Grades hydrogen fluoride

Commercially available hydrogen fluoride usually is not suitable for catalytic hydrogenation because of its sulfur dioxide content An oxidative treatment with manganese dioxide and distillation are needed for the preparation of hydrogena tion-grade hydrogen fluoride [d, 4]... 

Commercial grade salt containing 1% NH4F is made by gas-phase reaction of one mole of anhydrous ammonia with two moles of hydrogen fluoride NH3- 2HF NH4HF2... 

Commercial grade anhydrous hydrogen fluoride contains less than 0.5 wt% water and only small amounts of inorganic impurities. Thus, it can be used without purification in most fluorination reactions. Further purification for special purposes is customarily carried by fractional distillation.2 The water content and the purity are determinated by Karl-Fischer titration1 2 7 or by conductivity measurements.u2,a... 

Thus, the reaction of 1,4-dioxane with sulfur tetrafluoride and hydrogen fluoride in the presence of small amounts of sulfur chlorides or chlorine (0.3 0.5 %) at 185-220°C results in the replacement of 3-5 hydrogen atoms by fluorine to give mixtures of a polyfluoro-1,4-dioxane 1 or 3 and 2-fluoroethyl-l,2,2,2-tetrafluoroethyl ether (2) in a ratio dependent on the reaction temperature.237 Using technical grade sulfur tetrafluoride without addition of a sulfur chloride or chlorine, this reaction is not reproducible, but when carefully purified sulfur tetrafluoride is used the reaction does not give fluorinated products, instead a tar is formed.237... 

Reagents. Hydrogen fluoride can be obtained in convenient steel containers equipped with dependable needle valves. Excellent grades of the crystalline anhydrous fluorides of zinc and antimony are available commercially. 

Industrially hydrogen fluoride is manufactured by the reaction of sulfuric acid with fluorspar (acid grade) ... 

Derivation (1) Reaction of carbon tetrachloride and anhydrous hydrogen fluoride, in the presence of an antimony halide catalyst (2) high-temperature chlorination of vinyhdene fluoride (vinyhdene fluorides made by addition of hydrogen fluoride to acetylene). Grade 99.9% min purity. 

Polystyrene films were prepared by doubly dipping the substrate—a silicon wafer previously cleaned by pure solvents and etched by hydrogen fluoride—into solutions of 1 gL of pure polystyrene in carbon tetrachloride (spectroscopic grade) and allowing the solvent to evaporate. Thickness of the films thus obtained was estimated to be of the order of 100 A by elastic recoil diffiision analysis (ERDA) measurements [122]. 

Anhydrous hydrogen fluoride is available from a number of suppliers with grades ranging from 99.0 percent to 99.96 percent. The major impurities are water H2O) and sulfiir dioxide (SO2). A normal specification for 99.90 mole percent hydrogen fluoride is as follows ... 

Hydrogen fluoride is produced as by the action of sulfuric acid on pure grades of the mineral fluorite and also as a side-product of the extraction of the fertilizer precursor phosphoric acid from various minerals. 

Electronic-grade boron trifluoride gas (99.99-1-%), anhydrous pyridine (99.8%), anhydrous dichloromethane (99.8-1-%). It is essential to use dry solvents and reactants (including the mercury placed at the bottom of the calorimetric cell, to be dried under vacuum) because traces of humidity (and also other impurities) tend to induce an additional heat of reaction. Moreover, boron trifluoride releases hydrogen fluoride by slow hydrolysis, resulting in etching of the glass parts of the system. 

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