Question Details

The major product of the following reaction is


Options

A

B

C

D

Show Answer

Correct Answer :

Option A

Option 1

Solution :

The correct option is Option 1.

Step-by-Step Explanation:

1. Analysis of the Reactant and Reagents:
The starting material shown in the image (image_0.webp) is 4-oxo-4-phenylbutanenitrile:
C6H5-CO-CH2-CH2-CN
This compound contains two distinct electrophilic functional groups:
(a) A ketone group (-CO-) adjacent to the phenyl ring.
(b) A nitrile group (-CN) at the terminal position.

The reaction utilizes excess methylmagnesium bromide (CH3MgBr), which is a strong nucleophile (source of CH3-).

2. Reaction at the Ketone Carbonyl Group:
Ketones are highly electrophilic and react readily with Grignard reagents. One equivalent of CH3MgBr attacks the ketone carbonyl carbon:
C6H5-CO-CH2-CH2-CN+CH3MgBrC6H5-C(OMgBr)(CH3)-CH2-CH2-CN

3. Reaction at the Nitrile Group:
Because the Grignard reagent is in excess, a second equivalent reacts with the nitrile group (-CN). The nucleophilic methyl group attacks the cyano carbon, forming an imine magnesium salt:
C6H5-C(OMgBr)(CH3)-CH2-CH2-C(=NMgBr)CH3

4. Acidic Hydrolysis:
Upon adding aqueous acid (H3O+):
• The magnesium alkoxide intermediate is protonated to form a tertiary alcohol (-OH).
• The imine magnesium salt is hydrolyzed to yield a methyl ketone (-COCH3).
C6H5-C(OH)(CH3)-CH2-CH2-CO-CH3

This matches the structure shown in Option 1 (image_1.webp).

Unlock Our Free Library

Access expert-curated educational resources and study materials—completely free.

Discover more resources

You may also like

Mock Tests

View All
  • JEE
  • intermediate
  • 3 hours
  • chemistry, mathematics, physics
  • Proctored

  • JEE
  • intermediate
  • 3 hours
  • chemistry, mathematics, physics

Ask AI Tutor
5 left
Q1 View Question & Options
AI Tutor is solving this question...
Reading question context & options...