Fluorides double salts

Electrochemical oxidation of alkyl aryl ethers results in oxidative dealkylation and coupling of the intermediate radicals. Electro-oxidation of alkyl (4-fluorophenyl) ethers in the presence of a hydrogen fluoride double salt leads to 4,4-difluorocyclohexa-2,5-dienone in 50% yield (Table 10).182 In the electrochemical oxidation of methyl tetrafluorophenyl ethers with a hydrogen atom at the para position, coupled products 6 arc obtained.183 If the para position in the substrate is occupied by a fluorine substituent, then no reaction occurs. 

With alkali fluorides double salts are produced, the compositions of which are as yet unknown. They are less easily reduced, however, than the free octafluoride. Sodium hydroxide decomposes them with evolution of ozone. 

The fluorite stmcture, which has a large crystal lattice energy, is adopted by Ce02 preferentially stahi1i2ing this oxide of the tetravalent cation rather than Ce202. Compounds of cerium(IV) other than the oxide, ceric fluoride [10060-10-3] CeF, and related materials, although less stable can be prepared. For example ceric sulfate [13590-82-4] Ce(S0 2> certain double salts are known. 

In 1888, Turpin prepd a series of cool expls which were permissable, by incorporating materials such as alkali chlorides, Na or K bicarbonate (up to 50% content), fluorides, acetates, oxalates, Ba carbonate. 10H2O, chromates, hyposulfites, stannic acid, boric acid, borates, etc, in the expls listed above eg, a) K chiorate 45, double salt of Ca and K acetochlorate 35, tar 18, charcoal 5, and alkali bicarbonate or oxalate I5ps b) K chlorate 15, double salt of K and Amm chlorobichromate 35 K or Na nitrate 10, tar 18, charcoal 5, and K or Na bicarbonate 15ps... 

Nickel dioxide, 77 107 Nickel double salts, 77 113 Nickel electrodes, 3 430 72 216 Nickel electroplating solutions, 9 818t Nickel extraction, 70 791 Nickel ferrite brown spinel, formula and DCMA number, 7 348t Nickel fibers, 77 108 Nickel fluoride complexes, 77 111 Nickel fluoride tetrahydrate, 77 109-110 Nickel fluoroborate, 77 111 Nickel fluoroborate hexahydrate, 4 157t, 158, 159... 

Thermal dissociation produces ammonium fluoride and ammonia at elevated temperatures products contain ammonia and hydrogen fluoride. It forms a colorless double salt, ammonium iron fluoride SNEUF FeFs, with iron, a reaction of commercial apphcation for removing stains from fabric. It reacts with many metal oxides at elevated temperatures forming double fluorides ... 

The impure hydroxide obtained above is purified by converting to a double salt, ammonium beryllium fluoride, which subsequently, on thermal decomposition, gives beryllium fluoride. The latter is heated with magnesium metal... 

Reaction with alkali fluorides (except LiF) yields double salts, such as K3[Mo03F3], formed as colorless cubic crystals. 

CsCl HgCl2=3 1, 2 1, 1 1, 2 3, 1 2, and 1 5 and five caesium antimonious fluorides where CsF SbF3=l 1, 3 4, 4 7, 1 2, and 1 3. According to I. Remsen s rale (1889) When a halide of any element combines with a halide of an alkali metal to form a double salt, the number of molecules of the alkali salt which are added to one molecule of the other halide is never greater, and is generally less than the number of halogen atoms contained in the latter—for instance, in the double fluoride of sodium and aluminium, where the negative halide has three fluorine atoms, no more than three molecules of sodium fluoride will be found united with one of aluminium fluoride. 

MFS forms double salts with most ionic fluorides (Table 3). These can be obtained by direct mixing of the constituents in the molten state, or more usually by addition of an ionic fluoride to a solution of M205 in aqueous HF. Oxofluoro species were also formed as expected, this occurred more readily for Nb than for Ta. Thus the addition of the appropriate metal carbonate to M2Os solutions in HF yielded [NbOF5]2- and [TaF7]-2 salts.48... 

Vanadium Tetrafluoride, hypovanadic fluoride, VF4, is produced by the action of anhydrous hydrogen fluoride on the corresponding chlorine compound, VC14, at temperatures from —28° to 0° C. It is an extremely deliquescent brown powder which readily undergoes hydrolysis with water, so that it does not give rise to double salts as in the case of the trifluoride. Its density at 23° C. is 2 9749. It decomposes above 325° C., yielding a mixture of the pentafluoride and the trifluoride 1... 

Vanadyl Difluoride, VOF2, is prepared by the action of anhydrous hydrogen fluoride on vanadyl dibromide, VOBr2. It is a yellow substance. Density at 19° C., 3-3956.s A hydrated vanadyl difluoride, V0F2.a, H20, is obtained as microscopic blue crystals when hypovanadic oxide, V02, is dissolved in excess of hydrofluoric acid and the solution concentrated slowly over sulphuric acid.1 The following double salts have been prepared, all of which are crystalline and fairly stable —5... 

Vanadium Dioxyfluoride, VOaF, has not been isolated in the free state. It combines readily with other fluorides to form a series of yellow, easily crystallisable double salts, which can be heated to 100° C. or even above without undergoing change. The following have been prepared —1... 

Rubidium Niobium Fluoride, RbNbF6 or RbF.NbF5, is obtained by repeated crystallisation of rubidium niobium oxyfluoride, RbjNbOFg, from hydrofluoric acid.8 The double salt Rb2NbF7 or 2RbF.NbFs has also been reported.4... 

It fuses when heated in gaseous hydrogen fluoride to 1200-1300° C. to a ruby-red mass, and sublimes with difficulty at 1400° C.3 When heated with potassium hydrogen fluoride, KHF2, a double salt., CoF. KF, is obtained in garnet-red crystalline plates of density 3-22.4... 

The mineral acids dissolve the crystals completely. When ignited in air, ferric oxide is obtained, as also when the crystals are fused with an alkali carbonate. Double salts formed by union with the fluorides of the alkali and certain other metals have been described.3 These may be termed... 

The last-named is also obtained when hydrogen fluoride is passed over red-hot iron, ferric oxide, or ferric chloride 4 or by heating the double salt, ferric ammonium fluoride, FeF3.3NH4F, in an inert gas. 

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