The correct sequence of correct reagents for the following transformation is :
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In multi-step aromatic synthesis, the order of reactions is crucial. Consider the directing effects of the substituents. It's often easier to introduce an ortho, para-director first, or convert a meta-director (like -NO$_2$) into an ortho, para-director (like -NH$_2$) early in the sequence.
We need to convert nitrobenzene to 2-chlorophenol. This is a multi-step synthesis. Let's analyze the sequence of reactions. The target molecule has an -OH group and a -Cl group ortho to each other. Both are ortho, para-directing groups. The starting material has a -NO$_2$ group, which is a meta-directing deactivator.
Let's evaluate the sequence in option (B):
(i) Fe, HCl: This reagent is used for the reduction of the nitro group (-NO$_2$) to an amino group (-NH$_2$).
Nitrobenzene $\xrightarrow{\text{Fe, HCl}}$ Aniline.
This is a correct and standard first step. Aniline's -NH$_2$ group is an ortho, para-director.
(ii) NaNO$_2$, HCl, 0$^\circ$C: This is the reagent for diazotization of a primary aromatic amine.
Aniline $\xrightarrow{\text{NaNO}_2\text{, HCl, 0}^\circ\text{C}}$ Benzenediazonium chloride (C$_6$H$_5$N$_2^+$Cl$^-$).
This step is also correct.
(iii) H$_2$O/H$^+$ (warming): This step is the hydrolysis of the diazonium salt to form a phenol.
Benzenediazonium chloride $\xrightarrow{\text{H}_2\text{O, warm}}$ Phenol.
This is a standard method for preparing phenols.
(iv) Cl$_2$, FeCl$_3$: This is for the electrophilic aromatic substitution (chlorination) of phenol. The -OH group in phenol is a strongly activating ortho, para-director. The reaction will produce a mixture of the ortho-product (2-chlorophenol) and the para-product (4-chlorophenol).
Phenol $\xrightarrow{\text{Cl}_2\text{, FeCl}_3}$ 2-chlorophenol + 4-chlorophenol.
Since 2-chlorophenol is one of the products, this sequence is a valid pathway to synthesize the target molecule. The other options lead to different isomers (like meta) or involve incorrect reaction sequences.
