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Question #44953
The Question
An equimolar mixture containing each of D-Glucose, D-Mannose, D-Fructose, D-Galactose, L-Glucose, and D-Allose is treated with an excess of phenylhydrazine () in an acetate buffer at until all reactions are complete. Let be the total number of moles of phenylhydrazine consumed, be the total number of structurally distinct osazones formed, and be the total number of moles of aniline () produced as a byproduct. Calculate the value of .
Options
- A.
22
- B.
26
- C.
27
- D.
28
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
Epimerization vs Anomerization|Osazone Formation Logic|D-Glucose Anomeric Equilibrium
Why This Question Is Tricky
Common Mistakes
This question tests the 'epimeric convergence' principle in carbohydrate chemistry alongside rigorous reaction stoichiometry.
The primary trap is twofold: First, students often assume ketoses like fructose only consume 2 equivalents of phenylhydrazine, forgetting the oxidation of the C1 primary alcohol which consumes the 3rd equivalent and releases aniline.
Second, while students memorize that glucose, mannose, and fructose yield the same osazone, they frequently fail to apply the C3-C5 stereochemical preservation rule to C3 epimers (Allose) or enantiomers (L-Glucose), incorrectly assuming they might also converge or failing to recognize enantiomeric osazones as structurally distinct molecules.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Biomolecules - Class 12 |
| Concept | Epimerization vs Anomerization |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |