Greenriverose is a fake disaccharide composed of a β-D-tagatose and an α-D-allose (in that order) via a β-2,2 glycosidic bond (though tagatose will be on “bottom” of the resulting disaccharide).
a). Look up the Fisher structures of D-tagatose and D-allose online. Draw their Fischer projections and Haworth structures below. For the Haworth structures, draw them in the configuration stated in the problem above.
b). Draw the structure of greenriverose
c). Is this disaccharide a reducing sugar? Explain your answer. Include references to the terms mutarotation, anomeric carbons, and oxidation in the explanation.
d). A sample of greenriverose was subjected to acid-catalyzed hydrolysis. What tests from this lab could be used to distinguish among greenriverose, and the two monosaccharides produced from the hydrolysis reaction? Explain your answer in a sentence or two and then predict the results of the test for each sugar in the table below.
|Sugar||Iodine Test result (+ / -)||Benedict’s Test (+ / -)||Barfoed’s Test (+ / -)||Seliwanoff Test (+ / -)|
e). If both lactose and Greenriverose were two of the unknown carbohydrates in this lab, would you have been able to tell the difference between the samples based on their test results? Explain your yes/no answer in a sentence or two using your responses to parts a, b, c, & d of this question.