 1:1 clay of the kaolin group has received growing interest 1-3 . Apart from high thermal, chemical and mechanical stability, the cylindrical morphology and opposite chemical and electrical properties of inner and outer surfaces of Hal, make it distinguished from other clays and broaden its utility for many applications such as cleaning 4 , adsorbents 5,6 , energy storage, catalysis, flame retardancy 1 , sustainable release of drugs etc. Regarding catalysis, Hal not only can be utilized as a catalyst, but also can be applied as a support for the development of reusable catalysts. To date, various chemical, photochemical and electrochemical transformations such as coupling reactions 7,8 , hydrogenation 9,10 , oxidation have been promoted by using Hal-based catalysts [11][12][13][14][15] . Organic dyes such as methylene blue, rhodamine B (RhB) and methyl orange (MO) are toxic chemicals with potential health threat 16 . The release of these compounds in the industrial waste water has raised many concerns and motivated many studies for the efficient removal of these hazardous pollutants or their conversion into less toxic compounds 17,18 . In this context, several approaches, such as use of adsorbents, photodegradation, electrochemical degradations, membrane p...

“…Recently, functionalization of HNTs has been comprehensively reviewed by Riela and co‐workers . It has been shown that functionalized HNTs can be successfully used for the immobilization of various catalytically active species such as nanoparticles, heteropolyacids, ionic liquids, complexes, etc . It has been confirmed that functionalized HNTs not only can effectively suppress the leaching of supported catalytically active species but also can exert synergistic effects and improve the catalytic performance of a hybrid catalyst.…”

Section: Introductionmentioning

confidence: 99%

“…In continuation of our studies on HNTs as catalyst supports and considering the efficiency of CDs and HNTs for immobilization of Pd, herein we report, for the first time, a novel hybrid system based on covalent conjugation of tosylated CD to thiosemicarbazide‐functionalized HNTs (HNTs‐T‐CD) for immobilization of Pd nanoparticles and the development of a novel catalyst, Pd@HNTs‐T‐CD. Considering the synthetic importance of C–C coupling reactions, we report the catalytic activity of Pd@HNTs‐T‐CD for promoting ligand‐ and copper‐free Sonogashira coupling reactions (Scheme ) and a model Mizoroki–Heck reaction (Scheme ) in a mixture of water and ethanol.…”

Section: Introductionmentioning

confidence: 99%

Palladium nanoparticles immobilized on cyclodextrin‐decorated halloysite nanotubes: Efficient heterogeneous catalyst for promoting copper‐ and ligand‐free Sonogashira reaction in water–ethanol mixture

2018

Applied Organom Chemis

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Combining the excellent features of halloysite nanoclay and cyclodextrin, a novel hybrid system was designed and synthesized based on covalent attachment of tosylated cyclodextrin to thiosemicarbazide‐functionalized halloysite nanoclay and used for the immobilization of Pd nanoparticles. The resulting hybrid, Pd@HNTs‐T‐CD, was then characterized using various techniques, and successfully used for promoting copper‐ and ligand‐free Sonogashira coupling reactions of halobenzenes and acetylenes in a mixture of water and ethanol. Notably, under Pd@HNTs‐T‐CD catalysis, the reaction could proceed in relatively short reaction time to furnish the corresponding products in high yields. Additionally, the catalyst was recyclable and could be simply recovered and reused for several reaction runs. Results also established negligible leaching of Pd, indicating the efficiency of HNTs‐T‐CD for embedding Pd nanoparticles.