Search results for "fluori"
showing 7 items of 687 documents
Efficient regio- and stereoselective access to novel fluorinated ?-aminocyclohexanecarboxylates
2013
A regio- and stereoselective method has been developed for the synthesis of novel fluorinated 2-aminocyclohexanecarboxylic acid derivatives with the fluorine attached to position 4 of the ring. The synthesis starts from either cis- or trans-β-aminocyclohex-4-enecarboxylic acids and involves regio- and stereoselective transformation of the ring C–C double bond through iodooxazine formation and hydroxylation, followed by hydroxy–fluorine or oxo–fluorine exchange.
Spherical Top Theory and Molecular Spectra
2011
In this article, we present an overview of the present state of the art of the theory of high-resolution spherical-top spectra in the framework of the effective Hamiltonian approach. We describe the specific features of this class of molecules to explain the basic concepts of the theoretical methods used for the analysis (line positions and intensities) and the simulation of absorption (including pure rotation) and Raman spectra of such species. The non conventional formalism that we use is essentially based on irreducible tensor methods and is especially adapted to computational treatments and global analyses of complex interacting band systems. We give examples concerning mainly methane (…
Preparation of pH sensitive poly(vinilydenefluoride) porous membranes by grafting of acrylic acid assisted by supercritical carbon dioxide
2010
Aim of this work is to study the preparation of pH sensitive membranes for biomedical applications via thermal induced graft polymerization of acrylic acid (AA) on poly(vinilydenefluoride) (PVDF) assisted by supercritical carbon dioxide (scCO2). Using scCO2 as a solvent and swelling agent, the monomer and initiator (benzoyl peroxide) could diffuse faster and distribute more uniformly into the polymer matrix. A better control of the final molecular architecture should be achieved because bimolecular grafting reactions are accelerated with respect to chain degradation processes. Commercial hydrophobic PVDF porous matrixes were selected as model membranes. Grafted polymers were characterized b…
Fluorinated heterocyclic compounds: an assay on the photochemistry of some fluorinated 1-oxa-2-azoles: an expedient route to fluorinated heterocycles
2004
Abstract Photoinduced heterocyclic rearrangements of ON bond-containing azoles have been claimed in the synthesis of target fluorinated heterocyclic compounds. In this context, the photochemical behavior of some fluorinated 1,2,4-oxadiazoles has been investigated. Irradiations of 3-amino-5-perfluoroalkyl-1,2,4-oxadiazoles at λ =313 nm in methanol gave open-chain products arising from a reaction of the nucleophilic solvent with either the first formed ring-photolytic species or with a nitrilimine moiety generated from it. Differently, irradiations in methanol with the presence of triethylamine (TEA) followed competing phototransposition pathways leading to the ring-isomers 2-amino-5-perfluo…
A handy and accessible tool for identification of Sn(II) in toothpaste.
2021
AbstractAn easily accessible colorimetric probe, a carbazole–naphthaldehyde conjugate (CNP), was successfully prepared for the selective and sensitive recognition of Sn(II) in different commercially-available toothpaste and mouth wash samples. The binding mechanism of CNP for Sn2+ was confirmed by UV–Vis, 1H, and 13C NMR titrations. The proposed sensing mechanism was supported by quantum chemical calculations. Selective detection of Sn(II) in the nanomolar range (85 nM), among other interfering metal ions, makes it exclusive. Moreover, Sn2+ can be detected with a simple paper strip from toothpaste, which makes this method handy and easily accessible. The potential application of this system…
New methodologies in transition metal catalysis. Organofluorine chemistry as the benchmark application.
2017
A lo largo de las últimas décadas, los compuestos organofluorados han encontrado numerosas aplicaciones dentro del campo de las industrias farmacéutica y agroquímica, así como en ciencias de los materiales. Dadas las singulares propiedades del átomo de flúor, éste es capaz de inducir alteraciones significativas en propiedades físico-químicas de las moléculas como lipofilia, distribución de cargas, acidez-basicidad, capacidad de formar enlaces de hidrógeno e incluso, equilibrios conformacionales. Sin embargo, la presencia de flúor en productos naturales es escasa. De hecho, la gran mayoría de las moléculas orgánicas que contienen flúor son sintéticas. De ahí el gran interés por parte de la c…
Ortho -Functionalized Aryltetrazines by Direct Palladium-Catalyzed C−H Halogenation: Application to Fast Electrophilic Fluorination Reactions
2016
International audience; A general catalyzed direct C-H functionalization of s-tetrazines is reported. Under mild reaction conditions, N-directed ortho-C-H activation of tetrazines allows the introduction of various functional groups, thus forming carbon-heteroatom bonds: C-X (X=I, Br, Cl) and C-O. Based on this methodology, we developed electrophilic mono- and poly-ortho-fluorination of tetrazines. Microwave irradiation was optimized to afford fluorinated s-aryltetrazines, with satisfactory selectivity, within only ten minutes. This work provides an efficient and practical entry for further accessing highly substituted tetrazine derivatives (iodo, bromo, chloro, fluoro, and acetate precurso…