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Question #45094
The Question
Consider the heterolytic cleavage of the \ce{C-Cl} bond (the rate-determining step) during the solvolysis of the following tertiary alkyl chlorides in 80% aqueous ethanol at 298 K: (I) 1-chloro-1-methylcyclopropane (II) 1-chloro-1-methylcyclobutane (III) 1-chloro-1-methylcyclopentane (IV) 1-chloro-1-methylcyclohexane
Which of the following represents the correct decreasing order of the activation energy () for this heterolytic bond cleavage?
Options
- A.
I > II > IV > III
- B.
I < II < III < IV
- C.
III > IV > II > I
- D.
IV > III > II > I
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
Bond Cleavage Energetics|Cycloalkane Ring Strain|Reaction Intermediates Stability
Why This Question Is Tricky
Common Mistakes
This question targets the common student heuristic that 'strained rings are always more reactive'.
While highly strained rings (like cyclopropane) are reactive towards ring-opening, they are exceptionally unreactive towards reactions requiring the formation of an endocyclic sp2 hybridized intermediate (like an SN1 carbocation).
The sp2 geometry demands a 120-degree bond angle, which massively exacerbates the angle strain of the small ring.
This phenomenon, governed by I-strain (Internal strain) theory, perfectly discriminates between thermodynamic ring strain and kinetic inhibition.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Organic Chemistry – Some Basic Principles and Techniques - Class 11 Part 2 |
| Concept | Bond Cleavage Energetics |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |