نتایج جستجو برای: fluorination treatment
تعداد نتایج: 1395580 فیلتر نتایج به سال:
Ando, et a!., Direct interaction of elemental fluorine with diamond surfaces, Diamond and Related Materials 1996; 5: 1021-1025.* Kealey, et a!., Fluorination of polycrystalline diamond films and powders. An investigation using FTIR spectroscopy, SEM, energyfiltered TEM, XPS and fluorine-IS radiotracer methods, J. Mater. Chern. 2001; 11: 879-886.* Liu, et a!., Functionalization of Nanoscale Diam...
Side chain fluorination is often used to make analogs of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] resistant to degradation by 24-hydroxylase. The fluorinated nonsteroidal analogs CD578, WU515, and WY1113 have an increased prodifferentiating action on SW480-ADH colon cancer cells, which correlated with stronger induction of vitamin D receptor (VDR)-coactivator interactions and stronger repression ...
We report in full detail our studies on the catalytic, asymmetric α-fluorination of acid chlorides, a practical method that produces an array of α-fluorocarboxylic acid derivatives in which improved yield and virtually complete enantioselectivity are controlled through electrophilic fluorination of a ketene enolate intermediate. We discovered, for the first time, that a third catalyst, a Lewis ...
Hydrogen bonding phase-transfer catalysis offers a convenient solution to activate safe and economical metal alkali fluorides for enantioselective nucleophilic fluorination. Herein, we demonstrate the scalability of this protocol with fluorination 200 g racemic trans-N,N-dibenzyl-2-bromocyclohexan-1-amine in mechanically stirred 1 L glass reactor using 0.5 mol % bis-urea organocatalyst. In thes...
This article investigates the surface electrical properties of polyether-ether-ketone (PEEK) and cross-linked polyethylene (XLPE) before after fluorination modification. The samples are tested for conductivity, morphology, antiaging characteristics. also flashover voltage with ramping under 100, 20, 10 kPa. results showed that surfaces PEEK XLPE become slightly smoother increase in time conduct...
Titanium-based Lewis acids catalyze the α-fluorination of β-ketoesters by electrophilic N-F-fluorinating reagents. Asymmetric catalysis with TADDOLato-titanium(IV) dichloride (TADDOL = α,α,α',α'-tetraaryl-(1,3-dioxolane-4,5-diyl)-dimethanol) Lewis acids produces enantiomerically enriched α-fluorinated β-ketoesters in up to 91% enantiomeric excess, with either F-TEDA (1-chloromethyl-4-fluoro-1,4...
Synthesis of highly substituted 3-fluorofurans is reported. The sequence began with preparation of tert-butyldimethylsilyl alk-1-en-3-yn-1-yl ethers from 1,4-disubstituted alk-3-yn-1-ones. Subsequent fluorination of alkenynyl silyl ethers with Selectfluor gave 2-fluoroalk-3-yn-1-ones in almost quantitative yield. Subsequent 5-endo-dig cyclizations using chlorotriphenylphosphine gold(I)/silver t...
The effects of fluorine on the hot-carrier induced degradation in low-thermal-budget polysilicon-emitter NPN bipolar transistors have been examined. Forward Gummel plots, base-emitter (BE) diode characteristics, and stress currents were measured during reverse BE bias stress. Fluorinated devices behave similarly under stress to nonfluorinated devices retaining the initial improvement observed i...
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