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Question #45105
The Question
Consider the reaction of 1-bromo-3,4-epoxy-2,2-dimethylbutane with one equivalent of sodium methoxide in methanol at elevated temperature: Identify the major product .
Options
- A.
2-(methoxymethyl)-3,3-dimethyloxetane
- B.
3,4-epoxy-1-methoxy-2,2-dimethylbutane
- C.
4-methoxy-3,3-dimethyltetrahydrofuran
- D.
4-bromo-1-methoxy-3,3-dimethylbutan-2-ol
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Exception_Exposure
Learn to identify edge cases and boundary exceptions that JEE examiners hide in math problems.
Concepts Behind This Question
Bond Angle and Strain|Williamson Ether Synthesis Constraints
Why This Question Is Tricky
Common Mistakes
The question tests the limits of the Williamson ether synthesis by pitting a primary alkyl halide against an epoxide.
Students typically memorize that primary halides are ideal for SN2.
However, the 'hidden variable' is the neopentyl-like steric hindrance of the primary bromide, which completely shuts down intermolecular SN2.
The 'chemical exception' is that the thermodynamic strain relief of the epoxide allows it to act as the superior electrophile.
Furthermore, students must resist the trap of forming the thermodynamically more stable 5-membered ring (THF), recognizing that basic epoxide opening is strictly under kinetic control (attack at the less hindered site), followed by a Thorpe-Ingold assisted oxetane formation.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Organic Chemistry – Some Basic Principles and Techniques - Class 11 Part 2 |
| Concept | Bond Angle and Strain |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |