Sulphur dioxide addition

Sulphuranes - see also Dialkoxysulphuranes, Oxysulphuranes as intermediates 406 Sulphur bonding 484-493 Sulphur-containing groups, stereoelectronic effects of 584-594 Sulphur dioxide addition to 215-217 extrusion of 137, 140, 141, 158, 163, 397-402, 801, 805, 962, 1098 Sulphur monoxide, extrusion of 397-402 Sulphur trioxide, reactions of 217, 218 Sultenes, as intermediates 743 Sultines 679, 943 as photolytic products 881, 882... 

In the case of sulphur dioxide addition only the second limit is affected, so that a gas phase, termolecular chain breaking reaction must be... 

Clark TA and Mackie KL (1987) Steam explosion of the softwood Pinus radiata with sulphur dioxide addition process optimisation. Journal of Wood Chemistry and Technology, 7(3) 373-403... 

The emission of sulphur oxides may be controlled by adding substances into the combustion chamber, which are able to bind sulphur dioxide (additive method). Finely group limestone, calcium hydroxide, calcium oxide or sometimes dolomite may be used for this purpose. Limestone is calcinated at high temperature, yielding calcium oxide, which binds the sulphur dioxide. Sulphate, sulphite, non-reacted adsorbent and fly ash are separated in a separating system. The disadvantage of this process is its low efficiency (only about 20 to 40% SO2 are retained). 

Alternatively these salts can be prepared by first saturating a known volume of alkali with sulphur dioxide, giving a solution of the hydrogensulphite, from which sulphite can be prepared by the addition of a second equal volume of alkali. 

Barium sulphite is soluble in dilute hydrochloric acid unlike barium sulphate which is insoluble. Hence this reaction, and the evolution of sulphur dioxide on addition of an acid, distinguishes a sulphite from a sulphate. 

Most iodine produced commercially comes from the sodium iodate(V) remaining after sodium nitrate has been crystallised from Chile saltpetre. The iodatefV) is first reduced to iodide by blowing sulphur dioxide into the solution (or by addition of sodium sulphite) ... 

It is extensively used industrially as a catalyst, notably in the oxidation of sulphur dioxide to the trioxide in sulphuric acid manufacture. It is an essentially acidic oxide, dissolving in alkalis to give vanadates however, addition of acid converts the anionic vanadate species to cationic species, by processes which are very complex, but which overall amount to the following ... 

The addition of concentrated sulphuric acid to a solid dichromate mixed with a chloride produces a red vapour, chromium(VI)dioxide dichloride, Cr02Cl2 (cf. sulphur dioxide dichloride, SO2CI2). Chromium(VI) dioxide dichloride reacts with water immediately ... 

Oxidation of 10-undecynoic acid to sebacic acid. Dissolve 2 00 g. of the acid, m.p. 41-42°, in 50 ml. of water containing 0 -585 g. of pure anhydrous sodium carbonate. Saturate the solution with carbon dioxide and add O IN potassium permanganate solution (about 1500 ml.) slowly and with constant stirring until the pink colour remains for half an hour the addition occupies about 3 hours. Decolourise the solution with a httle sulphur dioxide and filter off the precipitated acid through a... 

Bisulphite compounds of aldehydes and ketones. These substances are decomposed by dilute acids into the corresponding aldehydes or ketones with the liberation of sulphur dioxide. The aldehyde or ketone may be isolated by steam distillation or by extraction with ether. Owing to the highly reactive character of aldehydes, the bisulphite addition compounds are best decomposed with saturated sodium bicarbonate solution so um carbonate solution is generally employed for the bisulphite compounds of ketones. 

Solvents mentioned include hexane, benzene, liquid sulphur dioxide, chloroform, methylene dichloride and ethyl bromide. Where chlorinated solvents are employed the polymer is separated by addition of methanol, filtered, washed with methanol and the product dried in vacuo at 60°C. 

A solution of magenta decolourised by sulphur dioxide becomes violet on the addition of a drop of aldehyde (Schiff . Prepare a weak solution of magenta by dissolving a crystal in half a test-tube of water and bubbling in sulphur dioxide until the colour disappears. Now add a few drops of aldehyde. 

Clarke and Andrew have developed a similar solution further activated by addition of chloride ions which deposits more substantial films shown to contain hexavalent chromium. The films give appreciable protection against salt spray and tarnishing by sulphur dioxide. 

Adams, J.B., Food-additive interactions involving sulphur dioxide and ascorbic acids a review. Food Chem., 59, 401, 1997. 

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. 

In addition to providing a detailed mechanism for the initial process of dissociation, the shock-tube studies have yielded a value360 for the absolute intensity of the sulphur dioxide afterglow... 

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