Bisulfite addition products, effect

The 7-iodoaminochromes also form addition products with sodium bisulfite, although formation of these adducts usually appears to be accompanied by some deiodination, with the consequent formation of the corresponding deiodinated complexes.155 The 7-iodonor-adrenochrome-sodium bisulfite addition product has been reported to be more stable in this respect (i.e. it shows less tendency to deiodinate) than the corresponding 7-iodoadrenochrome adduct.119 Although it has not proved possible to demonstrate effectively the presence of both the 7-iodoaminochrome complex and the corres-... 

In the preparation of a-keto acids from 2-phenyloxazolones, benzoic acid must be separated from the product. This separation has been effected by saturating the reaction mixture with sulfur dioxide, which forms a bisulfite addition product with the keto acid. Benzoic acid is then removed by filtration or extraction, and the keto acid is subsequently regenerated. These operations are avoided by the use of 2-methyloxazolones, with the added advantage that the 2-methyl... 

Addition of a nucleophile to the C-6 position of cytosine often results in fascile displacement reactions occurring at the N4 location. With hydroxylamine attack, nucleophilic displacement causes the formation of an N4-hydroxy derivative. A particularly important reaction for bioconjugate chemistry, however, is that of nucleophilic bisulfite addition to the C-6 position. Sulfonation of cytosine can lead to two distinct reaction products. At acid pH wherein the N-3 nitrogen is protonated, bisulfite reaction results in the 6-sulfonate product followed by spontaneous hydrolysis. Raising the pH to alkaline conditions causes effective formation of uracil. If bisulfite addition is done in the presence of a nucleophile, such as a primary amine or hydrazide compound, then transamination at the N4 position can take place instead of hydrolysis (Fig. 38). This is an important mechanism for adding spacer arm functionalities and other small molecules to cytosine-containing oligonucleotides (see Chapter 17, Section 2.1). 

Sulfoalkylated naphthol compounds are effective as dispersants in aqueous cement slurries. The compounds can also be applied in an admixture with water-soluble inorganic compounds of chromium to provide additives of increased overall effectiveness. Particularly suitable are sodium chromate or ammonium dichromate. a-Naphthol is reacted in an alkaline aqueous medium with formaldehyde to create condensation products. The aldehyde can be reacted with bisulfite to produce sulfoalkylated products [1404,1410]. 

A major difficulty in any examination of the literature in this field is the extreme variation in reaction conditions used by various workers. As mentioned previously, Kerp s data lacked significance in some respects by reason of their antedating general acceptance of the pH concept. In addition, his solutions were apparently no stronger than 1-molar (and were usually much more dilute than this) and usually the sugar-to-sulfite ratios were 1 1. In work with food products a ratio of this sort is quite unusual. It becomes necessary, therefore, because of the specifically different effects introduced by structures more or less peculiar to the saccharides, to give separate attention to the effects of various factors on K for the sugar bisulfite compounds. 

Alkali Salts of Sulfurous Acid The ease with which they could be used either in the dry form or as solutions has long made the alkali sulfites and bisulfites particularly attractive in sulfiting a wide variety of products. Potassium metabisulfite has long been used in wine making for disinfection, control of fermentation, and preservation. Stability, freedom from heavy metal and arsenic impurities, and cost are the chief factors that determine selection of salts. In addition their possible effect in reducing... 

Molybdenum-deficient animals are especially susceptible to the toxic effects of bisulfite, which is both a food additive and a product of the metabolism of sulfur-containing amino acids. Bisulfite toxicity is characterized by breathing difficulties and neurological disorders. 

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