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Question #44510
The Question
Consider the acid-catalyzed dehydration of 1-(1-methylcyclobutyl)ethan-1-ol using concentrated at . Which of the following represents the major organic product formed?
Options
- A.
1-ethenyl-1-methylcyclobutane
- B.
1-isopropylcyclobut-1-ene
- C.
1,5-dimethylcyclopent-1-ene
- D.
1,2-dimethylcyclopent-1-ene
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
Cycloalkane Ring Strain|E1/E2 Solvent and Base Effects|Reaction Intermediates Stability
Why This Question Is Tricky
Common Mistakes
This question tests the interplay between kinetic carbocation rearrangements and thermodynamic ring strain relief (Baeyer strain) in E1 eliminations.
Students often fall into the trap of applying Zaitsev's rule directly to the initial secondary carbocation (predicting 1-ethenyl-1-methylcyclobutane) or executing a simple methyl shift to form a tertiary carbocation without relieving ring strain (predicting 1-isopropylcyclobut-1-ene).
The critical 'hidden variable' is that ring expansion from a 4-membered to a 5-membered ring releases significant angle strain, making it the dominant pathway.
Once the 5-membered tertiary carbocation is formed, standard Zaitsev regioselectivity applies to yield the tetrasubstituted alkene.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Hydrocarbons - Class 11 Part 2 |
| Concept | Cycloalkane Ring Strain |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |