28. Carbohydrates

Convert the following monosaccharide into its Fischer representation. Is it a D or L-isomer?

Convert the following monosaccharide into a bondline representation. 

Draw the following aldotetrose in the proper Fischer projection.

The relative configurations of the stereoisomers of tartaric acid were established by the following syntheses: (1) D-(+)-glyceraldehyde (with HCN) --> diastereomers A and B (separated) (2) Hydrolysis of A and B using aqueous Ba(OH)2 gave C and D, respectively. (3) HNO3 oxidation of C and D gave (-)-tartaric acid and meso-tartaric acid, respectively. (a) You know the absolute configuration of D-(+)-glyceraldehyde. Use Fischer projections to show the absolute configurations of products A, B, C, and D. (b) Show the absolute configurations of the three stereoisomers of tartaric acid: (+)-tartaric acid, (-)-tartaric acid, and meso-tartaric acid.