scholarly journals Accelerated syntheses of amine-bis(phenol) ligands in polyethylene glycol or “on water” under microwave irradiation

2008 ◽  
Vol 86 (5) ◽  
pp. 435-443 ◽  
Author(s):  
Francesca M Kerton ◽  
Stacey Holloway ◽  
Angela Power ◽  
R Graeme Soper ◽  
Kristina Sheridan ◽  
...  

Pure amine-bis(phenol) ligands are readily accessible in high yield, often >90%, when the Mannich condensation reactions are performed “on water” or in poly(ethyleneglycol) (PEG). Microwave-assisted synthesis dramatically reduces the time and energy required to prepare these molecules, typically from 24 h to 5 min. The approach seems to be widely applicable (7 amines and 5 phenols were tested to yield a diverse set of bis(phenol) ligands). Significant improvements in yield were observed for ligands derived from di-tert-amyl and di-tert-butyl phenols, possibly resulting from a hydrophobic effect. Single crystal X-ray diffraction data for the ligand derived from p-cresol and N,N′-dimethylethylenediamine is reported.Key words: amine-phenol, Mannich condensation, on water, microwave, ligand, high-throughput.

2020 ◽  
Vol 7 (3) ◽  
pp. 183-195
Author(s):  
Musa Özil ◽  
Emre Menteşe

Background: Benzoxazole, containing a 1,3-oxazole system fused with a benzene ring, has a profound effect on medicinal chemistry research owing to its important pharmacological activities. On the other hand, the benzoxazole derivative has exhibited important properties in material science. Especially in recent years, microwave-assisted synthesis is a technique that can be used to increase diversity and quick research in modern chemistry. The utilization of microwave irradiation is beneficial for the synthesis of benzoxazole in recent years. In this focused review, we provide a metaanalysis of studies on benzoxazole in different reaction conditions, catalysts, and starting materials by microwave technique so far, which is different from conventional heating. Methods: Synthesis of different kind of benzoxazole derivatives have been carried out by microwave irradiation. The most used method to obtain benzoxazoles is the condensation of 2-aminophenol or its derivatives with aldehydes, carboxylic acids, nitriles, isocyanates, and aliphatic amines. Results: Benzoxazole system and its derivatives have exhibited a broad range of pharmacological properties. Thus, many scientists have remarked on the importance of the synthesis of different benzoxazole derivatives. Conventional heating is a relatively inefficient and slow method to convey energy in orientation to the reaction medium. However, the microwave-assisted heating technique is a more effective interior heating by straight coupling of microwave energy with the molecules. Conclusion: In this review, different studies were presented on the recent details accessible in the microwave- assisted techniques on the synthesis of the benzoxazole ring. It presents all examples of such compounds that have been reported from 1996 to the present. Benzoxazoles showed an extensive class of chemical substances not only in pharmaceutical chemistry but also in dyestuff, polymer industries, agrochemical, and optical brighteners. Thus the development of fast and efficient achievement of benzoxazoles with a diversity of substituents in high yield is getting more noteworthy. As shown in this review, microwave-assisted synthesis of benzoxazoles is a very effective and useful technique.


2018 ◽  
Vol 73 (12) ◽  
pp. 999-1003 ◽  
Author(s):  
Mohammad Hakimi ◽  
Homeyra Rezaei ◽  
Keyvan Moeini ◽  
Heidar Raissi ◽  
Vaclav Eigner ◽  
...  

AbstractA new cyclotriphosphazene, 2,2,4,4,6,6-hexakis (o-tolylamono)-1,3,5,2λ5,4λ5,6λ5-triazatriphosphinine (MPAP), was prepared using microwave irradiation and identified by elemental analysis, FT-IR, Raman, 31P NMR spectroscopy, and single-crystal X-ray diffraction. In the crystal, in addition to hydrogen bonds, the network is further stabilized by inter- and intramolecular π–π stacking interactions between aromatic rings.


2010 ◽  
Vol 93-94 ◽  
pp. 643-646
Author(s):  
Pusit Pookmanee ◽  
Supasima Makarunkamol ◽  
Sakchai Satienperakul ◽  
Jiraporn Kittikul ◽  
Sukon Phanichphant

Zinc oxide micropowder was synthesized by a microwave-assisted method. Zinc nitrate and ammonium hydroxide were used as the starting precursors with the mole ratio of 1:1. The white precipitated powder was formed after adding ammonium hydroxide until the pH of final solution was 9 and treated with the microwave radiation power at 1000 Watt for 2-6 min. The phase of zinc oxide micropowder was examined by X-ray diffraction (XRD). A single phase of hexagonal structure was obtained. The morphology and chemical composition of zinc oxide micropowder were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The particle was plate-like in shape with the range of particle size of 0.1-0.5 µm. The elemental composition of zinc oxide showed the characteristic X-ray energy value as follows: zinc of Lα = 1.012 keV, Kα = 8.630 keV and Kβ = 9.570 keV and oxygen of Kα = 0.525 keV, respectively.


2005 ◽  
Vol 09 (12) ◽  
pp. 872-879 ◽  
Author(s):  
B. Narayana Achar ◽  
T. Manjappa Mohan Kumar ◽  
K. Sannegowda Lokesh

Lead(II) phthalocyanine (PbPc); lead(II) tetranitrophthalocyanine (PbTNP) and lead(II) tetraaminophthalocyanine (PbTAP) were synthesized in pure state by microwave irradiation and conventional heating methods. The procedures for their synthesis by the microwave technique are standardized and reported for the first time. PbPc and PbTNP were synthesized in dry conditions and PbTAP complex was synthesized in aqueous medium. All the compounds are obtained in very high yield (~90%). The synthesized complexes are characterized with respect to elemental analysis, UV-visible, IR-spectroscopy and X-ray diffraction study. The microwave methods are advantageous over the conventional method of synthesis with respect to higher yield, rapidity and simplicity.


2011 ◽  
Vol 10 (03) ◽  
pp. 413-418 ◽  
Author(s):  
ARUP ROY ◽  
JAYANTA BHATTACHARYA

Calcium oxide ( CaO ) is an important inorganic compound, which is used across various industries as catalyst, toxic-waste remediation agent, adsorbent, etc. CaO nanoparticles were obtained by the microwave irradiation technique, using Ca(NO3)2 ⋅ 4H2O and NaOH as starting materials. The formation of monocrystalline CaO nanoparticles was confirmed by the XRD (X-ray diffraction) and TEM (transmission electron microscopy) as well as by SAED (selected area electron diffraction) analysis. The structure of the CaO nanocrystal was found to be cubic with particle size, 24 nm and surface area, 74 m2/g.


2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Alfonso Salinas ◽  
Maricela Lizcano ◽  
Karen Lozano

A rapid method for synthesizing β-silicon carbide (β-SiC) fine fiber composite has been achieved by combining forcespinning technology with microwave energy processing. β-SiC has applications as composite reinforcements, refractory filtration systems, and other high temperature applications given their properties such as low density, oxidation resistance, thermal stability, and wear resistance. Nonwoven fine fiber mats were prepared through a solution based method using polystyrene (PS) and polycarbomethylsilane (PCmS) as the precursor materials. The fiber spinning was performed under different parameters to obtain high yield, fiber homogeneity, and small diameters. The spinning was carried out under controlled nitrogen environment to control and reduce oxygen content. Characterization was conducted using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results show high yield, long continuous bead-free nonwoven fine fibers with diameters ranging from 270 nm to 2 µm depending on the selected processing parameters. The fine fiber mats show formation of highly crystalline β-SiC fine fiber after microwave irradiation.


2013 ◽  
Vol 470 ◽  
pp. 44-47
Author(s):  
Ming Kwen Tsai ◽  
Yueh Chien Lee ◽  
Chia Chih Huang ◽  
Sheng Yao Hu ◽  
Kwong Kau Tiong ◽  
...  

The luminescence investigations on the calcinated zinc tungstate nanopowder (ZnWO4 NP) synthesized by microwave-assisted synthesis are presented using photoluminescence (PL) and time-resolved photoluminescence (TRPL) analyses. The X-ray diffraction (XRD) patterns exhibit that the significant wolframite structure of ZnWO4 NP can be detected at calcination temperatures above 300 °C. The 12 K PL and TRPL results demonstrated that the deformation of WO6 octahedra is responsible for the low-energy side of PL spectra and dominate the red-shifted PL spectra with increasing calcination temperatures.


2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Gastón P. Barreto ◽  
Graciela Morales ◽  
Ma. Luisa López Quintanilla

The effect of different variables (precursor reagents, temperature, irradiation time, microwave radiation power, and additives addition) on the final morphology of nano-ZnO obtained through the microwave assisted technique has been investigated. The characterization of the samples has been carried out by field emission scanning electron microscopy (FE-SEM) in transmission mode, infrared (FTIR), UV-Vis spectroscopy, and powder X-ray diffraction (XRD). The results showed that all the above-mentioned variables influenced to some extent the shape and/or size of the synthetized nanoparticles. In particular, the addition of an anionic surfactant (sodium di-2-ethylhexyl-sulfosuccinate (AOT)) to the reaction mixture allowed the synthesis of smaller hexagonal prismatic particles (100 nm), which show a significant increase in UV absorption.


2012 ◽  
Vol 271-272 ◽  
pp. 255-258
Author(s):  
Guo Lei Zhang ◽  
Xiu Min Gao ◽  
Xiao Dong Xu

Zirconium dioxide (ZrO2) nanocrystals were prepared by the microwave-assisted ionic liquid method using an ionic liquid of 1-n-butyl-3-methyl imidazolium tetrafluoroborate ([BMIM]BF4). The X-ray diffraction (XRD) patterns indicated that the crystal structure was monoclinic. The morphology of ZrO2 nanocrystals was characterized by field emission scanning electron microscopy (FESEM) and transimission electron microscopy (TEM), which showed uniform ZrO2 nanoparticles without aggregation. Thermogravimetry (TG) and Fourier transform infrared spectrometer (FTIR) curves confirmed the adsorption of organic compounds on the surface of ZrO2.


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