Search results for "Trifluoride"
showing 9 items of 9 documents
Substituent effects on the reaction mode between 2-hydroxybenzyl alcohol derivatives and MEM chloride:synthesis and mechanistic aspects of seven-and …
2004
Abstract The synthesis of (RS)-2- or (RS)-3-methoxy-2,3-dihydro-5H-1,4-benzodioxepins and (RS)-5- or (RS)-3-methoxy-2,3,5,6-tetrahydro-8H-benzo-[1,4,7]-trioxecins has been developed. The mechanism of such a reaction via the boron trifluoride etherate-promoted transformation of 2-(methoxyethoxymethoxy)benzyloxyacetaldehyde dimethyl acetals or 2-(methoxyethoxymethoxymethyl)phenyloxyacetaldehyde dimethyl acetals has been proposed. Transannular versions of the reaction results in the facile ring contraction of 12-membered intermediates to the 10- and to 7-membered benzene-fused O,O-acetals. The characterization of the by-products strongly supports the mechanisms proposed.
Thermodynamic and19F NMR studies of antimony trifluoride in water
1993
Densities, specific heat capacities per unit volume and enthalpies of dilution at 25°C and osmotic coefficients at 37°C were measured for antimony trifluoride in water as functions of concentration. From the first three properties the apparent and partial molar volumes, heat capacities and relative enthalpies were derived. As well, pH measurements in water at 25°C and19F NMR spectra in water and methanol at 33°C were also carried out. All the thermodynamic properties together with the chemical shifts abruptly change in the very dilute concentration region (<0.1m) and, then, tend to a constant value. These trends have been rationalized through a simple model based on an equilibrium of dissoc…
Synthesis, antimony-121 mössbauer and infrared spectral characterization of antimony trifluoride and catecholatoantimony(III) fluoride adducts with t…
1988
Abstract The synthesis of the adducts SbF 3 (L) and (C 6 H 4 O 2 )SbF(L) [L = pyridine-2-carboxaldehyde- 2-pyridylhydrazone (paphyH); 2,2′:6′,2″-terpyridine (terpy) and 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tpta)] is reported. Infrared data are consistent with the occurred chelation from the terdentate ligand providing an overall pseudo-seven coordination at Sb. The stereoactivity of the antimony lone pair is inferred from the large value of the Mossbauer quadrupole coupling constant observed for all the compounds.
Studies on antimony trifluoride in thiocyanate salt matrices. Evidence for the formation of fluoro-thiocyanato anti-mony(III) species
1990
Abstract Antimony trifluoride can be dissolved in fused KNCS or NH4NCS giving yellow-orange solutions which are stable only for a short time just above their melting point. Infrared an Mossbauer results on solidified samples reveal the formation of mixed fluoro-thiocyanato antimony(III) species and indicate a different behaviour in the two matrices.
Antimony-121 Mössbauer and infrared spectral studies on 1,10-phenanthroline adducts of antimony(III) halides
1983
Abstract The syntheses of the mono-adducts of 1,10-phenanthroline with SbX 3 (X = F, Cl, Br) and PhSbI 2 are described. These compounds and the 1:1 adduct between 2,2′-bipyridine and PhSbI 2 have been characterized mainly in the solid state by infrared and Mossbauer spectroscopic techniques. The structures of the antimony trihalide complexes appear to be based on halogen bridged polymers in which the stereochemical activity of the lone pair of electrons varies with the halogen, the highest p-character of the lone pair being observed with the trifluoride adduct. Mossbauer results for the PhSbI 2 complexes suggest a ψ-octahedral stereochemistry with the lone pair and the Ph group in trans pos…
Comparative quantum chemistry study of the F-center in lanthanum trifluoride
2020
Abstract In this study we report the results of first principle quantum chemical modeling of electronic structure and spatial configuration of LaF3 crystal containing the F-center. Theoretical predictions of atomic and electronic properties of LaF3 are given by means of density functional theory. From our modeling we predict that the F-center placed at fluorine ion position between the lanthanum planes at tysonite LaF3 is the most energetically stable. In order to interpret the structure of the optical absorption spectrum of X-irradiated LaF3 we performed calculations of excited and transition states of the F-center within the embedded cluster formalism using time dependent density function…
Exciton emission and defect formation in yttrium trifluoride
2005
Two intrinsic emission bands at 220 and 280 nm have been detected in nominally pure YF3 powders at 10 K. Excitation spectra for both emissions have a sharp peak at 12 eV near the edge of interband transition. Observed emissions are assigned to the radiative decay of self-trapped excitons in YF3. The strong thermal quenching of intrinsic luminescence was observed at temperature above 120 K. It was supposed that non-radiative decay of self-trapped exciton at high temperatures lead to defect formation in YF3. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Stereoselective glycosylation of Alcohols and Silyl Ethers Using Glycosyl Fluorides and Boron Trifluoride Etherate
1985
The stereoselective glycosylation of alcohols and their silyl ethers has been achieved using O-alkyl-, O-acyl-, and acetal-protected glycosyl fluorides of the pyranose and furanose series and boron trifluoride etherate in CH2Cl2.
1,1prime-Binaphthyl-2-methylpyridinium-based peroxophosphotungstate salts: synthesis, characterization, and their use as oxidation catalysts
2009
A series of 1,1′-binaphthyl-2-methylammonium and pyridinium salts 6, 7, and 8 was synthesized through the coupling reaction of 2-(bromomethyl)-1,1′-binaphthalene (5) with the dendritic tetraallyl pyridinedicarbinol dendron 2 as well as triethylamine and 4-tert-butylpyridine. Tetraallyl pyridinedicarbinol dendron 2 was prepared by allylation of commercially available diethyl pyridine-3,5-dicarboxylate (1). The allylation of 2 with allyltrimethylsilane in the presence of boron trifluoride was unsuccessful, as tetraallyl pyridinedicarbinol trifluoroboron adduct 3 was obtained instead of expected hexaallylpyridine compound 4. The catalytic hydrogenation of allyl groups of the ammonium salt of 2…