Cyanohydrin Reaction

Osazone Reaction

Phenyl hydrazine is a mild oxidizing agent which reacts with the aldehyde group of glucose to form osazone, a bridge yellow crystalline substance. It is a specific test of identification of sugars.

Furfurals

Concentrated mineral acids cause dehydration of monosaccharides to form furfural compounds which give a coloured product when treated with phenol. However, sugars are stable to dilute acids.

Enolization

Dilute alkali brings about a rearrangement of sugars at the anomeric carbon and the one next to it even at room temperature. These are isomerization reactions. For example, D – glucose on treatment with dilute alkali forms an equilibrium mixture of D-glucose on , D – mannose and D – fructose through formation of enediol intermediates.