In liquid hydrogen fluoride

Cations like that present in (iv) exist in solutions of aromatic hydrocarbons in trifluoroacetic acid containing boron trifluoride, and in liquid hydrogen fluoride containing boron trifluoride. Sulphuric acid is able to protonate anthracene at a mero-position to give a similar cation. ... 

Dove, M F A, Clifford A F Inorganic Chemistry in Liquid Hydrogen Fluoride, Pergamon New York, 1971, p 156... 

An alternative route to the reaction of mercuric fluoride with fluoroolefins in liquid hydrogen fluoride [154] was developed during the early and middle 1970s This improved method involved the reaction of fluoroolefins and mercury salts in the presence of alkali metal fluorides m aprotic solvents [i5J, 156] (equation 118)... 

Solubilities of the later lanthanide trifluorides are similar in liquid hydrogen fluoride and in water, though they are slightly more soluble in the former. Solubilities in liquid hydrogen fluoride (probably 98% HF) decrease steadily from a value of 4 x 10-5 mol EuFs per 100 g HF to 2.1 x 10-5 mol LuF3 per 100 g HF, at 0°C (281). 

Conductometric measurements of SeF4 in liquid hydrogen fluoride prove it to be a weak base (25) [Eq. (2)] ... 

Various fluorinations, which need principally much energy for the generation of the reagent fluorine, are carried out electrochemically in liquid hydrogen fluoride, even in an industrial scale [66]. Owing to the extreme toxicity and the corrosive medium, special precautions are necessary. 

The other halogen halides, HC1, HBr, and HI, are insoluble in liquid hydrogen fluoride and are given off as gases in reactions in which they... 

Benzene is about 2% soluble in HF under ordinary conditions but about 20% soluble at 50°. Oxygen, nitrogen, and sulfur containing organic compounds are in general very soluble in liquid hydrogen fluoride. 

Aromatic Compounds with Sulfides and Mercaptans. Alkyl sulfides and mercaptans function very similarly to ethers and alcohols. Hydrogen sulfide is produced and it escapes as a gas not being significantly soluble in liquid hydrogen fluoride. In this respect the technique of procedure is similar to that used for alkyl halides. 

The electrofluorination of acetophenone and benzophenone takes place in anhydrous HF and in the presence of solvents such as chloroform and acetonitrile [38]. The fluorination of the aromatic rings occurred to various extent. Further uses of anhydrous hydrogen fluoride as a liquid environment for electrofluorination processes have been reported, for example, by Matalin etal. [39]. In particular, systems with low conductivity in liquid hydrogen fluoride and nonselective processes have been studied and optimized. The fluorination of benzene and halobenzenes in the presence of Et4NF—(HF) in an undivided cell has been studied by Horio et al. [40] Cathodic dehalogenation is observed to accompany the anodic fluorination process. 

Hydrofluoric acid like water is an associated liquid, and even the gas, as we shall soon see, is associated. It has the power of uniting with fluorides. It also seems to be an ionizing solvent for a soln. of potassium fluoride in liquid hydrogen fluoride is an excellent conductor it also possesses marked solvent powers. According to E. C. Franklin,7 the liquid readily dissolves potassium fluoride, ehloride, and sulphate sodium fluoride, bromide, nitrate, chlorate, and bromate acetamide and urea. The solvent action is not so marked with barium fluoride, cupric chloride, and silver cyanide while calcium and lead fluorides copper sulphate and nitrate ferric chloride, mercuric oxide, and magnesium metal, are virtually insoluble in this menstruum. Glass also is not affected by the liquid if moisture be absent. The liquid scarcely acts on most of the metals or non-metals at ordinary temp., though it does act on the alkali metals at ordinary temp., much the same as does water, with the simultaneous production of flame. 

Surfactants dissolved in liquid hydrogen fluoride form micelles if their concentration reaches the critical micelle concentration (CMC).3 5 However, the aggregation process is less favorable than in water. Consequently, the CMC values are higher and lower aggregation numbers are... 

The oxidative fluorination of C-H bonds of the side chain in toluene l43 and ethylbenzene derivatives 4 has been reported.45 4fi These alkyl aromatics bearing electronegative substituents are cleanly fluorinated on the alkyl group in liquid hydrogen fluoride in the presence of lead(IV) oxide,45 nickel(IV) oxide,45 silver(II) fluoride,46 cobalt(III) fluoride,46 or cobalt(III) acetate.46... 

The procedures discussed for aromatics can readily be adopted for the efficient preparation of fluoro-substituted heteroaromatics.141,143,149 150 Fluorodediazoniations of 2-ainino-, 3-amino-, 4-amino- and 2.6-diamino-substituted pyridines and some of the chloro or bromo derivatives have been carried out in liquid hydrogen fluoride with anhydrous sodium nitrite. About 1.2 equivalents of nitrite are used per amino group, and ammonium hydrogen fluoride has also been added. The corresponding fluoropyridines or their hydrochlorides have been obtained in 49-89% yield.150 For example, the reported synthesis150 is suitable for the preparation of larger quantities of 4-fluoropyridine hydrochloride (54% yield mp 100 C) examples are given by the formation of 5-7.150... 

Chlorofluorination in Liquid Hydrogen Fluoride General Procedure 24... 

A new study has been reported of the hydrolysis of the p-tolyldiazonium cation using a combination of carbon kinetic isotope effects, theoretical calculations, and dynamics trajectories. Overall, the results are in best accord with a process at the boundary between. S N 1 and. S N2Ar mechanisms.1 There has been a kinetic study of the thermolysis of o-carboxybenzenediazonium fluoride to give o-fluorobenzoic acid in liquid hydrogen fluoride under pressure.2... 

Fluorine. The distinguished chemist Henri Moissan first prepared fluorine by the electrolysis of a solution of potassium fluoride in liquid hydrogen fluoride. Because of the extreme chemical activity of this element, the electrolytic cell employed had to be made of platinum. At the present time, fluorine is produced in the laboratory and commercially by the electrolysis of fused potassium hydrogen fluoride (KHF2) in the manner described in the section on electrolysis. 

Electrochemical fluorination 168,169> is a commercial process for perfluorina-tion of aliphatic compounds. The reaction is performed in liquid hydrogen fluoride -potassium fluoride at a nickel anode. The mechanism is not known free fluorine cannot be detected during electrolysis, so it seems probable that fluorination is a direct electrochemical reaction. Theoretically, hydrogen fluoride-potassium fluoride should be a very oxidation-resistant SSE, and it might well be that the mechanism is analogous to that proposed for anodic acetamidation of aliphatic compounds in acetonitrile-tetrabutylammonium hexafluorophosphate 44 K... 

This technique is useful for monomers which are difficult to polymerize by other techniques. Thus, chlorotrifluoroethylene can be polymerized anodically with good efficiency by electrolysis in liquid hydrogen fluoride - potassium fluoride or trifluoroacetic acid - trifluoroacetic anhydride - potassium trifluoroacetate 631 ... 

Dimethyl tellurium in liquid hydrogen fluoride at — 70° was saturated with boron trifluoride. The dimethyl telluronium tetrafluoroborate was detected by 13C- and l25Te-NMR spectroscopy2. 

The cyanide ligands in [Fe(CN)2(LL)2] (LL = phen, bipy) are sensitive towards protonation successive protonation of both cyanide ligands causes the colour of the complex to change from violet through orange-red to yellow.508 509 Protonation in liquid hydrogen fluoride has also been examined in detail,510 and a cis configuration confirmed for the diprotonated cation. Both... 

Liquid chlorine trifluoride is soluble in all proportions in liquid hydrogen fluoride. The phase equilibria of the system, chlorine trifluoride-hydrogen fluoride, were investigated by McGill et al. [95],... 

Toluene derivatives bearing electronegative substituents are fluorinated on the methyl group when reacted with lead(IV) oxide, nickcl(IV) oxide, cobalt(IIl) fluoride, cobalt(lll) acetate. silver(II) fluoride, or silver(ll) oxide in liquid hydrogen fluoride. The product obtained is dependent on the substrate and the metal oxidant employed, with benzyl fluorides I or (difluoromethyl)benzenes 2 as the major products. 

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