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Question #44645

Difficulty: 8/10 | 🟢 Free

The Question

An aromatic compound $\textbf{X}$ , 1-bromo-4-(tert-butyl)benzene, is subjected to the following reaction sequence: \begin{enumerate} \item $\ce{HNO3}$ (conc.) / $\ce{H2SO4}$ (conc.), $298\text{ K} \rightarrow \textbf{P}$ (Major product) \item $\ce{Sn / HCl}$ , $\Delta$ ; then $\ce{NaOH (aq)} \rightarrow \textbf{Q}$ \item $\ce{NaNO2 / HCl}$ , $273-278\text{ K} \rightarrow \textbf{R}$ \item $\ce{CuCN / KCN}$ , $\Delta \rightarrow \textbf{S}$ \end{enumerate} Identify the major product $\textbf{S}$ .

Options

A.
2-Bromo-5-(tert-butyl)benzonitrile
B.
5-Bromo-2-(tert-butyl)benzonitrile
C.
4-Bromobenzonitrile
D.
4-(tert-butyl)benzonitrile

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

Aryl Halide Resonance|Electrophilic Substitution Control|Steric Hindrance in SN2

Why This Question Is Tricky

Common Mistakes

This problem tests the 'Steric Override in Electrophilic Aromatic Substitution'.

Students often blindly apply the rule that activating groups (like alkyls) control regioselectivity over deactivating groups (like halogens).

The trap is failing to recognize the massive steric bulk of the tert-butyl group, which makes the transition state for ortho-attack kinetically inaccessible.

Thus, substitution occurs ortho to the less sterically demanding bromine atom.

The subsequent steps test standard aromatic functional group transformations (Reduction, Diazotization, Sandmeyer reaction) to reveal the final regiochemistry.

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