Fluorine, properties

In contrast, some nonbonding electron-pair donor bases are very suitable for reducing the acidity, volatility and hazards of hydrogen fluoride, and also act to improve its fluorinating properties through increased selectivity.9 -1b31.32.3 is.3 n nhanced nucleophilicity of the fluoride ions is also associated particularly with these reagent systems. 

Addition of 2,2 -bipyridine to silver(I) fluoride also improves the fluorinating properties. Thus, this mixture converts 1-bromooctane into 1-fluorooctane in 99% yield after 45 minutes at 130°C.28... 

There are few reports on the reactions and fluorinating properties of mercury(I) fluoride (see Houben-Weyl, Vol. 5/3, p 196). 

Perchloryl fluoride is thermally stable up to 500° C. and very resistant to hydrolysis. It is a colorless gas in ordinary conditions with b.p., —46.7°C., and m.p., —147.8°C. It is a powerful oxidant at elevated temperatures. It exhibits selective fluorination properties and has been used as a perchlorylation reagent for introducing the C103 group on carbon in organic compounds. It is moderately toxic (maximum allowable concentration, 3 p.p.m.8). A comprehensive review of the production, physical properties, and reactions of perchloryl fluoride is available.9... 

HIGH-VALENT NICKEL FLUORIDES AND THEIR OXIDIZING AND FLUORINATING PROPERTIES... 

J. M. Whalen, L. Chacon and N. Bartlett, High-Valent Nickel Fluorides and Their Oxidizing and Fluorinating Properties, Electrochem. Soc. Proc. 97(15) (1997) 1-12. 

In particular, CeF4 seems to be a suitable catalyst for ethylene fluorination due to its good fluorinating properties [8], while CeOa possesses well-known oxidizing properties, with a redox potential able to promote the re-oxidation of other elements in complex catalytic systems. Therefore, CeOa might promote the regeneration of metallic components formed after fluorination. 

The lubricant properties of alkanethiols and fluorinated alkanes have been studied extensively by scanning probe techniques [163]. In agreement with experiments on LB monolayers it was found that the fluorocarbon monolayers show considerably higher friction than the corresponding hydrocarbon monolayers [164, 165 and 166] even though the fluorocarbons are known to have the lowest surface free energy of all organic materials. 

One surprising physical property of fluorine is its electron affinity which, at — 333 kJmoPS is lower than that of chlorine, -364 kJmol , indicating that the reaction X(g) + -> X (g) is more... 

Bromine has a lower electron affinity and electrode potential than chlorine but is still a very reactive element. It combines violently with alkali metals and reacts spontaneously with phosphorus, arsenic and antimony. When heated it reacts with many other elements, including gold, but it does not attack platinum, and silver forms a protective film of silver bromide. Because of the strong oxidising properties, bromine, like fluorine and chlorine, tends to form compounds with the electropositive element in a high oxidation state. 

Recent work indicates the existence offluoric I) acid. HFO, formed by the reaction of fluorine and water at 273 K. The acid forms colourless crystals, m.p. 156 K. is very unstable, and has, as expected, very strong oxidising properties. 

Carbon-fluorine bonds are quite strong (slightly stronger than C—H bonds) and like polyethylene Teflon is a very stable inert material We are all familiar with the most characteristic property of Teflon its nonstick surface This can be understood by com paring Teflon and polyethylene The high electronegativity of fluorine makes C—P bonds less polarizable than C—H bonds causing the dispersion forces m Teflon to be less than those m polyethylene Thus the surface of Teflon is even less sticky than the already slick surface of polyethylene... 

Turning now to electrophilic aromatic substitution in (trifluoromethyl)benzene we con sider the electronic properties of a trifluoromethyl group Because of their high elec tronegativity the three fluorine atoms polarize the electron distribution m their ct bonds to carbon so that carbon bears a partial positive charge... 

Key properties are its flexibility, translucency, and resistance to all known chemicals except molten alkali metals, elemental fluorine and fluorine precursors at elevated temperatures, and concentrated perchloric acid. It withstands temperatures from —270° to 250°C and may be sterilized repeatedly by all known chemical and thermal methods. 

The section on Spectroscopy has been retained but with some revisions and expansion. The section includes ultraviolet-visible spectroscopy, fluorescence, infrared and Raman spectroscopy, and X-ray spectrometry. Detection limits are listed for the elements when using flame emission, flame atomic absorption, electrothermal atomic absorption, argon induction coupled plasma, and flame atomic fluorescence. Nuclear magnetic resonance embraces tables for the nuclear properties of the elements, proton chemical shifts and coupling constants, and similar material for carbon-13, boron-11, nitrogen-15, fluorine-19, silicon-19, and phosphoms-31. 

Because of the extreme difficulty in handling fluorine, reported physical properties (Table 1) show greater than normal variations among investigators. A detailed summary and correlation of the physical, thermodynamic, transport, and electromagnetic properties of fluorine is given in Reference 20. 

Fluorine is the most electronegative element and thus can oxidize many other elements to their highest oxidation state. The small size of the fluorine atom facihtates the arrangement of a large number of fluorines around an atom of another element. These properties of high oxidation potential and small size allow the formation of many simple and complex fluorides in which the other elements are at their highest oxidation states. 

The reactivity of fluorine compounds varies from extremely stable, eg, compounds such as sulfur hexafluoride [2551-62 ] nitrogen trifluoride [7783-54-2] and the perfluorocarbons (see Fluorine compounds, organic) to extremely reactive, eg, the halogen fluorides. Another unique property of nonionic metal fluorides is great volatiUty. Volatile compounds such as tungsten hexafluoride [7783-82-6] molybdenum hexafluoride [7783-77-9] ... 

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