Chem2O6 - 1997/98

Problem Set #15 March 27, 1998

1. A) Draw the Fischer projections for the four aldotetroses

    B) Show which are the D-monosaccharides

    C) Which are enantiomers?

2 Mannose in aqueous solution exists as a mixture of -D-mannopyranose and -D-mannopyranose.

   Draw Haworth projections of each of these molecules.

3. D-Fructose when dissolved in water exists as an equilibrium mixture of -D-fructopyranose (3%), -D-fructopyranose (57%), -D-fructofuranose (9%), -D-fructofuranose (31%), and D-fructose (0.01%).

A)  Draw a Fischer projection of D-fructose.

B)  Draw chair type structures for the two pyranoses, clearly showing the stereochemistry.

C)  Draw stereodiagrams of the two furanoses, again clearly showing their stereochemistry.

D)  Write a mechanism for the interconversion of -D-fructopyranose and -D-fructofuranose in water. Assume the reaction is acid catalysed.

4. Also tackle some of the problems on amines given in Ege Chapter 22.

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27 mar 98; jp