Carbonyl Compounds bisulphite with

The carbonyl compound may be mixed with an aqueous solution of sodium or potassium cyanide and mineral acid is added, or the bisulphite compound may be treated with an equivalent quantity of sodium cyanide, for example ... 

For a given carbonyl compound, K will be influenced by the size of the nucleophile thus the value of K for addition of the very bulky bisulphite anion (S2O320, p. 213) to (MeCH2)2C=0 is only 4 x 10-4, compared with K = 38 for addition of HCN (above) to the very similar ketone, MeCH2COMe. The value of K is also influenced by the nature of the atom in the nucleophile that attacks the carbonyl carbon atom, and of the bond that is thereby formed as is observed in the following sequence for reaction with the same carbonyl compound ... 

A condition of equilibrium is reached (70-90 per cent of bisulphite compound with equivalent quantities of the reagents in 1 hour), but by using a large excess of bisulphite almost complete conversion into the addition compound results. Since the reaction is reversible, the carbonyl compound can be recovered by adding to an aqueous solution of the bisulphite compound sufficient sodium carbonate solution or hydrochloric acid to react with the free sodium metabisulphite present in the equilibrium mixture. Bisulphite compounds may therefore be employed for the purification of carbonyl compounds or for their separation from other organic substances. 

A carbonyl compound (an aldehyde or a ketone) can be separated from its admixture with non-carbonyl compounds by shaking the mixture with a saturated solution of sodium bisulphite. This treatment yields a crystalline addition bisulphite derivative of the carbonyl compound ... 

The chemical concentration method can also be used outside the chromatographic scheme. For example [136], the exhaust gases from an automobile engine were passed through bubblers at the rate of 0.5-1.01/min, the total volume of the gas passed being 60—901. The bubblers contained 15 ml of a 15% solution of sodium bisulphite cooled with ice-water. The carbonyl compounds absorbed were isolated by treatment with sodium carbonate. The pairs formed on neutralization were trapped by diethyl ether and the test components were also extracted by diethyl ether from the aqueous solution during 3-4 h. 

Sulphonic acids are also the products formed on reaction of carbonyl compounds with hydrogen sulphite (bisulphite addition compounds)182,183. a-Amino sulphonic acids are produced, albeit in low yield, upon reaction of hydrogen sulphite ions with aldehydes, in the presence of ammonia184. 

Removal of a carbonyl confound. A compound containing a carbonyl group may be removed from a mixture by treatment of the latter (or an ethereal solution of it) with saturated sodium bisulphite solution. After vigorous shaking, the bisulphite addition product of the carbonyl compoimd, if predpitated, is removed by filtration and decomposed by distilling with an excess of sodium carbonate solution, when the carbonyl compound is recovered from the distillate, or if it is non-volatile, by ether extraction of the residue in the distilling flask. In the event of the bisulphite compound being water-soluble, the aqueous solution is treated with sodium carbonate solution and the carbonyl compound recovered as already described. 

The aromatic halogenated ketones, unlike those of the aliphatic series, are quite stable compounds. Another difference is that the aromatic derivatives, although they contain a carbonyl group, form no additive compounds with bisulphite. ... 

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