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Question #44360
The Question
Consider the following reaction sequence:
\ce{2-Bromoanisole ->[NaNH2][liq. NH3, 240 K] \textbf{A} (Major)}
\ce{\textbf{A} ->[NaNO2, HCl][273-278 K] \textbf{B}}
\ce{\textbf{B} ->[Phenol, NaOH][pH 9-10, 273-278 K] \textbf{C} (Major)}
Identify the IUPAC name of the major product \textbf{C}.
Options
- A.
4-[(3-methoxyphenyl)diazenyl]phenol
- B.
4-[(2-methoxyphenyl)diazenyl]phenol
- C.
2-[(3-methoxyphenyl)diazenyl]phenol
- D.
4-[(4-methoxyphenyl)diazenyl]phenol
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
Benzyne Intermediate (Elimination-Addition)|Electrophilic Substitution Control|Azo Coupling Regioselectivity
Why This Question Is Tricky
Common Mistakes
This problem tests the regioselectivity of nucleophilic addition to a benzyne intermediate.
A common trap is assuming a standard mechanism, which would incorrectly yield the ortho-substituted product (Option B).
Students must recognize that the carbanion formed during benzyne addition resides in an orbital orthogonal to the aromatic -system; thus, the +M resonance effect of the methoxy group is irrelevant, and regiocontrol is strictly governed by its -I effect.
The subsequent azo coupling tests standard electrophilic aromatic substitution regioselectivity under specific pH conditions.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Haloalkanes and Haloarenes - Class 12 |
| Concept | Benzyne Intermediate (Elimination-Addition) |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |