Metal fluoride formation

The electron diffraction analysis of such systems [81] have revealed the formation of y-Fe203 and FeF2 particles for initial Fe(CO)s and revealed Co, C02O3, and C0F2 for initial Co2(CO)g. The metal fluoride formation is connected with the reactions involving the polymer chain and is accompanied by the C-F bond splitting ... 

CoF is used for the replacement of hydrogen with fluorine in halocarbons (5) for fluorination of xylylalkanes, used in vapor-phase soldering fluxes (6) formation of dibutyl decalins (7) fluorination of alkynes (8) synthesis of unsaturated or partially fluorinated compounds (9—11) and conversion of aromatic compounds to perfluorocycHc compounds (see Fluorine compounds, organic). CoF rarely causes polymerization of hydrocarbons. CoF is also used for the conversion of metal oxides to higher valency metal fluorides, eg, in the assay of uranium ore (12). It is also used in the manufacture of nitrogen fluoride, NF, from ammonia (13). 

Rubidium metal alloys with the other alkaU metals, the alkaline-earth metals, antimony, bismuth, gold, and mercury. Rubidium forms double haUde salts with antimony, bismuth, cadmium, cobalt, copper, iron, lead, manganese, mercury, nickel, thorium, and 2iac. These complexes are generally water iasoluble and not hygroscopic. The soluble mbidium compounds are acetate, bromide, carbonate, chloride, chromate, fluoride, formate, hydroxide, iodide. 

The addition of various alkali and alkaline earth cations to the cyclooligomerization of ethylene oxide by Dale and Daasvatn also provides strong presumptive evidence for the template effect. Recently, Reinhoudt, de Jong and Tomassen utilized several metal fluorides to effect crown formations . The reaction rates were found to be in the order Cs > Rb > > Na LE. Such an order would be expected on the basis of binding... 

The use of cesium fluoride is limited because of its cost and its availability as a truly anhydrous reagent. Its use with 18-crown-6 shows a 5 times higher rate for the formation of benzyl fluoride from benzyl bromide when compared with cesium fluonde or potassium fluoride supported on calcium fluoride [21] Either cesium fluoride or potassium fluoride supported on calcium fluoride (Procedures 5a and 5b, p 194) provides about a twofold improvement over either unsupported alkali metal fluoride [55, 69], Cesium fluoride and Aliquat 336 convert benzyl bromide to the fluoride in 94% yield. Using tetrabuty lammonium fluoride in place of Aliquat... 

Interaction between niobium oxide and fluorides, chlorides or carbonates of alkali metals in an ammonium hydrofluoride melt, yielded monooxyfluoroniobates with different compositions, MxNbOF3+x, where they were subsequently investigated [123-127]. According to DTA patterns of the Nb205 - 6NFL HF2 - 2MF system, (Fig. 18) a rich variety of endothermic effects result from the formation of ammonium monooxyfluoroniobate, its thermal decomposition and its interaction with alkali metal fluorides. The number of effects decreases and separation of ammonium ceases at lower temperatures and when going from lithium to cesium in the sequence of alkali metal fluorides. 

The catalytic pyrolysis of R22 over metal fluoride catalysts was studied at 923K. The catalytic activities over the prepared catalysts were compared with those of a non-catalytic reaction and the changes of product distribution with time-on-stream (TOS) were investigated. The physical mixture catalysts showed the highest selectivity and yield for TFE. It was found that the specific patterns of selectivity with TOS are probably due to the modification of catalyst surface. Product profiles suggest that the secondary reaction of intermediate CF2 with HF leads to the formation of R23. 

Crisp, Merson Wilson (1980) found that the addition of metal fluorides to formulations had the effect of accelerating cement formation and increasing the strength of set cements the effect was enhanced by the presence of (-I-)-tartaric acid (Table 5.13). Strength of cements formed from an SiOj-AljOg-Cag (P04)2 glass, G-247, can be almost doubled by this technique. 

This indirect proof of the appearance of CF3SF leads to the conclusion that fluorination of sulfenyl chlorides of the series CF Cl3 SCl (n = 0, 1, 2) with alkali metal fluorides follows the mechanism observed in the formation of sulfenyl fluorides the initial chlorine-fluorine exchange at the sulfur atom is followed by isomerization to the sulfenyl chloride containing the corresponding more highly fluorinated methyl group. 

Miller (90), King (209, 210), and Bruce (211) first observed the formation of neutral metal fluoride species and metal fluoride-containing ions in the mass spectra of pentafluorophenyl derivatives of phosphorus, germanium, silicon, and phosphido-bridged iron carbonyls (90) and aliphatic and aromatic fluorocarbon derivatives of iron, cobalt (209-211),... 

When no catalyst is used or if KF and NaF are present as catalysts, CIF is the main by-product. When the more basic alkali metal fluorides, RbF and CsF, are used, CIF3 is the favored coproduct. The formation of CIF 3 rather than CIF is presumably associated with the more ready formation of C1F2 intermediates with RbF and CsF. Yields of CIF3O from CljO are rather variable and may be affected by the particular alkali fluoride present. Yields of over 40% have been consistently obtained and have reached over 80% using either NaF or CsF. Since NaF does not form an adduct with CIF3O (64), stabilization of the product by complex formation does not seem to influence the CIF3O yields strongly. 

All metals react with fluorine to form metal fluorides. With alkali metals the reactions are violent and highly exothermic at ordinary temperatures. Other metals react at high temperatures. Many metals in their solid form react with fluorine at ordinary temperatures, forming protective coatings of metal fluorides which prevent any further fluoride formation. Such metals include copper, nickel and aluminum, which mostly are metals of construction. Protective coatings of these metal fluorides have very low volatility, thus preventing further fluorination. However, with certain metals such as titani-... 

In a study of the heats of formation of first row transition metal fluorides, AHf for K3CrF6 was found to be 2977 kJ mol-1.1062 The usual double-humped distribution of Ai7f vs. dn was... 

Alkali metal fluorides can also act as bases in dehydrofluorinations,14,41 e.g. formation of 20.14... 

Boron can complete its octet if another atom or ion with a lone pair of electrons forms a bond by providing both of the electrons. A bond in which both electrons come from one of the atoms is called a coordinate covalent bond. For example, the tetrafluoroborate anion, BF4 (38), forms when boron trifluoride is passed over a metal fluoride. In this anion, the formation of a coordinate covalent bond gives the B atom an octet. Another example of the formation of a coordinate covalent bond is the compound formed when boron trifluoride reacts with ammonia ... 

The diagram is an example of an energy cycle, specifically, the Born-Haber cycle. We can use the energy equation (Eq. 3.17) derived from it to discuss, for instance, the trends in the heats of formation of alkali metal fluorides and chlorides. It... 

The flavor of the effects of competitive reactions on metal complex formation can be revealed by considering the example of the hard acid-hard base adduct, A1F2, at low pH (pH < 3.5).9 Under this condition, two fluoride species, HF° and F, compete for the metal species A13 (H20)6 to form the inner-sphere complex, A1F2+(H20)5 ... 

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