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Imidazolium Hydroxides and Catalysis
Published in Pedro Lozano, Sustainable Catalysis in Ionic Liquids, 2018
In an archetypal example of the furocoumarin synthesis (Scheme 4.17), 1-(cyanomethyl)pyridinium bromide was formed in situ from pyridine and bromoacetonitrile. The 4-hydroxycoumarin then underwent a Knoevenagel condensation with p-tolualdehyde followed by a Michael reaction with the pyridinium-ylide formed in situ by deprotonation of the pyridinium salt, and finally heterocyclization occurred from the nucleophilic attack of the ketone to yield the final furocoumarins. The use of [C4C1im][OH] gave excellent yields, whereas organic bases such as triethylamine and 1,8-Diazabicyclo(5.4.0)undec-7-ene (DBU) gave relatively poor yields. 2 mole equivalents of [C4C1im][OH] were used with yields decreasing with lower loading, so its role as a catalyst is not clear. The method of [C4C1im][OH] synthesis and halide content was not reported, so it is possible that the actual hydroxide loading was lower than the reported 2 mole equivalents.
Synthesis and characterization of Se-doped ZnO nanocomposit material and its multi applications
Published in Inorganic and Nano-Metal Chemistry, 2022
Scanning electron microscopy (SEM) with elementary dispersive X-ray (EDX) analysis was carried out on a FEI Quanta FEG 200 instrument with an EDX analyzer facility at 25 C. The sample was prepared by placing a small quantity of the prepared material on a carbon coated copper grid and allowing the solvent to evaporate. HR-TEM images were captured using a JEOL-JEM-2010 UHR system with a lattice image resolution of 0.14 nm and a 200 kV acceleration voltage. At ambient temperature, Photoluminescence (PL) spectra were recorded at room temperature using a Perkin-Elmer LS 55 fluorescence spectrometer. Nanoparticles were dispersed in carbon tetrachloride and excited using light of wavelength 300 nm. Ultraviolet and visible (UV-vis) absorbance spectra were measured over a range of 200–800 nm with a Shimadzu UV-1650PC recording spectrometer using a quartz cell with a 10 mm optical path length. The fluorescence experiments using coumarin (1 mM of 4-hydroxycoumarin) were carried out using a Hitachi F-7000 fluorescence spectrophotometer. Than photovoltaic properties of the material were characterized by recording the photo current–voltage curve under illumination of Am.1.5 (100Mw/cm2)
Investigation of catalytic, anti-bacterial, anti-oxidant, and DNA cleavage properties of bimetallic and trimetallic magnetic nanoalloys base on cupper
Published in Inorganic and Nano-Metal Chemistry, 2018
Kaveh Parvanak Boroujeni, Ahmad Farokhnia, Mansooreh Shahrokh, Mohsen Mobini
Heterocyclic systems are common structural motifs in many biologically active compounds and therefore intense effort has been devoted by researchers constantly to introduce newer and efficient protocols for their synthesis. Coumarin and its derivatives are a large group of heterocycles with a wide variety of biological and therapeutic properties such as anti-HIV,[19] cytotoxicity and enzyme inhibitory,[20] anti-fungal,[21] anti-bacterial,[22] anti-oxidant,[23] anti-cancer,[24] and anti-coagulant properties.[25] Among coumarin derivatives, biscoumarins become more popular and are usually prepared by the condensation reaction of aldehydes with 4-hydroxycoumarin. This reaction can be catalyzed by several types of catalysts such as piperidine,[26] I2,[27] sodium dodecyl sulfate,[28] [poly(4-vinylpyridine)BuSO3H]Cl.xAlCl3,[29] MW irradiation,[30,31] [poly(4-vinylpyridine)–BuSO3H]HSO4,[32] indion 190 resin,[33] choline hydroxide,[34] poly(AMPS-co-AA)@Fe3O4,[35] Zn(OAc)2,[36] and triethylammonium hydrogen sulfate.[37] However, these methods are plagued by the limitation of prolonged reaction times, low yields, tedious work up, inefficiency of method when aliphatic aldehydes are used in the reaction, and the use of expensive, hazardous, difficult to handle or unreusable catalysts.