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Question #44836
The Question
An alkene, 3-(4-methoxyphenyl)-3-methyl-1-butene, is subjected to acid-catalyzed hydration using dilute at . Considering the kinetic and thermodynamic aspects of the reactive intermediates, identify the major product formed.
Options
- A.
3-(4-methoxyphenyl)-3-methylbutan-2-ol
- B.
2-(4-methoxyphenyl)-3-methylbutan-2-ol
- C.
3-(4-methoxyphenyl)-2-methylbutan-2-ol
- D.
2-(4-methoxyphenyl)-2-methylbutan-1-ol
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
Activation Energy Trap|Acid-Catalyzed Hydration Mechanism|SN1 Carbocation Rearrangement
Why This Question Is Tricky
Common Mistakes
This problem tests the 'Activation Energy Trap' in carbocation rearrangements.
Students typically predict rearrangements based solely on the thermodynamic stability of the resulting carbocation.
If they do, they will incorrectly choose the methyl shift (Option B) because it forms a highly stable benzylic carbocation.
The 'Chemical Exception' here is kinetic control via migratory aptitude: the electron-rich 4-methoxyphenyl group forms a bridged phenonium ion transition state, which drastically lowers the activation energy for its migration.
Thus, the kinetically favored aryl shift outcompetes the thermodynamically favored methyl shift.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Chemical Kinetics - Class 12 |
| Concept | Activation Energy Trap |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |