Iron anhydrous

The reaction provides a valuable method of preparing anhydrous chlorides of metals. It has been used to prepare the anhydrous chlorides of copper(II), zinc, cadmium, chromium(III), iron(III). cobalt(Il) and nickel. 

Anhydrous hydrogen fluoride (as distinct from an aqueous solution of hydrofluoric acid) does not attack silica or glass. It reacts with metals to give fluorides, for example with heated iron the anhydrous iron(II) fluoride is formed the same product is obtained by displacement of chlorine from iron(II) chloride ... 

Anhydrous hydrogen chloride is not particularly reactive, either as a gas at ordinary temperatures, or a liquid (b.p. 188 K) and does not react with metals such as iron or zinc, nor with dry oxides. A few reactive metals such as sodium, will bum in the gas to give the chloride and hydrogen ... 

The solid anhydrous halides of some of the transition metals are often intermediate in character between ionic and covalent their structures are complicated by (a) the tendency of the central metal ion to coordinate the halide ions around it, to form an essentially covalent complex, (b) the tendency of halide ions to bridge, or link, two metal ions, again tending to covalency (cf. aluminium chloride, p. 153 and iron(III) chloride, p. 394). 

Iron(III) chloride forms numerous addition compounds, especially with organic molecules which contain donor atoms, for example ethers, alcohols, aldehydes, ketones and amines. Anhydrous iron(III) chloride is soluble in, for example, ether, and can be extracted into this solvent from water the extraction is more effective in presence of chloride ion. Of other iron(III) halides, iron(III) bromide and iron(III) iodide decompose rather readily into the +2 halide and halogen. 

The thiocyanate ion SCN forms an intensely red-coloured complex (most simply represented as [Fe(SCN)(H20)5] ) which is a test for iron(III). However, unlike cobalt(III), iron(lll) does not form stable hexammines in aqueous solution, although salts containing the ion [FefNHj) ] can be obtained by dissolving anhydrous iron(III) salts in liquid ammonia. 

Other iron(If) salts include, notably the green sulphate heptahydrate FeS04.7H2O which on heating yields first the white anhydrous salt FeS04 and then decomposes ... 

Place 84 g. of iron filings and 340 ml. of water in a 1 - 5 or 2-litre bolt-head flask equipped with a mechanical stirrer. Heat the mixture to boiling, stir mechanically, and add the sodium m-nitrobenzenesulphonate in small portions during 1 hour. After each addition the mixture foams extensively a wet cloth should be applied to the neck of the flask if the mixture tends to froth over the sides. Replace from time to time the water which has evaporated so that the volume is approximately constant. When all the sodium salt has been introduced, boU the mixture for 20 minutes. Place a small drop of the suspension upon filter paper and observe the colour of the spot it should be a pale brown but not deep brown or deep yellow. If it is not appreciably coloured, add anhydrous sodium carbonate cautiously, stirring the mixture, until red litmus paper is turned blue and a test drop upon filter paper is not blackened by sodium sulphide solution. Filter at the pump and wash well with hot water. Concentrate the filtrate to about 200 ml., acidify with concentrated hydrochloric acid to Congo red, and allow to cool. Filter off the metanilic acid and dry upon filter paper. A further small quantity may be obtained by concentrating the mother liquid. The yield is 55 g. 

Anhydrous liquid ammonia (note 2) (900 ml) was drawn from a cylinder and introduced into the flask. Iron(III) nitrate (lOO mg) was added and, as soon as a uniformly brown solution had formed (after stirring for a few seconds), about 0.7 g of lithium (from the starting amount of 7 g) was cut into two or three pieces and immediately introduced into the flask. After 10-15 min the blue colour had disappeared completely and a white suspension of lithium amide had formed. The remainder of the 7 g (1 mol) of lithium was then cut up and introduced. In most cases the conversion was finished v/ithin about 30 min (note 3). 

Specifications, Shipping, and Analysis. Hydrogen fluoride is shipped in bulk in tank cars (specification 112S400W) and tank tmcks (specification MC312). A small volume of overseas business is shipped in ISO tanks. Bulk shipments are made of anhydrous HF as well as 70% aqueous solutions. A small amount of aqueous solution may be shipped as 50%. Cars and tmcks used for anhydrous HF transport are of carbon steel constmction. It is possible to ship 70% aqueous in steel from a corrosion standpoint however, mbber lining is commonly used to eliminate iron pickup, which is detrimental to product quaUty in a number of appHcations. Hydrogen fluoride of less than 60% strength must always be shipped in lined containers. 

Anhydrous iron(II) fluoride [7789-28-8] white soHd. The off-white to buff-colored appearance of the material is attributed to the partial... 

Fep2 was first prepared by the action of gaseous hydrogen fluoride over FeCl2 ia an iron boat (2). The reaction of anhydrous FeCl2, FeCl2 4H20, or FeSO and anhydrous HF in plastic reaction vessels such as vessels of polyethylene, polypropylene, or Teflon results in quantitative yields of very... 

Colorless crystals of iron(II) fluoride tetrahydrate [13940-89-1Fep2 4H2O, can be obtained by dissolving metallic iron or the anhydrous salt in hydrofluoric acid. The crystals of Fep2 4H2O are sparingly soluble in water and decompose to Fe202 when heated in air. 

Anhydrous FeF is prepared by the action of Hquid or gaseous hydrogen fluoride on anhydrous FeCl (see Iron compounds). FeF is insoluble in alcohol, ether, and ben2ene, and sparingly soluble in anhydrous HF and water. The pH of a saturated solution in water varies between 3.5 and 4.0. Low pH indicates the presence of residual amounts of HF. The light gray color of the material is attributed to iron oxide or free iron impurities in the product. 

Acetates. Anhydrous iron(II) acetate [3094-87-9J, Ee(C2H202)2, can be prepared by dissolving iron scraps or turnings in anhydrous acetic acid ( 2% acetic anhydride) under an inert atmosphere. It is a colorless compound that can be recrystaUized from water to afford hydrated species. Iron(II) acetate is used in the preparation of dark shades of inks (qv) and dyes and is used as a mordant in dyeing (see Dyes and dye intermediates). An iron acetate salt [2140-52-5] that is a mixture of indefinite proportions of iron(II) and iron(III) can be obtained by concentration of the black Hquors obtained by dissolution of scrap iron in acetic acid. It is used as a catalyst of acetylation and carbonylation reactions. 

Tetrasodium hexakiscyanoferrate decahydrate [14434-22-1], Na4[Fe(CN)g] IOH2O, or yellow pmssiate of soda, forms yellow monoclinic crystals that are soluble in water but insoluble in alcohol. It is slightly efflorescent at room temperature, but the anhydrous material, tetrasodium hexakiscyanoferrate [13601 -19-9], Na4[Fe(CN)J, is obtained at 100°C. The decahydrate is produced from calcium cyanide, iron(II) sulfate, and sodium carbonate in a process similar to that for the production of K4[Fe(CN)g] 3H2O. It is used in the manufacture of trisodium hexakiscyanoferrate, black and blue dyes, as a metal surface coating, and in photographic processing. 

Formates. lron(Il) formate dihydrate [13266-734], Fe(HC02)2 2H20, is a green salt which can be prepared from iron(Il) sulfate and sodium formate in an inert atmosphere. The compound is slightly soluble in water and fairly resistant to air oxidation. The anhydrous salt [3047-594] is known. 

Halides. AH of the anhydrous and hydrated binary haUdes of iron(Il) and iron(Ill) are known with the exception of the hydrated iodide of iron(Ill). A large number of complex iron haUdes have been prepared and characterized (6). 

Iron(III) fluoride [7783-50-8] prepared from FeCl and anhydrous HF or other fluorinating agents ia a flow system at elevated temperature. 

Fused Salt Electrolysis. Only light RE metals (La to Nd) can be produced by molten salt electrolysis because these have a relatively low melting point compared to those of medium and heavy RE metals. Deposition of an alloy with another metal, Zn for example, is an alternative. The feed is a mixture of anhydrous RE chlorides and fluorides. The materials from which the electrolysis cell is constmcted are of great importance because of the high reactivity of the rare-earth metals. Molybdenum, tungsten, tantalum, or alternatively iron with ceramic or graphite linings are used as cmcible materials. Carbon is frequently used as an anode material. 

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