Question

D-Glucose does not react with which of the following reagents?
I- $\text{NaHSO}_3$
II- $\text{NH}_2\text{OH}$
III- $(\text{CH}_3\text{CO})_2\text{O}$
IV- Schiff's reagent

• A. II, III only
• B. I, II, III only
• C. I, II only
• D. I, IV only

Hint:

The absence of reaction with $\text{NaHSO}_3$ and Schiff's reagent was the main historical reason for proposing the cyclic structure of glucose over the open-chain structure.

Answer 1

The Correct Option is D

Step 1: Remember what form glucose actually exists in.
D-glucose sits almost entirely as its cyclic hemiacetal form in solution, with only a tiny trace of the open-chain aldehyde form present at any moment.
Step 2: Check the reagents that don't need much free aldehyde.
Hydroxylamine ($\text{NH}_2\text{OH}$) reacts fast enough to pull the equilibrium open and form the oxime, and acetic anhydride simply acetylates the many -OH groups present, neither needs a large standing pool of open aldehyde, so both react fine.
Step 3: Check the two that do need a decent aldehyde concentration.
Sodium bisulfite addition and Schiff's reagent both require enough free -CHO to actually engage, and glucose's vanishingly small open-chain fraction isn't enough for either to give a visible reaction.
Final answer: Option 4, I and IV only.