Which among the following compounds will react with NBS | CCl| hν?

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  1. F1 Priya Teaching 5 11 2024 D35
  2. F1 Priya Teaching 5 11 2024 D36
  3. F1 Priya Teaching 5 11 2024 D37
  4. F1 Priya Teaching 5 11 2024 D38

Answer (Detailed Solution Below)

Option 3 : F1 Priya Teaching 5 11 2024 D37
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CONCEPT:

Reaction of Organic Compounds with NBS in CCl4 under Light

  • NBS (N-Bromosuccinimide) in the presence of CCl4 and light (hv) is used to brominate allylic or benzylic positions in organic compounds.
  • An allylic position is a carbon atom adjacent to a carbon-carbon double bond (C=C), and a benzylic position is a carbon atom adjacent to an aromatic ring (like benzene).
  • The reaction occurs because the allylic or benzylic hydrogen is easily abstracted, allowing for the formation of a stable radical, which then reacts with Br2 generated from NBS to form the brominated product.

EXPLANATION:

F1 Priya Teaching 5 11 2024 D39

  • Compound 1: No allylic or benzylic hydrogen is present, so it does not react with NBS.
  • Compound 2: Contains a benzylic hydrogen due to the phenyl group, making it reactive with NBS.
  • Compound 3: Contains both a benzylic and an allylic hydrogen, making it highly reactive with NBS.
  • Compound 4: Does not have an allylic or benzylic position, so it does not react with NBS.

The correct answer is Compound 3, as it has both benzylic and allylic positions available for bromination with NBS | CCl4 | hv.

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