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Bringing together the research and methods of leading scientists in the fluorine field, Efficient Preparations of Fluorine Compounds is the definitive manual to.
Table of contents
- ISBN 13: 9781118078563
- Efficient Preparations of Fluorine Compounds
- Guide Efficient Preparations of Fluorine Compounds
- Efficient Preparation of Fluorine Compounds
Levertijd We doen er alles aan om dit artikel op tijd te bezorgen. Het is echter in een enkel geval mogelijk dat door omstandigheden de bezorging vertraagd is. Bezorgopties We bieden verschillende opties aan voor het bezorgen of ophalen van je bestelling. Welke opties voor jouw bestelling beschikbaar zijn, zie je bij het afronden van de bestelling. Schrijf een review. E-mail deze pagina. Auteur: Flogel, Ulrich. Samenvatting Over the past decade, fluorine 19F magnetic resonance imaging MRI has garnered significant scientific interest in the biomedical research community owing to the unique properties of fluorinated materials and the 19F nucleus.
ISBN 13: 9781118078563
Fluorine has an intrinsically sensitive nucleus for MRI. There is negligible endogenous 19F in the body and thus there is no background signal. Fluorine-containing compounds are ideal tracer labels for a wide variety of MRI applications. Moreover, the chemical shift and nuclear relaxation rate can be made responsive to physiology via creative molecular design.
This book is an interdisciplinary compendium that details cutting-edge science and medical research in the emerging field of 19F MRI.
Efficient Preparations of Fluorine Compounds
Edited by Ulrich Floegel and Eric Ahrens, two prominent MRI researchers, this book will appeal to investigators involved in MRI, biomedicine, immunology, pharmacology, probe chemistry, and imaging physics. Toon meer Toon minder. Recensie s Since the first published images in the mid s, 19F MRI has made a significant comeback in molecular and cellular imaging during the last 10 years. This book is written by an international gathering of scientists who have been expert witnesses to this renaissance, covering every aspect from physical, chemical, and biological perspectives.
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Written by recognized experts in MRI pulse sequences, imaging hardware, contrast agent chemistry, pharmacy, and medicine, it covers the whole field from the technique to clinical application. An important and highly recommended book. Deoxofluorination agents effect the replacement hydroxyl and carbonyl groups with one and two fluorides, respectively.
One such reagent, useful for fluoride for oxide exchange in carbonyl compounds, is sulfur tetrafluoride :.
These organic reagents are easier to handle and more selective: . Many organofluorine compounds are generated from reagents that deliver perfluoroalkyl and perfluoroaryl groups. Trifluoromethyl trimethylsilane, CF 3 Si CH 3 3 , is used as a source of the trifluoromethyl group, for example. These species form Grignard reagents that then can be treated with a variety of electrophiles. The development of fluorous technologies see below, under solvents is leading to the development of reagents for the introduction of "fluorous tails". A special but significant application of the fluorinated building block approach is the synthesis of tetrafluoroethylene , which is produced on a large-scale industrially via the intermediacy of difluorocarbene.
Sodium fluorodichloroacetate CAS is used to generate chlorofluorocarbene, for cyclopropanations. The usefulness of fluorine-containing radiopharmaceuticals in 18 F- positron emission tomography has motivated the development of new methods for forming C—F bonds.
Because of the short half-life of 18 F, these syntheses must be highly efficient, rapid, and easy. Biologically synthesized organofluorines have been found in microorganisms and plants, but not animals. Organofluorine chemistry impacts many areas of everyday life and technology.
The C-F bond is found in pharmaceuticals , agrichemicals , fluoropolymers , refrigerants , surfactants , anesthetics , oil-repellents , catalysis , and water-repellents , among others. The carbon-fluorine bond is commonly found in pharmaceuticals and agrochemicals because it is generally metabolically stable and fluorine acts as a bioisostere of the hydrogen atom.
An estimated one fifth of pharmaceuticals contain fluorine, including several of the top drugs. Fluorine-substituted ethers are volatile anesthetics , including the commercial products methoxyflurane , enflurane , isoflurane , sevoflurane and desflurane. Fluorocarbon anesthetics reduce the hazard of flammability with diethyl ether and cyclopropane. Perfluorinated alkanes are used as blood substitutes. Fluorocarbons are also used as a propellant for metered-dose inhalers used to administer some asthma medications.
The current generation of propellant consists of hydrofluoroalkanes HFA , which has replaced CFC -propellant-based inhalers. CFC inhalers were banned as of [update] as part of the Montreal Protocol  because of environmental concerns with the ozone layer. Fluorosurfactants, which have a polyfluorinated "tail" and a hydrophilic "head", serve as surfactants because they concentrate at the liquid-air interface due to their lipophobicity. Fluorosurfactants have low surface energies and dramatically lower surface tension.
The fluorosurfactants perfluorooctanesulfonic acid PFOS and perfluorooctanoic acid PFOA are two of the most studied because of their ubiquity, toxicity, and long residence times in humans and wildlife. Fluorinated compounds often display distinct solubility properties. Dichlorodifluoromethane and chlorodifluoromethane were widely used refrigerants.
CFCs have potent ozone depletion potential due to the homolytic cleavage of the carbon-chlorine bonds; their use is largely prohibited by the Montreal Protocol. Hydrofluorocarbons HFCs , such as tetrafluoroethane , serve as CFC replacements because they do not catalyze ozone depletion. Oxygen exhibits a high solubility in perfluorocarbon compounds, reflecting again on their lipophilicity. Perfluorodecalin has been demonstrated as a blood substitutes , transporting oxygen to the lungs. The solvent 1,1,1,2-tetrafluoroethane has been used for extraction of natural products such as taxol , evening primrose oil , and vanillin.
The development of organofluorine chemistry has contributed many reagents of value beyond organofluorine chemistry. Their strong acidity is attributed to the electronegativity of the trifluoromethyl group that stabilizes the negative charge. The triflate-group the conjugate base of the triflic acid is a good leaving group in substitution reactions. Of topical interest in the area of "Green Chemistry,"  highly fluorinated substituents, e.
Because of the relative inertness of the C-F bond, such fluorous phases are compatible with even harsh reagents. This theme has spawned techniques of "fluorous tagging and fluorous protection. Illustrative of fluorous technology is the use of fluoroalkyl-substituted tin hydrides for reductions, the products being easily separated from the spent tin reagent by extraction using fluorinated solvents. Hydrophobic fluorinated ionic liquids , such as organic salts of bistriflimide or hexafluorophosphate , can form phases that are insoluble in both water and organic solvents, producing multiphasic liquids.
Organofluorine ligands have long been featured in organometallic and coordination chemistry. One advantage to F-containing ligands is the convenience of 19 F NMR spectroscopy for monitoring reactions. Most often, however, fluorocarbon substituents are used to enhance the Lewis acidity of metal centers. A premier example is " Eufod ," a coordination complex of europium III that features a perfluoroheptyl modified acetylacetonate ligand. This and related species are useful in organic synthesis and as "shift reagents" in NMR spectroscopy.
In an area where coordination chemistry and materials science overlap, the fluorination of organic ligands is used to tune the properties of component molecules.
Guide Efficient Preparations of Fluorine Compounds
For example, the degree and regiochemistry of fluorination of metalated 2-phenylpyridine ligands in platinum II complexes significantly modifies the emission properties of the complexes. The coordination chemistry of organofluorine ligands also embraces fluorous technologies.
For example, triphenylphosphine has been modified by attachment of perfluoroalkyl substituents that confer solubility in perfluorohexane as well as supercritical carbon dioxide. An active area of organometallic chemistry encompasses the scission of C-F bonds by transition metal-based reagents. Both stoichiometric and catalytic reactions have been developed and are of interest from the perspectives of organic synthesis and remediation of xenochemicals. An illustrative metal-mediated C-F activation reaction is the defluorination of fluorohexane by a zirconium di hydride , an analogue of Schwartz's reagent :.
Fluorine-containing compounds are often featured in noncoordinating or weakly coordinating anions. The fluorinated substituents render the anions weakly basic and enhance the solubility in weakly basic solvents, which are compatible with strong Lewis acids. Organofluorine compounds enjoy many niche applications in materials science. With a low coefficient of friction , fluid fluoropolymers are used as specialty lubricants. Fluorocarbon-based greases are used in demanding applications. Certain firearm lubricants such as "Tetra Gun" contain fluorocarbons. Capitalizing on their nonflammability, fluorocarbons are used in fire fighting foam.
Organofluorine compounds are components of liquid crystal displays.
Efficient Preparation of Fluorine Compounds
The polymeric analogue of triflic acid, nafion is a solid acid that is used as the membrane in most low temperature fuel cells. The bifunctional monomer 4,4'-difluorobenzophenone is a precursor to PEEK -class polymers. In contrast to the many naturally-occurring organic compounds containing the heavier halides , chloride, bromide, and iodide, only a handful of biologically synthesized carbon-fluorine bonds are known.
Others include fluorooleic acid, fluoroacetone , nucleocidin 4'-fuoro-5'-O-sulfamoyladenosine , fluorothreonine , and 2-fluorocitrate. Several of these species are probably biosynthesized from fluoroacetaldehyde. The enzyme fluorinase catalyzed the synthesis of 5'-fluorodeoxyadenosine see scheme to right.
Organofluorine chemistry began in the s with the development of organic chemistry. The nonflammability and nontoxicity of the chlorofluorocarbons CCl 3 F and CCl 2 F 2 attracted industrial attention in the s. In the s, scientists at duPont discovered polytetrafluoroethylene. Electrochemical fluorination " electrofluorination " was announced, which Joseph H. Simons had developed in the s to generate highly stable perfluorinated materials compatible with uranium hexafluoride. In , the anticancer activity of 5-fluorouracil was described. This report provided one of the first examples of rational design of drugs.