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Question #44607
The Question
An organic chemist attempts to synthesize the ether 2-methoxy-2,3-dimethylbutane using two different Williamson ether synthesis pathways:
Pathway P: Reaction of 2-chloro-2,3-dimethylbutane with in at . Pathway Q: Reaction of sodium 2,3-dimethyl-2-butoxide with in DMF at .
Which of the following correctly identifies the major organic products formed in Pathway P and Pathway Q, respectively?
Options
- A.
P: 2-methoxy-2,3-dimethylbutane ; Q: 2-methoxy-2,3-dimethylbutane
- B.
P: 2,3-dimethyl-2-butene ; Q: 2-methoxy-2,3-dimethylbutane
- C.
P: 2,3-dimethyl-1-butene ; Q: 2-methoxy-2,3-dimethylbutane
- D.
P: 2,3-dimethyl-2-butene ; Q: 2,3-dimethyl-2-butene
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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
C-X Bond Polarization and Polarizability|Williamson Ether Synthesis Constraints|Steric Hindrance in SN2
Why This Question Is Tricky
Common Mistakes
This question tests the 'Steric Hindrance in SN2' exception within the Williamson Ether Synthesis.
Students often fall into the trap of assuming that the strong inductive polarization of the C-X bond in tertiary halides makes them highly susceptible to nucleophilic attack.
However, they ignore the kinetic barrier: the steric congestion in the 5-coordinate transition state completely blocks the SN2 pathway.
When a strong base (alkoxide) is present, the reaction shifts entirely to E2 elimination.
The problem also tests the strategic workaround (Pathway Q), demonstrating that reversing the roles—using a bulky alkoxide with a methyl halide—bypasses the steric trap because methyl halides cannot undergo elimination and offer no steric resistance.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Haloalkanes and Haloarenes - Class 12 |
| Concept | C-X Bond Polarization and Polarizability |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |