Green synthesis of 1,4-benzodiazepines over La2O3 and La(OH)3 catalysts: possibility of Langmuir–Hinshelwood adsorption

Singh, Archana; Palakollu, Veerabhadraiah; Pandey, Aman; Kanvah, Sriram; Sharma, Sudhanshu

doi:10.1039/c6ra22719h

Cited by 29 publications

(17 citation statements)

References 48 publications

(53 reference statements)

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“…In the following reasonable mechanism for the above-mentioned reaction ( Scheme 3 ), La 2 O 3 nanoparticles acted as a Bronsted base [ 10 , 11 ] which deprotonated the active methylene group of malononitrile dimer ( 1 ) and gave the respective anion intermediate A . The latter carbanion attacked the β-carbon of enaminone ( 2a – h ) with displacement of dimethylamine, as a good leaving group, to give the non-isolable intermediate B .…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, lanthanum oxide (La 2 O 3 ) nanoparticles have shown considerable basic properties that adapt to many base catalyzed reactions [ 10 , 11 ]. Unfortunately, some difficulties limit its use, such as its difficult separation and reusability since the used catalyst could not be quantitatively recovered and the purification of the products being the biggest challenge.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of Chitosan-La2O3 Nanocomposite and Its Utility as a Powerful Catalyst in the Synthesis of Pyridines and Pyrazoles

et al. 2021

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Recently, the development of nanocatalysts based on naturally occurring polysaccharides has received a lot of attention. Chitosan (CS), as a biodegradable and biocompatible polysaccharide, is considered to be an excellent template for the design of a hybrid biopolymer-based metal oxide nanocomposite. In this case, lanthanum oxide nanoparticles doped with chitosan at different weight percentages (5, 10, 15, and 20 wt% CS/La2O3) were prepared via a simple solution casting method. The prepared CS/La2O3 nanocomposite solutions were cast in a Petri dish in order to produce the developed catalyst, which was shaped as a thin film. The structural features of the hybrid nanocomposite film were studied by FTIR, SEM, and XRD analytical tools. FTIR spectra confirmed the presence of the major characteristic peaks of chitosan, which were modified by interaction with La2O3 nanoparticles. Additionally, SEM graphs showed dramatic morphological changes on the surface of chitosan, which is attributed to surface adsorption with La2O3 molecules. The prepared CS/La2O3 nanocomposite film (15% by weight) was investigated as an effective, recyclable, and heterogeneous base catalyst in the synthesis of pyridines and pyrazoles. The nanocomposite used was sufficiently stable and was collected and reused more than three times without loss of catalytic activity.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis of Chitosan-La2O3 Nanocomposite and Its Utility as a Powerful Catalyst in the Synthesis of Pyridines and Pyrazoles

et al. 2021

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“…In addition, lanthanide compounds, such as La 2 O 3 and La(OH) 3 diffraction peaks were not observed for P-LM3, P-LM6, P-LM9, and P-LM12 samples, which was due to the low content of the La element. Nano-sized La 2 O 3 has been synthesized by SCS in earlier studies [24,25,26]. Gangwar et al [24] reported that a pure La 2 O 3 phase can be synthesized by SCS followed by calcination treatment, while La 2 O 3 converts to La(OH) 3 upon exposure to the atmosphere due to its hygroscopic nature.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of La2O3 Uniformly Doped Mo Nanopowders by Solution Combustion Synthesis Followed by Reduction under Hydrogen

Qin

Zhang

et al. 2018

Materials

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This work reports the preparation of La2O3 uniformly doped Mo nanopowders with the particle sizes of 40–70 nm by solution combustion synthesis and subsequent hydrogen reduction (SCSHR). To reach this aim, the foam-like MoO2 precursors (20–40 nm in size) with different amounts of La2O3 were first synthesized by a solution combustion synthesis method. Next, these precursors were used to prepare La2O3 doped Mo nanopowders through hydrogen reduction. Thus, the content of La2O3 used for doping can be accurately controlled via the SCSHR route to obtain the desired loading degree. The successful doping of La2O3 into Mo nanopowders with uniform distribution were proved by X-ray photon spectroscopy and transmission electron microscopy. The preservation of the original morphology and size of the MoO2 precursor by the La2O3 doped Mo nanopowders was attributed to the pseudomorphic transport mechanism occurring at 600 °C. As shown by X-ray diffraction, the formation of Mo2C impurity, which usually occurs in the direct H2 reduction process, can be avoided by using the Ar calcination-H2 reduction process, when residual carbon is removed by the carbothermal reaction during Ar calcination at 500 °C.

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“…37-1493) [22]. The orthorhombic structure peaks are located at 24.02 [23] phases are observed, and La 2 O 3 and La(OH) 3 exhibit hexagonal structures [24]. The peaks corresponding to La(OH) 3 are 39.36 • and 43.46 • , while the peaks of La 2 O 3 are 62.44 • and 64.02 • .…”

Section: Phase and Morphology Analysesmentioning

confidence: 94%

Double Perovskite LaFe1−xNixO3 Coated with Sea Urchin-like Gold Nanoparticles Using Electrophoresis as the Photoelectrochemical Electrode to Enhance H2 Production via Surface Plasmon Resonance Effect

Tsai

2022

Nanomaterials

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The surface plasmon resonance (SPR) effect and the hetero-junction structure play crucial roles in enhancing the photocatalytic performances of catalysts for the water-splitting reaction. In this study, a series of double perovskites LaFe1−xNixO3 was synthesized. LaFe1−xNixO3 particles were then decorated with sea urchin-like Au nanoparticles (NPs) with the average size of approximately 109.83 ± 8.48 nm via electrophoresis. The d-spacing became narrow and the absorption spectra occurred the redshift phenomenon more when doping increasing Ni mole concentrations for the raw LaFe1−xNixO3 samples. From XPS analysis, the Ni atoms were inserted into the lattice of the matrix, resulting in the defect of the oxygen vacancy, and NiO and Fe2O3 were formed. This hybrid structure was the ideal electrode for photoelectrochemical hydrogen production. The photonic extinction of the Au-coated LaFe1−xNixO3 was less than 2.1 eV (narrow band gap), and the particles absorbed more light in the visible region. According to the Mott–Schottky plots, all the LaFe1−xNixO3 samples were the n-type semiconductors. Moreover, all the band gaps of the Au-coated LaFe1−xNixO3 samples were higher than 1.23 eV (H+/H2). Then, the hot electrons from the Au NPs were injected via the SPR effect, the coupling effect between LaFe1−xNixO3 and Au NPs, and the more active sites from Au NPs into the conduction band of the semiconductor, improving the hydrogen efficiency. The H2 efficiency of the Au-coated LaFe1−xNixO3 measured in ethanol was approximately ten times larger than the that of Au-coated LaFe1−xNixO3 measured in 1-butanol at any testing temperature because ohmic and kinetic losses occurred in the latter solvent. Thus, the activation energies of ethanol at any testing temperature were smaller. The maximum real H2 production was up to 43,800 μmol g−1 h−1 in ethanol. The redox reactions among metal ions, OH*, and oxides were consecutively proceeded under visible light illumination.

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Green synthesis of 1,4-benzodiazepines over La₂O₃ and La(OH)₃ catalysts: possibility of Langmuir–Hinshelwood adsorption

Abstract: Adsorption of all the reactants and order of addition play a key role in the synthesis of 1,4-diazepines depicting possibility of Langmuir–Hinshelwood mechanism.

Cited by 29 publications

References 48 publications

Synthesis of Chitosan-La2O3 Nanocomposite and Its Utility as a Powerful Catalyst in the Synthesis of Pyridines and Pyrazoles

Synthesis of Chitosan-La2O3 Nanocomposite and Its Utility as a Powerful Catalyst in the Synthesis of Pyridines and Pyrazoles

Fabrication of La2O3 Uniformly Doped Mo Nanopowders by Solution Combustion Synthesis Followed by Reduction under Hydrogen

Double Perovskite LaFe1−xNixO3 Coated with Sea Urchin-like Gold Nanoparticles Using Electrophoresis as the Photoelectrochemical Electrode to Enhance H2 Production via Surface Plasmon Resonance Effect

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