Ferrous sulphate reduction

Nitric oxide is made commercially by oxidation of ammonia above 500°C in the presence of platinum, or by reduction of nitrous acid with ferrous sulphate or feiTous halides. The physical ... 

For the reduction of nitro-compounds containing a group which may be attacked by nascent hydrogen, as, for example, an aldehyde group, an unsaturated side chain, and so on, special methods must he applied. In such cases ferrous hydroxide or iron powder (cf. Chap. VII. 5, arsanilic acid) are often used. The reduction is carried out thus a weighed amount of ferrous sulphate is caused to act, in the presence of alkali (potassium or sodium hydroxide, baryta), on the substance to he reduced. In this way it is possible to reduce, for example, o-nitro-benzaldehyde to aminobenzaldehyde, and o-nitrocinnamic acid to amino-cinnamic acid. 

Iron Vanadate is, metallurgically, the most important vanadate. Precipitation of a solution of a vanadate with ferrous sulphate gives rise to a precipitate of indefinite composition, ortlio-, pyro-, meta-, and perhaps a poly-vanadate being present, as well as ferric or ferrous oxide. Reduction of the vanadate to a vanadyl salt may also ensue. The precipitate is usually colloidal and carries down with it some sodium vanadate. The dried powder may be either green, yellow, brown, or red the more nearly the precipitate approximates to a red colour the lower is its vanadium content. An iron vanadate has also been prepared by electrolysis of a solution of sodium vanadate between iron poles.1... 

When heated, the salt first melts and at a higher temperature it decomposes to form silver 7 reduction to the metal occurs more readily when heated with carbon.8 Partial reduction also occurs when the orthoarsenate is treated with formaldehyde 9 or with ferrous sulphate solution 10 in the former ease silver is formed, but in the latter silver suboxide. 

To estimate arsenite and arsenate when present together, the former may first be determined in a portion of the solution by titration with iodine in the presence of sodium bicarbonate. Another portion is acidified strongly with hydrochloric acid, some ferrous sulphate and potassium bromide are added and the whole of the arsenic is distilled off as chloride and collected in water.2 The reduction may also be accomplished by cuprous chloride.3 The arsenious acid in the aqueous distillate is determined as above and the arsenic acid found by difference. 

By Reduction to Nitrite. This is based on reduction of the nitrate to nitrite by ferrous sulphate and sulphuric add and on the colour reaction of nitrous add with starch paste and iodide. 

Certain iron compounds have been used for reduction. Ferrous sulphate in aqueous solution, with ammonia, baryta, or sodium hydroxide, may be used for reducing, as also may ferrous potassium oxalate in neutral, alkaline, or weakly acid solution. 

The following are examples of the reduction of nitro-compounds by ferrous sulphate nitro-phenyl propiolic acid1 and nitro-dichlor-benzaldeliyde2 the method has been used to reduce several nitro-acids to the corresponding amino-acids.3... 

When mildly reduced, for example with sodium sulphide or hydrosulphite or with ferrous sulphate, picric acid is converted into picramic acid, a very useful intermediate in the dyestuffs industry and a starting material for the preparation of dinitrodiazophenol, a primary explosive (Vol. III). Stronger reduction may lead to the formation of triaminophenol. 

The most unstable form of the amorphous variety is colloidal silver, prepared by reduction of an ammoniacal or dilute alcoholic solution of silver nitrate with sodium citrate, sodium potassium tartrate, dextrin, tannin, or formaldehyde, with subsequent addition of ferrous sulphate.13 If forms a chocolate, pale-lilac, blue, or green mass, and dissolves in water to a deep-red solution. The colour depends partly on the mode of... 

The presence of gold in any of the precipitates described can be detected by solution in aqua regia, and reduction to metallic gold by various reagents, including ferrous chloride, ferrous sulphate, mercurous nitrate, stannous chloride, hypophosphorous acid, oxalic add,3 sulphurous acid, hydrogen peroxide and potassium hydroxide, formaldehyde, and hydroxylamine hydrochloride.4... 

In photography ferrous sulphate is used for the reduction of auric chloride, metallic gold being precipitated. Thus... 

Ferrous pyrophosphate, Fe2P207, is obtained 5 as an unstable white powder by double decomposition of ferrous sulphate and sodium pyrophosphate by heating ferrous orthophosphate and by reduction of ferric phosphate with hydrogen. Upon exposure to air it turns green and ultimately brown. 

Reduction of these nitro-acids gives the amino-acids, the usual reducing agent being ferrous sulphate in alkaline solution, but in one ease sodium amalgam in methyl alcohol has been used. The hydroxy-acids are isolated from the amino-acids by the aid of the diazo reaction. The acids are crystalline solids, usually soluble in water. The following scheme shows the compounds known ... 

Amino-2-carboxyphenylarsinic acid is the reduction product of the preceding nitro-acid, using ferrous sulphate in alkaline solution. It is an intermediate in the preparation of 2 2 -dicarboxy-4 4 -dihydroxyarsenobenzene, but is not isolated in the solid state (p. 855). 

AmIno-3-hydroxy-l 4-benzisoxazine-6-arsinic acid results when 2 6-diacetamidophenoxyacetic acid-4-arsinic acid is treated with boiling 5N sodium hydroxide or SN hydrochloric acid. It may also be prepared in the usual way, by ferrous hydroxide reduction of the 8-nitro derivative. It forms staggered plates, unmelted at 800° C., insoluble in water, but dissolving in dilute mineral acids and alkalis. The sulphate crystallises in rhombs, sparingly soluble in water, the barium salt forms colourless prisms, lie calcium soli white needles, and the magnesium salt is amorphous. 

Indoine is formed by reduction of orthonitrophenylpropiolic acid with ferrous sulphate in sulphuric acid solution. It closely resembles indigo, but may be distinguished by the following reactions —It dissolves in cold concentrated sulphuric acid with a blue colour (indigo gives a green solution), and is only converted into a sulphonic acid with difSculty. It is also easily soluble in aniline and in aqueous sulphurous acid, forming blue solutions. 

The reduction is effected by adding to the substance to be reduced, in tire presence of an alkali (potassium-, sodium-, or barium-hydroxide), a weighed quantity of ferrous sulphate. By this reaction, o-nitro-benzaldehyde is reduced to o-amidobenzaldehyde o-nitrocinnamic acid to o-amidocinnainic acid. 

Su C, Ludwig RD. (2005). Treatment of hexavalent chromium in chromite ore processing residue solid waste using a mixed reductant solution of ferrous sulphate and sodium dithionite. Environmental Science and Technology 39 6208-6216. 

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