Answer to Question #181984 in Organic Chemistry for Amani Ismail

Question

Different enantiomers are metabolised differently by the body. The monosaccharide below has been patented proposed as a low-calorie sweetener. Do a D and L assignment for the enantiomer below, explain your assignment and how this would affect the calorific value of the rhamnose isomer. Provide an explanation for the following:

1.    Would the monosaccharides below more likely adopt a pyranose or furanose?

2.    Is the sugar considered a reducing sugar?

3.    Would the optical rotation of the enantiomer below change in the solution?

Answer 1

1.Pyranose since the pyranose ring is formed by the reaction of the hydroxyl group on carbon 5 (C-5) of a sugar with the aldehyde at carbon 1. This forms an intramolecular hemiacetal.

2. Yes since it is oxidised by mild oxidising agents.

3.No.