A D-aldotetrose on oxidation with concentrated \(HNO_3\) resulted in optically inactive dicarboxylic acid. The structure of the D-aldotetrose is:
The Correct Option is A
Solution and Explanation
Step 1: Understanding the Concept:
Oxidation of an aldose with concentrated \(HNO_3\) converts both the aldehyde (\(-CHO\)) and primary alcohol (\(-CH_2OH\)) groups into carboxylic acid groups (\(-COOH\)), forming a saccharic/aldaric acid. If the resulting diacid has a plane of symmetry, it is a meso compound and thus optically inactive.
Step 3: Detailed Explanation:
There are two D-aldotetroses: D-Erythrose and D-Threose.
- In D-Erythrose, both hydroxyl groups are on the same side in the Fischer projection. Oxidation produces meso-tartaric acid, which has a plane of symmetry and is optically inactive.
- In D-Threose, the hydroxyl groups are on opposite sides. Oxidation produces D-tartaric acid, which is chiral and optically active.
The question specifies an optically inactive product, which identifies the starting material as D-Erythrose.
Step 4: Final Answer:
The correct structure is D-Erythrose (both -OH groups on the right side).
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