- Preparation and Application of Silica Films Supported Imidazolium-Based Ionic Liquid as Efficient and Recyclable Catalysts for Benzoin Condensations
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Abstract: Two silica films -immobilized imidazolium-based ionic liquids (TMICl @silica films) were prepared, characterized and utilized as efficient catalysts for the benzoin reaction. Combined characterization results from FT-IR, elemental analysis, N2 adsorption–desorption isotherms and SEM, suggested that the imidazolium-based ionic liquids were successfully immobilized on the silica films. Moreover, the catalytic performance tests demonstrated that silica films immobilized imidazolium-based ionic liquids (ILs) exhibited excellent activity for the benzoin reactions of aromatic aldehydes. The influence of catalyst concentration, temperature and reaction duration on the catalytic activity were investigated by employing 0.7TMICl @silica film(catalyst C) as the catalyst. The results also showed that the benzoin condensations of aromatic aldehydes could give desired products with satisfactory yields under the optimized conditions. Additionally, the catalyst can be effortlessly separated by filtration and reused more than five times without significant loss of activity. Graphic Abstract: [Figure not available: see fulltext.]
- Qian, Cunwei,Yao, Changsheng,Yang, Liujun,Yang, Bo,Liu, Shuchun,Liu, Zongtang
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p. 1389 - 1396
(2019/11/21)
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- POLYCYCLIC COMPOUND AND AN ORGANIC ELECTROLUMINESCENCE DEVICE COMPRISING THE POLYCYCLIC COMPOUND OR THE COMPOSITION
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Specific polycyclic compounds, a material for an organic electroluminescence device comprising said specific polycyclic compound, an organic electroluminescence device comprising said specific polycyclic compound, an electronic equipment comprising said organic electroluminescence device, a process for preparing said polycyclic compounds, and the use of said polycyclic compounds in an organic electroluminescence. (Formula I) (I)
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Page/Page column 272-273
(2020/11/03)
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- Tetraaryl Cyclopentadienones: Experimental and Theoretical Insights into Negative Solvatochromism and Electrochemistry
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The synthesis of a series of tetraaryl cyclopentadienones comprising different substitution patterns is reported. Their photophysical and electrochemical properties are investigated by UV/Vis spectroscopy and cyclic voltammetry as well as by supporting quantum chemical simulations and reveal a distinct effect of substituents on the redox behavior of the molecules as well as the absorption properties of this class of compounds. While electrochemical data display a shift in reduction potential of up to 200 mV between the differently substituted cyclopentadienones, their photophysical investigations in differently polar solvents suggest a negative solvatochromic effect, although protic solvents induce a bathochromic shift. Crystal structure analyses of some derivatives confirm similarity with related cyclopentadienones while providing insight into intermolecular C–H···O and C–H···π interactions in the solid state.
- Meitinger, Nicolas,Mengele, Alexander K.,Witas, Kamil,Kupfer, Stephan,Rau, Sven,Nauroozi, Djawed
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p. 6555 - 6562
(2020/10/02)
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- Predicting the Outcome of Photocyclisation Reactions: A Joint Experimental and Computational Investigation
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Photochemical oxidative cyclodehydrogenation reactions are a versatile class of aromatic ring-forming reactions. They are tolerant to functional group substitution and heteroatom inclusion, so can be used to form a diverse range of extended polyaromatic systems by fusing existing ring substituents. However, despite their undoubted synthetic utility, there are no existing models—computational or heuristic—that predict the outcome of photocyclisation reactions across all possible classes of reactants. This can be traced back to the fact that “negative” results are rarely published in the synthetic literature and the lack of a general conceptual framework for understanding how photoexcitation affects reactivity. In this work, we address both of these issues. We present experimental data for a series of aromatically substituted pyrroles and indoles, and show that quantifying induced atomic forces upon photoexcitation provides a powerful predictive model for determining whether a given reactant will photoplanarise and hence proceed to photocyclised product under appropriate reaction conditions. The propensity of a molecule to photoplanarise is related to localised changes in charge distribution around the putative forming ring upon photoexcitation. This is promoted by asymmetry in molecular structures and/or charge distributions, inclusion of heteroatoms and ethylene bridging and well-separated or isolated photocyclisation sites.
- Wonanke, A. D. Dinga,Ferguson, Jayne L.,Fitchett, Christopher M.,Crittenden, Deborah L.
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supporting information
p. 1293 - 1303
(2019/02/25)
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- Unexpected transformation of aldehydes into benzoins with Copper(I)/Samarium
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The reductive coupling of aldehydes to afford pinacolic alcohols using all kinds of reducing agents involving samarium is well known. In this report, however, treatment of aromatic aldehydes with Cu(I)/Sm system produces benoins and/or benzils in good yields. A possible mechanism is proposed where Cu(I) not only activates the Sm metal but also promotes the dehydrogenation of the intermediates, during which a Cu(III) species may be involved. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Liu, Yongjun,Wang, Hui,Fu, Yulong,Qi, Yan,Yang, Kuiwei
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p. 259 - 266
(2013/12/04)
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- Synthesis and spectral characterisation of dicyanopyrazine-related cyanoheterocycles
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Four dicyanopyrazine-related cyanoheterocycles have been synthesised and characterised; they show different absorption maxima values and molar absorptivity in absorption spectra. HOMO and LUMO energy levels have been obtained by electrochemical measurements and DMol3 calculation and show little difference in HOMO values but big differences in LUMO values. Their UV-Vis absorbance and fluorescence spectra have been investigated in chloroform and toluene and their aggregation decreases as the concentration decreases in toluene.
- Song, Cheol Jun,Jang, Chun Keun,Yao, Wang,Jaung, Jae Yun
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p. 268 - 272
(2013/07/27)
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- 5,6-Diphenyl-1,2,4-Triazinic Dimeric Derivatives and the Use Thereof in the Form of Sun-Protective Agents
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The invention relates to 5,6-diphenyl-1,2,4-triazinic compounds of general formula (I), wherein identical or different R1, R2, R3 and R4 represent a hydrogen, fluoride, chloride or bromine atom, C1 to C12 linear or branched alkyl, C1 A C18 linear or branched hydroxy, alkoxy poly(ethoxy)-alkoxy with a C1 to C4 alkyl fragment and an ethoxy number ranging from 1 to 4, amino or mono or di-alkylamino with a C1 to C4 alkyl fragment group, X is ortho-, meta- or paraphenylene, 4,4′-biphenylene, 2,4- or 2,6- or 3,4- or 3,5-pyridinylene, 2,2′-bipyridinylene, meta- or paraphenylenediamino, ethylenediamine, 2,2′-piperazinylene, diacyl of formula -(R4CO)2-, wherein r represents a phenyl radical, a 3 to 10 carbon, phenanthrene or anthracene atoms alkyl chain except 1,4-bis(5,6-diphenyl-1,2,4-triazin-3-yl)benzene of 2,4-bis(5,6-diphenyl-1,2,4-triazin-3-yl)pyridine and of 2,6-bis(5,6-diphenyl-1,2,4-triazin-3-yl)pyridine, to cosmetic compositions containing said compounds and to the use thereof in the form of sun filters or light-protective agents.
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Page/Page column 12
(2008/12/04)
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- Acyl-CoA::cholesterol O-Acyl Transferase (ACAT) Inhibitors. 1. 2-(Alkylthio)-4,5-diphenyl-1H-imidazoles as Potent Inhibitors of ACAT
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A potent, bioavailable ACAT inhibitor may have beneficial effects in the treatment of atherosclerosis by (i) reducing the absorption of dietary cholesterol, (ii) reducing the secretion of very low density lipoproteins into plasma from the liver, and (iii) preventing the transformation of arterial macrophages into foam cells.We have found that a mevalonate derivative 2, which contains a 4,5-diphenyl-1H-imidazol-2-yl moiety, inhibits rat hepatic microsomal ACAT in vitro and produces a significant hypocholesterolemic effect in the cholesterol-fed rat.Structure-activity relationships for analogues of 2 demonstrate that the 4,5-diphenyl-1H-imidazole moiety is a pharmacophore for inhibition of rat microsomal ACAT.
- Harris, Neil V.,Smith, Christopher,Asthon, Michael J.,Bridge, Andrew W.,Bush, Raymond C.,et al.
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p. 4384 - 4392
(2007/10/02)
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- Preparation of Diaryl and Aryl tert-Butyl α-Thioxoketones
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The preparation of the α-haloketones 6, 13-16, 19, and 20 is reported. 13 or its precursor, the acyloin 9, respectively, is conveniently obtained by a Seebach synthesis. - Reaction of the haloketones with tetraethylammonium thiosulfate (21) yields the Bunte salts 22-27 wich form the thioketones 28-33 on cleavage with aqueous alkali. 29 is stable as a crystalline, blue monomer in contrast with other aromatic α-thioxoketones.This ist also true for the aromatic-aliphatic derivatives 30 and 31 as well as their isomers 32 and 33 wich do not dimerize.
- Hahn, Bernd,Koepke, Brigitte,Voss, Juergen
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