Aqueous Potassium Fluoride Research Articles

Investigation of structural, dynamics, and dielectric properties of an aqueous potassium fluoride system at various concentrations by molecular dynamics simulations

Potassium-ion-based batteries have emerged as promising alternatives to traditional lithium-ion batteries for energy storage systems due to their affordability, wide accessibility and comparable chemical characteristics to lithium. This study employs molecular dynamics simulations to explore the physical phenomena of potassium fluoride in aqueous solutions. The interatomic interactions were defined using the OPLS-AA force field, while the SPC/E water model and ions were represented as charged Lennard?Jones particles. The simulations were conducted across concentrations ranging from 0.1 to 1.0 mol kg-1. The insights derived from this investigation provide valuable understanding into the behaviour of KF electrolytes and their potential utility in energy storage systems. A comprehensive comprehension of the impact of KF electrolyte concentration on structural, dynamic and dielectric properties is pivotal for the design and optimization of potassium-ion batteries, as well as other electrochemical devices leveraging KF-based electrolytes. This research significantly contributes to the ongoing endeavours aimed at developing efficient and economically viable energy storage solutions that transcend the confines of traditional lithium-ion batteries.

Thermodynamic Analysis of Homologous α-Amino Acids in Aqueous Potassium Fluoride Solutions at Different Temperatures

Partial molal volumes (\(V_{\phi} ^{0}\)) and partial molal compressibilities (\(K_{\phi} ^{0}\)) for glycine, L-alanine, L-valine and L-leucine in aqueous potassium fluoride solutions (0.1 to 0.5 mol⋅kg−1) have been measured at T=(303.15,308.15,313.15 and 318.15) K from precise density and ultrasonic speed measurements. Using these data, Hepler coefficients (\(\partial^{2}V_{\phi} ^{0}/\partial T^{2}\)), transfer volumes (\(\Delta V_{\phi} ^{0}\)), transfer compressibilities (\(\Delta K_{\phi} ^{0}\)) and hydration number (nH) have been calculated. Pair and triplet interaction coefficients have been obtained from the transfer parameters. The values of \(V_{\phi} ^{0}\) and \(K_{\phi} ^{0}\) vary linearly with increasing number of carbon atoms in the alkyl chain of the amino acids. The contributions of charged end groups (\(\mathrm{NH}_{3}^{+}\), COO−), CH2 group and other alkyl chains of the amino acids have also been estimated. The results are discussed in terms of the solute–cosolute interactions and the dehydration effect of potassium fluoride on the amino acids.

Ion spatial distributions at the liquid–vapor interface of aqueous potassium fluoride solutions

X-Ray photoemission spectroscopy operating under ambient pressure conditions is used to probe ion distributions throughout the interfacial region of a free-flowing aqueous liquid micro-jet of 6 M potassium fluoride. Varying the energy of the ejected photoelectrons by carrying out experiments as a function of X-ray wavelength measures the composition of the aqueous-vapor interfacial region at various depths. The F(-) to K(+) atomic ratio is equal to unity throughout the interfacial region to a depth of 2 nm. The experimental ion profiles are compared with the results of a classical molecular dynamics simulation of a 6 M aqueous KF solution employing polarizable potentials. The experimental results are in qualitative agreement with the simulations when integrated over an exponentially decaying probe depth characteristic of an APPES experiment. First principles molecular dynamics simulations have been used to calculate the potential of mean force for moving a fluoride anion across the air-water interface. The results show that the fluoride anion is repelled from the interface, consistent with the depletion of F(-) at the interface revealed by the APPES experiment and polarizable force field-based molecular dynamics simulation. Together, the APPES and MD simulation data provide a detailed description of the aqueous-vapor interface of alkali fluoride systems. This work offers the first direct observation of the ion distribution at an aqueous potassium fluoride solution interface. The current experimental results are compared to those previously obtained for saturated solutions of KBr and KI to underscore the strong difference in surface propensity between soft/large and hard/small halide ions in aqueous solution.

Pd-Catalyzed Silicon Hydride Reductions of Aromatic and Aliphatic Nitro Groups

[reaction: see text] Room-temperature reduction of aromatic nitro groups to amines can be accomplished in high yield, with wide functional group tolerance and short reaction times (30 min) using a combination of palladium(II) acetate, aqueous potassium fluoride, and polymethylhydrosiloxane (PMHS). Replacing PMHS/KF with triethylsilane allows aliphatic nitro groups to be reduced to their hydroxylamines.

Preparation of Re(I)- and (99m)Tc(I)-metallocarboranes in water under weakly basic reaction conditions.

A new method for the preparation of Re- and (99m)Tc-metallocarboranes in water under mild reaction conditions was developed. Three nido-carborane ligands were reacted with [Re(CO)(3)Br(3)](2)(-) in the presence of aqueous potassium fluoride to give the corresponding eta(5)-Re(CO)(3)-carborane complexes. The use of KF as a base afforded the desired Re-metallocarboranes in good yields while avoiding the formation of Re clusters, which are byproducts commonly observed when reactions are carried out in the presence of strong aqueous bases. The reaction was also performed at the tracer level producing the first (99m)Tc-carborane complex, which was isolated in 80% radiochemical yield following a simple Sep-Pak purification process. The resulting organometallic complex was stable to cysteine and histidine challenges for more than 24 h.

Evaluation of the polyethylene glycol–KF–water system in the context of purifying PEG–protein adducts

Covalent binding of PEG to proteins leads to conjugates widely investigated in several biotechnological processes. Their use as pharmaceuticals requires both careful purification and proper characterization. In this context, this paper examines the potentialities offered by hydrophobic interaction chromatography and compares aqueous potassium fluoride and ammonium sulfate as the eluents. Relative contribution of the various forces which dictate the chromatographic behaviour of PEG–protein adducts on Fractogel TSK–Butyl 650 is discussed.

Reactivation of phosphorodiamidated acetylcholinesterase and neuropathy target esterase by treatment of inhibited enzyme with potassium fluoride

It has been thought that the phosphorus-enzyme bond in inhibited esterases inhibited by such agents as mipafox ( N,N′-di-iso-propylphosphorodiamidate) was refractory to reactivating agents either because an ‘aging’ reaction occurs soon after inhibition or because the bond was intrinsically very strong. We have found that both acetylcholinesterase (AChE) and neuropathy target esterase (NTE) which had been inhibited with either mipafox or with a di- n-butylphosphorodiamidate could be reactivated by prolonged treatment with aqueous potassium fluoride (KF): the reaction proceeded with first-order kinetics. Furthermore there was no time-dependant loss of reactivatability (aging). Di-isopropylphosphoro-butyrylcholinesterase could be fully reactivated by this treatment but after 18 h to allow aging the monoisopropyl phosphoro-enzyme was totally refractory to KF. We conclude that it is likely that the mipafox-enzyme bond in inhibited NTE and AChE is relatively strong but that aging has not occurred. The local disturbance around the active site of NTE caused by attachment of the phosphorodiamidate molecule appears to be sufficient to initiate delayed neuropathy without necessity for an ‘aging’ reaction.

Organic sulfur mechanisms. 37. Mechanisms of hydrolysis of (trimethylsilyl)methanesulfonyl chloride. Sulfene-enamine reactions in water

Kinetic, product analysis, and deuteration experiments are consistent with the following mechanisms of hydrolysis of (trimethylsilyl)methanesulfonyl chloride (1) (in 0.01 M KCI at 1 o C): (a) pH ≤10.0, attack of water at silicon to form sulfene (5) which is trapped by water to give methanesulfonate anion (3), (b) pH ≥10.0, attack of hydroxide anion (i) at silicon to yield sulfene (5) and (ii) at an α-hydrogen to form (trimethylsilyl)sulfene (4), in each case follonved by trapping of the sulfene to give either methanesulfonate (3) or (trimethylsilyl)methanesulfonate (6) salts. Aqueous potassium fluoride catalyzes the hydrolysis of 1 with formation of the methanesulfonate 3, evidently by way of silicophilic attack of fluoride anion on 1 with formation of sulfene (6)

Interactions in vitro of some organophosphoramidates with neuropathy target esterase and acetylcholinesterase of hen brain.

For organophosphates or phosphonates to initiate delayed neuropathy two steps are necessary: (1) progressive covalent reaction with neuropathy target esterase (NTE) to produce a form of inhibited NTE which can be reactivated by incubation with aqueous potassium fluoride (KF) and (2) progressive "aging" of inhibited NTE to a form which can no longer be reactivated by KF. However, it has been shown recently that certain N-unsubstituted organophosphoro-monoamidates (analogues of methamidophos) cause delayed neuropathy even though the inhibited NTE appeared not to have aged (Johnson et al. (1991). Arch. Toxicol., 65, 618-624). In order to study the generality of this phenomenon, we have examined some N-substituted compounds. We report in vitro studies of inhibition and reactivation and aging of both NTE and acetylcholinesterase (AChE) prior to toxicological tests. All the compounds studied were less inhibitory to both NTE and AChE in concentrated rather than in dilute suspensions of EDTA-washed brain particles without added cofactors. There was an apparent disposal of up to 100 mumoles of test compound by particles from 95 mg hen brain, which is far greater than can be explained by covalent binding. The activity is distinct from calcium-dependent "A" esterase. Several N-alkyl phosphoromonoamidates were found to be potent and selective inhibitors of NTE: second-order rate constant for O-n-pentyl N-benzylphosphoramido-fluoridate (Cmpd 6) = 5.6 x 10(7) M-1 min-1 at 37 degrees, which is about 100x higher than for acetylcholinesterase (AChE). Inhibited NTE and AChE from several chiral phosphoromono-amidates did not reactivate spontaneously (21 hours at 37 degrees). Virtually 100% reactivation by KF of AChE inhibited by phosphoromonoamidates was achieved at all times tested. Acetylcholinesterase inhibited by 2,5-dichlorophenyl N,N'-di-n-butylphosphorodiamidate was 42-56% reactivated by incubation with KF (192 mM in pH 5.2 buffer for 30 minutes at 37 degrees). We believe this is the first report of reactivation of any enzyme after inhibition by a phosphorodiamidate. For NTE inhibited by tabun (O-ethyl N-dimethylphosphoroamidocyanidate), virtually complete and rapid aging (t1/2 = 5.5-8.4 minutes) was observed. Consistent but only partial reactivation by KF was achieved 2 or more hours after inhibition of NTE by Cmpd 6 or by its 2,6-difluoro-analogue (Cmpd 7). However, a small but significant aging (approximately 15-20% loss of reactivatability) was measured soon after a 1 minute inhibition by Cmpd 7, but no further change occurred in 21 hours.(ABSTRACT TRUNCATED AT 400 WORDS)

Morphology and electrochemistry of polypyrrole- and poly-N-methylpyrrole-films

When the potentiodynamic deposition of polypyrrole on a glassy carbon substrate is performed from aqueous potassium fluoride solutions, the starting potential is found to be low compared to other electrolyte solutions. However, the rate of deposition decreases rapidly from cycle to cycle, further polymer formation is strongly impeded. On the contrary, poly-N-methylpyrrole can be prepared easily from aqueous KF solutions, the morphology of the resulting polymers depending on the polymerization charge. In the case of polypyrrole - toluenesulfonate, the dependence of electrochemical properties on film thickness, which was investigated by a.c. impedance analysis, is only apparent and can be interpreted by a fractal model for the polymer surface.

Diffusion of aqueous hydrofluoric acid and aqueous potassium fluoride

A conductimetric technique has been used to determine binary diffusion coefficients of aqueous hydrofluoric acid and aqueous potassium fluoride at 25°C. Measurements were made at concentrations from 0.001 to 0.1 mol dm −3. In dilute solutions ionization of HF molecules to F − and highly mobile H + (HF ⇌ F − + H +) leads to a rapid increase in the overall rate of diffusion of the HF component. Provided the association equilibrium HF + F − ⇌ HF − 2 is included in the analysis, the results are in good agreement with behaviour predicted by theory for diffusion of incompletely dissociated electrolytes. The limiting diffusion coefficient of the HF molecule, 1.68 (±0.02) × 10 −9 m 2 s −1, has been determined. Contrary to an earlier report, diffusion of dilute KF solutions is correctly described by Onsager-Fuoss theory.

Reaction of Alkyl Halides and Methanesulfonates with Aqueous Potassium Fluoride in the Presence of Phase-Transfer Catalysts: a Facile Synthesis of Primary and Secondary Alkyl Fluorides

Reaction of Alkyl Halides and Methanesulfonates with Aqueous Potassium Fluoride in the Presence of Phase-Transfer Catalysts: a Facile Synthesis of Primary and Secondary Alkyl Fluorides

Halogen exchange in reactions of boron halides with o-(trifluoromethyl)-phenyltrimethyl derivatives of silicon and tin

The reaction of boron trifluoride with o-CF3C6H4SnMe3 in carbon tetrachloride gives o-CF3C6H4BF2, which with aqueous potassium fluoride is converted to K[o-CF3C6,H4BF3]. Boron trichloride and o-CF3C6H4SnMe3 undergo halogen exchange to give, after hydrolysis, o-CCl3C6H4B(OH)2. Halogen exchange also occurs between boron trichloride and o-CF3C6H4Y (Y = H, SiMe3) to give boron trifluoride and o-CCl3C6H4Y. The long range HF and FF nuclear magnetic resonance (n.m.r.) coupling constants observed for o-CF3C6H4-derivatives are briefly discussed.