Question

Major product B of the following reaction has ____ \(\pi\)-bond.

Answer 1

Correct Answer: 5

To determine the major product B and its number of π-bonds, we follow this reaction sequence:

1. Oxidation: The toluene (ethylbenzene) undergoes oxidation with KMnO₄ and KOH, transforming the ethyl group into a carboxyl group. The product A is benzoic acid.
2. Nitration: Benzoic acid is nitrated using HNO₃/H₂SO₄. This results in meta-nitrobenzoic acid as the major product B due to the electron-withdrawing nature of the carboxyl group directing the nitro group to the meta position.

Now, calculate the number of π-bonds in B:

• The benzene ring contributes 3 π-bonds.
• The carboxyl (-COOH) group has 1 π-bond (C=O).
• The nitro (-NO₂) group has 1 π-bond (one N=O bond counts as a π-bond).

Summing these gives a total of 5 π-bonds for B.

As required, the calculated value of 5 π-bonds matches the expected range (5,5).

Answer 2

Count the $\pi$-bonds:
Two $\pi$-bonds in the aromatic ring.
One $\pi$-bond in the carboxyl group.
Two $\pi$-bonds in the nitro group.
\[ \text{Total number of $\pi$-bonds} = 5. \]
Final Answer: \[ 5. \]