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Question #45099
The Question
Consider the following carbonyl compounds: I. \ce{CF3COCF3} II. Cyclohexanone III. Cyclopentanone IV. \ce{(CH3)3CCOC(CH3)3} Identify the correct decreasing order of the equilibrium constant () for their reaction with aqueous \ce{NaCN}/\ce{HCN} buffer at and 298 K to form cyanohydrins.
Options
- A.
I > II > III > IV
- B.
I > III > II > IV
- C.
II > I > III > IV
- D.
I > II > IV > III
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
Steric Hindrance (B-Strain)|Nucleophilic Addition Sterics|Esterification Reversibility
Why This Question Is Tricky
Common Mistakes
This problem tests the multidimensional factors governing nucleophilic addition equilibria.
Students typically rely solely on electronic effects or simple steric bulk.
The trap lies in differentiating between I-strain (internal strain) and B-strain (back-strain).
Students often incorrectly assume cyclopentanone is more reactive than cyclohexanone due to a smaller ring size, ignoring the torsional strain generated upon rehybridization.
Furthermore, the extreme B-strain in di-tert-butyl ketone demonstrates how geometric constraints can completely override electronic favorability, effectively prohibiting the reaction.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Organic Chemistry – Some Basic Principles and Techniques - Class 11 Part 2 |
| Concept | Steric Hindrance (B-Strain) |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |