Question:
Why does fructose reduce Fehling's solution?
Why does fructose reduce Fehling's solution?
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Fructose is a ketose, yet it reduces Fehling's solution because of a special group next to its ketone.
Updated On: Nov 12, 2026
- Due to the presence of hydroxy group.
- Due to the presence of aldehydic group
- Due to the presence of ketonic group.
- Due to the presence of alpha-hydroxy ketonic group
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The Correct Option is D
Solution and Explanation
Step 1: Understanding the Concept
Ordinary ketones do not reduce Fehling's solution. Fructose does because it has an alpha-hydroxy ketone unit, \(-\text{CO-CH}_{2}\text{OH}\).
Step 2: Why it works
In the alkaline reagent, the alpha-hydroxy ketone tautomerises through an enediol to aldoses such as glucose and mannose. These aldoses reduce \(\text{Cu}^{2+}\) to red \(\text{Cu}_{2}\text{O}\).
Step 3: Compare the options
Fructose has no aldehyde group, so (B) is wrong. A simple ketone or hydroxy group alone would not do it. The reason is the alpha-hydroxy ketonic group.
Final Answer:
Fructose reduces Fehling's solution due to its alpha-hydroxy ketonic group. \[ \boxed{\text{(D) }\text{Due to the presence of alpha-hydroxy ketonic group}} \]
Ordinary ketones do not reduce Fehling's solution. Fructose does because it has an alpha-hydroxy ketone unit, \(-\text{CO-CH}_{2}\text{OH}\).
Step 2: Why it works
In the alkaline reagent, the alpha-hydroxy ketone tautomerises through an enediol to aldoses such as glucose and mannose. These aldoses reduce \(\text{Cu}^{2+}\) to red \(\text{Cu}_{2}\text{O}\).
Step 3: Compare the options
Fructose has no aldehyde group, so (B) is wrong. A simple ketone or hydroxy group alone would not do it. The reason is the alpha-hydroxy ketonic group.
Final Answer:
Fructose reduces Fehling's solution due to its alpha-hydroxy ketonic group. \[ \boxed{\text{(D) }\text{Due to the presence of alpha-hydroxy ketonic group}} \]
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