Preparation Of Fluorides Research Articles

EFluorination for the Rapid Synthesis of Carbamoyl Fluorides from Oxamic Acids.

In this letter, we disclose the anodic oxidation of oxamic acids in the presence of Et3N·3HF as a practical, scalable, and robust method to rapidly access carbamoyl fluorides from readily available and stable precursors. The simplicity of this method also led us to develop the first flow electrochemical preparation of carbamoyl fluorides, demonstrating scale-up feasibility as a proof of concept.

Preparation and optical properties of rare earth fluoride and its related composite materials

Rare earth fluoride and its composite materials have shown broad application prospects in fields such as optoelectronics and photocatalysis. In this study, we prepared rare earth fluoride (β-NaYF4 nanocrystals) and its related composite materials (β-NaYF4/ZnO composite and GQDs@NaYF4 nanomaterials) using a solvothermal method and investigated their optical performance. The characterization and performance of the prepared materials were analyzed using a transmission electron microscope, X-ray diffraction, upconversion emission spectra, and fluorescence lifetime imaging microscopy. The results show that the crystal thickness of β-NaYF4 nanocrystals is approximately 45.0 nm when the F−: Ln3+ value is 6. Furthermore, X-ray diffraction analysis reveals that diffraction peak positions in β-NaYF4 nanocrystals correspond to the peak positions of standard card at different doping concentrations of Zn2+ Moreover, it was observed that the highest fluorescence lifetime of Tm3+ ion in 1G4 is 778 μs when the doping concentration of Zn2+ is 1 mol%. When the concentration of exonuclease III increases to 22.5U, the upconversion fluorescence emission intensity of GQDs@NaYF4 nanomaterial is about 34 ∗ 106 a.u. When the activation reaction time is 90 minutes, the upconversion emission intensity of GQDs@NaYF4 nanomaterial is about 37 ∗ 106 a.u. In conclusion, we successfully prepared rare earth fluoride and its composite materials with excellent optical properties through the solvothermal method.

Mild Strategy for the Preparation of Alkyl Sulfonyl Fluorides from Alkyl Bromides and Alcohols Using Photoredox Catalysis and Flow Chemistry.

Facile access to sp3-rich scaffolds containing a sulfonyl fluoride group is still limited. Herein, we describe a mild and scalable strategy for the preparation of alkyl sulfonyl fluorides from readily available alkyl bromides and alcohols using photoredox catalysis. This approach is based on halogen atom transfer (XAT), followed by SO2 capture and fluorination. The method features mild conditions enabling fast access to high-value derivatives and has been scaled up to 5 g using a continuous stirred tank reactor cascade.

Recovery of aluminum oxide and iron oxide from aluminum electrolysis iron-rich cover material and preparation of aluminum fluoride.

In aluminum electrolysis, the iron-rich cover material is formed on the cover material and the steel rod connecting the carbon anode. Due to the high iron content in the iron-rich cover material, it differs from traditional cover material and thus requires harmless recycling and treatment. A process was proposed and used in this study to recovery F, Al, and Fe elements from the iron-rich cover material. This process involved aluminum sulfate solution leaching for fluorine recovery and alkali-acid synergistic leaching for α-Al2O3 and Fe2O3 recovery were obtained. The optimal leaching rates for F, Na, Ca, Fe, and Si were 93.92, 96.25, 94.53, 4.48, and 28.87%, respectively. The leaching solution and leaching residue were obtained. The leaching solution was neutralized to obtain the aluminum hydroxide fluoride hydrate (AHFH, AlF1.5(OH)1.5·(H2O)0.375). AHFH was calcined to form a mixture of AlF3 and Al2O3 with a purity of 96.14%. The overall recovery rate of F in the entire process was 92.36%. Additionally, the leaching residue was sequentially leached with alkali and acid to obtain the acid leach residue α-Al2O3. The pH of the acid-leached solution was adjusted to produce a black-brown precipitate, which was converted to Fe2O3 under a high-temperature calcination, and the recovery rate of Fe in the whole process was 94.54%. Therefore, this study provides a new method for recovering F, Al, and Fe in iron-rich cover material, enabling the utilization of aluminum hazardous waste sources.

Preparation of aluminum fluoride from carbon residue in aluminum electrolysis cell by roasting-leaching method

The carbon residue is a hazardous waste generated by the aluminum electrolysis production process, which contains a large amount of electrolyte fluoride salts. In order to recover the electrolyte components in carbon residue, this paper proposes a new method of using carbon residue to prepare aluminum fluoride by converting Na5Al3F14 and Na3AlF6 in carbon residue into aluminum fluoride to realize the recycling of fluoride in carbon residue. In the initial step, optimal parameters for carbon removal during roasting have been determined, including an oxygen flow rate of 7 g/min, a roasting temperature of 670 °C, and a roasting time of 80 min. The roasted clinker is obtained, and the removal rate of carbon reaches 99.95 % while the loss rate of fluorine is 0.48 %. In the second step, the mix anhydrous Al2(SO4)3 with roasted clinker for roasting. The optimal roasting temperature of 670 °C, the time of 10 min, and the mass ratio of anhydrous Al2(SO4)3 to roasted clinker of 5:5 could convert fluoride to AlF3 products, with a conversion rate of 99.76 % and a loss rate of fluorine of 1.05 %. Finally, by removing sulfate impurities through water leaching for 15 min at 35 °C and with a liquid-solid ratio of 6 ml/g, the loss rate of fluorine is 3.98 %. This process yields AlF3 with a purity of 94.30 %. The recovery rate of fluorine in the whole process is 94.56 %, which successfully achieves the recycling of fluorine in the carbon residue to obtain AlF3 products.

Facilitated luminescence via pH regulation of GdF3:5%Eu3+ and NaGdF4:5%Eu3+ morphologies

Gadolinium fluoride micromaterials with eight morphologies of embroidered sphere, copper coin, rotor, irregular rhombus, cocoon pupa, rod, and hollow tubes (small and large) were synthesized in the absence of any surfactant and templating agent using gadolinium nitrate and sodium fluoroborate as raw materials and green water as a solvent. The physical and chemical properties of the products were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG), infrared spectroscopy (FT-IR) and fluorescence spectroscopy (PL). The composition and morphology of the products were mainly regulated by pH value, with pH = 1.7, 3.7, 5.7, 7.7 and 8.7 resulting in the formation of embroidered spherical, copper coin, rotor, irregular diamond and cocoon pupae shaped GdF3:5%Eu3+ microparticles, and with pH = 9.7, 10.7 and 11.7 leading to the shaping of rod, small hollow tube and large hollow tube NaGdF4:5%Eu3+ microparticles. Their luminescent properties were also significantly distinguishable. As a whole, the luminescence of GdF3:5%Eu3+ is stronger than that of the NaGdF4:5%Eu3+ microparticles, both emitting orange‒red light. Among them, the embroidered spherical GdF3:5%Eu3+ microparticles prepared at pH = 1.7 showed the strongest luminescence with a fluorescence lifetime of 10.11 ms and CIE color coordinates of 0.6061 and 0.3934. Possible mechanisms for the preparation of gadolinium fluorides with various morphologies at different pH values were analyzed, and the reasons for their effect on fluorescence properties were further investigated. GdF3 micromaterials not only provide the basis for a wide range of applications in upconversion luminescence but also have potential applications in downconversion luminescence, providing good research support for the synthesis and application screening of micronanomaterials containing gadolinium for morphology modulation.

Study on preparation of aluminum fluoride from cryolite

As China's aluminum electrolysis industry expanded its production capacity, it produced a large amount of bath materials– cryolite based molten salt, which is not utilized fast enough and piled up in aluminum factories. It is of great significance to find a proper way to process the accumulated bath materials. Through the method introduced in this paper, aluminum fluoride can be produced from cryolite-based electrolyte and fed back into the aluminum electrolysis cell as a necessary additive. This method includes four steps: Calcination of crystalline aluminum nitrate with cryolite. Cryolite and crystalline aluminum nitrate are mixed and preheated. The main chemical reaction that occurs in this step will produce sodium nitrate (NaNO3), β-aluminum fluoride (β-AlF3), chiolite (Na5Al3F14) and the aluminum hydroxyfluoride hydrate (AHF). After calcination, the products are washed with water to separate soluble NaNO3 from the other products. The insoluble products obtained after washing are calcined with ammonium bifluoride to convert AHF into AlF3. The mixture obtained after preheating is then washed with an aqueous solution of aluminum salt (such as Al(NO3)3) to remove Na5Al3F14. Aluminum fluoride of high purity is obtained in the end. Calcination step is the most important among the four steps. The effects of calcination temperature (85 – 135 ℃) and molar ratio of crystalline aluminum nitrate to cryolite (0.5 – 2) on the conversion rate of cryolite were studied. The experimental results show that the highest conversion rate of cryolite can reach 97.03%. Through SEM, EDS, ICP and other analysis methods, it was found the final products contained more than 98.8 wt% aluminum fluoride and less than 0.4 wt% sodium, and the average particle size of aluminum fluoride is approximately 15 – 20 µm.

Oxidation of Difluorocarbene by Pyridine N‐Oxide and Ensuing Access to Carbamoyl Fluorides†

Comprehensive SummaryA practical one‐pot preparation of carbamoyl fluorides from easily obtained pyridine N‐oxide, commercially available secondary amines and synthetically versatile difluorocarbene precursors (Ruppert‐Prakash reagent or Chen's reagent) was developed herein, which dexterously resorted to the oxidation of difluorocarbene by external pyridine N‐oxide to produce the toxic and gaseous fluorophosgene in situ. Notable features of this method include nice functionality tolerance, late‐stage modification of drug molecules and the recovery and recycle of quinoline.

Synthesis of Porous MgF2 Coating by a Sol–Gel Method Accompanied by Phase Separation

Surfaces with translucent and wear-resistant effects have a wide range of applications, especially as protective layers. In this work, a simple and convenient method for the preparation of porous magnesium fluoride (MgF2) coatings was proposed. Nano-porous MgF2 powder was prepared with sol–gel and phase separation methods by optimizing the polymer amount and used for the preparation of thick layers onto PVC substrates. The automated surface area and porosity analyzer (BET) and scanning electron microscopy (SEM) confirmed that the layers containing 0.028‰ PEO presented a 3D structure with pore sizes in the range of 16 nm. The layer reached 93% transmittance in the visible region, a Vickers hardness value of 2889.1 kg/mm2, and a friction coefficient of 0.2 in the wear test.

Highly regio- and enantioselective Cu/Pd co-catalyzed allylic alkylation of α-pyridyl-α-fluoroesters: construction of quaternary C-F stereocenters.

New methods for preparation of chiral alkyl fluorides have been studied intensively in recent years due to the favorable physicochemical and biological properties of those structures. Herein, we describe the regio- and enantioselective allylic alkylation of α-pyridyl-α-fluoroesters with allyl acetates promoted by Cu/Pd synergistic catalysis, constructing the carbon- fluorine quaternary stereocenters. In this co-catalytic system, palladium catalyst mainly constructed the C-C bond, while chiral copper catalyst controlled the enantioselectivity. A series of aryl- and aliphatic-substituted allyl acetates are applied, giving the corresponding products in high yield, excellent enantioselectivity and E/Z (up to 98% yield, 98:2 er, E/Z >20:1).

Preparation of polyvinylidene fluoride coating modified by well-dispersed MEA-ATO@HNTs and its photocatalytic, antistatic and thermal insulation properties

In this study, Antimony-doped tin oxide (ATO) fixed and loaded on one-dimensional halloysite nanotubes (HNTs) were fabricated using the co-precipitation method to improve photocatalytic efficiency and dispersion of ATO. After that well dispersed ATO@HNTs nanofiller (AH) modified by monoethanolamine (mAH) was also embedded in the polyvinylidene fluoride (PVDF) coating by solution blend to further broaden the application fields. The results showed the introduction of HNTs accelerates electron transfer and promotes the decomposition of rhodamine B (Rh B). More significantly, with the effect of the well-dispersed mAH nanofillers, PVDF coating containing 15% mAH degraded more than 90% of Rh B under ultraviolet (UV) irradiation for 2 h, which was 1.2 times higher than that of PVDF coating. In addition, the PVDF/mAH-15% coating exhibits excellent antistatic stability under the harsh conditions of photoaging and thermal aging. Moreover, by comparing temperature differences, the thermal insulation performance of PVDF/mAH-15 coating with 70.24% visible light transmittance is significantly improved by reducing heat conduction and radiation at the same time.

Synthesis of Sulfonyl Fluorides Using Direct Chloride/Fluoride Exchange in Potassium Fluoride and Water/Acetone

A multitude of synthetic routes are available for the preparation of sulfonyl fluorides (R-SO2F) whose discovery is now almost a century old. These syntheses are often limited by the scope, hazardous materials, and elaborate procedures. The simple and mild procedure based on direct chloride/fluoride exchange from a sulfonyl chloride (R-SO2Cl) starting material in a KF and water/acetone biphasic mixture is investigated. Seventeen examples in high yield (84-100%) with wide scope are described.

Synthesis of aza-S(VI) motifs

Sulfoximines and sulfonimidamides are of interest as design options for medicinal chemists. This article describes the development of methods for the synthesis of sulfoximines by metal-free NH-transfer to sulfoxides, and NH/O transfer to sulfides, using convenient sources of ammonia and hypervalent iodine reagents. Similarly, sulfonimidamides are prepared from sulfenamides. Methods for the preparation of enantioenriched sulfonimidoyl fluorides are also described, as are their stereospecific reactions with amines and Grignard reagents. This work was presented at the 29th International Symposium on the Organic Chemistry of Sulfur (Guelph, July 2022).

Preparation of a Janus-polyvinylidene fluoride micro/nano fiber membrane by centrifugal spinning and investigation into its unidirectional water transfer and oil–water separation functions

Traditional oil–water separation membranes have a high energy consumption and complicated operation. To solve this problem, an asymmetric wetting polyvinylidene fluoride (PVDF) fiber membrane with a hydrophobic side and a hydrophilic side was prepared. Octamethylcyclotetrasiloxane was grafted onto one side of a centrifugal spun PVDF fiber membrane by plasma initiation, and dopamine was sprayed on the other side of the fiber membrane. The Janus-PVDF fiber membrane prepared can separate a mixture of water and dibromoethane, a toluene–water emulsion and a mixture of n-hexane and water. The initial interception rates were 98.53% ± 1.31%, 98.52% ± 1.12% and 98.61% ± 1.23%, respectively. After five cycles of separation, the separation rates remained at 96.15% ± 1.25%, 95.02% ± 1.21% and 96.91% ± 1.42%, respectively. The Janus-PVDF fiber membrane has excellent unidirectional water transfer capability and possesses well-repeated separability. The preparation of its unique Janus structure also provides a new direction for the field of oil–water separation.

Divergent dehydroxyfluorination and carbonation of alcohols with trifluoromethyl trifluoromethanesulfonate.

Preparation of alkyl fluorides and carbonates via divergent dehydroxyfluorination and carbonation of alcohols with trifluoromethyl trifluoromethanesulfonate (CF3SO2OCF3) is described. The reactions performed with BTMG in THF provided alkyl fluorides in good yields, whereas those of two different alcohols with Et3N in DCM formed asymmetric carbonates in moderate to excellent yields. CF3SO2OCF3 was demonstrated to be either a "F" or a "CO" reagent in the reactions by changing the base, allowing the selective construction of alkyl fluorides and carbonates from the corresponding alcohols with high efficiency. Notably, the fluorine-containing asymmetric carbonates that are difficult to synthesize by other methods were comprehensively prepared by this method, which would have great application potential in both academic and industrial fields.

Preparation of benzoyl fluorides and benzoic acids from phenols via a dearomatization–rearomatization strategy

We describe here a method to generate both benzoyl fluorides and benzoic acids using 2,5-cyclohexadienones prepared from phenols.

Preparation of anhydrous aluminum fluoride

Because direct roasting of aluminum fluoride hydrate will hydrolysis, resulting in higher alumina content in aluminum fluoride products. To solve this problem, a two-step process for the preparation of anhydrous AlF3 from AlF3·3H2O and NH4HF is described in this paper. First, AlF3·3H2O was dried at 220 ℃ for 9–12 h, and then NH4HF (the mass ratio of AlF3·3H2O to NH4HF was 1:20) was added, and the mixture was roasted from room temperature to 650 ℃. The results showed that the hydrolysis of aluminum fluoride can be avoided effectively by the two-step roasting method with NH4HF, the purity of the anhydrous AlF3 was 99.8 wt%, and the concentration of alumina, the main impurity, was less than 0.1 wt%.

A cost effective method for the preparation of sodium fluoride [18F]NaF for PET-CT imaging by using an in-house designed module

We report the development of a manual module for the preparation of [18F]NaF for metastatic bone cancer imaging. By using this simple module, [18F]NaF production can be carried out inexpensively without using commercially available kits. The module can be used for making [18F]NaF from freshly irradiated H218O water or with left over activity in the target after [18F]FDG production. The product meets all quality control parameters.

Segregation Melting in the LiAlSi2O6–Na2SO4–NaF System as a Method for the Preparation of Lithium Fluoride

Segregation Melting in the LiAlSi2O6–Na2SO4–NaF System as a Method for the Preparation of Lithium Fluoride

Stereospecific synthesis of monofluoroalkenes and their deuterated analogues via Ag-catalyzed decarboxylation

Fluorinated organic molecules have found numerous applications in medicinal chemistry, as the incorporation of fluorine often improve metabolic stability, lipophilicity and bioactivity. Although the preparation of aryl and aliphatic fluorides have been extensively investigated, alkenyl fluoride synthesis remains to be under-developed due to challenges associated with stereoselectivity control. Herein, we report a practical method for stereospecific synthesis of terminal alkenyl fluorides, and especially their deuterated analogues using an Ag-catalyzed decarboxylative protonation/deuteration strategy. The synthetic utility is demonstrated by broad substrate scope, scale-up experiment and product derivatization. DFT computations recognize bimolecular NMP coordination to Ag as the favourable mode, elucidate the mechanistic pathway, and provide in-depth insights into the origin of reactivity difference, which fully support the experimental data.