After a series of Kiliani-Fischer syntheses on (+)-glyceraldehyde, an unknown sugar is isolated from the reaction mixture. The following experimental information is obtained:
(1) Molecular formula C6H12O6.
(2) Undergoes mutarotation.
(3) Reacts with bromine water to give an aldonic acid.
(4) Reacts with phenylhydrazine to give an osazone, mp 178 °C.
(5) Reacts with HNO3 to give an optically active aldaric acid.
(6) Ruff degradation followed by HNO3 oxidation gives an optically inactive aldaric acid.
(7) Two Ruff degradations followed by HNO3 oxidation give meso-tartaric acid.
(8) Formation of the methyl glycoside (using CH3OH and HCl), followed by periodic acid oxidation, gives a mixture of products that includes (+)-glyceraldehyde.
(a) Draw a Fischer projection for the open-chain form of this unknown sugar. Use Figure 23-3 to name the sugar.
(b) Draw the most stable conformation of the most stable cyclic hemiacetal form of this sugar, and give the structure a complete systematic name.