The intermediate compound ‘X’ in the following chemical reaction is :

The correct answer is Option A: C₆H₅CH(OCrOHCl₂)₂

Understanding the Reaction (Étard Reaction):

The reaction shown in the question image is the Étard Reaction. It depicts:
Toluene (C₆H₅CH₃) reacting with chromyl chloride (CrO₂Cl₂) in CS₂ (carbon disulfide) as solvent to form an intermediate X, which upon hydrolysis with H₃O⁺ yields benzaldehyde (C₆H₅CHO).

Step 1: What is the Étard Reaction?

The Étard reaction is a named organic reaction that involves the oxidation of a methyl group (−CH₃) directly attached to an aromatic ring to an aldehyde (−CHO) using chromyl chloride (CrO₂Cl₂) in an inert solvent like CS₂. This is a selective and controlled oxidation — it stops at the aldehyde stage and does not over-oxidise to a carboxylic acid.

Step 2: Mechanism — Formation of the Chromium Complex (Intermediate X)

When toluene reacts with CrO₂Cl₂ in CS₂, the chromyl chloride attacks the benzylic C−H bonds of the methyl group. Two equivalents of CrO₂Cl₂ insert into two of the three C−H bonds of the −CH₃ group. This forms a brown-coloured, insoluble chromium complex that precipitates out of the CS₂ solution.

The intermediate complex X has the structure:

C₆H₅CH(OCrOHCl₂)₂

In this complex, the original −CH₃ carbon now bears one hydrogen and is bonded to two −OCrOHCl₂ groups. Each chromium atom is bonded through an oxygen atom to the benzylic carbon, with a hydroxyl group and two chlorine atoms also attached to chromium.

Step 3: Hydrolysis of the Intermediate

When this chromium complex (X) is treated with H₃O⁺ (acidic hydrolysis), the Cr−O bonds are cleaved. The two −OCrOHCl₂ groups are removed, and the benzylic carbon, which was at the oxidation state of an aldehyde carbon in the complex, is released as benzaldehyde (C₆H₅CHO).

The overall transformation is:

C₆H₅CH₃ → [C₆H₅CH(OCrOHCl₂)₂] → C₆H₅CHO

Step 4: Why not the other options?

Option B — C₆H₅CH(OCOCH₃)₂ — This contains acetyl (−OCOCH₃) groups. There is no source of acetyl groups in this reaction (no acetic acid or acetic anhydride is used), so this is incorrect.

Option C — C₆H₅CHCl₂ (benzal chloride / benzylidene dichloride) — This would be the product of side-chain chlorination of toluene, not an intermediate in oxidation with CrO₂Cl₂. Also, hydrolysis of benzal chloride would give benzaldehyde, but this is not the actual intermediate formed in the Étard reaction mechanism.

Option D — C₆H₅CH₂Cl (benzyl chloride) — This is a mono-chlorinated product from free-radical side-chain chlorination. Hydrolysis of benzyl chloride gives benzyl alcohol (C₆H₅CH₂OH), not benzaldehyde. Hence, this is incorrect.

Conclusion: The intermediate X formed in the Étard reaction of toluene with CrO₂Cl₂ in CS₂ is the chromium complex C₆H₅CH(OCrOHCl₂)₂, which upon hydrolysis with H₃O⁺ gives benzaldehyde. This corresponds to Option A.