Ammonium sulphite

Nitrophenylhydrazine may be similarly prepared from p-nitroplienyl-diazonium chloride by reduction with sodium or ammonium sulphite ... 

P-Nitronaphthalene is not formed by direct nitration. For the preparation of p-naphthylamine, the Bucherer reaction may be applied to p-naphthol, i.e., by heating with ammoniacal ammonium sulphite solution at 150° (under pressure). The reaction involves the addition of the bisulphite to the keto form of p-naphthol ... 

The alkaline sodium sulphite solution may be replaced by saturated amtnonlum sulphite solution prepared as follows. Pass sulphur dioxide into a mixture of 1 part of concentrated ammonia solution (sp. gr. 0-88) and two parts of crushed ice in a freezing mixture imtil the liquid smells strongly of sulphur dioxide, and then neutralise with ammonia solution. This solution slowly deposits ammonium sulphite crystals and contains about 0-25 g. of SOj per ml. Use 60 ml. of this ice-cold ammonium sulphite solution to which 8 ml. of concentrated ammonia solution are added. After the addition of the solution of p-nitrophenyldiazonium chloride, allow the mixture to stand for 1 hour in a freezing mixture, filter oft the yellow precipitate of ammonium p-nitrophenyUiydrazine disulphonate, heat it on a water bath with 20 ml. of concentrated hydrochloric acid at 70-80° for 7 minutes, cool the blood-red solution, and dissolve the resulting precipitate of p-nitrophenylhydr-azine hydrochloride and ammonium salts in water, and isolate the base as above. 

The napkthols are in many respects still more reactive than phenol. This is shown most distinctly by the fact that the naphthyl ethers can be obtained by the method used for the preparation of esters of carboxylic acids, namely, directly by the action of hydrogen chloride on the phenol in the presence of the alcohol. The naphthols, moreover, react readily with zinc-ammonium chloride and with ammonium sulphite and ammonia to yield naphthylamines. The second of these two methods is a general one. It was investigated by H. Bucherer. 

The addition of sodium monohydrogen arsenate to a solution of an aluminium salt results in the precipitation of a white powder which is probably aluminium hydrogen arsenate,5 Al2(HAs04)3. The powder dissolves in acids and the solution in hydrochloric acid when boiled with ammonium sulphite yields a precipitate of aluminium hydroxide, the arsenic remaining in solution. When heated in a current of hydrogen, arsenic is volatilised.6... 

The reaction is usually carried out under pressure, and the yield is improved by the presence of sodium or ammonium sulphite (Bucherer s method), the sulphurous esters of phenols reacting more readily than... 

Ammonium Sulphite.—S02 from a siphon is passed in a vigorous stream into 2 parts of cone, ammonia solution (D. 0-880) and 1 part of ice, surrounded by a freezing mixture. The solution gradually assumes a light yellow colour. When no more S02 is absorbed the solution is neutralised with cone, ammonia, giving a saturated solution of ammonium sulphite which sometimes deposits crystals on standing. 

The direct replacement of the hydroxyl group in simple phenols by an amino or substituted amino group requires drastic conditions and the method is not suitable for laboratory preparations. With the polyhydric phenols, and more particularly with the naphthols, such replacements occur more readily. Thus 2-naphthol is converted into 2-naphthylamine by heating with ammoniacal ammonium sulphite solution at 150°C in an autoclave. The reaction (the Bucherer reaction) depends upon the addition of the hydrogen sulphite ion to the keto form of the naphthol and the subsequent reaction with ammonia. 

It is also precipitated by the action of ammonia on a solution containing sodium chloride and ammonium sulphite in equimolecular proportions.10 Hartley and Barrett11 have described a method of preparation from sulphur dioxide and sodium carbonate. It is a white, crystalline salt. 

Ammonium sulphite, (NH4)2S03,Hs.O.—Neutralization of sulphurous acid by ammonia yields a solution from which the normal sulphite can be obtained as monohydrate in the form of prismatic crystals.1 At 120° C. the hydrated salt loses part of its water, and is partly converted into the pyrosulphite.2 It can be sublimed at 150° C. in a current of nitrogen, but the vapour is decomposed into sulphur dioxide, ammonia, and water.2 In the dry state the salt is more susceptible to oxidation than when moist.8 The slow oxidation to ammonium sulphate is much accelerated by keeping the solution alkaline with ammonia, by the presence of oxygen-carriers, and by pressure.4 Its heat of formation in the anhydrous form from its elements is 215-4 Cal.5 At 12° C. it dissolves in its own weight of water, yielding a solution of alkaline reaction. 

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