Procedures 10. Examine the crystals under low power objective
Results and Discussions The reaction is stepwise;
Osazone formation involves hydrazone formation at C-1 of an aldose (or C-2 of a ketose) and oxidation of C-2 (or C-1) of an alcohol group to a ketone (or an aldehyde). The new carbonyl group is also converted to a hydrazone. Fructose Mannose Glucose
Osazone crystals have a characteristic shape under the light microscope and help in the identification of the sugar type. Disaccharides - like Lactose - like tight balls Monosaccharides - like sunflowers of needles needle-shaped or broomstick
Making Osazone Crystals The difference in the structure of the monosaccharides is caused by the diverse groups attached to the first and second carbons of the sugar molecules. Their needle-shaped crystals show that the position of the first and second carbons do not matter in the crystal formation.
Time to Form The time needed to create osazone crystals varies among the various sugars involved, but helps to identify the sugars being tested. For an osazone crystal to be presented from a hot solution will take as long as follows: fructose, two minutes; Actual Time: glucose, four to five minutes; Xylose – 20 mins xylose, seven minutes; Galactose – 25 mins galactose, 15-19 minutes; Glucose – 30 mins maltose, osazone soluble in hot Sucrose – 47 mins water Fructose – 57 mins Maltose – 59 mins
Application For identifying sugars esp. Reducing sugars. Osazones are used as dyes