Containers fluorine

Several cortisone derivatives with glucocorticoid effects are most active, if they contain fluorine in the 9or-position together with an Il(9-OH group. Both substituents are introduced by the cleavage of a 9,11 -epoxide with hydrogen fluoride. The regio- and stereoselective formation of the -epoxide is achieved by bromohydrination of a 9,11-double bond and subsequent alkali treatment (J. Fried, 1954). 

Compounds containing fluorine and chlorine are also donors to BF3. Aqueous fluoroboric acid and the tetrafluoroborates of metals, nonmetals, and organic radicals represent a large class of compounds in which the fluoride ion is coordinating with trifluoroborane. Representative examples of these compounds are given in Table 5. Coordination compounds of boron trifluoride with the chlorides of sodium, aluminum, iron, copper, 2inc, tin, and lead have been indicated (53) they are probably chlorotrifluoroborates. 

A number of inhalation anesthetics have been introduced to clinical practice, some of which are Hsted in Table 1. AH agents introduced after 1950, except ethyl vinyl ether, contain fluorine. Agents such as ether, chloroform, trichloroethylene (Tdlene), cyclopropane, and fluoroxene (Fluoromar), which were once used, have been displaced by the newer fluorinated anesthetics. 

The measurements of concentration gradients at surfaces or in multilayer specimens by neutron reflectivity requires contrast in the reflectivity fiDr the neutrons. Under most circumstances this means that one of the components must be labeled. Normally this is done is by isotopic substitution of protons with deuterons. This means that reflectivity studies are usually performed on model systems that are designed to behave identically to systems of more practical interest. In a few cases, however (for organic compounds containing fluorine, for example) sufficient contrast is present without labeling. 

In order to produce a rubbery material the polymer must have a flexible baekbone, be suffieiently irregular in structure to be non-crystalline and also contain a site for cross-linking. These are of course requirements applicable equally to any potential elastomer whether or not it contains fluorine. 

Furnace mortars are used over a very wide range of conditions. They are resistant to nonoxidizing acids, alkalis, and solvents up to 190°C. Carbon fillers should be used for conditions involving strong alkalis and compounds containing fluorine. 

Synthetic cryolite solved the supply problem, but synthetic cryolite requires fluorine which is actually more abundant in the Earth s crust than chlorine, but dispersed in small concentrations in rocks. Until the 1960s, fluorspar (CaFj) a mineral long known and used as a flux in various metallurgical operations was the source. A source is phosphate rock that contains fluorine i.s 3% quantity,... 

Halocarbon (HCFC) A class of refrigerants that contain fluorine, chlorine, carbon, and hydrogen. 

Fluorgehalt, m. fluorine content, fluorhaltig, a. containing fluorine. 

Nevertheless, Ta5+ and Nb5+ interact with aqueous media containing fluorine ions, such as solutions of hydrofluoric acid. On the other hand, as was clearly shown by Majima et al. [448 - 450], the increased hydrogen ion activity can also significantly enhance the dissolution rate of oxides. The activity of hydrogen ions can be increased by the addition of mineral salts or mineral acids to the solution. 

Synthesis and Biological Activities of Compounds Containing Fluorinated Carbohydrates. 186... 

Table 5 shows the most important NMR data of halophosphates. In the species containing fluorine, apart from the chemical shifts of the P-spectra, the F-spectra and the coupling constants Jpp are available for the discussion of bonding. The importance of NMR spectroscopy for purity control, for equilibrium measurement, as kinetical method in the investigation of reaction processes and for the identification of unstable compounds shall not be discussed here, though these apphcations are of great importance for the halophosphates too. 

The latter compound has the practical advantage over the former of not containing fluorine, which might on repeated application accumulate in the soil and poison it. Schrader (38) prepared the pyrophosphoramide as follows ... 

The balance of the compounds in Table VIII support the earlier statement that any compound containing fluorine is toxic to moths. These fluorinated hydrocarbons, phenols, acids, sulfonic acids, and sulfones probably act against moths as stomach poisons. The fluorosulfonic acid derivatives and the sulfone with a fluorinated substituent were key compounds whose toxicity to moths laid the groundwork for the deductions which led to the synthesis and testing of DDT as an insecticide. 

There has been an increased exploration in the organofluorine compounds since 1940, when an authoritative and comprehensive article giving the toxicity of 551 miscellaneous organic compounds to young screwworms did not include a single compound containing fluorine (13). 

Fluorine s unique polar and steric properties as a substituent, and the influence that fluorinated substituents can have upon the physical and chemical properties of molecules, have induced increasing numbers of synthetic organic chemists to incorporate fluorine into target compounds of synthetic interest. In preparing compounds that contain fluorine, one first faces the daunting task of learning the intricacies of fluorine s often unique synthetic methodologies. 

The reason that organic chemists are interested in compounds that contain fluorine is simple. Because of fluorine s steric and polar characteristics, even a single fluorine substituent, placed at a propitious position within a molecule, can have a remarkable effect upon the physical and chemical properties of that molecule. Discussions of the impact of fluorine on physical and chemical properties of compounds have appeared in numerous reviews and textbooks.1-8 There are also a number of recent reviews on the subject of fluorine in medicinal chemistry.9-13... 

Any spin system that contains fluorine substituents that are chemically equivalent, but not magnetically equivalent is, by definition, second order. Such spectra can appear deceptively simple, or more commonly they can be amazingly complex. The fluorine and proton spectra of the simple, symmetrical compound, 1,1-difluoroethene exemplify the latter situation (Figures 2.5 and 2.6). 

However, as the interest in compounds that contain fluorine has grown, along with the quality of available instrumentation, so has the interest in 2D 19F NMR techniques. An excellent recent review by Bat-tiste and Newmark on the applications of 19F multidimensional NMR is available and should be consulted for detailed information about the hardware requirements and the application of the various available 19F 2D NMR techniques.23... 

Unlike the one dimensional NMR techniques to which this book is largely devoted, those 2D 19F NMR techniques to be briefly discussed below will not generally be required for day to day structure elucidation by the working organic chemist. However, there will inevitably be situations where these techniques will be indispensible in determining the detailed 3-dimensional structure of compounds that contain fluorine, and at such times it may be necessary for the synthetic chemist to turn to an NMR specialist for assistance. 

For compounds that contain a limited number of fluorine atoms, heteronuclear correlation spectroscopy experiments such as F H HETCOR and 2H-19F heteronuclear Overhauser enhancement spectroscopy (HOESY) can provide considerable assistance distinguishing structural isomers and diastereomers as well as for conformational analysis. HOESY experiments have been frequently used for conformational analysis of biomolecules containing fluorine labels.18... 

Higashiguchi K, Matsuda K, Asano Y, Murakami A, Nakamura S, Irie M (2005) Photochro-mism of dithienylethenes containing fluorinated thiophene rings. Eur J Org Chem 91-97... 

Elastomers containing fluorine, also called fluorelastomers. These combine the good physical properties of organic elastomers with the thermal stability of inorganic materials. Trade names are Viton, Fluorel, Kel-F and Technoflon. 

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