Aldehydes bisulfite compounds

Solid sodium metabisulfite (200 g.) is added to 81 g. of 37% aqueous formaldehyde solution with cooling to form an aqueous solution of the aldehyde bisulfite compound. After no more heat is evolved from... 

Nitriles from aldehyde-bisulfite compounds CH(OH)S03H —CH2CN Synthesis with addition of 1 C-atom... 

A large number of oc-amino sulfonic acids have been prepared from the hydrogen sulfite adducts ( -hydroxy sulfonic acids) and ammonia or amines at or slightly above room temperature. 976They are very important intermediates in the Knoevenagel-Bucherer form of the Strecker amino acid synthesis (cf. page 877). In this synthesis the aldehyde-bisulfite compounds are converted by ammonia or amines into a-amino sulfonic acids and thence by alkali cyanide or hydrogen cyanide into oc-amino nitriles, which are then hydrolysed ... 

However, reaction of aldehyde bisulfite compounds is more widely applicable for preparation of 1-amino-1-alkanesulfonic acids.76... 

In general the reaction of nitroalkanes with aldehydes can be carried out by one of three processes 125 (1) Just sufficient alkali may be added to provide a sufficiently rapid reaction without dehydration or polymerization the reaction is slow and with the more complex reactants yields are also much lowered. (2) An equimolar amount of 10N-sodium hydroxide solution may be added at not more than 10°, but this method gives good yields only with nitromethane and straight-chain aldehydes and it fails with secondary nitroalkanes. (3) A solution of the aldehyde bisulfite compound may be treated with a warm solution of the sodium salt of the nitroalkane, primary nitro compounds then giving 70-80% yields. 

Stewart, T. D., and Donnally, L. H. 1932a. The aldehyde bisulfite compounds. I. The rate of dissociation of benzaldehyde sodium bisulfite as measured by its first order reaction with iodine. J. Am. Chem. Soc. 64, 2333. 

On reaction of formaldehyde solution, sodium bisulfite, and ammonia at 1Q-7TYC an arnino derivative of the aldehyde bisulfite compound is produced. On cooling and acidifying, the parent acid crystallizes from the reaction mixture b Backer and Mulder haA e showm that this product is aminomethanesulfonic acid (NHaCHjSOgH) and not a sulfurous ester, as was fiii st supposed. This evidence ser es as an additional check on the bisulfite compound structure. The formation of sodium aminomethane sulfonate is indicated in the following equation ... 

Benzyl alcohol, 23, 14 BeNZYLAMINE, a-METHYL-, 23, 68 Benzyl carbamate, 23, 14 Benzyl chloride, 21, 99 Benzyl chloroeormate, 23, 13 Benzyl cyanide, 23, 71 Bisulfite compound, use for purification of an aldehyde, 23, 78 use for purification of a ketone, 23, 79 Blood, defibrinated, 21, 53 Booster pump, use of, for hydrogenation, 23, 69... 

The products are useful for two reasons. They are usually crystalline and so can be used to purify liquid aldehydes by recrystallization. This is of value only because this reaction, like several you have met in this chapter, is reversible. The bisulfite compounds are made by mixing the aldehyde or ketone with saturated aqueous sodium bisulfite in an ice bath, shaking, and crystallizing. After purification the bisulfite addition compound can be hydrolysed back to the aldehyde in dilute aqueous acid or base. 

The reversibility of the reaction makes bisulfite compounds useful intermediates in the synthesis of oilier adducts from aldehydes and ketones. For example, one practical method for making cyanohydrins involves bisulfite compounds. The famous practical book Vogel3 suggests reacting acetone first with sodium bisulfite and then with sodium cyanide to give a good yield (70%) of the cyanohydrin. 

The second reason that bisulfite compounds are useful is that they are soluble in water. Some small (that is, low molecular weight) aldehydes and ketones are water-soluble—acetone is an example. But most larger (more than four or so carbon atoms) aldehydes and ketones are not. This does not usually matter to most chemists as we often want to carry out reactions in organic solvents rather than water. But it can matter to medicinal chemists, who make compounds that need to be compatible with biological systems. And in one case, the solubility of bisulfite adduct in water is literally vital. 

The solution is to make a bisulfite compound from it. You may ask how this is possible since dapsone has no aldehyde or ketone—just two amino groups and a sulfone. The trick is to use the formaldehyde bisulfite compound and exchange the OH group for one of the amino groups in dapsone. 

Bisulfite addition products are readily formed at wine pHs (1, 23, 24). The bisulfite addition product is thought to be a more sensory-neutral compound and may be exploited by winemakers as a means of decreasing the aldehydic character of wines (1). Bisulfite addition has also been used to mask the stale flavor of beer which is thought to be largely due to the formation of trans-l-noneml (25). Kaneda et al. (25) used HPLC with fluorescent detection of an o-phthalaldehyde derivative to quantitate and identify individual aldehyde-bisulfite products, however, only acetaldehyde-bisulfite adducts were observed in commercial beers with this method. Hydrolysis of the adducts occurs at pHs greater than 8, therefore by adjusting the pH prior to analysis, total aldehydes (free plus bisulfite bound) can be estimated. At low pHs accurate estimation of free aldehydes is complicated however, by analysis conditions which alter the equilibrium between bound and free forms (temperature, dilution, solvent extraction, analysis time, etc.). 

Aromatic aldehydes react with sodium hydrogen sulfite to yield bisulfite compounds. Further reaction with sodium cyanide forms the hydroxynitrile (cyanohydrin), which can sometimes be formed directly from the aldehyde by reaction with hydrogen cyanide (Scheme 6.11). 

Quite often, the bisulfite product is isolated and purified before the treatment with alkali cyanide, particularly in the conversion of aromatic aldehydes since their bisulfite compounds are easily manipulated. The preparation of aromatic cyanohydrins from their bisulfite products is advantageous since benzoin formation, which is catalyzed by alkali cyanides, is largely avoided. Furthermore, because of the basic environment, hydrogen cyanide fumes are curtailed. 

An elegant method for the gentle and selective oxidation of aldehydes to carboxylic acids is the oxidation of the aldehyde-bisulfite addition compound by dimethyl sulfoxide. Depending on the workup of the reaction mixture, the acid, its ester, or its amide can be prepared at room temperature (equation 353) [773]. 

Finally, several equilibrium and kinetic properties of aldehyde-bisulfite adducts were found to be linearly related Taft s a parameter (Betterton et al.t 1988). These compounds, which include a-hydroxymethane sulfonate and other a-hydroxyalkyl sulfonates, may be important reservoirs of S(IV) species inj clouds, fog, and rain. Fairly good relationships were found between equilibrium properties (e.g. acidity constants) and Sir values, but rates constants for) nucleophilic addition of S03 to the aldehydes showed only a crude fit, Similarly, poor results were found in applying a to hydrolysis reactions of] volatile alkyl chlorides (T. Vogel, University of Michigan, personal communh cation, 1989), and this has been shown to be a general characteristic of reactioni of alkyl halides with nucleophiles (Okamoto et al., 1967). 

Bisulfite derivatives are used in the purification of aldehydes. A solution of the impure aldehyde is converted into its solid bisulfite compound, which is separated by filtration and so freed from impurities. Hydrolysis then liberates the purified aldehyde. 

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