Journal of Fluorine Chemistry最新文献

The interaction of perfluoropropylbenzene with 1,2,3,4-tetrafluorobenzene or 1,2,4,5-tetrafluorobenzene in an SbF₅ medium at r.t. yields corresponding 1-(tetrafluorophenyl)perfluoro-1-phenylpropanes, which undergo cyclization into perfluoro-9-ethylfluorene or 1,2,3,4,5,7,8,9-octafluoro-9-(pentafluoroethyl)fluorene along with 1,2,3,4-tetrahydro-9H-fluorenes under the reaction conditions. The reaction of perfluoropropylbenzene with 1,2,3,5-tetrafluorobenzene under the same conditions leads to the formation of 1-(2,3,4,6-tetrafluorophenyl)perfluoro-1-phenylpropane, which does not give cyclization products at 50–55 °C.

The pyrolysis behaviors of 2,3,3,3-tetrafluroropropene (R1234yf) had been first studied in a flow reactor pyrolysis apparatus coupled with the synchrotron vacuum ultraviolet photoionization mass spectrometry and gas chromatography. The pyrolysis temperature, reaction products and intermediates were measured at atmospheric pressure. The experimental results revealed that the initial pyrolysis temperature of R1234yf was 1040K and the thermal decomposition was accelerated with the increase of temperature. It was found that the pyrolysis reaction of R1234yf will be replaced by a self-polymerization reaction at 1160 K. In order to explore the chemical process of R1234yf pyrolysis, a detailed kinetic simulation was performed and compared with experimental results. The calculated results indicated that the unimolecular decomposition paths took a dominant role in the whole pyrolysis processes. The intermediates of C₂H₂, C₂HF, CF₂, CHF₃, CF₄ and CF₃CF₃ were detected in the pyrolysis experiments. Moreover, the distribution characteristics and sensitivity analysis of the vital fluorinated species of CF₂, C₂H₂, CF₄, CF₃CF₃ and HF were discussed. All of these founding could provide reliable data for the development of pyrolysis models and guidance for the use of R1234yf in the refrigeration system.

CF₃I, as a novel “Halon” replacement fire-extinguishing agent, has the characteristics of low fire-extinguishing concentration, high efficiency, and safety. However, there are still some gaps in its thermal decomposition studies when it is released into the high-temperature fire, so the thermal decomposition of CF₃I in oxidizing environments was studied to simulate its diffusive decomposition. The decomposition of CF₃I was demonstrated to be accelerated by O₂ through experiments in the temperature range of 100°C-800°C in air and N₂ atmosphere. The effects of initial concentration, temperature, and residence time on the decomposition rate of CF₃I and decomposition characteristics were investigated by tube furnace simulation. The kinetics of thermal decomposition was calculated using the Arrhenius equation in which activation energy E_a is 15.18 kJ/mol and pre-exponential factor (A) is 13.87s⁻¹. Additionally, the thermal decomposition products were examined by GC-MS and FTIR. The experimental results showed that the pyrolysis gas products were mainly CF₄, C₂F₆, and CF₂O. Using quantum chemistry and density flooding theory (DFT) calculations, it was concluded that the main decomposition pathway was the reaction of CF₃I with singlet oxygen. The reaction pathway of the thermal decomposition of CF₃I under a high-temperature fire oxidation environment was proposed based on the products.

Density Functional Theory (DFT) and Hartree-Fock (HF) approaches were used to study the spectroscopic, pharmacological and other molecular properties of structural isomers of fluoroaniline such as 5-nitro-2-fluoroaniline (5N2FA) and 2-nitro-5-fluoroaniline (2N5FA). The geometrical properties, vibrational properties, electronic properties, and chemical shifts of fluoroaniline isomers have been thoroughly investigated. In the gas phase, the energy gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of fluoroaniline isomers is found to be 3.874 / 8.248 eV (DFT/HF) for 5N2FA and 3.979 / 8.176 eV (DFT/HF) for 2N5FA. The current study reveals that the dipole moment values for 5N2FA and 2N5FA were computed (using DFT / HF) to be approximately 4.5318 / 4.2777 D and 3.6551 / 3.5440 D, respectively. Absorption, distribution, metabolism, and excretion (ADME) properties have been predicted to evaluate the toxicity and pharmacokinetic profile of fluoroaniline isomers. Moreover, the Natural Bond Orbital (NBO), Mulliken population, and Molecular Electrostatic Potential Surface (MESP) analyses have been performed to get a crystal clear insight into the bonding characters, and reactive sites of structural isomers of fluoroaniline. Molecular docking simulation is used to investigate the biological activities of fluoroaniline isomers by forming a stable complex with inducible Nitric Oxide Synthase (iNOS) with a binding affinity of -5.6 kcal/mol (5N2FA), and -5.3 kcal/mol (2N5FA), which shows that of an enzyme inhibitor.

We have developed synthetic routes to new luminescent materials which are fully halogenated analogues of the zinc(II) complex of 2-(2-hydroxyphenyl)benzothiazole. 2,4-Difluoro-6-methoxybenzoyl chloride is a useful intermediate in this approach, which involves condensation with fluorinated arylamines to form the arylamide, cyclisation using P₂S₅, demethylation with BBr₃ and halogenation to replace hydrogen atoms present on the phenolic ring. When 2-amino-1,3,4,5,6,7,8-heptafluoronaphthalene was used as the amine component the cyclisation step caused loss of F-1 in preference to F-3, and thus to the formation of the angular naphtho[2,1-d]thiazole ring system (confirmed by X-ray diffraction and NMR). The introduction of chlorine and bromine atoms at specific positions allows fine tuning of emission properties, compared with the analogous fully fluorinated materials.

A facile approach towards 4-halo-5,5-alkyl/aryl-N-phenyl-2-(trifluoromethyl)-2,5-dihydrofuran-2-amines by the reaction of readily available tertiary N-phenyl CF₃-iminopropargylic alcohols with hydrohalic acids (HCl, HBr, HI) was developed. The obtained 4-halo-2,5-dihydrofurans were shown to readily undergo the reactions demonstrating their potential utility in the synthesis of various CF₃-containing compounds.

Ce³⁺/Tb³⁺ ions doped CaF₂, NaYF₄, and NaGdF₄ nanoparticles (NPs) were prepared by the EDTA chelating-based thermal decomposition process. X-ray diffraction (XRD) profile shows the cubic phase in CaF₂ and NaYF₄ host lattice, whereas NaGdF₄ in hexagonal phase, highly crystalline with an average grain size is estimated to be 20, 10, and 25 nm, respectively. Fourier transforms infrared (FTIR) spectra were employed to determine the superficial chemistry of the metal fluoride NPs. UV/Visible spectra measured in H₂O solution exhibited good optical properties, and excellent colloidal stability of the luminescent NPs, implying the surface-attached organic moieties. Optical bandgap energies were estimated to determine the optical performance of the NPs. The excitation and emission spectra revealed the good photoluminescence properties of the respective host matrices. In a comparative analysis, CaF₂:Ce/Tb NPs host lattice revealed efficient charge transmission from Ca²⁺ to the activator Tb³⁺ resulting in observed emission transitions of the Tb³⁺-ions are remarkably high luminescence efficiencies. The lifetime estimated for the Ce³⁺/Tb³⁺-doped CaF₂, NaYF₄, and NaGdF₄ NPs is found to be 7.32, 4.169, and 4.81 ms, respectively. These findings show that the synthesized luminescent NPs presented novel luminescent properties in which CaF₂:Ce/Tb NPs produce remarkable crystallinity and photoluminescent properties to be highly useful in fluorescent-based biomedical and technological applications.

The active geminal chloro‑copper (CF₃CFClCu) and vinyl copper (CF₃CF=CCuCF₃) intermediates produced good results (> 70%) in preparing F-epoxides and F-enones, respectively. The elimination of copper chloride as the driving force in F-epoxide formation occurred intra-molecularly and intermolecularly in F-enones. The copper intermediates were prepared in situ from the corresponding silver precursors via a Ag-Cu exchange reaction. The subsequent epoxide ring-opening with metal fluorides gave ketones in > 80% yields, showing that this approach can produce other functionalized fluorocarbons. Stable CF₃CF₂Cu yielded 30% of ketones when reacted with fluorinated acid chlorides. The geminal chlorine atom makes a big difference in stability and performance between CF₃CF₂Cu (stable, low yield in ketones) and CF₃CFClCu (unstable, the higher output of epoxides).

By negative pressure sublimation, various supported AlCl₃ catalysts were prepared and further applied in the gas-phase isomerization of (E)-1‑chloro-3,3,3-trifluoropropene at higher temperatures ranging from 250 °C to 330 °C. Among these, the 2.0 wt%AlCl₃ supported on active carbon catalyst exhibited high catalytic activity within 44 h but was significantly deactivated from 44 h to 100 h. And the possible deactivation reasons of the AlCl₃ catalyst were first revealed as the following aspects: 1) The loss of AlCl₃; 2) The covering of active sites by fluorinated olefin polymerization; 3) The conversion of AlCl₃ to AlCl_xF_3-x (0 ≤ x ≤ 3) leading to the significant enhancement of strong acid sites. This work will pave the way for the subsequent development of AlCl₃ catalyst suitable for high-temperature gas-phase reaction system.

Dihydroquinolines and dihydroisoquinolines decorated with 2- or 4-polyfluoroalkylphosphoryl groups and N-acylethenyl, cyanoethenylphenyl substituents were synthesized in up to 91% yield via straightforward strategy including simultaneous catalyst- and solvent-free mild (room temperature, 0.2–20 h) N-ethenylation/C-phosphorylation of quinolines and isoquinolines with electron-deficient acetylene / bis(polyfluoroalkyl)phosphonate pairs. The structural interplay between 2 and 4-regioisomers was studied. The reaction with terminal acylacetylenes afforded N-acylethenyl-2-phosphoryl-1,2-dihydroquinolines of the E-configuration relative to the double bond. On the contrary, with cyanophenylacetylene, under similar conditions, a mixture of 1,2- and 1,4-regioisomers was formed (the N-ethenyl substituents having both the E- and Z-configuration) along with double phosphorylated bisadducts, 2,4-bis(polyfluoroalkylphosphoryl)-1,2,3,4-tetrahydro(iso)quinolines. The 1,4-isomers prove to be the thermodynamic products since they can be exclusively obtained by heating (70–75 °С) a mixture of 2- and 4-regioisomers. The synthesized compounds represent a new family of possible drug precursors.