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Question #44631
The Question
Consider the following alkyl bromides subjected to the Finkelstein reaction (treatment with in dry acetone at ): (I) 1-Bromobutane (II) 2-Bromobutane (III) 1-Bromo-2,2-dimethylpropane (IV) 1-Bromobicyclo[2.2.1]heptane
Identify the correct decreasing order of their initial rates of reaction.
Options
- A.
I > II > III > IV
- B.
I > III > II > IV
- C.
III > I > II > 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
Finkelstein and Swarts Exchange|Steric Hindrance in SN2|SN2 Stereochemical Inversion
Why This Question Is Tricky
Common Mistakes
The question tests the 'Chemical Exception' where students blindly correlate 'primary alkyl halide' with 'fast SN2'.
The trap lies in (III) neopentyl bromide, which despite being primary, is highly sterically hindered at the beta-carbon, making its SN2 transition state higher in energy than a typical secondary halide.
Furthermore, (IV) tests the geometric constraints of the SN2 mechanism; bridgehead carbons cannot undergo inversion or permit backside attack, rendering them completely inert to SN2 regardless of conditions.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Haloalkanes and Haloarenes - Class 12 |
| Concept | Finkelstein and Swarts Exchange |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |