Question

Compound A is a D-aldopentose that can be oxidized to an optically active aldaric acid B. On Kiliani-Fischer chain extension, A is converted into C and D; C can be oxidized to an optically inactive aldaric acid E, but D is oxidized to an optically active aldaric acid F.

What is the structure of compound C?

Use the wedge/hash bond tools to indicate stereochemistry.

You do not have to explicitly draw H atoms.

If a group is achiral, do not use wedged or hashed bonds on it.

Show stereochemistry in a meso compound.

Do not include lone pairs in your answer. They will not be considered in the grading.

Answer 1

Answer:

The molecule (A) is a 5-carbon carbohydrate (pentose) having an aldehyde group (aldopentose), this aldopentose is oxidized with nitric acid, and gives rise to a Aldaric acid (B) having optical activity .

Subsequently, the molecule (A) is subjected to chain extension, through synthesis Killiani-Fisher, producing a pair of "epimers"; they are not more than a couple of compounds derived from (A) and differing in the spatial orientation of a group (H-C-OH or HO-C-H ), producing compounds aldohexose type (C) and (D).

Finally the nitric acid oxidation of compounds (C) and (D) generate two aldaric acids, respectively (E) and (F), the Aldaric acid (E) is optically inactive and the Aldaric acid (F) is optically active .