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Question #44014
The Question
An aqueous solution of D-glucose is treated with an excess of 2,4-dinitrophenylhydrazine (2,4-DNP) in a mildly acidic buffer () and heated to . What is the major organic product isolated from this reaction?
Options
- A.
D-Glucose-2,4-dinitrophenylhydrazone
- B.
D-Glucose-2,4-dinitrophenylosazone
- C.
2,4-Dinitrophenyl--D-glucopyranoside
- D.
D-Mannose-2,4-dinitrophenylhydrazone
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Mechanism_Trap
Don't get tricked by the process! Learn the mechanical traps used in competitive exam questions.
Concepts Behind This Question
Reaction with DNP|Osazone Formation Logic|Reducing Sugar Criteria
Why This Question Is Tricky
Common Mistakes
Students often memorize the heuristic 'reducing sugars + excess hydrazine derivative = osazone' based on the classic phenylhydrazine test.
This question traps students who fail to consider the mechanistic requirements for osazone formation.
The hidden variable is the electronic effect of the 2,4-dinitro substitution: the strong electron-withdrawing nature of the nitro groups prevents the crucial tautomerization (Amadori rearrangement) step, stopping the reaction at the mono-hydrazone stage despite the presence of excess reagent and heat.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Aldehydes, Ketones, and Carboxylic Acids - Class 12 |
| Concept | Reaction with DNP |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |