Journal of Fluorine Chemistry最新文献

On a laboratory scale, a complete technological extractive distillation cycle of an industrial azeotropic mixture of 2,2,2-trifluoroethanol (TFE) – isopropanol (IPA) of equimolar composition using N-methyl-2-pyrrolidone (NMP) as a separation agent (SA) was implemented. All technological stages (extractive distillation, target component separation and SA regeneration) were carried out in one apparatus – a batch distillation column. It was shown that this approach makes it possible to separate the TFE – IPA mixture into individual components, as well as to regenerate NMP. The proposed method is an alternative to traditional chemical methods and allows to eliminate the use of aggressive auxiliary reagents and the formation of by-products, to reduce the number of stages and apparatuses from 5 to 1.

The reactions of representative organochlorosilanes and organochlorogermanes with alkali metal fluorides (LiF, NaF, KF, RbF, CsF) were investigated by NMR spectroscopy and showed not only the fluorination to organofluorosilanes or organofluorogermanes but also the formation of organofluorosilicates and organofluorogermanates. The synthesis and crystal structures of two new polymeric organofluorogermanates, [K][Ph₂GeF₃]∙0.75 MeCN and [Cs][Ph₂GeF₃]∙THF, are presented.

Fluorinated carbons combining accordion-like morphology, high content of (C₂F)_n phase (43%), and residual non-fluorinated carbons were synthetized by two routes, i.e. fluorination of expanded graphite and simultaneous exfoliation/fluorination of expandable graphite. The latter allows the synthesis in a one-step process to be achieved. Accordion-like morphology allows the accommodation of LiF without detrimental accumulation onto the fluorocarbon sheet edges during the discharge in primary lithium battery. The faradic yield is then close to 100 % up to a discharge rate of 6C. Residual sp² carbons (sub-fluorination) ensure the electron flux during the electrochemical process and enhance the power density (9828 W.Kg^-1). High content of (C₂F)_n phase results in a flat galvanostatic discharge curve. The combination of those features results in a good compromise between energy and power densities, making fluorinated exfoliated graphite one of the best cathodes for primary lithium batteries.

This study investigated the reaction between LiF, Mo metal, and CuF₂ as a solid-state fluorine source to form a complex fluoride, tetragonal trirutile (TR)-type Li₂MoF₆, in an Ni metal tube by in situ synchrotron X-ray diffraction (SXRD) experiments. As a result, two formation pathways of TR-type Li₂MoF₆ were identified: one involving a reaction among intermediate phases, i.e., MoF₃, and an unknown Mo-containing fluoride, and the starting materials, i.e., LiF, Mo, and CuF₂, the other involving a direct reaction between LiF, Mo, and CuF₂. The combination of in situ SXRD with differential scanning calorimetry (DSC) revealed that the direct reaction was facilitated by the presence of the liquid phase of LiF-CuF₂. Further, the first-order phase transition of Li₂MoF₆ with a great volume change of 21% was found to occur in the vicinity of 520 °C–550 °C reversibly. Finally, this study demonstrated that an in situ SXRD experiment supported by DSC measurement is a powerful tool for revealing the reaction routes and identifying new phases occurring in sample-loaded metal tubes.

A convenient method for synthesis of alkyl(difluoromethyl)ethers, including subsequent stages of chlorination and fluorination of the O-formyl derivatives was investigated on series of aliphatic alcohols and glycols. Primary and secondary alcohols are converted to the corresponding O-difluoromethyl derivatives in high yield, polydifluoromethyl derivatives of 1,3-propyleneglycol, diethyleneglycole and pentaerythritol can only be successfully obtained with this procedure.

Perfluorooctane sulfonamide derivatives have been extensively used by industry for their surfactant properties and as building blocks for other perfluoroalkyl substances (PFAS). Due to their environmental impact and their potential degradation to other harmful PFAS, short-chain sulfonamide derivatives alternatives were introduced. However, these are now also suspected to be present in different environmental matrices and there is a lack of labelled and unlabelled reference standards to perform analyses. To address this gap, 40 native and deuterium labelled short-chain perfluoroalkane sulfonamide derivatives were synthesized, utilizing commercial perfluoroalkane sulfonyl fluoride as starting materials. All products were synthesized and then purified to obtain linear n-isomer reference standards. NMR, GC-FID-MS and LC-MS techniques were used for product identification and purity assessment. Recrystallization method was developed to selectively isolate the n-isomer from the isomer mixtures, thereby providing valuable reference and internal standards for environmental and toxicological investigations.

Described herein is the direct amidation of a range of carboxylic acids, in moderate to excellent yields, using potassium hexafluorotitanate (K₂TiF₆) as a catalytic activator. The ready commercial availability, low cost, and ease of handling of the catalyst, as well as the simple, chromatography-free work-up of the reaction renders the process very appealing.

A new strategy for the synthesis of peptides incorporating racemic hexafluorovaline (hfVal) is presented. The synthetic pathway relies on the anti-Michael addition of benzyl amine derivatives to ad hoc prepared β-bis-trifluoromethyl-acryloyl-α-amino esters which proceeds in mild condition, high yields, even if with low stereocontrol. The following elaboration of the intermediates, namely deprotection of the benzyl moiety and coupling with α-amino esters allowed us to synthetize the targeted tripeptides in four overall synthetic steps, resulting in a synthetic pathway more favorable respect to those appeared in literature based on the synthesis and isolation of racemic Boc-hfVal-OH (eight synthetic steps).

The detection of organic pollutants in the environment is crucial due to their significant impact on human health. Formyl fluoride (HFCO) and carbonyl fluoride (COF₂) are toxic gasses that contribute to stratospheric ozone depletion. To explore a potential sensor material for these compounds, the adsorption properties of HFCO and COF₂ on pristine (8, 0) single-walled carbon nanotubes (SWCNTs), aluminum-doped SWCNTs (Al-SWCNTs), nitrogen-doped SWCNTs (N-SWCNTs), and aluminum nitride nanotube (AlNNTs) were investigated using density functional theory (DFT) calculations. Obtained structural and electronic results reveal no significant after HFCO and COF₂ adsorption on pristine SWCNT. However, the conductivity and polarizability of Al- SWCNT increases throw HFCO and COF₂ adsorption. It was shown that this adsorption strongly depends on molecular orientation toward SWCNT. Structural and electronic findings show that studied molecules undergoes a physical adsorption to N- SWCNT. However, AlNNT was also found to show significant changes in structural and electronic properties after HFCO and COF₂ adsorption. This adsorption leads to a significant (nearly 45%) reduction in the HOMO-LUMO gap of AlNNTs. Therefore, it is proposed from this study that Al-SWCNTs and AlNNTs are promising candidates for HFCO and COF₂ gas sensors. Moreover, AlNNTs exhibit intrinsic detection capabilities without structural manipulation via doping which makes AlNNTs particularly attractive for sensor applications. Moreover, the capability of AlNNT without manipulating makes this nanotube a good and easy made candidate for these compounds adsorption.

Analysis of the physicochemical parameters of saturated (hetero)cyclic carboxylic acids and their α-fluorinated analogues is described. Measured pK_a values revealed a significant influence of the single fluorine substituent on the compound's acidity (pK_a decreased by 1.3–2.4 units). This effect did not demonstrate additivity with electronic effects of other heteroatom (i.e., cyclic ether moiety). On the contrary, lipophilicity (LogP) of the corresponding anilides was almost unaffected upon α-substitution with a fluorine atom and mainly governed by the nature of the (hetera)cycloalkyl substituent. The obtained results suggest that polarization of the C–F bonds themselves does not define the fluorine effect on the compound's lipophilicity.