Hydrogen fluoride, anhydrous liquid

Liquid hydrogen fluoride (anhydrous hydrofluoric acid), which is industrially produced on a large scale, can be used as a fluorine source. 

Properties. Antimony pentafluoride [7783-70-2], SbF, is a colorless, hygroscopic, very viscous liquid that fumes ia air. Its viscosity at 20°C is 460 mPa-s(=cP) which is very close to the value for glycerol. The polymerization of high purity SbF at ambient temperature can be prevented by addition of 1% anhydrous hydrogen fluoride, which can be removed by distillation prior to the use of SbF. The pure product melts at 7°C (11), boils at 142.7°C,... 

Highly irritating and poisonous Very soluble in water. Liquid liberates heat as it dissolves in water. The entrapment of water in an anhydrous hydrogen fluoride cylinder can cause rapid generation of heat and pressure which can lead to an explosion. Containers should never be heated to >52°C. A liquid hydrogen fluoride spill area should not be entered unless protective clothing (impervious to the compound) and a self-contained gas mask are worn Fumes in air... 

Anhydrous hydrogen fluoride (135 ml., approx. 7 moles) is liquefied by passing the gas through an 8-ft. spiral of i-in. I.D. copper tubing surrounded by an isopropyl alcohol-dry ice bath (Note 2). The liquid is delivered to a 500-ml. polyethylene... 

Under a gentle stream of nitrogen and with stirring, the flask is charged with 400 ml. of methylene chloride, 41 ml. (65.5 g., 1.00 mole) of red fuming nitric acid (95%), and 22 ml. (22 g., 1.10 moles) of cold, liquid, anhydrous hydrogen fluoride (Note 5). 

Chlorine dioxide Copper Fluorine Hydrazine Hydrocarbons (benzene, butane, propane, gasoline, turpentine, etc) Hydrocyanic acid Hydrofluoric acid, anhydrous (hydrogen fluoride) Hydrogen peroxide Ammonia, methane, phosphine or hydrogen sulphide Acetylene, hydrogen peroxide Isolate from everything Hydrogen peroxide, nitric acid, or any other oxidant Fluorine, chlorine, bromine, chromic acid, peroxide Nitric acid, alkalis Ammonia, aqueous or anhydrous Copper, chromium, iron, most metals or their salts, any flammable liquid, combustible materials, aniline, nitromethane... 

HF anhydrous hydrogen fluoride heat generation, liberating toxic vapors heat generation, liberating toxic vapors strong acid corrosive toxic vapor and liquid ... 

Liquid anhydrous hydrogen fluoride, specific heat of, 14 3 Liquid argon, shipping, 17 364 Liquid atomization... 

The term hydrogen fluoride is used as the name for the substance containing hydrogen and fluorine, and the formula HF used regardless of the fact that the vapor has been shown to exist as an equilibrium of polymers. By implication the liquid and crystalline material are even more highly polymerized. When emphasis is needed to call attention to the fact that water free material is designated, the term anhydrous hydrogen fluoride is used. The term anhydrous hydrofluoric acid is self-contradictory as hydrofluoric acid is the name for the aqueous solution. In addition, completely anhydrous material is not always necessary or even desirable for catalytic work. The commercial material labeled anhydrous... 

Hydrofluoric acid in contact with water behaves anomalous when compared to the heavier halogens. The hydrogen-fluoride bond is relatively strong and ion pairs of the type H3 0+F exist rather than free hydronium ions [10]. Anhydrous HF is an electrically conducting liquid (3HF = H2F+ + HF2 occurs) with a normal boiling point of 19.5 °C. Scheme (1) summarizes the most important forms, the standard potentials in acidic aqueous media, and typical applications of fluorine. 

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. 

Anhydrous Hydrogen Fluoride, HF, mw 20.01 colorless, corrosive gas which forms at temp below 19.4°, colorless, fuming, corrosive, poisonous liquid, producing painful burns on the skin. It freezes at -83° and its sp gr is 0.988 at 3.6° (Lange). Both gas and liquid consist of associated molecules the vapor density corresponds, to HF only at high temps. 

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... 

The addition of bromine monofluoride to alkenes using equimolar quantities of /V-bro-moamides in excess anhydrous hydrogen fluoride gives the expected l-bromo-2-fluoroalkanes and small amounts (3-8 %) of isomeric 2-bromo-l-fluoroalkanes.29 1-Bromo-2-fluoroheptane can be prepared in 60-77% yield from hept-l-cnc, /V-bromoacetamide and hydrogen fluoride in diethyl ether at — 78"C.30 The bromofluorination of methyl methacrylate (1) with 1,3-di-bromo-5.5-dimethylhydantoin (DBH) and liquid hydrogen fluoride exemplifies this procedure.31... 

These are performed in anhydrous hydrogen fluoride (anhyd HF),24 and in inert solvents27-29 (hexane, CH2C12, CHC13, CC14, and various fluorocarbons and chlorofluorocarbons) at up to reflux temperatures. Liquid-phase fluorinations are not used as much as vapor-phase ones. 

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