نتایج جستجو برای: fluorine
تعداد نتایج: 7204 فیلتر نتایج به سال:
The purpose of this study was to develop a new method of releasing fluorine in a controlled manner for applications in the field of orthodontic Ti-based wire, namely the coating of fluorides on Ti. Thin films of two fluoride compounds, CaF(2) and MgF(2), were coated on Ti via the electron-beam evaporation method. The fluorine was released rapidly from the as-deposited MgF(2) coating within a sh...
Double-walled carbon nanotubes (DWCNTs) are fluorinated using (1) fluorine F2 at 200 °C, (2) gaseous BrF3 at room temperature, and (3) CF4 radio-frequency plasma functionalization. These have been comparatively studied using transmission electron microscopy and infrared, Raman, X-ray photoelectron, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. A formation of covalent C-F ...
The structures and reactivity of fluoridated Keggin-aluminum tridecamers (K-Al13) in aqueous solution were studied using density functional theory (DFT) in order to explore the fluorine substitution process and the influence of F(-) on the chemical behavior of Keggin polynuclear Al species. The structures of fluoridated K-Al13 were optimized with the consideration of both explicit and bulk solv...
This research was conducted for the purpose of studying the effect of CaF2 content in the composition of hot metal pretreatment flux, based on lime. It was followed in regards to the importance of fluorine amount decrease in hot metal pretreatment and steel making processes. For this purpose, lime based fluxes including 40, 30, 20 and 10 percent calcium fluoride were prepared and hot metal pret...
Chromium-vanadium (Cr-V) bimetallic catalysts are prepared by the introduction of vanadium into the Phillips catalyst which is one of the most significant industrial ethylene polymerization catalysts for tuning the Phillips catalyst performances and improving polyethylene properties. In the present work, titanium species were introduced into the fluorine-modified chromium-vanadium bimetallic ca...
Stereoselective synthesis of two fluorine-bearing drug-like scaffolds, dihydroquinazolone and benzooxazinone, has been accomplished through asymmetric fluorocyclization reactions initiated by the fluorination process. The reaction employs double axially chiral anionic phase-transfer catalysts to achieve high diastereo- and enantioselectivities, and a wide range of fluorine-containing dihydroqui...
Addition of the carbon-fluorine bond of a series of perfluorinated and polyfluorinated arenes across the Mg-Mg bond of a simple coordination complex proceeds rapidly in solution. The reaction results in the formation of a new carbon-magnesium bond and a new fluorine-magnesium bond and is analogous to Grignard formation in homogeneous solution.
Fluorine interaction assisted AIEE characteristic in an expanded calixbenzophyrin is presented by single-crystal X-ray-diffraction analysis and molecular modelling approaches. Selective exposure to volatile organic compounds such as ketones and esters results in the breaking of fluorine interaction, leading to enhanced monomer emission.
Whereas for 3-fluorodihydropyridine-substituted carboxylic acids electrophiles such as HCl, iodine, bromine and peracids discriminate the double bond lacking and that bearing fluorine, no such differentiation took place in the case of electrophilic fluorine since the formation of both mono and gem-difluorolactones took place.
A two-step Ir-catalyzed borylation/Pd-catalyzed dehalogenation sequence allows for the net synthesis of fluoroarenes where the boronic ester is ortho to fluorine. Key elements of this approach include the use of a halogen para to the fluorine to block meta Ir-catalyzed borylation and the chemoselective Pd-catalyzed dehalogenation by KF activated polymethylhydrosiloxane (PMHS).
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