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JEE Main · 2021 · 24 Feb 2021 · Shift 1 · Haloalkanes and Haloarenes

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The product formed in the first step of the reaction of



with excess is :
  1. (A)(see structure)
  2. (B)(see structure)
  3. (C)(see structure)
    ✓ Correct
  4. (D)(see structure)

Answer: (C)

Solution

When a dibromide reacts with excess magnesium in dry ether (), a Grignard reagent is formed at each bromine site. In the first step, one of the bromine atoms is replaced by to form a Grignard reagent.

For the given compound (2,4-dibromopentane), the first step involves the formation of a Grignard reagent at one of the bromine positions while the other bromine remains unreacted initially.

The product of the first step is:

This corresponds to option (3), which shows the structure with one group and one group still attached to the carbon chain.

JEE Main · 2021 · 24 Feb 2021 · Shift 1 · Single correct option

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