Polysulphide, reaction

However, the sulphide ion can attach to itself further atoms of sulphur to give polysulphide ions, for example Sj , Sj , and so these are found in solution also. Further, the sulphite ion can add on a sulphur atom to give the thiosulphate ion, S203 which is also found in the reaction mixture. 

It is convenient to include under Aromatic Amines the preparation of m-nitroaniline as an example of the selective reduction of one group in a polynitro compound. When wt-dinitrobenzene is allowed to react with sodium polysulphide (or ammonium sulphide) solution, only one of the nitro groups is reduced and m-nitroanUine results. Some sulphur separates, but the main reaction is represented by ... 

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. 

Prepare a saturated solution of sodium sulphide, preferably from the fused technical sodium polysulphide, and saturate it with sulphur the sulphur content should approximate to that of sodium tetrasulphide. To 50 ml. of the saturated sodium tetrasulphide solution contained in a 500 ml. round-bottomed flask provided with a reflux condenser, add 12 -5 ml. of ethylene dichloride, followed by 1 g. of magnesium oxide to act as catalyst. Heat the mixture until the ethylene dichloride commences to reflux and remove the flame. An exothermic reaction sets in and small particles of Thiokol are formed at the interface between the tetrasulphide solution and the ethylene chloride these float to the surface, agglomerate, and then sink to the bottom of the flask. Decant the hquid, and wash the sohd several times with water. Remove the Thiokol with forceps or tongs and test its rubber-like properties (stretching, etc.). 

In 1928 J. C. Patrick attempted to produce ethylene glycol by reacting ethylene dichloride with sodium polysulphide. In fact a rubbery polymer was formed by the reaction ... 

The general method of preparation of the polysulphides is to add the dihalide slowly to an aqueous solution of sodium polysulphide. Magnesium hydroxide is often employed to faeilitate the reaction, which takes 2-6 hours at 70°C. 

During emulsion polymerization, a high conversion of monomer to polymer produces cross-linked rubber which is insoluble. To obtain a high conversion in the polymerization reaction and a processable polymer, suitable polymer modification should be made. The use of sulphur moieties allows this goal to be reached [2]. Sulphur-modified polychloroprenes contain di- and polysulphide sequences in the polymer chains. After the polymerization reaches the desired degree, reaction is stopped by adding thiuram disulphide ... 

Polymerisation resulting from a chemical reaction involving condensation. The synthetic elastomers produced by condensation polymerisation include polysulphide rubbers, silicone rubbers and the ester and isocyanate rubbers. 

These materials are formed by the reaction of a dihalide with sodium polysulphide, the main chain of the polymer formed from this reaction containing the following grouping ... 

A similar study of the dye Cl Sulphur Orange 1, obtained by heating 2,4-diaminotoluene with sulphur led to the isolation of compound 6.136 after reaction of the alkali melt of the dye with chloroacetic acid. It was concluded that the commercial dye is a polybenzothiazole. The final hue of the product depends on the temperature and the duration of the sulphurisation the use of a smaller proportion of sulphur produces Cl Sulphur Brown 10. A similar product (Cl Sulphur Brown 8) is obtained when 2,4-dinitrotoluene is baked with sodium polysulphide. A brown sulphur dye of high fastness to light (Cl Sulphur Brown 52) results when the polycyclic hydrocarbon decacyclene (6.137) is baked with sulphur at 350 °C [57]. 

Cl Sulphur Black 1, which is produced from the relatively simple intermediate 2,4-dinitrophenol and aqueous sodium polysulphide. A similar product (Cl Sulphur Black 2) is obtained from a mixture of 2,4-dinitrophenol and either picric acid (6.148 X = N02) or picramic acid (6.148 X = NH2). A black dye possessing superior fastness to chlorine when on the fibre (Cl Sulphur Black 11) can be made from the naphthalene intermediate 6.149 by heating it in a solution of sodium polysulphide in butanol. An equivalent reaction using the carbazole intermediate 6.150 gives rise to the reddish blue Cl Vat Blue 43 (Hydron blue). This important compound, which also possesses superior fastness properties, is classified as a sulphurised vat dye because it is normally applied from an alkaline sodium dithionite bath. Interestingly, inclusion of copper(II) sulphate in the sulphurisation of intermediate 6.150 leads to the formation of the bluish black Cl Sulphur Black 4. 

Photocorrosion can be prevented by adding a redox couple to the electrolyte whose potential is more favourable than the decomposition potential such that the redox reaction occurs preferentially. When n-CdS is used as photoanode in aqueous electrolytes, the electrode is photocorroded since the reaction, CdS -1- 2h - S -1- Cd, occurs readily. By adding NaOH and sodium polysuphide to the electrolyte (Ellis et al, 1976), photocorrosion is prevented. The /S redox couple preferentially scavenges the photoholes. At the anode, sulphide is oxidized to polysulphide (free sulphur) and free sulphur is reduced back at the dark cathode. Similarly n-Si anodes have been stabilized by using a nonaqueous electrolyte containing a ferricinium/ferrocene redox couple (Legg et al, 1977 Chao et al, 1983). Unfortunately, a similar stabilization technique cannot be applied to photoelectrolysis cells. Some examples of electrode... 

According to G. Calcagni, 100 c.c. of a cold 66 per cent, of sodium hydroxide dissolves 24 55 grms. of sulphur or 57 parts of sulphur per 23 parts of sodium while 100 c.c. of a similar soln. of potassium hydroxide dissolves 17 70 grms. of sulphur, or 59 35 parts of sulphur per 39 15 parts of potassium. The soln. reacts for sulphides, polysulphides, thiosulphates, and sulphites. The reaction between alkali hydroxides and sulphur is complex probably sulphides are first formed from which thiosulphates are produced, and by the dissolution of more sulphur, polysulphides the thiosulphates Ipse part of their sulphur forming sulphites. In the more cone. soln. of sulphur part of the latter appears to be uncombined because these soln. yield sulphur to hot benzene. All the soln. are decomposed by carbon dioxide yielding sulphur and hydrogen sulphide. 

Explain the different reaction of ammonium sulphide and polysulphide with tin(II) sulphide and tin(IV) sulphide. 

Hydrogen trisulphide is much more easily combustible than the crude parent hydrogen polysulphide. Exposure to light tends to accelerate its decomposition. It slowly reduces concentrated sulphuric acid to sulphur dioxide, whilst on contact with dry silver oxide, cupric oxide, lead dioxide or mercuric oxide, it bursts into explosive combustion,2 a residue of the metallic sulphide being obtained. Many other metallic oxides and most salts bring about a less vigorous decomposition metals in the massive condition only react with it slowly. With potassium permanganate or dichromate the reaction is violent. 

Of these, the first reaction is the one usually recorded, and in the majority of cases it is the one that occurs to the largest extent. The presence of alkali pushes the equilibrium well to the left, so that in alkaline solution the thiosulphate is stable. This explains the formation of thiosulphates on boiling alkaline sulphite solutions with sulphur. The laws of chemical equilibria, however, demand the presence of perfectly definite although perhaps very small quantities of sulphite and free sulphur in solution, and if alkaline thiosulphate solutions containing alkali sulphide are boiled in the absence of air, they become deep yellow, owing to polysulphide formation, the extra sulphur for which is obtained from the thiosulphate. Assuming the sodium derivatives to be used, the equation may be written... 

In the oxidation of alkali sulphides or polysulphides by potassium permanganate solution at the ordinary temperature, trithionic acid has been found amongst the reaction products, in addition to sulphuric acid and sulphur.7... 

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. 

During the reduction, nitrite ions and polysulphides are produced. The hydrolysis reaction (17) is rather slow, if performed in a medium of alkaline hydroxides alone. It can proceed considerably more rapidly if carried out in the presence of HS ions (18). 

Wh/kg. As indicated in the sodium-sulphur phase diagram given in Fig. 8.15, sodium pentasulphide and sulphur are not mutually soluble at the temperature of cell operation, so that two liquid phases are present in the cathode compartment and the cell voltage is invariant. As the discharge progresses and the available elemental sulphur is consumed, a series of reactions commences as the sodium pentasulphide is converted to lower polysulphides, all of which are mutually soluble ... 

---