Use Of Potassium Fluoride Research Articles

Oxidative Fluorination of Heteroatoms Enabled by Trichloroisocyanuric Acid and Potassium Fluoride.

In synthetic method development, the most rewarding path is seldom a straight line. While our initial entry into pentafluorosulfanyl (SF5) chemistry did not go according to plan (due to inaccessibility of reagents such as SF5Cl at the time), a “detour” led us to establish mild and inexpensive oxidative fluorination conditions that made aryl‐SF5 compound synthesis more accessible. The method involved the use of potassium fluoride and trichloroisocyanuric acid (TCICA)—a common swimming pool disinfectant—as opposed to previously employed reagents such as F2, XeF2, HF, and Cl2. Thereafter, curiosity led us to explore applications of TCICA/KF as a more general approach to the synthesis of fluorinated Group 15, 16, and 17 heteroatoms in organic scaffolds; this, in turn, prompted SC‐XRD, VT‐NMR, computational, and physical organic studies. Ultimately, it was discovered that TCICA/KF can be used to synthesize SF5Cl, enabling SF5 chemistry in an unexpected way.

Oxidative Fluorination of Heteroatoms Enabled by Trichloroisocyanuric Acid and Potassium Fluoride

AbstractIn synthetic method development, the most rewarding path is seldom a straight line. While our initial entry into pentafluorosulfanyl (SF5) chemistry did not go according to plan (due to inaccessibility of reagents such as SF5Cl at the time), a “detour” led us to establish mild and inexpensive oxidative fluorination conditions that made aryl‐SF5compound synthesis more accessible. The method involved the use of potassium fluoride and trichloroisocyanuric acid (TCICA)—a common swimming pool disinfectant—as opposed to previously employed reagents such as F2, XeF2, HF, and Cl2. Thereafter, curiosity led us to explore applications of TCICA/KF as a more general approach to the synthesis of fluorinated Group 15, 16, and 17 heteroatoms in organic scaffolds; this, in turn, prompted SC‐XRD, VT‐NMR, computational, and physical organic studies. Ultimately, it was discovered that TCICA/KF can be used to synthesize SF5Cl, enabling SF5chemistry in an unexpected way.

Inhibition of dentin matrix-bound cysteine cathepsins by potassium fluoride.

Matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs) can break down unprotected type I collagen fibrils in dentin matrix. This study investigated the use of potassium fluoride (KF) as a potential inhibitor of MMPs and CCs in dentin. Demineralized dentin beams were divided into groups (n=10 in each group) and incubated in artificial saliva (AS, control), either alone or with one of seven concentrations of KF (6-238mM fluoride) for 1, 7, and 21d. After 21d, all groups were further aged in AS for 6months. Total MMP activity was screened using the colorimetric MMP assay. The activities of MMP-2 and MMP-9 were investigated using gelatin zymography. At the end of each incubation, changes in loss of dry mass and CC-mediated or total dissolution of collagen peptides were measured via precision weighing, C-terminal crosslinked telopeptide of type I collagen (CTX), and hydroxyproline (HYP) assays. The beams were examined using scanning electron microscopy. After 21d, total MMP activities, dry mass loss, and CTX release for the groups exposed to 179 and 238mM fluoride were significantly lower compared with the control group. After 6months, all groups showed similar total MMP activity, dry mass loss, and HYP release, and CTX levels were significantly lower when the fluoride concentration was ≥24mM. Calcium fluoride (CaF2 )-like precipitates were observed over the beams. In summary, KF significantly inhibited the catalytic activity of dentin matrix-bound CCs but did not seem to be effective for MMP-mediated activity.

Phosphine‐Free Palladium Catalytic System for the Selective Direct Arylation of Furans or Thiophenes bearing Alkenes and Inhibition of Heck‐Type Reaction

AbstractPalladium acetate associated to potassium carbonate as catalytic system has been found to efficiently catalyse the direct 5‐arylation of furans or thiophenes bearing enal, enone or acrylate functions at carbon C‐2, and to inhibit the Heck‐type reaction. The nature of the base is crucial to control the selectivity of the arylation. In the presence of electron‐deficient aryl bromides and potassium carbonate as the base, the direct arylation is favoured, whereas the use of potassium fluoride gave selectively the Heck‐type product, and tri‐n‐butylamine the reductive addition product.

ChemInform Abstract: An Improved Synthesis of 2-Diazo 1,3-Diketones.

The sodium hydride/dibenzo-18-crown-6 ether system was found to be an effective base for the synthesis of 1,3-diketones by the Claisen condensation. The use of potassium fluoride (with or without crown ether) as the base in diazo-transfer reactions extends this reaction to the synthesis of hindered diazo diketones. In the case of isomeric 1,3-diketones, the stereoselectivity of the process considerably rises

Inhibition of microbial growth, study of solution stability, growth and characterization of potassium fluoride mixed l-arginine phosphate single crystals

In order to alleviate the major problem of microbial growth and colouration in l-arginine phosphate (LAP), the use of potassium fluoride (KF), a new additive having higher dipole moment, has been proposed. The stabilities of the pure and KF mixed LAP solution at different temperatures have been determined. Pure and KF mixed LAP crystals were grown by the temperature lowering technique. The presence of potassium in the crystal was identified by inductively coupled plasma analysis (ICP). The lattice parameters for the grown crystals were determined from X-ray powder diffraction. The molecular vibration and thermal behaviour of KF mixed LAP were found from Fourier transform infrared (FTIR) spectroscopy and thermal analysis (DTA &TGA) respectively.

Desilylation of t-butyldimethylsilyl ethers of hydroxyquinones

Desilylation of a series of hydrolytically stable hydroxyquinone t-butyldimethylsilyl ethers was achieved in high yields by the use of potassium fluoride in the presence of catalytic amounts of aqueous 48% hydrobromic acid (HBr), or basic aluminium oxide (Al 2 O 3 ), and tetra-n-butylammonium fluoride (Bu 4 NF) as cleaving agents.

Selective desilylation of [formula omitted]-butyldimethylsilyl ethers of phenols using potassium fluoride-alumina and ultrasound

The use of potassium fluoride on basic alumina in acetonitrile with ultrasound for the selecting deprotection of tert -butyldimethylsilyl ethers of phenols is described. The method, which features a non-aqueous work-up, readily cleaves tert- butyldimethylsilyl ethers of phenols at room temperature, whereas tert -butyldimethylsilyl ethers of benzyl alcohols or 2-(trimethylsilyl)ethoxymethyl ethers of phenols are stable.

An Improved Synthesis of 2-Diazo-1,3-diketones

The sodium hydride/dibenzo-18-crown-6 ether system was found to be an effective base for the synthesis of 1,3-diketones by the Claisen condensation. The use of potassium fluoride (with or without crown ether) as the base in diazo-transfer reactions extends this reaction to the synthesis of hindered diazo diketones. In the case of isomeric 1,3-diketones, the stereoselectivity of the process considerably rises

ChemInform Abstract: Use of Potassium Fluoride in the Cyclization of 3‐Hetero‐1,5‐dialdehydes with Nitromethane and Ethyl Nitroacetate.

AbstractKF is an efficient catalyst for cyclization reactions of dialdehydes (hemialdals) with nitromethane (II) or with ethyl nitroacetate (IV).

Use of potassium fluoride in the cyclization of 3-hetero-1,5-dialdehydes with nitromethane and ethyl nitroacetate

The use of potassium fluoride as catalyst in the cyclization reactions of dialdehydes is described for the first time. This compound is an efficient catalyst in the cyclizations with nitromethane and ethyl nitroacetate. The yields obtained are similar or higher than those reported when other catalysts are used and the stereoselectivity was major when the dialdehyde prepared by periodate oxidation of methyl α-L-rhamnopyranoside was used.

Fluorination of halides with potassium fluoride; an old reaction—a new catalyst

The use of potassium fluoride in the exchange of fluorine for other halogens is a well known reaction. The literature contains many conflicting reports on yields and conditions necessary to achieve given reactions. This may be due to the fact that these reactions are, in some cases, subject to catalysis by impurities. We have recently uncovered a striking example of catalysis in the fluorination of active chlorides by potassium fluoride. Examples will be presented and the nature of the catalyst will be discussed.

アルミナとヘマタイトの浮選分離に関する研究

Flotation behavior of artificial alumina and artificial hematite, alone and in 1: 1 mixture, was investigated by laboratory flotator in a wide range of pH using C6-C12 fatty acid soaps with the intention of separating alumina from hematite.Experimental results are summarized as follows.1) Separation of artificial alumina and artificial hematite was possible with caprylate (C8) flotation by making use of potassium fluoride as a depressant for alumina. It was essential to regulate the pH of solution at 5.5-6.5 in order to obtain successful results. Both grade and recovery of alumina as a sink were more than 85% in the case where 2×10-3M (2.3kg/ton of ore) Potassium fluoride and 7×10-5-1×10-4M (0.2-0.3kg/ton of ore) sodium caprylate were used. Natural hematite was also used for comparison.2) In the case of the mixture of artificial alumina and natural hematite, no satisfactory results were obtained by the above method, which may be interpreted in terms of the poor floatability of natural hematite as compared to artificial one. In this system, separation was achieved by using tartaric acid as a depressant for natural hematite at pH 6.4 with caprate (C10) soap flotation; the grade and recovery of alumina as a froth were 82% and 96%, respectively, under the conditions of 5×10-4M (2kg/ton of ore) sodium caprate, 1×10-3M (3kg/ton of ore) tartaric acid, and pH 6.4.3) Preferential depression of hematite by tartaric acid was also applicable to the mixture of artificial alumina and artificial hematite, although less marked results was indicated as compared to the system containing natural hematite; the grade and recovery of alumina as a froth were 60-70% and 80%, respectively, at 1.5×10-4M (0.6kg/ton of ore) sodium caprate, 1×10-3M (3kg/ton of ore) tartaric acid, and pH 5.5-6.5.

A practical synthesis of 2-deoxy-2-fluoro- d-arabinofuranose derivatives

A seven-step synthesis of 1,3-di- O-acetyl-5- O-benzoyl-2-deoxy-2-fluoro- d-arabinofuranose, a versatile intermediate in the synthesis of chemotherapeutically important nucleosides, was achieved from 1,2:5,6-di- O-isopropylidene-3- O-tosyl-α- d-allofuranose. The crucial steps were the fluorination by use of potassium fluoride in acetamide and the conversion of 6- O-benzoyl-3-deoxy-3-fluoro- d-glucofuranose into 5- O-benzoyl-2-deoxy-2-fluoro-3- O-formyl- d-arabinofuranose by periodate oxidation. Also described is the synthesis of 1-(2-deoxy-2-fluoro-β- d-arabinofuranosyl)cytosine. This procedure affords good overall yields of products without formation of undesirable, isomeric intermediates and is suitable for large-scale preparations.

The Synthesis of Highly Fluorinated Compounds by Use of Potassium Fluoride in Polar Solvents

The Synthesis of Highly Fluorinated Compounds by Use of Potassium Fluoride in Polar Solvents

Scientific Serials

THE Journal of Anatomy and Physiology, January 1884, contains:—A. Milnes Marshall, M.D., certain abnormal conditions of the reproductive organs of the frog.—S. A. Waddell, M.B., the urea elimination under the use of potassium fluoride in health.—B. C. A. Windle, M.A., M.D., primary sarcoma of the kidney.—R. J. Anderson, M.D., transverse measurements of human ribs.—Arthur W. Hare, M.B., a method of determining the position of the fissure of Rolando and some other cerebral fissures in the living subject.—G. Hoggan, M.B., new forms of nerve terminations in mammalian skin.—J. Symington, M.B., the fold of the nates.—W. Ainslie Holles, M.D., researches into the histology of the central gray substance of the spinal cord and medulla oblongata.—D. J. Cunningham, M.D., the musculus sternalis.—C. W. Cathcart, M.B, movements of the shoulder-girdle involved in those of the arm on the trunk.—J. B. Sutton, the relation of the orbito-sphenoid to the region pterion in the side wall of the skull.—Anatomical notices.