Sugars oxidation-reduction reactions

The electron transfers in the oxidation-reduction reactions of organic compounds are not fundamentally different from those of inorganic species. In Chapter 7 we considered the oxidation of a reducing sugar (an aldehyde or ketone) by cupric ion (see Fig. 7-10a) ... 

As you know, oxidation-reduction reactions can involve molecules, ions, free atoms, or combinations of all three. To make it easier to discuss redox reactions without constantly specilying the kind of particle involved, chemists use the term species. In chemistry, a species is any kind of chemical unit involved in a process. For example, a solution of sugar in water contains two major species. In the equilibrium equation NH3 + H2O NH/ + OH , there are four species the two molecules NH3 and H2O and the two ions NH/ and OH. ... 

Oxidation-reduction reactions are among the most important in chemistry, biochemistry, and industry. Combustion of coal, natural gas, and gasoline for heat and power are redox reactions, as are the recovery of metals such as iron and aluminum from their oxide ores and the production of chemicals such as sulfuric acid from sulfur, air, and water. The human body metabolizes sugars through redox reactions to obtain energy the reaction products are liquid water and gaseous carbon dioxide. 

MUTAROTATION The a- and /T forms of monosaccharides are readily interconverted when dissolved in water. This spontaneous process, called mutarotation, produces an equilibrium mixture of a- and /1-forms in both furanose and pyranose ring structures. The proportion of each form differs with each sugar type. Glucose, for example, exists primarily as a mixture of a- (38%) and j8- (62%) pyranose forms (Figure 7.11). Fructose is predominantly found in the a-and /J-furanose forms. The open chain formed during mutarotation can participate in oxidation-reduction reactions. 

What are some oxidation-reduction reactions of sugars ... 

What are some oxidation-reduction reactions of sugars Monosaccharides can undergo various reactions. Oxidation reactions make up one important group. 

Nucleotides are monomers that link together to form polymers called nucleic acids deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Each nucleotide comprises a C5 sugar, a phosphate group, and a nitrogen base. Nucleotides are major constituents of the hereditary material and can act as energy currency (ATP) in cells. Some derivatives of nucleotides can function in oxidation-reduction reactions in the cell. 

Figure 3.8. Structures of vitamins or vitamin-derived molecules that function in oxidation-reduction reactions. The oxidation of these redox groups in the inner mitochondricil membrane contributes to the electron transport chain that carries electrons from the oxidation of glucose to oxygen and in the process pumps protons from one side to the other of the inner mitochondrial membrane (see Chapter 8 for details). The proton gradient thus formed is used to phosphorylate ADP to form 32 of the 36 ATPs resulting from the oxidation of one glucose molecule to six CO2 and six H2O molecules. A Vitamin B3, also called niacin or nicotinic acid, becomes converted to the amide (nicotinamide) and dressed up with a ribose sugar. Then, in a manner like that of riboflavin in B becomes phosphorylated to form nicotinamide mononucleotide (NMN) or further reacted with the addition of adenosine monophosphate (AMP) to form nicotinamide adenine dinucleotide (NAD). B Vitamin B2, also known as riboflavin, is shown converted to the forms involved in redox reactions such as those of the electron transport chain. (From Biochemistry, Second Edition, D. Voet and J. Voet, Copyright 1995, John Wiley Sons, New York. Reprinted with permission of John Wiley Sons, Inc.)...

Many important chemical reactions involve oxidation and reduction. Photosynthesis, which stores energy from the sun in plants by converting carbon dioxide and water to sugar, is a very important oxidation-reduction reaction. In fact, most reactions used for energy production are redox reactions. In humans, the oxidation of sugars, fats, and proteins provides the energy necessary for life. Combustion reactions, which provide... 

When a beaker of hot nitric acid is poured on ordinary sugar, a violent oxidation-reduction reaction occurs. 

Enediol forms of a-hydroxycarbonyl compounds react with a-dicarbonyl compounds with interconversion, in which a-hydroxycarbonyl compounds are transformed into a-dicarbonyl compounds and vice versa (Figure 4.66). The reaction explains a number of oxidation-reduction reactions that occur in degradation products of sugars and in the Maillard reaction. The transfer of two protons takes place within the complex of the a-dicarbonyl compound, with the endiol in either the basic energy singlet state or in the excited triplet state, through the more advantageous biradical mechanism. 

A tripeptide containing a sulphydryl group which has a role in maintaining the integrity of erythrocytes by virtue of it being an important regulator of oxidation-reduction reactions. It is known to interfere in some methods of blood sugar estimation. 

The formation of 2,3-dihydro-3,4-dihydroxy-5-acetyIfuran (48), a flavour component in baking, in the reaction between D-fructose and p-alanine has been reported." Anionic ruthenium iodocaibonyl complexes acted as dehydroxylation catalysts of C3 - Cs polyols and C sugars in aqueous solution, due to their bifunctional nature (acidity and hydrogenation ability). By exposure to [Ru(CO)3l3] in the presence of CO and Hj, glucose, fructose, and xylitol have been transformed to yvalerolactone (49), in up to 40% yield, via levulinic acid (fcumed well known acid-catalysed dehydration and internal oxidation-reduction reactions)."... 

Allcock, H, R., and Scopelianos, A. G., Sjmthesis of sugar-substituted cyclic and polymeric phosphazenes, and their oxidation, reduction, and acetylation reactions. Macromolecules. 36. 715, 1983. 

Grollmann U, Schnabel W (1980) On the kinetics of polymer degradation in solution, 9. Pulse radiolysis of polyethylene oxide). Makromol Chem 181 1215-1226 Hamer DH (1986) Metallothionein. In Richardson CC, Boyer PD, Dawid IB, Meister A (eds) Annual review of biochemistry. Annual Reviews, Palo Alto, pp 913-951 Held KD, Harrop HA, Michael BD (1985) Pulse radiolysis studies of the interactions of the sulfhydryl compound dithiothreitol and sugars. Radiat Res 103 171-185 Hilborn JW, PincockJA (1991) Rates of decarboxylation of acyloxy radicals formed in the photocleavage of substituted 1-naphthylmethyl alkanoates. J Am Chem Soc 113 2683-2686 Hiller K-O, Asmus K-D (1983) Formation and reduction reactions of a-amino radicals derived from methionine and its derivatives in aqueous solutions. J Phys Chem 87 3682-3688 Hiller K-O, Masloch B, Gobi M, Asmus K-D (1981) Mechanism of the OH radical induced oxidation of methionine in aqueous solution. J Am Chem Soc 103 2734-2743 Hoffman MZ, Hayon E (1972) One-electron reduction of the disulfide linkage in aqueous solution. Formation, protonation and decay kinetics of the RSSR radical. J Am Chem Soc 94 7950-7957... 

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