Identify compound X in the following sequence of reactions:Toluene (C₆H₅–CH₃) → (Cl₂ / hν) → X → (H₂

Q: What is NEET?

NEET is a competitive examination conducted in India. This question is from the 2020 NEET Chemistry paper.

Q: How can I prepare for NEET Chemistry?

To prepare for NEET Chemistry, practice previous year questions (PYQs), understand concepts thoroughly, and solve mock tests regularly. This 2020 question covers Organic Chemistry - Some Basic Principles and Techniques topic.

Q: What is the difficulty level of this question?

This NEET 2020 Chemistry question has a medium difficulty level and is marked as an important question.

Q: Where can I find more NEET previous year questions?

You can find more NEET previous year questions on AspirantMitraa. Browse by subject, topic, year, and difficulty level to practice effectively.

Question

Identify compound X in the following sequence of reactions:Toluene (C₆H₅–CH₃) → (Cl₂ / hν) → X → (H₂O, 373 K) → Benzaldehyde (C₆H₅–CHO)

Accepted Answer

Correct Answer: B — C₆H₅–CHCl₂ (Benzal chloride)Step-by-step Solution:Chlorination of toluene in the presence of light (free radical mechanism) at the side chain gives:With one Cl₂: C₆H₅–CH₂Cl (benzyl chloride)With two Cl₂ (controlled conditions): C₆H₅–CHCl₂ (benzal chloride)Hydrolysis of benzal chloride (gem-dichloride) with hot water at 373 K gives benzaldehyde:C₆H₅–CHCl₂ + H₂O → C₆H₅–CHO + 2HClThis is because the geminal diol intermediate (C₆H₅–CH(OH)₂) spontaneously loses water to give the aldehyde.Why other options are incorrect:Option A (benzyl chloride, C₆H₅–CH₂Cl): hydrolysis gives benzyl alcohol (C₆H₅–CH₂OH), not benzaldehyde. Option C (benzotrichloride, C₆H₅–CCl₃): hydrolysis gives benzoic acid (C₆H₅–COOH), not benzaldehyde. Option D (dichlorobenzene) is a ring-chlorinated product formed under different conditions (Lewis acid catalyst) and does not give benzaldehyde on hydrolysis.Key Concept: Side-chain chlorination of toluene follows free radical mechanism. Mono-, di-, tri-chlorination gives benzyl chloride, benzal chloride, benzotrichloride respectively. Hydrolysis: benzal chloride → benzaldehyde; benzotrichloride → benzoic acid.

Identify compound X in the following sequence of reactions:Toluene (C₆H₅–CH₃) → (Cl₂ / hν) → X → (H₂O, 373 K) → Benzaldehyde (C₆H₅–CHO)

Master NEET with Our Test Series

More Questions from Organic Chemistry - Some Basic Principles and Techniques

Frequently Asked Questions

Identify compound X in the following sequence of reactions:Toluene (C₆H₅–CH₃) → (Cl₂ / hν) → X → (H₂O, 373 K) → Benzaldehyde (C₆H₅–CHO)

Master NEET with Our Test Series

More Questions from Organic Chemistry - Some Basic Principles and Techniques

Frequently Asked Questions