Reducing sugars Reduction

Reduced viscosity Reducing bleaches Reducing sugars Reduction... 

The formation of a red precipitate of copper(I) oxide by reduction of Cu(II) is taken as a positive test for an aldehyde Carbohydrates that give positive tests with Benedict s reagent are termed reducing sugars... 

Emmerich Method. This method is for determination of trace amounts of reducing sugars in pure sucrose and white and refined sugars with reducing sugar content up to 0.15%. The test is carried out in a nitrogen atmosphere and is based on the reduction of 3,6-dinitrophthahc acid. 

Knight and Allen. This is a copper reduction method for reducing sugars in white sugar up to 0.02%. It utilizes EDTA to determine excess unreacted copper. Tests undertaken in 1994 to extend the range of this method were unsuccesshil. In spite of poor performance in ring tests, it remains an official ICUMSA method. 

Colorimetric Methods. Numerous colorimetric methods exist for the quantitative determination of carbohydrates as a group (8). Among the most popular of these is the phenol—sulfuric acid method of Dubois (9), which rehes on the color formed when a carbohydrate reacts with phenol in the presence of hot sulfuric acid. The test is sensitive for virtually all classes of carbohydrates. Colorimetric methods are usually employed when a very small concentration of carbohydrate is present, and are often used in clinical situations. The Somogyi method, of which there are many variations, rehes on the reduction of cupric sulfate to cuprous oxide and is appHcable to reducing sugars. 

Rearrangement reaction, 138 Reducing sugar, 992 Reduction, 229. 348 acid chlorides, 804 aldehydes, 609-610. 709 aldoses, 992 alkene, 229-232 alkyne, 268-270 amides, 815-816 arenediazonium salt, 943 aromatic compounds and, 579-580... 

In some instances, reducing sugars are present that can be reductively aminated without prior periodate treatment. A reducing end of a monosaccharide, a disaccharide, or a polysaccharide chain may be coupled to a diamine by reductive amination to yield an aminoalkyl derivative bound by a secondary amine linkage (Figure 1.96). Also see Section 4.6, this chapter, for an extensive discussion on carbohydrate modification techniques. 

BNAH may be coupled to reducing sugars without reduction, since the linkage formed between a hydrazide and an aldehyde is much more stable than that with an amine. 

A number of conditions are available for the reduction of the anomeric acetals to the reduced sugars. Among these are the combinations Et3SiH/BF3-OEt2/ TFA483 and Et3SiH/TMSOTf,503,504 although some isomerization is found to... 

Reduction of the aldehyde or ketone group in a sugar is readily achieved using a variety of reducing agents. Reduction occurs on the small amount of open-chain form present at equilibrium. As the open-chain form is removed, the equilibrium is disturbed until total reduction is achieved. The products are polyhydroxy compounds termed alditols. Reduction... 

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