Ferric sulphite

Dithionic Acid, H2S2O0, is obtained only in aqueous solution. If sulphur dioxide is passed into an aqueous suspension of ferric hydroxide at 0° C., a red solution of ferric sulphite is first produced, which then changes to a pale green solution of ferrous sulphite and ferrous dithionate 4... 

Ferric sulphite, Fe2(S03)3, has not been isolated. It is obtained in unstable solution on dissolving ferric hydroxide in sulphurous acid. If the ferric hydroxide is pure and well washed, it dissolves exceedingly... 

Basic ferric sulphites,such asFe2(S03)3.7Fe(0H)3andFe2(S03)3.6Fe(0H)3, have been prepared.4... 

A well-defined series of complex alkali salts of ferric sulphite has been prepared,5 analogous to the ferri-sulphate derivatives of ferric sulphate (see p. 162), but containing one S04 radicle. 

Reduction to S(IV) is the basis of two spot tests of Feigl, although these apply to other S(VI) classes, e.g. sulphonamides. Thus Feigl and Lenzer fused the sample with alkali to yield sulphite, then treating with hydrochloric acid and warming to expel sulphur dioxide they detected the latter with nickel(II) hydroxide on test paper, which yielded ultimately the black Ni(IV) oxyhydrate (see also Section C). In the other test FeigF fused the sample with sodium formate/alkali, cooled and acidified with sulphuric acid to liberate sulphur dioxide in this case also. This was detected by a ferric chloride/potassium ferricyanide reagent which yielded a blue colour (Prussian, Turnbull s). 

The sodium chloride and sulphate regularly found in Leblanc soda ash are not usually injurious the insoluble matter should not exceed 1 to 1J per cent. It consists principally of calcium carbonate, alumina, silica, and ferric oxide. The sulphides should not be detectable by lead paper thiosulphates are destroyed in calcining the ash sulphites are usually present and can be detected by iodine soln. and sodium hydroxide, except in the so-called caustic ash, does not usually exceed 1 per cent. The moisture in fresh ash ranges below one per cent. Owing to the mode of preparation, ash by Solvay s process is more pure than that prepared by Leblanc s process. It does not contain sodium hydroxide, sulphides, sulphites, or thiosulphates it may contain a slight excess of carbon dioxide a little sodium sulphate is always present iron, alumina, and silica are present in minute traces sodium chloride is perhaps the only... 

Qualitative Tests.—The solution of the extract is reddish-yellow with a more or less brown tint by acids it is turned to orange and rendered slightly turbid and by alkalies crimson. Stannous chloride gives a red precipitate with the solution, ferric chloride a reddish-brown precipitate and alum and then sodium carbonate a red precipitate. The solution of the extract is decolorised by chloride of lime and also by sodium sulphite (difference from red sandalwood and the like). 

Sulphur dioxide may be passed into a solution of a ferric salt for a similar purpose, or it may be generated in the solution by addition of an alkali sulphite and a little dilute mineral acid.6 Thus, ferric sulphate is reduced in accordance with the equation... 

Potassium ferri-disulphite, K3Fe(S03)2S04, results when a solution of potassium ferro-heptanitroso sulphide is digested at 4° C. with sodium hydrogen sulphite for about a month. It yields lustrous, dark yellow leaflets which are practically insoluble in cold water, but in boiling water are decomposed, yielding ferric hydroxide and a soluble ferric salt. 

Potassium ferri-sulphite, KFe(S03)S04, is prepared by the action of potassium hydrogen sulphite upon ferric ammonium alum. It crystallises in slender needles, which are sparingly soluble in cold water. With hot water, ferrous and potassium sulphates pass into solution, leaving an insoluble yellow residue. 

Ammonium ferri-sulphite, NH4.Fe(S03)S04.H20, may be obtained by treating ferric ammonium alum with ammonium hydrogen sulphite. It crystallises in slender, yellow needles which are but slightly soluble in cold and hot water. Prolonged boiling decomposes the salt. 

Iron and Sulphur—Subsulphides of Iron—Ferrous Sulphide—Ferric Sulphide-Double Sulphides—Iron Pyrites—Marcasite—Magnetic Pyrites—Ferrous Sulphite—Ferri-sulphites—Ferrous Sulphate—Double Sulphates—Fern-sulphates—Alums—Anndo-sulphonates, Thiosulphate, Disulphate, and Thionates of Iron. 

Reaction of nitrosyl disulphonate, 0N(S03), with hydroxylamine-N-sulphonate is reported to be subject to catalysis by ferric salts at low concentrations, and to depend on the alkalinity through the hydrolysis of the catalyst . In mildly alkaline solution (pH 6-11), the rates of decomposition of this sul-phonate have been shown to be consistent with the existence of two reaction paths, one forming NO and the other sulphite radicals . The processes are assumed to represent bimolecular nucleophilic substitution by water. 

In practice this determination is carried out by adding to a weighed quantity of the chloropicrin in a small flask fitted with a condenser, an excess of an aqueous-alcoholic solution of sodium sulphite, prepared by dissolving 10 gm. sodium sulphite in 250 ml. water and diluting with an equal volume of ethyl alcohol. The liquid in the flask is then carefully heated so as to distil off all but about 10 ml. This is then diluted with water to 100 ml. and 10 ml. of nitric acid and an excess of a standardised solution of silver nitrate are added. The solution is then warmed to drive off the nitrous gases and to coagulate the silver chloride, and then cooled and the excess silver nitrate titrated with a solution of ammonium thiocyanate (ferric alum indicator). 

The problems of identification are not nearly so acute when dealing with metalloproteins as they have a wide range of g values, and a number of these have been observed in whole tissue. Thus, the low spin ferric form of cytochrome P-450 has been observed in liver and its concentration found to be reduced in Morris hepatomas [82]. Adrenal ferredoxin in adrenal glands [83], sulphite oxidase in liver [84], iron-sulphur proteins in pigeon heart [85], methaemoglobin and erythrocyte catalase in whole blood are further examples in mammals. 

Three studies on the oxidation of sulphite have been published. A kinetic expression for the oxidation of solid sodium sulphite by oxygen was the result of the first study,whilst the effects of copper ions and ferric ions " on the autoxidation of sulphite were the subject of the remaining papers. 

It is also manufactured by heating a-naphthol with an aqueous solution of ammonia and ammonium sulphite at 120°-150° in an antoclave. It possesses a disagreeable fsecal-like odor, sublimes readily, and turns brown in the air. It crystallizes in colorless needles or prisms, melts at 50°, and boils at 300°. Solutions of its salts give a blue precipitate with ferric chloride and other oxidizing agents. 

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