Development of new synthetic method for P(O)-F compounds from P(O)-OH is an important issue in organic chemistry. In this study, we found that the reaction of diphenylphosphinic acid with KF and octafluorotoluene under heating conditions afforded diphenylphosphinic fluoride in good yield. It was revealed that 2,3,5,6-tetrafluoro-4-(trifluoromethyl)phenol is produced as a byproduct, and a plausible reaction mechanism which involves a novel P(O)-O bond activation by a SNAr reaction was proposed. DFT studies supported the reaction mechanism. Various organophosphinic fluorides could be synthesized in good yields by this method. Furthermore, it was revealed that methyl pentafluorobenzoate, pentafluorobenzonitrile, and pentafluoropyridine could also be used for the deoxyfluorination of diphenylphosphinic acid.
C4F7N is considered a promising alternative to SF6, but potential leakage during practical operation may pose safety and inhalation exposure risks. Under fault conditions, its decomposition products may further affect the toxicity characteristics of the gas system. In this study, the effect of O atoms on the product distribution and toxicity of C4F7N decomposition is investigated within a thermodynamic equilibrium framework. Reaction networks for the pure C4F7N system and the C4F7N/O system are constructed based on density functional theory calculations. Equilibrium product distributions from 1000 to 3000 K are analyzed, and a Key Toxicity Index (KTI) is introduced for relative toxicity evaluation. The results show that the introduction of O atoms alters the decomposition product distribution and reaction pathways of C4F7N over the temperature range of 1000 to 3000 K. At 1000 K, the presence of O atoms promotes a higher initial decomposition degree of C4F7N compared to the pure system, leading to a higher absolute equilibrium amount of C2N2. However, this more extensive fragmentation into smaller species increases the total moles of gas products, which dilutes the system, lowers the mole fraction of C2N2, and consequently reduces the Key Toxicity Index (KTI). At temperatures of 1100 K and above, both systems reach a near-complete decomposition state. Within the 1100–3000 K range, O atoms effectively shift CN intermediates away from recombination into C2N2 toward competitive oxidation into OCN, CO, and NO, thereby decreasing the proportion of cyanide species. Overall, the KTI of the C4F7N/O system is lower than that of the pure system across the studied temperature range, demonstrating that O atoms mitigate the relative toxicity primarily by regulating the transformation pathways of key intermediates.
Thermal treatment is a promising method for the mineralization of per- and polyfluoroalkyl substances (PFAS) contained in waste. However, its efficiency is often constrained by the requirement for high temperature and the challenge of controlling hydrogen-fluoride (HF) emission in the flue gas. This study investigates the performance of an industrial-scale thermal treatment configuration for polymeric PFAS and evaluates the Destruction Efficiency (DE) and Destruction and Removal Efficiency (DRE) achieved during the thermal treatment of polyvinylidene fluoride (PVDF). Industrial trials were carried out in a hazardous waste incinerator with materials containing polyvinylidene fluorides (PVDF) mixed with polyethylene (PE 98 % / PVDF 2 %). The thermal treatment was performed in a rotary kiln and in a Secondary Combustion Chamber (SCC) with an average conventional and typical combustion temperature of 950 °C and an average residence time of 2.3 s. Trials were performed with a calcium based reagent injection into the SCC and with PVDF injection rates in the kiln from 0.5 to 5 kg/h. The US OTM-45 method was used for the PFAS emissions measurements at two sampling points: at the boiler outlet and at the stack. The findings demonstrate that the industrial thermal treatment configuration tested achieved DE and DRE values equal to or exceeding 99.99 % and 99.9999 %, respectively, for all PVDF injection rates investigated.Furthermore, the PFAS concentrations at both sampling points were systematically below the quantification limits and were comparable to those observed in the blanks without PVDF injection, and the HF regulatory emission limit (1 mg/Nm³ dry at 11 % O₂) was fully respected with concentrations below 0.08 mg/Nm³.
The objective of this study was to assess the effective mineralization of polytetrafluoroethylene (PTFE) during thermal treatment under municipal solid waste incinerator (MSWI) conditions and to evaluate the potential formation of per-and polyfluoroalkyl substances (PFAS) and select other products of incomplete destruction (PIDs). Analyses were performed on aqueous phase impinger samples (long chain PFAS under a modified EPA Method 537, and short chain C1-C3), as well as gas phase byproducts under OTM-50. A commercial grade PTFE sample was first subjected to elemental analyses and then incinerated in a bench-scale combustion system designed to represent conditions typical of MSWIs in the United States and European Union. Experimental system setpoints were chosen by computational fluid dynamic modeling and compared with an empirically measured temperature profile, to achieve a bulk material temperature as high as 1150 °C and remain in the reactor for approximately 2 s. These parameters were informed by a comprehensive literature review of MSWI operating conditions.The experiment was run in triplicate and all instances demonstrated that all target analytes as non-detectable, or below the respective method reporting limit. In-line FTIR monitoring of hydrogen fluoride (HF) concentration achieved between 95.6 % and 97.4 % fluorine recovery, compared to between 79.0 % and 80.4 % fluorine recovery via aqueous fluoride-ion based calculations. Calculated destruction efficiency across the experiments averaged 99.99962 % for PTFE. These findings indicate that PTFE undergoes effective mineralization under typical incineration conditions, and that MSWI is a means of responsible end-of-life management for the fluoropolymer.
Perfluoro-3,6-dimethyl-1,4-dioxan-2-one 4 is a key intermediate in the synthesis of fully fluorinated polymers and is conventionally synthesized in a two-step process from hexafluoropropylene oxide (HFPO, 1), which typically requires organic oxygen sources thereby generating organofluorinated byproducts. Herein, we report the one-step formal dimerization of HFPO to 4 using K2CO3 and H2O as inorganic oxygen sources. Furthermore, subsequent addition of a catalytic amount of KF promoted transformation of 4 to the 1,3-dioxolanes 5 and 6. This process can be telescoped in one-pot. DFT calculations provide a mechanistic rationale for the oxygen-source effect and elucidate the roles of fluoride species in the reaction network. The developed method suppresses the formation of organofluorinated byproducts and provides a more sustainable approach to perfluorinated building blocks.
Polyfluorinated chalcones react with hydroxylamine hydrochloride to form oximes, 3-hydroxylaminooximes, dihydroquinoline and benzisoxazole derivatives, depending on the chalcone structure and the reaction conditions. The last two structure types are formed as a result of intramolecular cyclization by replacing the ortho-fluorine atom in the perfluoro phenyl ring next to the carbonyl group.
The perfluorinated ketone perfluoro-2-methyl-3-pentanone (1) is a fire protection fluid of great merchandise importance whose analysis of purity can be easily carried out by NMR techniques. However, while 1 is very stable (at least one year) in the neat state, it reacts with moisture when dissolved in NMR solvents such as acetone-d6, acetonitrile-d3 or dimethylsulfoxide-d6 producing the gem‑diol perfluoro-2-methyl-3,3-pentandiol (2) as the major product in acetone-d6 or in acetonitrile-d3; and a perfluoropropionic acid/CF3CFHCF3 (3/4) mixture in dimethylsulfoxide-d6. Good stability was observed in CDCl3 or in C6D6. A multinuclear NMR analysis using both a low-field machine (80 MHz benchtop spectrometer) and a medium-field machine (400 MHz spectrometer) and a DFT study that confirmed the existence of through-space spin-spin coupling for 1, as well as the mechanism of water induced degradation of 1, is reported.
Fluorine-graphite intercalation compounds (FGICs) have been extensively studied for their enhanced conductivity, yet their reported composition-structure relationships remain scattered. Here, we present an empirical analysis of FGICs focusing on interlayer spacing d(i), carbon-to-fluorine ratio C/F, and stage number s, compiling literature data spanning multiple decades. Variations to graphite host (including highly oriented pyrolytic graphite, natural graphite, powder, fiber, mesophase pitch, microbead, and specialized carbon sources) and synthetic methods are also considered. Despite substantial variability in experimental protocols, the data (184 entries) collapse into three regimes across stages 1-4 with C/F similar to 0.63-16.7 (71.5-8.6 wt%F). The d(i) similar to 4.4, similar to 6.0, and similar to 11.4 & Aring; regimes have been interpreted in the literature as corresponding to fluorine nesting, semi-ionic fluorine intercalation, and graphite bi-intercalation structures, respectively. Other smaller subsets are also identified at d(i) similar to 5.5 & Aring; (coexistence of planar sp(2) C=C/puckered sp(3) C-F), 6.0 & Aring; (covalent C-F), and 7.8 & Aring; (F-2 perpendicular to graphene sheets). This diversity reflects the anisotropic mechanical response of graphite: stiffness along the stacking direction constrains expansion, while in-plane softness accommodates compositional variation. We introduce V-gal representing the available gallery volume (i.e., at the interlayer space) per carbon atom which does not require assumptions about fluorine size. This descriptor preserves such three regimes, whereas the traditional packing fraction varies widely and may exceed physically meaningful limits. Taken together, this work provides an interpretative classification of FGICs, consolidating insights into fluorine intercalation that are not evident from individual reports while helping place future FGICs within, and potentially extend, the known composition-structure landscape.
A ring-opening three-component reaction of carboxylic acid, a cyclic (thio)ether and a difluorocarbene precursor Ylide-CF2H was reported, affording difluoromethyl(thio)ethers in good yields. The reaction proceeds under simple and mild conditions, with good substrate compatibility. Although the mechanism remains speculative, a proposed pathway involves the initial activation of the Ylide-CF2H species through protonation of the malonate moiety, leading to the generation of difluorocarbene. Nucleophilic attack of difluorocarbene by the cyclic (thio)ether forms an oxonium ylide or sulfonium ylide, which undergoes protonation followed by nucleophilic attack of the α-carbon of the intermediate to afford the difluoromethyl(thio)ethers. Additionally, by switching the solvent to toluene, a direct difluoromethylation of carboxylic acids was observed, which provides an alternative transformation under modified conditions.
We report the synthesis and reactivity of a novel bis(hypervalent iodine) reagent incorporating a perfluoroalkylene chain. This reagent was readily synthesized in two steps from commercially available α,ω-dibromoperfluoroalkanes, and fully characterized by NMR spectroscopy and high-resolution mass spectrometry. Furthermore, we demonstrated that the reagent reacts with various alkenes and nucleophiles in the presence of a copper(I) catalyst, enabling efficient three-component transformations at both termini of the perfluoroalkylene chain under mild conditions. This methodology provides a new and efficient strategy for incorporating of perfluoroalkylene chains into organic molecules.
Recently, numerous in-situ, ex-situ and in-flow methodologies have emerged for accessing fluorinated inorganic gases and volatile species (e.g. SOF2, SO2F2, SOF4, SO2F2, SF5Cl, NSF3, Cl2NSF5 and (SCF3)2) used by organic chemists. The reinvestigation of their synthetic pathways is driven by the gradual disappearance of suppliers, skilled laboratories and because they provide access to valuable compounds and reagents. This review highlights their fundamental, industrial and modern syntheses and will extend to additional important species (e.g. ClCN, SiH4 and PH3) as well as important safety considerations.
This paper describes an efficient and regioselective approach for the synthesis of seven examples of a new series of 3-fluoro-and 7-trifluoromethyl-substituted pyrazolo[1,5-a]pyrimidines, namely 5-aryl(heteroaryl)-3-fluoro-2-methyl-7-(trifluoromethyl)pyrazolo[1,5-a]pyrimidines (4), where the 5-aryl(heteroaryl) groups included Ph, 4-tolyl, 4-OMeC6H4, 4-FC6H4, 4-BrC6H4, 1-naphthyl, and 2-thienyl. The synthetic route starts from a [3+3] cyclocondensation reaction of selected 4-methoxy-4-aryl(heteroaryl)-1,1,1-trifluorobut-3-en-2-ones (1) with 5-amino-3-methyl-1H-pyrazole (2), yielding 5-aryl(heteroaryl)-2-methyl-7-(trifluoromethyl)pyrazolo[1,5-a]py-rimidines (3). Subsequently, selective fluorination of compounds 3 using F-TEDA-BF4 (SelectfluorTM) afforded yields of 37-57% when the reactions were carried out in acetonitrile under reflux for 8 h. Structural characterization of heterocycles 4 by 1H-, 13C-,19F-, and 15N-NMR, HMBC, and SC-XRD revealed that the fluorination was regioselective at C-3 of the heterocyclic system 3, irrespective of electron-withdrawing or electron-donating groups at C-5. Computational studies (molecular electrostatic potential and frontier molecular orbital analyses) corroborated the experimental synthetic results.
Fluorination strongly affects the stability and conformation of cyclohexanes through a balance of steric, electrostatic, and stereoelectronic effects. In this theoretical study, isodesmic reactions were investigated at the B3LYP/def2-TZVP level to evaluate the energetic impact of introducing fluorine atoms at axial and equatorial positions in cyclohexane, mono-, and difluorinated cyclohexanes. Monofluorination favors the equatorial conformer, consistent with steric expectations. However, further fluorination leads to nonintuitive stability trends governed by electrostatic interactions. Notably, the 1a -> 2ae transformation is the most favorable pathway, driven by stabilizing intramolecular F & sdot;& sdot;& sdot;C and C-F & sdot;& sdot;& sdot;H-C contacts. Analysis of natural Coulomb electrostatic energies shows that these interactions can outweigh steric penalties and dictate conformational preferences. In trifluorinated systems, greater stabilization is achieved when a single axial fluorine interacts with multiple electropositive hydrogens. At higher fluorination levels, positive electrostatic contributions indicate that additional effects, such as hyperconjugation, also contribute to stability. These findings highlight the role of electrostatic interactions in fluorinated cyclohexanes and provide a basis for the rational design of organofluorine compounds.
Four fluorinated cast-carrier explosives were prepared using fluorinated benzene rings as raw materials via a high-temperature nitration method: 2,4-difluoro-3-methyl-1,5-dinitrobenzene (mDFDNT), 3-Fluoro-2-methyl4,6-dinitroaniline (mDFDNTN), 1,2-difluoro-4-methyl-3,5-dinitrobenzene (qDFDNT), and 6-fluoro-3-methyl2,4-dinitroaniline (qDFDNTN). The densities of the four explosives were 1.86, 1.681, 1.680, and 1.683 g cm(-1) , respectively, with melting points of 79.6 degrees C, 182.3 degrees C, 52.7 degrees C, and 129.3 degrees C, respectively. They exhibited moderate mechanical sensitivity, among them, mDFDNT, mDFDNTN and qDFDNT possess an impact sensitivity (IS) >= 35 J and friction sensitivity (FS) >= 360 N, while qDFDNTN shows IS >= 30 J and FS >= 324 N. The enthalpy of formation was calculated using the Gaussian 09 program at the CBS-4M level and obtained through an atomization reaction scheme. The heats of formation were -342.09 kJ/mol, -191.44 kJ/mol, -334.11 kJ/mol, and -181.07 kJ/mol, respectively; the detonation velocities were 7017, 6833, 7035, and 6791 m/s, respectively; and the corresponding detonation pressures were 21.4, 20.2, 21.5, and 19.8 GPa. mDFDNTN had the highest melting point due to the enhanced intermolecular hydrogen bonding caused by the introduction of amino groups; Hirshfeld surface analysis also confirmed this conclusion. Though mDFDNT/qDFDNT and mDFDNTN/qDFDNTN have the same molecular formula, their substituents are located at different positions, and differing only in the position of the substituents, the four compounds exhibited significant differences in melting points, indicating that the position and type of substituents have a crucial influence on the melting point of cast-supported explosives.
Base promoted polycondensation of bisphenols with two model perfluoroolefin monomers representing perfluoroalkyl substances (PFAS), perfluoro-4-methylpent-2-ene (PFP) and perfluorohept-1-ene (PFH, the decarboxylation product of perfluorooctanoic acid (PFOA)), afforded a new series of unsaturated semi-fluorinated poly (aryl ethers). Step-growth addition-elimination polymerization of bisphenol-A (BPA) and bisphenol-AF (BPF) with the model perfluoroolefin monomers provided unsaturated, amorphous, and highly branched homopolymers and copolymers with moderate to high molecular weight and ability to form freestanding films from solution. Glass transition temperatures ranged from 72 degrees C to 200 degrees C and represent a new class of reactive semifluorinated poly(aryl ethers) with versatile thermal crosslinking capability. This method suggests a plausible route to generate high-performance fluorinated macromolecules and pre-network resins with controlled alkene cure sites, while simultaneously upcycling waste PFAS into polymers of low concern (PLC).
A series of novel 6-fluoropyrimidones was synthesized via the reaction of ethyl 3,3-difluoro-2-phenylacrylate with amidines. Their structures were confirmed by X-ray crystallography, and the tautomeric forms were examined in both solution and solid state. It was shown that 6-fluoropyrimidones possess potential as aglycones in the synthesis of galactopyranosides via Koenigs-Knorr glycosylation.
Ionic liquids (ILs) are promising entrainers for the separation of azeotropic refrigerant mixtures, particularly within the ongoing transition toward low-global-warming-potential (GWP) alternatives. The development of extractive distillation processes requires reliable vapor-liquid equilibrium (VLE) data and accurate thermodynamic models. In this work, the solubility of several hydrofluorocarbons (R-32, R-125 and R-134a), hydrofluoroolefins (R-1234yf and R-1234ze(E)) and CO2 in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([C2C1im][FSI]) was experimentally determined over temperatures from 283.15 to 323.15 K and pressures up to 1.1 MPa applying the isochoric saturation method. All refrigerant/IL systems were satisfactorily described using both the Peng-Robinson equation of state coupled with the Boston-Mathias mixing rule and the Non-Random Two-Liquid (NRTL) activity coefficient model, yielding average absolute deviations below 1% and 6%, respectively. The relative absorption performance was assessed through the Henry's law constants and mixing thermodynamic properties, showing that the IL selected exhibited high ideal selectivity towards different refrigerant blends. In the case of R-410A, a near-azeotropic mixture of R-32 and R-125, the [C2C1im][FSI] selectivity was higher than previously reported for any other IL with a fluorinated anion, yet lower than for nitrile-based ILs. Furthermore, an upper-bound relationship between the ideal R-32/R-125 selectivity and R-32 absorption capacity was reported for the first time, establishing a quantitative benchmark for future IL screening and design. The presented data and its subsequent analysis expand the available thermodynamic knowledge for refrigerant/ IL systems and provide a basis for future development an IL-based separation process for R-410A.
A photo-induced charge transfer complexation strategy with phosphonium iodides has been developed to enable arylthiodifluoromethylation reactions of isocyanides. The transformation proceeds via addition of the arylthiodifluoromethyl radical which is generated by photolysis of the arylthiodifluoromethyl phosphonium iodide to the isonitrile group followed by intramolecular cyclization. This strategy provides a convenient, mild, and green approach for the synthesis of arylthiodifluoromethylated phenanthridines and isoquinolines.
Fluorine-labeling is a powerful technique in biomolecular NMR, yet its application is often hindered by a lack of standardized reference data for non-natural residues. In this work, we report the multinuclear random coil chemical shifts (1H, 13C, 15N, and 19F) for three commercially available, trifluoromethyl-bearing amino acids: trifluoroaminobutyric acid (TfAbu), trifluoronorvaline (TfNva), and 2-trifluoromethyltryptophan ((2-Tfm)Trp). These residues exhibit steric profiles comparable to the canonical amino acids Val, Leu, and Trp, respectively, making them suitable reporters for on-site 19F-labeling of proteins. Random coil data was recorded using a well-established hexapeptide model (Gly-Gly-X-Ala-Gly-Gly). The obtained chemical shifts are highly consistent with the dataset established by Wishart et al. (1995), thereby providing the foundational framework for NMR-based structure elucidation of complex, fluorine-labeled biomolecules.
