Question

Which of the following reactions of glucose can be explained only by its cyclic structure?

• A. Glucose forms pentaacetate
• B. Glucose reacts with hydroxylamine to form an oxime.
• C. Pentaacetate of glucose does not react with hydroxylamine.
• D. Glucose is oxidised by nitric acid to gluconic acid.

Answer 1

Answer: (C)

Hydroxyl amine particularly reacts with free carbonyl group to form oxime. In case of glucose there is no response to hydroxyl amine. This conforms that glucose carbonyl part forms an acetal in cyclic form.
In other cases like forming of pentaacetate and its oxidation to gluconic acid there is no confirmation of cyclic structure.