Which of the following reagent(s) is required for the conversion of Benzene to methyl benzoate?

(A) $Br_2/FeBr_3$
(B) Mg, dry Ether
(C) $CO_2, H_3O^+$
(D) Methanol, Conc. $H_2SO_4$

Choose the correct answer from the options given below:

(A), (B), (C) and (D)

The correct answer is Option (3) → (A), (B), (C) and (D)

Step-by-Step Conversion Pathway

Step 1: Bromination (Reagent A)

Benzene reacts with $\text{Br}_2 / \text{FeBr}_3$ via electrophilic aromatic substitution to form bromobenzene. $\text{FeBr}_3$ acts as a Lewis acid catalyst to generate the $\text{Br}^+$ electrophile.

$\text{C}_6\text{H}_6 + \text{Br}_2 \overset{{\text{FeBr}_3}}{\longrightarrow} \text{C}_6\text{H}_5\text{Br} + \text{HBr}$

Step 2: Grignard Reagent Formation (Reagent B)

Bromobenzene is treated with $\text{Mg}$ in dry ether to form phenylmagnesium bromide, a powerful nucleophile. Dry ether is essential to stabilize the Grignard reagent and prevent it from reacting with moisture.

$\text{C}_6\text{H}_5\text{Br} + \text{Mg} \overset{\text{dry ether}}{\longrightarrow} \text{C}_6\text{H}_5\text{MgBr}$

Step 3: Carboxylation (Reagent C)

The Grignard reagent reacts with $\text{CO}_2$ (often as dry ice), followed by acidic hydrolysis ($\text{H}_3\text{O}^+$), to produce benzoic acid. The nucleophilic carbon of the Grignard reagent attacks the electrophilic carbon of $\text{CO}_2$.

$\text{C}_6\text{H}_5\text{MgBr} + \text{CO}_2 \to \text{C}_6\text{H}_5\text{COOMgBr} \overset{\text{H}_3\text{O}^+}{\longrightarrow} \text{C}_6\text{H}_5\text{COOH}$

Step 4: Esterification (Reagent D)

Finally, benzoic acid is reacted with methanol ($\text{CH}_3\text{OH}$) in the presence of concentrated $\text{H}_2\text{SO}_4$ (catalyst) to undergo Fischer esterification, yielding methyl benzoate.

$\text{C}_6\text{H}_5\text{COOH} + \text{CH}_3\text{OH} \overset{\text{H}^+}{\longrightarrow} \text{C}_6\text{H}_5\text{COOCH}_3 + \text{H}_2\text{O}$

Summary of Reagents

Since all four steps are necessary to complete the conversion from the starting material (benzene) to the final product (methyl benzoate), all four reagent sets are required.

The correct answer is: (A), (B), (C) and (D)