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

(A) Br₂ / FeBr₃

(B) Mg, dry Ether

(C) CO₂, H₃O⁺

(D) Methanol, Conc. H₂SO₄

Choose the correct answer from the options given below:

The correct option is (A), (B), (C) and (D).

To convert benzene into methyl benzoate, a multi-step synthetic pathway is required. Each of the given reagents plays a key role in a specific step of the overall transformation as described below:

Step 1: Bromination of Benzene
Benzene is reacted with bromine (${\mathrm{Br}}_2$) in the presence of iron(III) bromide (${\mathrm{FeBr}}_3$), which acts as a Lewis acid catalyst. This electrophilic aromatic substitution reaction yields bromobenzene.

$C_6{H}_6+{\mathrm{Br}}_2\stackrel{{\mathrm{FeBr}}_3}{\to }{C}_6{H}_5\mathrm{Br}+\mathrm{HBr}$

This step requires reagent (A) Br₂ / FeBr₃.

Step 2: Formation of the Grignard Reagent
Bromobenzene is treated with magnesium ($\mathrm{Mg}$) metal in the presence of dry ether. This insertion reaction forms phenylmagnesium bromide, which is a nucleophilic Grignard reagent.

$C_6{H}_5\mathrm{Br}+\mathrm{Mg}\stackrel{\text{dry ether}}{\to }{C}_6{H}_5\mathrm{MgBr}$

This step requires reagent (B) Mg, dry Ether.

Step 3: Carboxylation to form Benzoic Acid
The Grignard reagent is reacted with carbon dioxide (${\mathrm{CO}}_2$) to form a carboxylate salt intermediate. Subsequent acidic workup with hydronium ions ($H_3{O}^{+}$) protonates the intermediate to yield benzoic acid.

$C_6{H}_5\mathrm{MgBr}\underset{\text{2. acid hydrolysis}}{\overset{1.{\mathrm{CO}}_2}{\to }}{C}_6{H}_5\mathrm{COOH}$

This step requires reagents (C) CO₂, H₃O⁺.

Step 4: Fischer Esterification to form Methyl Benzoate
Finally, benzoic acid is reacted with methanol (${\mathrm{CH}}_3\mathrm{OH}$) in the presence of concentrated sulfuric acid ($H_2{\mathrm{SO}}_4$) acting as a catalyst and dehydrating agent. This esterification reaction yields the target compound, methyl benzoate.

$C_6{H}_5\mathrm{COOH}+{\mathrm{CH}}_3\mathrm{OH}\stackrel{\text{conc.}{H}_2{\mathrm{SO}}_4}{\rightleftharpoons }{C}_6{H}_5{\mathrm{COOCH}}_3+H_{2}O$

This step requires reagents (D) Methanol, Conc. H₂SO₄.

Thus, all four sets of reagents (A, B, C, and D) are required to complete the conversion sequence from Benzene to methyl benzoate.