Reduction of monosaccharides

The carbonyl group of aldoses and ketoses can be reduced by various reagents. The products are polyols, called alditols. For example, catalytic hydrogenation or reduction with sodium borohydride (NaBH4) converts D-glucose to D-glucitol (also called sorbitol review Sec. 9.12). 

Reaction occurs by reduction of the small amount of aldehyde in equilibrium with the cyclic hemiacetal. As that aldehyde is reduced, the equilibrium shifts to the right, so that eventually all of the sugar is converted. Sorbitol is used commercially as a sweetener and sugar substitute. 

When the aldehyde group of an aldose Is oxidized, the product Is an aldonic acid. 

PROBLEM 16.9 o-Mannitol, which occurs naturally in olives, onions, and mushrooms, can be made by NaBH4 reduction of D-mannose. Draw its 

Benedict s reagent (blue) reacts with an aldose to give CU2O (red precipitate). 

Aldehyde and ketone groups in monosaccharides can be reduced by strong reducing agents. For example D-glucose can be reduced to D-glucitol (sorbitol) by NaBH4 or H2 in the presence of Pt. 

Write the reactions of D-ribulose (a ketopentose) with a. Tollens reagent b. NaBH4 

Condensation compounds derived by the elimination of a water molecule from two monosaccharide molecules are called disaccharides. The two monosaccharides are linked via an oxygen bridge. 

The aldol condensation is the reaction of two identical aldehydes or ketones in the presence of a base such as sodium carbonate, barium hydroxide or dilute sodium hydroxide. 

If sucrose is heated above its melting point it turns into caramel which is used in the production of candies. 

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Previously, the reduction of monosaccharide isocyanides by tributyltin hydride had been reported,105 107 and their chemistry has been discussed.108... 

Describes the procedure for reduction of monosaccharides using NaBHi in DMSO solution followed by acetylation using 1 -methylimidazole as the catalyst. 

Mechanism 23-2 Base-Catalyzed Epimerization of Glucose 1115 Mechanism 23-3 Base-Catalyzed Enediol Rearrangement 1115 23-9 Reduction of Monosaccharides 1116... 

Marmitol may be extracted from the dried sap of manna and other natural sources by means of hot alcohol or other selective solvents. It is commercially produced by the catalytic or electrolytic reduction of monosaccharides such as mannose and glucose. 

The success of the Kolbe electrosynthesis and the method of reduction of monosaccharides with sodium amalgam that was introduced by... 

Identify the products of oxidation or reduction of monosaccharides determine whether a carbohydrate is a reducing sugar. 

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