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71.
Alexander O. Terent’ev Igor B. Krylov Vera A. Vil’ Zhanna Yu. Pastukhova Sergey A. Fastov Gennady I. Nikishin 《Central European Journal of Chemistry》2012,10(2):360-367
It was found that oximes undergo deoximation in the presence of the H2O2aq-HBraq system to form ketones and bromo ketones. This reaction provided the basis for the synthesis of dibromo ketones in yields
varying from 40% to 94%. This method is environmentally friendly, sustainable, and easy to perform. The results of this investigation
extend the potential of the use of oximes for the protection of carbonyl group, thus offering the ability to perform not only
conventional deoximation but also the subsequent bromination of ketones. The reaction is easily scaled up and dibromo ketones
can be prepared in gram amounts.
相似文献
72.
Vera Yu Mishina Mikhail K. Gratchev Konstantin L. Anfilov Il'dar G. Mustafin Anna R. Bekker Edward E. Nifantyev 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract The effective methods of phosphorylation of complex systems with specifically orientated in space hydroxyl groups, namely dianhydro-D-mannitol(A), -D-sor-bitol(B), cyclodextrines(C), and cellulose(D) (A-D, where R=H), have been elaborated. 相似文献
73.
Andrea Piazzalunga Vera Bernardoni Paola Fermo Roberta Vecchi 《Analytical and bioanalytical chemistry》2013,405(2-3):1123-1132
In the last decade, our research group set up and optimised analytical techniques for the characterisation of the major components of atmospheric aerosol (i.e. secondary inorganic ions and carbonaceous material) and source markers (e.g. levoglucosan, carbonates). In this study, we present a complete overview on the most problematic aspects that can be encountered during the quantification of the two main components of aerosol, i.e. the ionic and carbonaceous fractions. More in detail, different liquid chromatographic approaches were set up for main ions and anhydrosugars determination. Quality assurance procedures (i.e. tests on data reliability) were applied during the set-up phase and they are presented in this work. As regards the carbonaceous component characterisation, two evolved gas analysis techniques were set up and applied: the thermogravimetric technique coupled to the Fourier transformed infrared spectroscopy (TGA/FTIR) and the thermal–optical transmittance method (TOT). A suitable protocol for organic and elemental carbon separation was set up for the TGA/FTIR system and a comparison with the results obtained by the TOT method was carried out. Studies on the impact of filter load, field blanks, and sample composition on OC/EC quantification by the TOT method were performed. Moreover, approaches for carbonate carbon quantification on different kinds of filters were developed. It was demonstrated that this approach allows to reach the ionic balance in samples impacted by carbonate compounds. The optimised methods have been applied for the analysis of thousands of PM filters allowing the obtainment of reliable results. 相似文献
74.
Vera C.M. Duarte Hélio Faustino Maria J. Alves António Gil Fortes Nuno Micaelo 《Tetrahedron: Asymmetry》2013,24(18):1063-1068
Two d-erythrose 1,3-butadienes were reacted with electrophilic achiral t-butyl 2H-azirine 3-carboxylate giving cycloadducts with good yields and moderate selectivity. The isomers could be separated to give the major (R)-isomers at C-2 in approximately 50% yield in both cases. Alternatively LACASA-DA methodology was applied to one of the reactions leading to homochiral (R)- and (S)-products by changing the chiral nature of an extra chiral BINOL inductor used. 相似文献
75.
I. S. Kim S. C. Oh H. S. Im J. M. Hur H. S. Lee 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(2):1413-1417
Electrolytic reduction of the uranium oxide in LiCl–Li2O molten salt for the treatment of spent nuclear fuel requires the separation of the residual salt from the reduced metal product, which contains about 20 wt% salt. In order to separate the residual salt and reuse it in the electrolytic reduction, a vacuum distillation process was developed. Lab-scale distillation equipment was designed and installed in an argon atmosphere glove box. The equipment consisted of an evaporator in which the reduced metal product was contained and exposed to a high temperature and reduced pressure; a receiver; and a vertically oriented condenser that operated at a temperature below the melting point of lithium chloride. We performed experiments with LiCl–Li2O salt to evaluate the evaporation rate of LiCl salt and varied the operating temperature to discern its effect on the behavior of salt evaporation. Complete removal of the LiCl salt from the evaporator was accomplished by reducing the internal pressure to <100 mTorr and heating to 900 °C. We achieved evaporation efficiency as high as 100 %. 相似文献
76.
77.
Johannes Oschwald Dr. David Reger Dr. Stefan Frühwald Vera Warmbrunn Prof. Dr. Andreas Görling Prof. Dr. Norbert Jux Prof. Dr. Thomas Drewello 《Chemphyschem》2023,24(21):e202300496
Gas-phase complexes of [n]helicenes with n=6, 7 and 8 and the silver(I) cation are generated utilizing electrospray ionization mass spectrometry (ESI-MS). Besides the well-established [1 : 1] helicene/Ag+-complex in which the helicene provides a tweezer-like surrounding for the Ag+, there is also a [2 : 1] complex formed. Density functional theory (DFT) calculations in conjunction with energy-resolved collision-induced dissociation (ER-CID) experiments reveal that the second helicene attaches via π-π stacking to the first helicene, which is part of the pre-formed [1 : 1] tweezer complex with Ag+. For polycyclic aromatic hydrocarbons (PAHs) of planar structure, the [2 : 1] complex with silver(I) is typically structured as an Ag+-bound dimer in which the Ag+ would bind to both PAHs as the central metal ion (PAH–Ag+–PAH). For helicenes, the Ag+-bound dimer is of similar thermochemical stability as the π-π stacked dimer, however, it is kinetically inaccessible. Coronene (Cor) is investigated in comparison to the helicenes as an essentially planar PAH. In analogy to the π-π stacked dimer of the helicenes, the Cor−Ag+−Cor−Cor complex is also observed. Competition experiments using [n]helicene mixtures reveal that the tweezer complexes of Ag+ are preferably formed with the larger helicenes, with n=6 being entirely ignored as the host for Ag+ in the presence of n=7 or 8. 相似文献
78.
Krasnov Victor P. Zarubaev Vladimir V. Gruzdev Dmitry А. Vozdvizhenskaya Olga А. Vakarov Sergey А. Musiyak Vera V. Chulakov Evgeny N. Volobueva Alexandrina S. Sinegubova Ekaterina O. Ezhikova Marina А. Kodess Mikhail I. Levit Galina L. Charushin Valery N. 《Chemistry of Heterocyclic Compounds》2021,57(4):498-504
Chemistry of Heterocyclic Compounds - A number of novel amides were synthesized by coupling of 6-[(9H-purin-6-yl)amino]hexanoic acid to heterocyclic amines. The antiviral activity of the obtained... 相似文献
79.
Lee Jun Young Hur Min Goo Kong Young Bae Lee Eun Je Yang Seung Dae Choi Pyeong Seok Park Jeong Hoon 《Journal of Radioanalytical and Nuclear Chemistry》2021,330(2):455-460
Journal of Radioanalytical and Nuclear Chemistry - 89Zr is an emerging radionuclide with promising application in nuclear medicine for the non-invasive diagnosis of various cancers with PET... 相似文献
80.
Improving the water resistance of epoxy–anhydride matrices by the incorporation of bentonite 下载免费PDF全文
Epoxy–anhydride‐based polymers are commonly used as a matrix in pipeline systems exposed to water during their in‐service life. Water absorption at moderate temperatures and/or at long exposure times could lead to irreversible hydrolysis reaction decreasing considerably the polymer overall performance. A strategy to enhance the barrier properties of epoxy resins is to add nanofillers to traditional matrices. In this work, we added bentonite and chemically modified bentonite to this purpose. Water absorption of the resulting materials at three different temperatures (22°C, 80°C, and 93°C) was studied, and simultaneously, the evolution during the immersion tests of glass transition temperature and flexural modulus was recorded. Long‐term gravimetric results showed that composites with chemically modified bentonite produce a delay on the hydrolysis of epoxy–anhydride matrix, which is a relevant result, because of the tough application and uses of the system, from the technological point of view. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献