Ammonium polysulphides

When an alkyl aryl ketone is heated with yellow ammonium polysulphide solution at an elevated temperature, an aryl substituted aliphatic acid amide is foimed the product actually isolated is the amide of the ci-aryl carboxylic acid together with a smaller amount of the corresponding ammonium salt of the oarboxylio acid. Thus acetophenone affords phenylacetamide (50 per cent.) and ammonium phenylacetate (13 per cent.) ... 

The conversion of a carbonyl compound by ammonium polysulphide solution into an amide with the same number of carbon atoms is known as the Willgerodt reaction. The procedure has been improved by the addition of about 40 per cent, of dioxan or of pyridine to increase the mutual solubility of the ketone and aqueous ammonium polysulphide the requisite temperature is lowered to about and the yield is generally better. 

A further improvement is embodied in the Klndler variation of the Willgerodt reaction this consists in heating the ketone with approximately equal amounts of sulphur and a dry amine instead of aqueous ammonium polysulphide. The principal product is a thioamide, and hydrolysis with acid or alkali affords the carboxylic acid, usually in good yield. 

The sulphide, dissolved in benzene or alcohol, reacts with hydrogen sulphide forming ammonium polysulphide or ammonium thiosulphate, respectively.2... 

According to Merrow and van Dolah [51] (+)2-octyl nitrate reacts with hydrazine at room temperature to yield 84% (+)2-octanol, whilst by the reaction of the laevo-rotatory nitrate and ammonium polysulphide as much as 99 parts of (-)2-octanol are produced. The fact that to a large extent the original rotation was preserved indicates that in the cases cited the initial step was rupture of the N—O bond. 

A Polysulphide, of formula PtS 15(NH4)a.2HaO, is described8 as resulting on addition of ammonium polysulphide to chlor-platinic acid. It yields large, red, rhombic crystals which, when dry, are stable. 

The precipitate is insoluble in ammonium sulphide, ammonium polysulphide, ammonia, potassium cyanide, or sodium thiosulphate. Silver sulphide can be precipitated from solutions containing diammine-, dicyanato- or dithiosulphato-argentate complexes with hydrogen sulphide. 

Cations of the second group are traditionally divided into two sub-groups the copper sub-group and the arsenic sub-group. The basis of this division is the solubility of the sulphide precipitates in ammonium polysulphide. While... 

The dissolution of sulphides in ammonium polysulphide can be regarded as the formation of thiosalts from anhydrous thioacids. Thus the dissolution of arsenic(III) sulphide (anhydrous thioacid) in ammonium sulphide (anhydrous thiobase), yields the formation of ammonium- and thio-arsenite ions (ammonium thioarsenite a thiosalt) ... 

AU the sulphides of the arsenic sub-group dissolve in (colourless) ammonium sulphide except tin(II) sulphide to dissolve the latter, ammonium polysulphide is needed, which acts partly as an oxidizing agent, thiostannate ions being formed ... 

Yellow ammonium sulphide (ammonium polysulphide), (NH4)2S2 dissolves the precipitate, when thioarsenate AsS ions are formed ... 

Arsenic pentasulphide, like the trisulphide, is readily soluble in alkali hydroxides or ammonia (a), ammonium sulphide (b), ammonium polysulphide... 

Hydrogen sulphide orange-red precipitate of antimony trisulphide, Sb2S3, from solutions which are not too acid. The precipitate is soluble in warm concentrated hydrochloric acid (distinction and method of separation from arsenic(III) sulphide and mercury(II) sulphide), in ammonium polysulphide (forming a thioantimonate), and in alkali hydroxide solutions (forming antimonite and thioantimonite). 

Hydrogen sulphide yellow precipitate of tin(IV) sulphide SnS2 from dilute acid solutions (0 3m). The precipitate is soluble in concentrated hydrochloric acid (distinction from arsenic(III) and mercury(II) sulphides), in solutions of alkali hydroxides, and also in ammonium sulphide and ammonium polysulphide. Yellow tin(IV) sulphide is precipitated upon acidification. 

Dilute hydrochloric acid hydrocyanic acid, HCN, with an odour reminiscent of bitter almonds, is evolved in the cold. It should be smelled with great caution. A more satisfactory method for identifying hydrocyanic acid consists in converting it into ammonium thiocyanate by allowing the vapour to come into contact with a little ammonium polysulphide on filter paper. The paper may be conveniently placed over the test-tube or dish in which the substance is being treated with the dilute acid. Upon adding a drop of iron(III) chloride solution and a drop of dilute hydrochloric acid to the filter paper, the characteristic red colouration, due to the iron(III) thiocyanate complex, Fe(SCN)3, is obtained (see reaction 6 below). Mercury(II) cyanide is not decomposed by dilute acids. 

Iron (III) thiocyanate test This is another excellent test for cyanides and depends upon the direct combination of alkali cyanides with sulphur (best derived from an alkali or ammonium polysulphide). A little ammonium polysulphide solution is added to the potassium cyanide solution contained in a porcelain dish, and the whole evaporated to dryness on the water bath in the fume cupboard. The residue contains alkali and ammonium thiocyanates together with any residual polysulphide. The latter is destroyed by the addition of a few drops of hydrochloric acid. One or two drops of iron(III) chloride solution are then added. A blood-red colouration, due to the iron(III) thiocyanate complex, is produced immediately ... 

If it is intended to use ammonium polysulphide in the separation of Groups IIA and IIB, the addition of H202 is not essential since (NH4)2S2 will oxidize SnS to SnS2 and the latter dissolves as the thiostannate SnSf. ... 

V.10 SEPARATION OF GROUP II CATIONS INTO GROUPS IIA AND IIIB Having precipitated the sulphides of the Group II cations (cf. Section V.8, Table V. 12) the next task is to separate these into Groups IIA (Hg2+, Bi3+, Pb2+, Cu2+ and Cd2+) and IIB (As3+, As5+, Sb3+, Sb5+, Sn2+, Sn4+). There are two methods recommended for the purpose, one making use of (yellow) ammonium polysulphide, the other making use of potassium hydroxide. 

If the ammonium polysulphide extract is boiled for some time in air, a red antimony oxide sulphide Sb2OS2 may be precipitated. 

If the precipitate is completely soluble in ammonium polysulphide, Group IIA is absent. 

For the separation of Group II cations into Groups IIA and IIB two methods were suggested (cf. Section V.10, Tables V.14 and V.15). To separate and identify the Group IIB cations, one of the two recommended procedures must be followed, according to the method chosen in the previous step. If the ammonium polysulphide method (method a) has been followed in Section V.10, then method (a) has to be applied here. Method (b), on the other hand, has to be used if the potassium hydroxide method was followed to separate Groups IIA and IIB. 

Table V.18 Separation of Group IIB cations with the ammonium polysulphide method...

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