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Question #44646
The Question
Consider the reaction of 2-chloro-1-methoxy-4-methylbenzene with \ce{NaNH_2} in liquid \ce{NH_3} at 195 K. Identify the major organic product formed.
Options
- A.
2-methoxy-5-methylaniline
- B.
5-methoxy-2-methylaniline
- C.
3-methoxy-4-methylaniline
- D.
2-amino-5-methylphenol
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
Aryl Halide Resonance|Benzyne Intermediate (Elimination-Addition)|E2 Regioselectivity (Saytzeff vs Hoffmann)
Why This Question Is Tricky
Common Mistakes
The question tests the regioselectivity of nucleophilic addition to an asymmetric benzyne intermediate.
The primary trap is the misapplication of resonance (+M) effects.
Students often assume the strongly electron-donating -OMe group will destabilize an ortho-carbanion via resonance, leading them to predict attack at C2 (yielding the direct substitution product, Option A).
The 'Hidden Variable' is that the benzyne carbanion occupies an orbital orthogonal to the -system, rendering resonance impossible.
Regioselectivity is dictated purely by inductive effects.
The strong -I effect of the -OMe group stabilizes the C2 carbanion, directing the nucleophile to C3 and resulting in cine-substitution.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Haloalkanes and Haloarenes - Class 12 |
| Concept | Aryl Halide Resonance |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |