Question

From the given following (A to D) cyclic structures, those which will not react with Tollen's reagent are : 

• A. A and D
• B. B and C
• C. A and B
• D. B and D

Hint:

Check the anomeric carbon (the one bonded to two oxygens). If it has an -OH group (hemiacetal), it's a "reducing" sugar and will react with Tollen's.

Answer 1

The Correct Option is D

To determine which cyclic structures will not react with Tollen's reagent, we need to understand the basic principle behind the reaction. Tollen's reagent is used to test for aldehydes and α-hydroxy ketones. It forms a silver mirror when it reacts with these functional groups.

Let's analyze each structure:

1. Structure A: This structure contains a free hemiacetal group (an aldehyde in its cyclic form), which can react with Tollen's reagent.
2. Structure B: This structure has an OCH₃ group, indicating a methylated form where the hemiacetal hydroxyl group is replaced, preventing it from reacting with Tollen's reagent.
3. Structure C: This is a cyclic acetal, and due to the presence of a free hemiacetal group, it can react with Tollen's reagent.
4. Structure D: Similar to B, this structure does not have a free hemiacetal group or aldehyde group, and hence, it will not react with Tollen's reagent.

Based on this analysis, Structures B and D will not react with Tollen's reagent.

Therefore, the correct option is B and D