Sugar reaction with concentrated sulfuric

Uronic acids were traditionally measured by the carbazole reaction. In this procedure, sugars were treated with concentrated sulfuric or hydrochloric acid to yield products that reacted with carbazole. For example, Dische (1947) used carbazole for the determination of uronic acid in solutions of sulfuric acid, but the method was subject to interference from neutral sugars that were also present in the solution. The... 

Phenomena. In the first step, one could clearly look at aggressive effects - the well-known phenomena of acidic and basic solutions. Concerning acids, one can demonstrate the spectacular reaction of concentrated sulfuric acid with sugar (see E7.1) or that of the behavior of acidic solutions with metals (see E7.2). One should discuss, in both cases, the statement that an acid is something which eats material away [5], and can demonstrate that other substances are produced by those acid reactions sulfuric acid and sugar produce black carbon and steam metals react to produce hydrogen and a salt solution, from which solid white salts may be obtained by the evaporation of water. In addition, acidic household cleaners like those that remove lime deposits could be introduced one could demonstrates that when lime deposit is removed by a cleaner solution, salt solution and carbon dioxide gas are produced (see E7.3). 

The total content of RNA + DNA in tissues may be estimated from the phosphorus content or by color reactions of the sugars.37 545 These reactions depend upon dehydration to furfural or deoxyfurfural by concentrated sulfuric acid or HC1 (Eq. 4-4). Furfural formed from RNA reacts with orcinol (3,5-dihydroxy-toluene) and ferric chloride to produce a green color useful in colorimetric estimation of RNA. A similar reaction of DNA with diphenylamine yields a blue color. 

An acid hydrolysis process using sulfuric, hydrochloric, nitric, or phosphoric acids cleaves the glycosidic bonds [6]. The a(l-3) and a(l-2) bonds being more labile, hydrolysis releases first L-arabinose residues. Then the bonds in the xylan chains and with other substituents are hydrolyzed. The reaction products are mainly monomeric sugars. Hydrolysis is performed between 80 and 150°C for reaction times between 300 min and 20 min, respectively, and with concentrations in wheat bran of up to 150 g/L. The amount of acid used is 0.1-0.5 mol/L. Yields of hydrolysis range from 70 to 95% in sugars released. 

Violent exothermic reaction can occur when concentrated sulfuric acid is mixed with acrylonitrile, picrates, bromine penta-fiuoride (Mellor 1956), and chlorine trifluoride. Reactions with caustic alkalies, amines, alcohols, aldehydes, epoxides, vinyl and ally compounds, cellulose, and sugar are vigorously exothermic. 

The M. show the following common reactions 1) copper, silver, and bismuth salts are reduced in solution. - 2) M. react with bases to form alcoholates, with concentrated alkali resinification occurs to furnish yellow and dark-colored products. - 3) No reaction occurs with hydrogen sulfite or fuchsin/sulfurous acid because the aldehyde group is masked. - 4) Reduction leads to multifunctional alcohols, e.g., hexitols. - 5) Oxidation gives rise to mono- and dicarboxylic acids (sugar acids). - 6) The alcohol groups can be esteri-fied. - 7) Addition of hydrogen cyanide occurs. - 8) Osazones are formed with phenylhydrazine. 

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