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JEE Main · 2017 · 02 Apr 2017 · Offline · Biomolecules

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Which of the following compounds will behave as a reducing sugar in an aqueous KOH solution?
  1. (A)(see structure)
  2. (B)(see structure)
    ✓ Correct
  3. (C)(see structure)
  4. (D)(see structure)

Answer: (B)

Solution

A sugar reduces only if it can open to expose a free carbonyl. In warm alkali the structure able to ring-open and reveal a free aldehyde will act as a reducing sugar, whereas one locked at the anomeric carbon as a glycoside cannot open and stays non-reducing. The structure that can unmask a free aldehyde is the reducing sugar here.

JEE Main · 2017 · 02 Apr 2017 · Offline · Single correct option

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