Hydrogen sulphites

It is readily oxidized by air to benzoic acid. With aqueous KOH gives benzyl alcohol and benzoic acid. Gives addition products with hydrogen cyanide and sodium hydrogen sulphite. 

CCls CHO. A colourless oily liquid with a pungent odour b.p. 98°C. Manut actured by the action of chlorine on ethanol it is also made by the chlorination of ethanal. When allowed to stand, it changes slowly to a white solid. Addition compounds are formed with water see chloral hydrate), ammonia, sodium hydrogen sulphite, alcohols, and some amines and amides. Oxidized by nitric acid to tri-chloroethanoic acid. Decomposed by alkalis to chloroform and a methanoate a convenient method of obtaining pure CHCI3. It is used for the manufacture of DDT. It is also used as a hypnotic. 

Sulphur dioxide, SO2, m.p. — 72-7°C, b.p. — I0"C. Colourless gas with characteristic smell. Formed by burning S, metal sulphides, H2S in air or acid on a sulphite or hydrogen sulphite. Powerful reducing agent, particularly in water. Dissolves in water to give a gas hydrate the solution behaves as an acid - see sulphurous acid. Used in the production of SO3 for sulphuric acid. 

Evaporation and crystallisation of the sodium sulphite solution gives crystals of the heptahydrate NajSOj.THjO. However, on evaporation of the hydrogensulphite solution, the solid obtained is chiefly sodium pentaoxodisulphate(IV) ( metabisulphite ) Na2S20j, and contains little if any of the hydrogensulphite. However, the hydrogen sulphite ion is obtained when the solid redissolves in water ... 

A solution of mcpba (11.5 mmol) in dichloromethane (30 ml) was added to a stirred solution of the vinylsilane (10 mmol) in dichloromethane (50 ml) at 0°C. After stirring for 1 h, the mixture was washed with aqueous sodium hydrogen sulphite (50 ml), saturated sodium hydrogen carbonate solution and brine. The organic solution was then dried and concentrated, prior to purification by distillation or chromatography. 

NDA derivatization has also been automated for analysis of amino acids in brain tissue and microdialysates (Shah et al, 1999). NDA reacts with primary amines in the presence of cyanide to form a highly stable N-substituted l-cyanobenz[/] isoindole (GBI) derivative. Addition of a nucleophile, such as cyanide, hydrogen sulphite, isothiocyanate, or 2-mercaptoethanol, is essential for the formation of the derivative. 

Carboxylalkyltellurium trichlorides, obtained by the reaction of tellurium tetrachloride with carboxylic acid anhydrides, are reduced to the corresponding ditellurides with potassium hydrogen sulphite. - ... 

This reagent, together with potassium hydrogen sulphite,has been used to reduce aryltellurium trichlorides since the early period of tellurium chemistry, and continues to find wide application. 

Sodium hydrogen sulphite,hypophosphorous acid and concentrated hydrobromic acid cleave 3-oxo-2,3-dihydrobenzoteUurophenes. 

Sorensen, P. E., and V. S. Andersen, The Formaldehyde-Hydrogen Sulphite System in Alkaline Aqueous Solution Kinetics, Mechanism, and Equilibria, Acta Cltem. Scand., 24, 1301-1306 (1970). 

The first heterohelicene (72) ever made was obtained by Fuchs and Niszel 56) in 1927 by heating 2,7-dihydroxynaphthalene with phenylhydrazine and sodium-hydrogen sulphite. The reaction was also investigated by Zander57). 

On the basis of these experiments a sheath was introduced in England filled with sodium hydrogen sulphite, a cheap substance and fairly efficient when in the form of a mantle about 2.5 mm thick, protected from the outside by non-impregna-ted watertight paper. The explosives which may be used with a sheath of this kind are designated by the symbol S (sheathed). 

Absorption of solvent nsing water and aqneons solutions. This method, though of no value for alcohol and ether, was used for the recovery of acetone in cordite manufacture in Great Britain. Acetone was also recovered by using a solution of sodium hydrogen sulphite. 

Again if reaction (1.21) is held in a pre-equilibrium state, the overall rate of conversion of A to B can show a cubic form. This realization of cubic autocatalysis seems to be of importance for the iodate-arsenite and iod-ate-hydrogen sulphite reactions. There the corresponding elementary steps include... 

The species HOI is then rapidly converted to iodide, by reaction first with I" to produce I2 which is then reduced by the arsenite of hydrogen sulphite. Thus, identifying A with the reactant iodate and B with iodide, the system shows a cubic autocatalysis with rate proportional to [IOJ][I-]2 at constant pH. 

A mixture of sodium sulphite and sodium hydrogen sulphite in aqueous solution at 150° C. undergoes a change in accordance with the equation ... 

The result is different if sodium hydrogen sulphite is used instead of sulphurous acid the addition of excess of mercuric chloride then gives rise to an equimolecular proportion of hydrochloric acid, the titration of which provides a convenient method for estimating the quantity of hydrogen sulphite originally present 8... 

By taking a sulphurous acid solution and titrating with sodium hydroxide and methyl orange until the sodium hydrogen sulphite is formed, then adding excess of mercuric chloride and completing the titration, sulphurous acid itself may be estimated. 

Another method which is applicable also to the estimation of solutions containing sulphites and hydrogen sulphites is the addition of a known excess of acidified hydrogen peroxide to the solution of sulphurous acid. The excess of peroxide may then be titrated with standard permanganate solution. The reactions are as follows ... 

It is also possible with sulphurous acid solutions, using methyl orange as indicator, to titrate with a standard solution of an alkali to the halfway bisulphite stage.6 If necessary the alkali hydrogen sulphite may then be estimated by the addition of mercuric chloride and further titration with alkali, as already described. By this double titration method it is possible to estimate sulphurous aeid in the presence of other sulphur acids.7... 

Other saline derivatives of sulphur dioxide are known corresponding with a hypothetical acid H2S205 for example, alkali metabisulphites or pyrosulphites of the composition M2S2Os are known, which may be considered as structurally derived from two molecules of the hydrogen sulphites MHS03 by elimination of one molecule of water. They are well-defined compounds obtained by crystallisation from aqueous solutions of the sulphites of the alkali metals in the presence of excess of sulphur dioxide.1... 

Foerster and Kubel, Zeitsch. anorg. Chern., 1924, 139, 261. For various physical properties of the alkali sulphites and hydrogen sulphites, see Lewis and Rivett, Trams. Chem.Soc., 1924,125,1156,1162 Foerster,BroscheandNorborg-Schulz,Zeitsch.physikal. Ghem., 1924, no, 435 Sabalitschka and Kubisch, Arch. Pham., 1924, 262, 105 Schiller and Wilhelm, Zeitsch. angew, Chem., 1919, 32, 198. 

Reinders and Vies, Bee. Tran, chim., 1925,44,249. For changes occurring in solutions of various hydrogen sulphites m the presence of selenium as catalyst, see Sandonnini, Atti B. Aecad, Idncei, 1923, [v.], 32, ii., 84. 

By the action of alkali hydrogen sulphites on alkali nitrites, compounds are obtained the structure of which may be derived from that of ortho-nitrous acid, N(OH)a, by substituting the sulphonic acid group, — S02-0H, for one or more hydroxyl groups. 

The acid sulphites possess the property of forming crystalline additive compounds with aldehydes and ketones. Sodium hydrogen sulphite is therefore largely used for the purification of compounds of these classes the sulphite adds on at the carbonyl group, >C O, forming the group-OH... 

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